350 tbi idle rpm problems

Last UpdatedMarch 5, 2024

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There is a Torx screw on the Re: high idle with tbi 350 08-26-06 05:07 PM - Post# 989948 In response to bowtie-badboy As for Bowtie-badboy's problem, if he rebuilt the TBI unit and soaked the IAC in carburetor cleaner, or sprayed carb cleaner on it while holding the plunger pointing up, the IAC is most likely damaged from the cleaning. It stumbles as if it's missing a couple of cylinders when you accelerate. 050-inch tappet lift with 0. For surging idle on a TBI I would start with a thorough check for vacuum leaks, especially at the throttle shaft and at the base of the throttle body. Throttle body injection. One thing I learned about speed-density systems (TBI or TPI), is that you cannot adjust the TPS. Runs great and has under 100k kilometres on it, but at idle it bogs down to a near stall before returning to normal idle speed. It's always when I'm half throttle at cruising speeds it will surge 2-300 rpms and it's annoying as fuck. The distributor I bought new and is less then two years old. turn ignition switch off for ten seconds 3 . I know it is a tbi motor but it almost acts like it needs a carb float adjustment! You have to pat the accelerator in 2nd gear to keep it from bucking like a wild horse. I just put new heads on my 5. 16 VSS - Vehicle Speed Sensor Signal Loss. Engine serial number 0M033393. « Reply #5 on: February 19, 2017, 09:21:45 AM ». #1 · Oct 31, 2010. but it runs great when accelerating or about Apr 14, 2024 · 5. When it gets to operating temperature and the idle drops more it is more noticeable. 5L rough idle, sputter, almost stall. Alright, i had posted before about my surging idle. I'm seeming to have quite a bit of trouble adjusting my timing/ idle speed. Reconnect IAC valve. Nov 28, 2011 · 350 sbc bogs and sputters at moderate acceleration. Coolant temp Feb 5, 2011 · The engine seemed to run fine while driving. Start the engine and allow it to idle, disconnect the vacuum hose from the EGR valve and connect a hand pump. « Reply #2 on: September 28, 2019, 07:45:30 PM ». 4. This was quite bothersome descending hills in low range/first. Jul 16, 2015 · OBS Enthusiast. Wait a moment, turn truck back on. I am at my wits end with this problem. I’ve had a previous thread and it went all over the place, I’m here now because my problem is back and I never got a fix. I am using a Auto Ray EZ scan 5000. it surges at idle and at a steady rpm cant figure it out. When I rev up the engine, either in neutral or under load, the engine works fine. 7 TBI This is a very easy fix to possibly remedy your idle problem. 1994 GMC K1500, 350 engine. The throttle body gasket had broken and was letting in too much air caus Sep 25, 2019 · Re: Pulsing/Erratic Idle Issues. I have a 87 Chevy R1500 w/ 350 TBI. There are various actions you can take to attempt and fix the problem if your TBI-equipped car exhibits idle surge and stumble. It fires right back up very easily. Once the engine gets to around 110-120 the rough idle/RPM hunting behavior begins. It ran ok, but was in need of a tune-up. You are now going to adjust "minimum air". Setting the correct idle speed is bike specific (from 1700-2200 RPM) and there is a recommended RPM quoted in the manual. First I start with a new Fuel pump, STOCK 75lph TBI fuel pump will only support about 230hp before the fuel pressure drops like a rock. My mechanic put it on a mechanical guage. It's my first GMC ever . Jun 15, 2004 · 1. Aug 3, 2010 · 5. I followed the idle adjustment procedure (Jump "A" and "B" on ASDL, turn key on, wait 30 seconds, diconnect the IAC harness, fire motor and adjust throttle plate for May 5, 2008 · General Specs: Mid 80's 350 with Early mid 80's TPI system (Not TBI) 700R4, 373 posi, 2500 stall. Voltage should be less than 1. 7L 350 TBI Surging/Sputtering/Missing. Don't drive it until it's plenty warm. 7 with minor bolt-ons: Throttle body spacer, injector spacer, Ultimate mods, aftermarket coil, fresh tune up (spark plugs/plug wires Mar 9, 2019 · The LT1 B-body cams work great with no tuning in the TBI engines. It does have allot of miles on it (275,000) but for the most part it runs like a clock. As mentioned above, if it's "backfiring" through the throttle body, odds are you're running lean causing lean pops. SYSTEM. If the intake gaskets, base plate gaskets, or Oct 30, 2005 · Aug 16, 2021. 1. Mileage down from 13avg to around 8. Apr 4, 2022 · 5 posts · Joined 2022. I got the heads done with 16 new valves and the hole works. Lets start with the high idle. I've replaced the fuel filter. 398/0. I had not tools or experience to tell me this. As it warms up, pressure drops to 6-8 lbs. There should be a grounding lug on the box. #1 · Aug 17, 2002. Jun 21, 2021 · If you don't have a OBD2 set air screw to 4 turns out then adjust idle screw to OEM spec if you have a gauge or by ear. if i unplug tps is mellows out but still there i have a dynamic efi computer that i use tuner pro to tune it with. Sometimes, the truck idles in park at 800-900 RPM and is able to adjust the idle to the load of the AC being turned on. I had 10-11 psi and replaced with a acdelco pump and got 13 and problem went away. 3 ElCamino has recently had its original motor rebuilt. - New fuel pump and fuel filter. 12 Diagnostic Checking for operation of CEL bulb. Jun 27, 2011 · 1. 5 turns out. Measure the vacuum level in the intake system with a Jun 13, 2024 · If the resistance is outside that range, the idle control motor needs to be replaced. 3 V6 Auto 2WD. I have a 1994 GMC Sierra 4x4 with the 5. I tow my jeeps with a 88 suburban with 350 TBI, 700R4. I don't think that applies to an 89 TBI. I am having a terrible time with getting it to idle smooth. I run 93 octane exclusively. It's a 350 TBI. - 2 1/2 X 10 air filter. Ive searched and looked over most stuff mentioned but I wanted a better opinion. Go to ALDL plug close to hood release, jump ports A and B, turn key to "on" (not crank) Wait maybe 10 seconds for IAC plunger to full extend. The known issue is that the exhaust manifold gasket leaks horrendously, which melts the front left plug wire. I am idling rich with occassional idle variations an occassional, almost imperceptible stumble during idle right now on my 350 tbi. At cold start-up, it reads 40 lbs. Jul 17, 2008 · Remove the paper clip, start engine and turn up the base idle at the throttle plates using a T20 screwdriver on the curb idle screw next to the throttle cable, maybe 500-600 rpm. Without the shroud, at idle and low speed where the fan is intended to work for you, the airflow across the fins is only in-front of the fan reducing the Jul 9, 2017 · I guess I should post a final conclusion just in case someone else has a similar problem. To recap for my Chevy 350 dying at idle. 1 2. Gray wire should be 5 volts. Apr 15, 2018 · Wait 10 seconds and then unplug the IAC. Jumper the A & B connections on the diagnostic link with a paper clip or what not. FYI, New distribtor, Idle Air Control Motor, and EGR. 3. Sep 21, 2008. If this truck has the electronic transmission like a 4l60e or 4l80e the faulty coolant or tps reading will definitely affect the transmission. Mar 25, 2023 · A rough idle in a 1994 Chevy 1500 350 fixed using basic tools! If the video was helpful to you be sure to like and help out the channel, thanks! Feb 7, 2017 · Re: 87 idle surging/stalling issues. Poor idle can be caused by about a hundred different things. Twist and pull the vacuum off of the bottom of the air cleaner and lay the air cleaner aside. You may have a vacuum leak. 5 volts at WOT. Jun 2, 2008 · This weekend I put a new idle air control valve and o2 sensor in, and the symptoms still persist. 2. Remove air cleaner, adapter and gaskets. 7/23/18 9:06 a. Gasket gets sucked into the intake manifold, resulting in an extremely lean condition which the computer interprets as needing more fuel to correct the mixture. The confusing part is this- there seems to be no rhyme or reason as to the low idle. I was towing two jeeps on a long car trailer in the Mts and blew a head gasket. Timing at 0 degrees BTDC in bypass, but around 8 degrees at idle under control of the ESC. bd, I adjusted the idle as follows: Let the engine warm up to full operating temperature. Feb 2, 2007 · It works independent of your throttle blade, meaning your throttle blade may appear closed against the idle stop, as the engine is racing. Use the throttle screw to obtain the “125 rpm less” idle Dec 26, 2007 · 1,430. It goes open loop, then the EGR and AIR Injection solenoids are on, idle mixture is actually rich (based on odor). Here's a list of what I've done so far. A higher idle RPM can reduce stalling and the sensation of closed Jul 23, 2018 · Need Help with My '93 Chevy K3500 - 454 TBI problems. Engine Size. Idle surge or idle hunting and high idle. Next on the list is to replace the throttle body gasket along with the distributor cap and rotor. Start engine and bring it to normal operating temperatures (85-100 degrees Celsius). 7 L truck and after an oil pressure problem got Jul 15, 2005 · Sep 14, 2008. I just bought a 2020 TE250i and the idle was low. Cold start idle to warm is fine and truck idles around 650/700 Jun 24, 2019 · After trying several other fixes I finally diagnosed and repaired the problem part. 4-Start engine, and let it settle into idle speed. THIS I May 31, 2023 · The timing specs for a chevy 350 tbi are 0 degrees btdc at idle with the electronic spark control unplugged and 10-16 degrees btdc at idle with the electronic spark control connected. No power loss or hesitation. You can check this by backing the red knob out (unscrewing) so that the bike will not idle. The IAC also supplies more air to compensate for the extra load when the A/C is on. 7 Mercruiser EFI Stern Drive, Bravo III. Mine will run rough on warm up. Basicly, I have limited power, off idle stumble, and a slight pop out of the exhaust when shifting. #4. 15 Coolant Sensor Circuit Excessive Low temperature indicated. Jan 8, 2021 · This cam is designed specifically for the TBI 350 small-block and specs at 194/214 degrees of duration at 0. here's a link to th Nov 25, 2016 · Code 15 means the coolant temp sensor is reporting the temp is stuck at -40*. This usually causes an extremely rich mixture or flooding and no starts. Adjust idle to around 600RPM. Base idle, Extended IAC no ECM control, would be 500-650 rpm. Use the command in the scan tool to increase the engine’s idle. Turn key off. While the idle speed is fluctuating my voltage drops dramatically. I have a little update. 3 to 5. It is a 1991 motor using the painless harness. #1 · Apr 1, 2008. Check controlled idle speed and perform idle air control system check first. Jul 24, 2016 · 1995 K1500 5. Now, go remove the connector from the IAC. 5 to 5. The problem I'm having is intermittently, 1-2 days a Not necessarily. Buttery ignition voltage is supplied to the light bulb. Feb 12, 2011 · Running very rich, down on power. New MAP, EGR, O2, TPS, ESC, distributor and coil. I've been procrastinating fixing this Jul 28, 2021 · 3) disconnect the throttle cable from the tbi unit while diagnosing issues (removes this from possible issues) 4) the target warm idle is 650rpm in the ECU, on starting it may idle at around 1-1. Trouble starting after it sits for awhile do to not getting fuel right away. ECM controlled idle should be 750-900 rpm. It doesn't effect anything other than the idle. Sep 19, 2005 · My dads '89 Suburban has 80,000 mile on engine and we did a 3" lift, 4. Typically 2 problems. if it is still 2000rpm, you probably have a large vacuum leak or the min air screw (t15 or t20 set screw on front of TBI on driver side Aug 6, 2014 · Another cause of "sudden" high-idle scenarios on Gen1 4. The IAC (and computer) is what gives the engine a “fast idle” speed when started cold. You must perform a IAC relearn after removing. Logged. It runs fine but I can't get the idle to drop. You'll hear the IAC screw resetting. It's basically a controlled vacuum leak. Start engine. Voltage. So, the truck is a 92 k1500, has 20,000 miles on the new GM crate 350, new throttle body, rebuild trans about same time eng was put in. It can drive ok sometimes with marginal fuel pressure as you tend to use more throttle than you would normally to get to speed. #1 · Apr 4, 2022. when I put it in gear it bogs down and will sometimes stall then the idle comes up a little bit and Feb 6, 2009 · This 1986 4. I did have to patch the old lines into the new lines at the pump. then unplug the harness connector to IAC so it will stay closed. Sometimes idles perfect, other times it will lope till it dies like a Nov 22, 2001 · Adjusting the screw on the throttle body will only change the minimum air flow. The gasket is notorious for failing. If the idle does not change or changes very little replace the EGR valve. 8 V at 4000 to 5000 ft. UnPlug IAC, Turn key to "off". 2 to 4. Turned the key switch to "ON". . start engine and verify proper engine speed ( should be about 450-475 for automatic trans slightly higher for manual ) i hope this helps you . Manifold Pressure/Vacuum Sensor Specifications, Electrical: Voltage Values. 030 over on the bore. 7 TBI motor. I just replaced the Idle Air Control valve because i was told that could be it. TBI being a MAP sensor based system will see the leak just like opening the throttle blades and will feed the leak and then you have a high idle. In gear it bogs slightly and feels like i put a bigger cam in it. Fire up the engine and using the idle adjustment screw somewhere on the throttle body, adjust the idle to where you want it. 92 Silverado. it sputters and bogs when it gets under load in gears. Idle control valve/motor may not be working properly. - All rubber fuel lines. #1 · Dec 31, 2010. Turned the engine off. Indicating. Feb 3, 2007 · I've spent countless hours trying to troubleshoot my 89 350TBI engine in my 240,000 mile otherwise incredibly dependable Suburban The engine runs like crap, ECM says code 44 - lean condition. Jun 9, 2019 · Truck Year. Dec 15, 2009 · TBI Intermittent High Idle Problem. Jun 20, 2020 · It's a 89 k1500 5. Replaced: Distributor, Fuel pump, TPS, IAC, ignition coil, ESC, knock sensor, coolant temp sensor, O2 sensor, MAP sensor, ECM (reman). Mar 1, 2017 · Help Boosted 350 tbi surging problem. 1 V6. These are attached to the bottom of the air cleaner. Apr 11, 2011 · Re: 87 Silverado 350 tbi idling rough. Aug 12, 2019 · These idle issues are sometimes hard to diagnose. The ECM sets this. Jul 23, 2008 · SBC 350 Vacuum Advance/ Idle issues. Disconnected spark advance and started up. Along with the erratic idle, the engine has absolutely zero power. try a tap test on the ECM and see if it changes anything. Once it does it fires no problem and idles very nice in park and neutral. Apply vacuum with the pump, the engine should run roughly or stall. 7L tbi 350 Will Not Idle/Stalls. Apr 4, 2011 · 1993 Chevy K1500 5. With key on, slowly open throttle while observing meter reading. The engine is a tbi from heads up but has an older block. System is going lean, and after 20-30 seconds of running lean, then goes into open loop forever. The symptons are: When I start the engine from cold, I allow the engine to warm up at idle. Unknown member Discussion starter. It has a hard time with ANY load (even the A/C compressor). I recommend upgrading to the 1996 Vortec 155lph fuel pump which can support up to 450hp and plugs right into a factory TBI sending unit. More and more lately after startup the engine will idle erradically and bounce from 500-900 rpm and once in a while it dies. It will go from about 14 on the volt meter Oct 3, 2011 · The carb is a Edelbrock Performer I bought new, is less then two years old and has never given me any problems. 041 volts at 10 seconds. 6 to 5. The truck still shifts at the normal rpm and drives at normal rpm. The next day it wouldn't even start unless you used starting fluild or poured gas down the throttle body. Once its done, turn off ign and plug the IAC back in. At idle in park, the engine revs up Jan 28, 2004 · Claremont, CA. I don't see any vaccum lines disconnected. If I accelerate really slowly then I can get it up to speed. TurboS10 is right about the TPS resetting. Trouble Code. New engine about 5-6 years ago. Aug 17, 2002 · G. The IAC (and computer) control the idle speed. Just finished a 350 TBI / 700R4 / 3. its a 1990 chevy k1500 with a 350 tbi engine. Jun 15, 2010 · The shroud is there for idle and low speed cooling when the fan isn't being turned very fast. I believe idle is supposed to be 525 in D on a warmed up engine. This will apply mostly to 1987-1998 vehicles with Throttle Body Inje Jun 8, 2022 · Neither of these fixed the problem. a little history on the engine i built its a 1987-1995 Chevy Idle Air Valve replacement to fix Idle issues on the 5. Adjust the idle speed and Air/fuel slightly to were i'm idling around 850 in park/neutral and idling at 650 in gear. 0 V at 3000 to 4000 ft. It runs great, slight surge sometimes at idle and like I said when cruising. jumper AB on ALDL for about 30sec to force IAC closed. May 23, 2019 · 89 Suburban R1500, 79 C10. Done. I have had consistently high idle since I bought the truck in may. Nov 24, 2001 · Hey guys, I am a Newbie (atleast post wise) from the jeep tech board. Turn engine "OFF". It is not consistent in that sometimes it is worse than at others. Reinstall air cleaner and remove the paper clip from the ALDL connector. "Any time there is a high idle on a TBI or other fuel injection setup, there is too much air getting into the motor. 7 hesitation problem. Mar 29, 2023 · No it did not. I got the ODB and it’s really erratic. Step 1. - Replaced the TBI base gasket. Hi guys, I've been having a problem with my truck for quite some time now. RECOMMENDED 350 TBI MODS. This vacuum leak can be at the IAC valve. The throttle body also sticks after you open it up all the way. 7 TBI. I pull and plug the vac advance line, set the timing to 12 BTDC. if it is bogging and idling low, I'd suspect the leaking injector may actually be a big part of the issue. The mallory HEI is less then 2 years old and so are the spark plug wires. If it doesn't come down, it may be suspect. When idling, a distinctive stumble is heard and throttle response is not that great. Use a bidirectional scan tool to increase idle speed in a Chrysler. Turn off engine and disconnect the negative battery terminal from the battery. #1. Nov 8, 2009 · Recently bought a used 92 Sub with 5. volvoclearinghouse UberDork. Revving seems normal. You want the engine RPM to be at least 125 rpm less than what the “target idle speed” is set for in the chip. All went well except I experienced the engine surging at idle. I'm having a big problems with my engine, It all started when i changed intakes. I installed the unit and its idle is somewhere around 1500. The symptoms: The truck starts fine when cold or hot. Voila it ran beautifully! Today I replaced my O2 sensor and both CV axles. Start engine and let it run for around 5 seconds. Maybe 45k on motor. You can probe dark blue wire on TP sensor. the idle will remain the same because the PCM controls the idle speed through an air bypass valve or idle control motor. Dec 2, 1999 · Idle problem w/ 1988 IROC-Z 305 tpi. I've replaced the fuel pump, fuel pressure regulator in the throttle Apr 1, 2008 · 6. You may need to give it a little throttle to get it running. The truck will idle all day but when I try to take off it sputters and misfires. only annoying at this point but am concerned as to where this is going. Remove jumper. The ECM will control the light and turn it "ON" by providing a ground path through CKT 419. 3's (TBI) is a throttle-body base-gasket failure. The tranny is a 700R4 and shifts at appropiate rpm's. If the idle is to high, you may have a problem with that valve or you may have a vacuum leak which is Nov 19, 2022 · Engine Size. This goes smoothly everytime. 350. Dec 31, 2010 · 5568 posts · Joined 2004. Alright so ive been getting a high idle every once in a while the past few days. And it will pass with a camshaft in the 210@. It takes alot to get the rpms up and seems to lose power about 4500 rpm. So I begin every project with a new upgraded Idle Air Control Tools needed: Torx bit # T-20 Paper Clip Small Punch Take the paper clip and open it up and form it into a big "U" shape. hello 3 years ago i started this project. You say new fuel pressure regulator, did you check your pressure after that? It s/b 9 - 13 PSI (according to GM specs), at idle and under acceleration, preferably 11 - 13PSI. I jumped terminals A & B on the ALDL. 1 V at 2000 to 3000 ft. Shut down and reconnect IAC plug. It won't idle on its own, you have to step on the gas to keep it going. 8 posts · Joined 2008. Jun 22, 2018 · Turn the screw to adjust the idle speed to 650 RPM +/- 50 RPM. I went to start it up so I could bleed the power steering (replaced the Jan 6, 2011 · 1994 TBI idle problem New Distributer, rebuilt throttle body, new IAC new injectors, timing setPROPERLY. Leaking Vacuum Lines. Start engine and let it settle into the idle. Feb 11, 2005 · With pressures between 195-205, I'll bet that engine has a lot of miles on it and probably a lot of carbon built up on the valves. 1990 Suburban manual transmission 5. It seemed to be struggling with idle so I turned the connector for my IAC 180 degrees and tried again. I replaced the plugs, wires, cap, rotor, and air filter. turn ignition switch to on for 10 seconds , do not start 2. Oct 19, 2017 · 95 GMC TBI 350 accelerating problems. Not sure what it is exactly, but sounds to me like around 1200 RPM. 25 at idle position and about 4. This may be contributing to the problem. I recently purchased the holley throttle body 670 cfm 502-9 for my tbi 350. - Oil and filter 10W30. New PCV , good cap/rotor/wires/plugs, 6500 miles on new engine ( Flat tops eddelbrock 3702 cam, 3 angle valve job, headers hi flow cat glass pack) new oxygen sensor. Idles and revs fine in Part unless I cant seem to adjust the idle speed to anything less than 850 rpm's Carburetor is Holley Truck Avenger and the distributor Dec 11, 2019 · First off, 1988 350 tbi fully rebuilt kept it stock other than . It has about 200k. When i hook the vac advance back up, idle speed in Jul 21, 2023 · R1500. 7L. 50 ProComp ATs, regeared transfercase speedo. I have pinned out the PCM grounds and checked circuit resistances (all good), All scan tool parameters are within proper Mar 15, 2009 · 1987 tbi 350 manual trans surging idel and at 3200 rpm the truck runs great. Will die on acceleration, and only restart with WOT. Oct 31, 2010 · 12 posts · Joined 2010. May 21, 2017 · There is a switch in the throttle position sensor that is supposed to be triggered when the throttle lever goes to idle to tell the computer to idle. After 30 seconds unplug the IAC valve. If the timing is not changing, except for centrifugal at higher RPM's I would suspect the ignition module. The new motor runs fine, but one thing I now notice is that the idle speed seems slow. Reverse, Drive, 2nd, 1st) my car idle "settles" around 750 on the tach, but then starts to fluctuate around there, moving up to 900 (or so) then dips down to about 500 on the tach. Runs GREAT except for idle issue as discribed above. This problem might also happen if the Jan 22, 2017 · The truck will stay in high idle (about 1800 rpm in neutral/park and 1000-1100 in gear) until the truck warms up then idle returns to normal (Usually about 10ish minutes). The hunting up/down @ idle is the idle enrichment kicking in to save it when rpm drops, revs up, repeats. 350, 350, 350. Aug 9, 2012 · 1994 5. 60mxer Discussion starter. If you have a vacuum leak at the throttle body to manifold, which is common, or anywhere else, that may be causing lean pops too. #1 · Jun 20, 2009. May 20, 2010 · If I remember correctly, when you hook the by-pass wire back up and recheck timing, it should be sitting on about 10 degrees advance. No power, struggles up hills, runs a little better at higher rpm's, won't climb a hill from a stop hardly at all. Jul 25, 2011 · Hey everyone, new member here! My truck in question is a 1988 GMC Suburban V2500 350 TBI / TH400. Nov 2, 2010 · The IAC (Idle Air Control) controls the air passing through a throttle pate bypass passage. Ran better, but still stalled. IAC valve is a regulated vacuum leak, controlled by the ECM. this is most often caused by a vacuum leak. Here are a few potential answers: 1. 8 Atlas II transplant last Sunday. Put it together and now it doesn't always idle. m. 7L 350, TBI, Auto, 220Kmiles Its been a great truck, for the most part it runs and drives great! but at low idle or low rpm's it missis,sputters,surges and if im just barely giving it any gas it almost wants to stall out. 14 Coolant Sensor Circuit Excessive HIGH temperature indicated. May 27, 2018 · tan and black wire should have 5v if RPM>400. These trucks can start and run with a faulty ECM. Got timing roughly set around 0. 7L tbi and timed it. 1987 Chevrolet V20 350 TBI Frankenstein engine and sm465 trans. Check Vacuum Lines for Leaks: A vacuum leak in the intake system is one of the most frequent causes of idle surge and stumble. 7L TBI. I am wondering how you can adjust the idle. Has anybody solved the issue of the 2. Waited about 30 seconds. As you can tell, it doesn't deliver Mar 24, 2012 · 1994 Chevy Truck K 1500 Truck 4WD V8-350 5. Installed stock rebuilt engine a few weeks ago. then see what RPM is after you start it. It insures that what air is being pulled in is done across the entire face area of the radiator. Once you start driving it goes away. - New MAP sensor and IAC sensor. Nov 24, 2010 · 5. 050 will pick up almost 50 hp from stock. I've looked in all the forums and I find people with a similar problem to mine and have tried their fixes with no luck. Connect a bidirectional scan tool to the same OBD port you would plug a code scanner into. We have found idle speed is an excellent tuning tool for riders. Remove the wing nut on top of the air cleaner and lift the air cleaner off the throttle body to access the vacuum lines. 1990. Some other symptoms to look out for to ensure that the problem is indeed a vacuum leak are hissing sound from the engine bay Sep 27, 2022 · PlaywithTBI. The three adjustments I made were #1 adjusting initial timing to 12 BTDC, #2 removing the carb, lightly bottoming out the idle mixture screws and then opening them to 1. Runs good but after warmup at idle it surges probably 300-500 rpm. When it drops down to idle speed, it will stay in closed loop for about 10 seconds, meanwhile the O2 sensor is trying to reach zero getting as low as 0. I have spent countless hours going over the engine looking for vacuum leaks and believe every thing is OK on that front. Truck would want to idle @600-650 RPM when warmed up but often while just sitting there already idling at 600-650 it would start to idle up to almost 1,500 rpm at times. But since the linkage didn’t go to the stop, the idle switch wasn’t turned on so the computer didn’t know to idle and caused the engine to run rough. So I'm getting a light "surging" with my engine. Oct 3, 2020 · I had very similar problem. If it is stuck open, it is a larger than necessary vacuum leak. Insert the clip ends into the ALDL in the 'A' and 'B' pins. You could disconnect the battery to erase what it has learned and the IAC fault, then reconnect battery and turn In this video, I will show you how to set the base idle for your Chevy or GM V8 engine. The engine has a little over 500 miles on it. 5. 7L TBI intermittently stumbles/stalls at idle, and frequently falls flat on acceleration down the road. Early sound clip of a Speed FX (Flow 40 Clone) Jun 20, 2009 · 136 posts · Joined 2009. The pickup in the distributor may be worn to the point that it is sloppy at idle but normal at higher rpm. 56 gears/rear locker, TBI spacer, exhaust, 33/10. Wait 30 seconds. Apr 1, 2016 · Engine specs: 5. The drop in engine speed he's referring to occurs after warming up. Turn on the ignition, but don't start the engine. 5k but settle to down after 10s or so in increments (idle depends on engine temp) Oct 7, 2013 · Hey guys, I've been having a problem with my '68 camaro. It would stall while sitting at idle in park or when in gear at a stop sign. I recently finished up a rebuild on my 1989 C2500 TBI 5. 7. Set parking brake and block drive wheels. The 229,000 mile 454 in my '93 Chevy has been running on 7 or so cylinders for a while now. I just fired up the new Chevy 350 TBI in the FJ60. If California emissions allows a EBL modded pcm, you can run just about any camshaft you want, 2 widebands. I just had to replace one on my 89' Buick Regal Grand Sport 3. Check your fuel pressure 1st. Plug the vacuum lines with golf tees or other suitable item. Dragged the CJ-7 up to Northern California and ran the Rubicon last week. I have a 91 Silverado K1500 4x4, 5. I highly recommend the EBL flash from dynamicefi. If the IAC is working properly, the idle will come down on it's own after several minutes of high idle. This could explain your surging idle. Connect the scanner to the ALDL and check the engine RPM. Stock 1995 5. Spray some carb clean at the base of the TBI with it running and see if changes engine speed. I have replaced the engine temp sensor, the connections Jun 1, 2023 · Top 6 Reasons Why Your Chevy 350 TBI Bogs On Acceleration. Picked up a 1988 K3500 last year with what I believe to be a TBI 350. Shut off and let sit for at least 30 seconds. There is no adjustment on the TBI. When in gear (ex. Black is a ground. Howdy, So I recently bought an 87' GMC SIERRA short box with the 350 TBI and When I start it, it surges bad and trys to die, and then begins to idle better but still not right it sounds like a misfire. 442-inch lift. Aug 11, 2008 · 1 . Recently rebuilt the 454 in my 1990 TBI Burb. 95' S-10 Teal/Silver Ext Cab 4. Reaction score. Location. Reconnect the battery terminal after 5 minutes and test drive the vehicle. A vacuum leak results in supplying the wrong air/fuel ratio into the engine, thus, resulting in bogging or rough and slow acceleration. Canada. Dec 23, 2006 · If not hopefully you have digital volt meter. While cold with the idle still on the high side it seems smooth and normal. 13 Oxygen Sensor Circuit No signal to computer. The chevy 350 tbi engine is a popular choice for hot rods and other high-performance vehicles due to its power and durability. By adding a real idle screw your TPI now acts similar to a carb when addressing the low circuits. There should always be a steady "Service Engine Soon" light when the ignition is "ON" and engine stopped. V 2500 Suburbans. Aug 9, 2007 · Replace any questionable hose. Assuming your engine is in good mechanical condition, there are only a few options. Oil pressure gauge was low. Oct 7, 2022 · I thought the idle was low. Start cold and let it warm up. Dark blue is signal to computer. Truck Model. I have replaced every sensor, wires, distibutor,intake with a after market , timing set,water pump, coil, injectors, check a … read more Oct 7, 2018 · Make sure that the ECM can recognize a fault code, tap the block near the knock sensor and see if the ECM sets a code or unplug the ECT in the manifold and see if the ECM sets a code. Apr 11, 2008. Truck sat for about 7 yrs and am getting it road ready for my nephew. 2 V at 1000 to 2000 ft. Other than the idle, the truck runs fine. Check for vacuum leaks and or a blown TBI base gasket. 350, 502. so high idle is a separate problem than your code 42. But the car died once when I was slowing down, so I thought I'd try it out. qo yb vn ca qz my pq nf rl ex