1995 5.7 serious idle & intermittent throttle issues

[jadimon]

My 1995 2dr 5.7 liter is running as though it's not getting an even flow of fuel or a hand is being placed over the carb. (But it is a fuel injected model).

Once it warms up or is under load, the problem improves slightly, but not much, then when the motor is shut off, to say, run inside the grocery store, the warm engine does not want to restart and lunges through the parking lot. Very irritating. dies, then I throw it in neutral, start it and it gets going again.

I don't know much beyond basic maintenance and must fix this on the cheap. Obviously a couple mechanics I have taken it too don't know much either, because I was charged for various parts with no correction. I now have to do this myself as I'm broke.

Here is what has been replaced:
fuel filter
air filter
plugs
wires
cap
rotor
starter
battery
cat
o2 sensor
muffler
3 different fuel injector cleaners with fresh tanks of gas

I want to think it could be the TPS, but I can't find a photo or location or test method on the net. Maybe that's not even it.

Any advice very much appreciated. I've put $1,400 into this truck so far and this is very frustrating.

Thanks,

 

[Sepiroth]

It reads to me as if your IAC and EGR and its corresponding ports are plugged with carbon.

 

[2000 limited]

It reads to me as if your IAC and EGR and its corresponding ports are plugged with carbon.

you hit it on the nose...:thumbsup:

 

[SoTahoe]

School me!

Wuthahell is a IAC and EGR??? Please lemme know I'm curious and want to learn

 

[Sepiroth]

The IAC= Idle Aic Control valve. What this valve does is keep the vehicle running when your foot is off the throttle. It has a stepper motor. These stepper motors can get carboned up and that carbon can hinder the performance of the IAC.

This valve is almost always located on the throttle body somewhere.


EGR= Exhaust Gas Recirculation valve. This valve opens when the vehicle hits a cruising speed. What this does is help keep NOx temps and pressures down as well as reburn any unspent fuel from the previous conbustion. This happens so fast it is not noticeable.

Now when the EGR becomes plugged with carbon, this will keep the valev open partially or all the way. This will result in poor idle. If the carbon has clogged the EGR track, this will prevent the EGR from doing its job correctly.

The easiest way to clean both and their passages is to use carb cleaner or GM Top Engine Cleaner.

 

[SoTahoe]

wow

Hey thanks for the info! I'm looking forward to learning more about my truck from people like you!

 

[Sepiroth]

No problem, that's what we are here for.

 

[jadimon]

It reads to me as if your IAC and EGR and its corresponding ports are plugged with carbon.

That is exactly what the problem was. I replaced both with Carquest parts and the problem is fixed!

 

[Txfight07]

Same issue

Wow my 1996 is doing the same thing, idles like I have a cam in it then sputters at take off and then grabs and takes off. Then when I put it in park and turn the AC off the truck turns off.