Low idle slight stutter

40

Asked by Jan 05, 2015 at 10:20 PM about the 1994 Chevrolet C/K 1500 Silverado Extended Cab SB 4WD

Question type: General

94 5.7 tbI I have replaced every sensor on
motor had igniton timing redone. The truck
has full power while driving. Just low idle at
400rpm and has a slight stutter. While
driving if you.let of gas sounds like a
gargling sound like quiet pops from
exhaust ...

21 Answers

8,420

Are you running a new set of A/C delco plugs and are they all firing ? and can it be possible there is an exhaust leak ?

1 of 1 people found this helpful.
40

Yes full tune up not sure on the firing but there is no hesitate on driving it. Full power before this low idle it wad loping and stalling that's when I dropped money and replaced every sensor and redid igniton timing now just a really low idle

3 of 3 people found this helpful.
8,420

When inspecting the base timing, is there a procedure on yours for disconnecting a spout wire or pip signal type wire ? The low speed at idle and the noise makes me want to turn your distributor till it runs good.

1 of 1 people found this helpful.
8,420

You have a new fuel filter, and your cap is not full of ashes, right? and a/c delco wires?

8,420

After rechecking your work and the basics, that has TBI right? Is there a jobbie in the throttle body assembly with a plunger. You used to remove them and clean them and press the plunger in, then reinstall them and have them recalibrate when the key was turned. It meters air to bypass the throtlle to help control idle speed, it's one of the system prechecks before a tunup

3 of 3 people found this helpful.
40

If this helps at all when I start it it will crank 4 or 5 times then fire if I shut it off and try again it will just crank never start shut it off try again 4 or 5 cranks and it will fire

18,765

Don't waste too much money trying to track it down. Most tbi chevy I've owned have started doing this. It make be worn valve train but recently I've contributed it to high ethonal content in fuel. These trucks weren't made to run that crap and never will be.

1 of 1 people found this helpful.
8,420

Hard starting too then, noticed it cycles where there is actually a no start at times. what does it lose during the no start sequence? spark, fuel, compression, or timing ? It has to be one of those 4. (like it leans out?) This is an if theory, loses injector pulse ? Or the injector malfunctions, or the injector needs professional flush chemical cleaning? You used to be able to test and check pattern, replace screen, and get a cleaning at napa or dr. injector. with it off the car.

8,420

valve deposits and combustion chamber deposits can be working with other factors to take away your volatility of fuel , to use andrew's idea. were your previous plugs fouling with ashen deposits or gas additive build up? Like coated thickly with layers of ash or like after adding techroline? and is your fuel pressure in spec ? holds rest pressure? delivers volume ? I know it is not the easiest set of tests, but old parts can be failing slowly or partially failed. But read all this again because I haven't really been getting any answers.

8,420

You dont have hoses that fit loosely ? grommets that are hard , or hoses that are baked and stiff, do you ? like pcv leaks vacuum ? fits loosely, is aftermarket and different from A/C delco ? These are causes of hard start, and delayed start, and no start. Hoses at the front, base of the TBI need to fit snug.

8,420

How many inches of vacuum do you read at a manifold source at idle before and after correcting those things? Just brainstorming for a 20 year old truck that I cannot inspect or listen to, or view the injector pattern.

1 of 1 people found this helpful.
40

We're Gunna do a fuel pressure test tonight I'll update yall we did the ignition timing which stopped the surging issue I had before now just low idle hard start

40

Also is there a way to have this app notify you if someone answers

8,420

It just emails me. But I cannot walk too far from it.

8,420

Next thing I was going to ask after the readings is, does it have a baggy timing chain or an intake leak ?

40

This all started after spraying motor down after mudding instant idle issues wanted to stall and would at red lights and stops then it started surging redid the ignition timing fixed the surge now it's just low idle with stutter and hard to start so really it could be a number of things .... if my ecm was bad wouldn't the truck not run At all

1 of 1 people found this helpful.
8,420

Answer all the tests and checks I asked so far, regardless, you need to define the part of combustion requirements you lack when it is having the no start. if its lean, you have to find if there is a vacuum leak, fuel delivery concern with the amount, or with the pressure, or the volume. It would benefit you to remove the parts you bought so far that havent fixed anything if that were possible, to return what you did not need. There may be inexpensive GM parts at a wrecking yard that are better than some aftermarket stuff i have seen.

Best Answer
8,420

The washing can leave trapped water somewhere. You want a a/c delco module and pickup in your distributor, and ecm issues with ck eng light or no light should be given, and the code reader can be helpful. If you believed your usage had immersed the ecm, that can damage things. A used ecm can be had very inexpensive at a u-pull-it type yard. I do not understand if the cause was old fuel pump failure or service code related at this point.

10

Check the Pig Tail connection to the AIR IDLE CONTROL Sensor. This will impact the IDLE if the connection is bad - This will cause spike and low idling if the four prongs are wired wrong or not making proper connections. ABCD AB is Coil 1 and CD is Coil 2. Just trying to help.

1 of 1 people found this helpful.
10

If you still have the problem, or anyone else does, I had a similar problem with only 95,000 miles, and i threw every sensor I could think at it, with a new fuel filter and fuel pump, and then it turns out the computer was bad, so I was getting error codes for parts that were fine...

1 of 1 people found this helpful.

I will try another ECM.

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