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350 tbi engine cutout/hesitation????

This is a discussion on 350 tbi engine cutout/hesitation???? within the TBI Tuning (87-95 / OBD I) ECM/PCM forums, part of the Performance category; I have a 95' GMC 350 tbi and i have had this problem for like 7 months and im getting ...

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    GMC_TRUCK
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    Question 350 tbi engine cutout/hesitation????


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    I have a 95' GMC 350 tbi and i have had this problem for like 7 months and im getting tired of it. the problem is that when i push on the accellerator the engine will cutoff the go and i have had my timing checked, new air filter, new fuel filter, fuel pressure checked, new cap rotar, pluggs and wires, also unplugged th egr valve, checked oil and tranny fluid..And it still does it F*** Man i have a Helix TB Spacer but that was on it when i bought it and that is the only thing i think that could be causing something should i take it off??? or what else should i do please help!!!

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    HOT -N- READY 8{} g9m3c's Avatar
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    Re: 350 tbi engine cutout/hesitation????

    Explain "cutoff the go" better.
    -Grant

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    GMC_TRUCK
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    Re: 350 tbi engine cutout/hesitation????

    The cut off part is like when i press on the gas it pauses then acellerates. or it like chokes out then the engine goes. does that help out???

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    HOT -N- READY 8{} g9m3c's Avatar
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    Re: 350 tbi engine cutout/hesitation????

    Quote Originally Posted by bosstruck95
    The cut off part is like when i press on the gas it pauses then acellerates. or it like chokes out then the engine goes. does that help out???
    Check the gaskets on that spacer first of all.
    -Grant

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    Re: 350 tbi engine cutout/hesitation????

    Quote Originally Posted by bosstruck95
    I have a 95' GMC 350 tbi and i have had this problem for like 7 months and im getting tired of it. the problem is that when i push on the accellerator the engine will cutoff the go and i have had my timing checked, new air filter, new fuel filter, fuel pressure checked, new cap rotar, pluggs and wires, also unplugged th egr valve, checked oil and tranny fluid..And it still does it F*** Man i have a Helix TB Spacer but that was on it when i bought it and that is the only thing i think that could be causing something should i take it off??? or what else should i do please help!!!
    Quote Originally Posted by bosstruck95
    The cut off part is like when i press on the gas it pauses then acellerates. or it like chokes out then the engine goes. does that help out???
    Still need more info. Need to explain how the truck is being used when it happens, and how hot or cold is the engine when it happens. Also you need to check the PCM for codes and plug the EGR back up. Do you have any other mods, besides the spacer?
    1993 S10, 355ci.V8, Edelbrock MPFI, 2" TB, 6395 ECM, $0D Mask, Comp 280H Magnum cam, Edelbrock Performer RPM heads, Lincoln Mark VIII e-fan, 4L60E, 8.8 rear, 8.80s @ 79 MPH (1/8 mile), and cost to much.

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    JUGS Racing SuperStepside's Avatar
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    Re: 350 tbi engine cutout/hesitation????

    Check your fuel pressure. You may be running lean.

    1995 350 "Tool Box Injection"
    Going 4/6 with 20" Billet Specialties

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    GMC_TRUCK
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    Re: 350 tbi engine cutout/hesitation????

    my fuel pressure was 16 and it does it most of the time i accellerater on the gas. NO all i have is a TB Spacer and K&N air-filter kit. I think i might have to check those gaskets tho but they seem pretty thick. but will be my next move.

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    Registered User pasquinic's Avatar
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    Re: 350 tbi engine cutout/hesitation????

    Yeah mine seems to hesitate under 1k - 1500 rpms on acceleration when the motor is at normal temp, but once I get passed 1500 rpms it runs fine. I did notice if I keep the gas peddel at the same point of the "hesitation/bogg down" it kinda spudders a little. I was thinking of the TPS or IAC
    Last edited by pasquinic; 02-04-2008 at 10:42 PM.
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    1994 Chevy K1500 350 TBI Holly Intake manifold, Edelbrock Headers, 4 inch Pro Comp lift Kit, 35 inch BF Goodrich Tires.

    :fsc:

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    Re: 350 tbi engine cutout/hesitation????

    Quote Originally Posted by pasquinic
    Yeah mine seems to hesitate under 1k - 1500 rpms on acceleration, but once I get passed 1500 rpms it runs fine. I did notice if I keep the gas peddel at the same point of the "hesitation/bogg down" it kinda spudders a little. I was thinking of the TPS or IAC
    mine did that and it was the egr valve but my pickup still cuts out when you go from idle to wot right away it does it in both closed loop and open loop but if i hold the break and give it gas to about 1k the hesitation is gone any help would be sweet too thanks
    Last edited by 95_C1500; 02-04-2008 at 10:45 PM.
    95 2wd ecsb 383 with a cam, world heads, and tpi, full length headers, dual in and dual out magnaflow muffler, stage 3 raptor trans with raptor drive package and 2k stall

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    Re: 350 tbi engine cutout/hesitation????

    i'm having the same problem right now, i rebuilding my TBI unit to see of that will help.


    165K , 3.73 , 15 MPG, 32 Gal, TBI Spacer, airbox!, Flowmaster. http://www.cardomain.com/id/94scrmnchkn
    USMC

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    Registered User pasquinic's Avatar
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    Re: 350 tbi engine cutout/hesitation????

    Well I found that my egr was bad. It turns out that if you buy a EGR from Autozone or Kragen, they don't work as well as GM parts from the Dealer. No I am not a rep from GM but I bough one from GM and my truck has no hesitation or shudder.

    Thnx Guys for all your help!
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    1994 Chevy K1500 350 TBI Holly Intake manifold, Edelbrock Headers, 4 inch Pro Comp lift Kit, 35 inch BF Goodrich Tires.

    :fsc:

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    TEE
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    Re: 350 tbi engine cutout/hesitation????

    16 PSI ?
    Your high unless you have some serious mods. The computer will have to be reprogrammed after 15 PSI.
    Back it back down to 14 and see what happens.
    Oh BTW....I've heard the Helix spacers cause hesitation so you may try that too.
    Last edited by TEE; 03-10-2008 at 06:07 AM.

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    Re: 350 tbi engine cutout/hesitation????

    my truck does the same thing. im stock except for a s&b cai and the exhaust. its very irritating.
    91 z71 stepside
    3" ory/si/so magnaflow
    s&b intake
    285/75/16

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    Re: 350 tbi engine cutout/hesitation????

    Mine as well.
    1970 chevy blazer 4x4, built 700r4, 355, L98heads, CompCam RV type cam, 89 TBI, TBI spacer, long tube headers, electric fans, full dual exhaust, 4.56 gears and 35's

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    pfk
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    Re: 350 tbi engine cutout/hesitation????

    It is a fairly common problem on many vehicles. Unfortunately there are many different things that can cause it.

    EGR: valve itself either no good or spring no strong enough (common in cheap aftermarket versions), leaking solenoid, plugged vent on solenoid (usually results in a poor idle as well),or restricted exhaust flow (bad cat etc resulting in too much backpressure which in turns opens the egr)

    Air/Fuel: Fuel pressure either too high or too low (they feel different but would be described the same way online), injector or pod leaking (wrong injector),vacuum leaks (TB gasket, intake gasket, hoses, brake booster)

    Spark: bad cap, rotor or wires, ignition module, pickup coil

    I have seen everything I have mentioned result in a "bog" or dead spot while accelerating. some of them usually have other symptoms along with it but it is a decent list to work with.

    On a stock vehicle, I would probably focus on the egr system first. If modded, the most likely cause would be in the fuel pressure setting with a lack of change to the pcm to reflect the new pressure. When I've thought about it, the only thing I can see as a benefit to raising the fuel pressure on a stock tune would be the AE. In theory, if the pressure is within an operational range, the computer will maintain the same air fuel ratio throughout normal operation by normal blm adjustments. If this new AE amount of fuel is too much for your engine, it is bound to result in a bog feeling while accelerating. If I felt it was necessary to make a change to the fuel pressure without retuning for it, I would try 1psi increments at a time to see what the results were, if I got a bog, I'd go back down.
    1995 GMC K1500 Suburban, 385cc, .040" over stroker,Patriot heads ,1.6:1 roller rockers,224-236 113 lsa cam , Edelbrock Intake (performer RPM) Holley TBI Adapter, BBC TBI with vAFPR,Transgo Shift Kit, Dynomax cat back with Edelbrock ceramic TES Headers. Paxton SN93 s/c, electric fans 4.10 posi

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    Registered User 91chevyon22s's Avatar
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    Re: 350 tbi engine cutout/hesitation????

    My truck does this only when i dont let it idle in the morning for about 5 minutes if i start it up and start driving right away it'll hesitate, i have a Helix spacer headers cam and an edelbrock intake.

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    Registered User alamantia's Avatar
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    Re: 350 tbi engine cutout/hesitation????

    Did anyone figure out what this is or is the entire TBI community still living with this hesitation? I have the same peoblem, just started sunday, I replaced the EGR and EGR solenoid to no avail. However if I unplug the EGR solenoid the truck runs fine again. My guess is that its a vaccume leak somewhere, I am going to replace the TBI base gasket tonight. I have googled this problem and I have found 100 threads from variouls forums all having the exact same problem but not one dude posted a solution yet. According to google 100 people have this problem and not one pwrson fixed it? c'monnn

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    Re: 350 tbi engine cutout/hesitation????

    My 94 chevy truck had the same problem when it was basically stock and after the supercharger install. When I accelerate hard, it bogs or hesitate, then go. I minimized the problem by moving the base timing on the distributor from 0 to 4-6 degrees BTDC. This might just be a bandaid for the real problem until I can research it better, but my truck runs strong with no knocking so I'm happy. Hope this helps. Give it a try.
    94 C1500 Extended cab, 350 TBI, whipple, gibson headers, edelbrock cat back, MSD ignition, electric fans.

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    Re: 350 tbi engine cutout/hesitation????

    Sounds like the accelerator pump function of the TPS not doing its job. My truck was doing this and a new fuel filter and rebuilding the FPR seemed to alleviate it.
    Quote Originally Posted by Quyonmob View Post
    Straight pipes are for peckerheads. . .
    '98 K1500 ECSB 5.7, 4L80E, 14BSF, 4.10/G80, 7,200# GVW springs, 8600# GVW calipers/pads, 411/EFI Live, TB mod, UDs, block, crank, 285s, and a lot of stuff on the shelf.

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    Registered User alamantia's Avatar
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    Re: 350 tbi engine cutout/hesitation????

    Good to know, i checked the TPS on my scanner and it was showing 0.52mv, map, iac, o2 etc. looked good as well. Im wondering if carbon has built up in the MAP vaccume port. God damn frustrating, soon as I figure that out the next thing I will try to solve is how my sig is so damn big.

 

 
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