Service Engine Soon Light

[jdmccright]

From what you describe, it sounds like the EGR is stuck open, but there's no response post that you checked for other vacuum leaks which can also cause intermittent stumbling and hesitation when accelerating.

[EDIT]
I forgot to mention the possibility of the IAC valve being stuck as well, even though it doesn't show up on your code reader. If it doesn't open at idle like it should or operate correctly it too can cause poor idle and stumbling.

[snshddog]

The way I read the initial question is it only runs bad in overdrive, by that I assume when you drive and are coming to a stop it runs bad then switching to drive clears it up. Or is it bad just starting it up and going into OD? If it is only when coming to a stop in overdrive I might suspect the lock up converter sticking, going to drive forces the lockup off. Or did I read the question wrong?

[j cAT]

Originally Posted by snshddog

The way I read the initial question is it only runs bad in overdrive, by that I assume when you drive and are coming to a stop it runs bad then switching to drive clears it up. Or is it bad just starting it up and going into OD? If it is only when coming to a stop in overdrive I might suspect the lock up converter sticking, going to drive forces the lockup off. Or did I read the question wrong?

he says on his first post of his issue:
Having issues for awhile with my 1992 C1500 5.7L Chevy pickup. It has had a rough idle and "stumbles" below 1500 rpm .

what he needs is to buy some equipment to properly troubleshoot this. so far he has given no details on HIS findings ..very vague !

if he has a bad vacuum or a failed EGR it will idle like crap and shift erratic.

[pete44]

Update again: Will try to be more specific. It is like jcat said need better diagnostic tools. Here is what I have done so far:

checked EGR (with vacuum gauge-applied vacuum engine went from slight stumble to rough stumble to nearly dieing)

checked EGR solenoid (placed vacuum on intake line (from carb)..It held vacuum fine-NO LEAKS)

looked/poked around vacuum hoses..nothing obvious or loose

I have replaced:
TPS- I went by Haynes manual to check for voltage increase with throttle increase..It had a .06 volt and stayed at that..no voltage increase with throttle..



MAP...same thing..took voltage readings according to Haynes procedure..found nill to no voltage...So I replaced



Looking at now:BUT Haynes say to take it in to shop to check properly

IAC...Check resistance over four terminals on it according to Haynes
ECM...The HEART of everything..No way for me to check...Just replace..$100 and up


Codes I get is:

22...TPS too low
32... EGR System problem

*** Just a note..AutoZone has an OBDI1 tester for $30 to $35 dollars...AutoZone or Advanced Auto cannot diag anything below a 1996 year.***
Thanks again to all replies and help!

Pete

[MT-2500]

Originally Posted by pete44

Update again: Will try to be more specific. It is like jcat said need better diagnostic tools. Here is what I have done so far:

checked EGR (with vacuum gauge-applied vacuum engine went from slight stumble to rough stumble to nearly dieing)

checked EGR solenoid (placed vacuum on intake line (from carb)..It held vacuum fine-NO LEAKS)

looked/poked around vacuum hoses..nothing obvious or loose

I have replaced:
TPS- I went by Haynes manual to check for voltage increase with throttle increase..It had a .06 volt and stayed at that..no voltage increase with throttle..



MAP...same thing..took voltage readings according to Haynes procedure..found nill to no voltage...So I replaced



Looking at now:BUT Haynes say to take it in to shop to check properly

IAC...Check resistance over four terminals on it according to Haynes
ECM...The HEART of everything..No way for me to check...Just replace..$100 and up


Codes I get is:

22...TPS too low
32... EGR System problem

*** Just a note..AutoZone has an OBDI1 tester for $30 to $35 dollars...AutoZone or Advanced Auto cannot diag anything below a 1996 year.***
Thanks again to all replies and help!

Pete

Ton start with.
Pitch that haynes manual in the trash can and get some good repair info.

All Data has a good online DIY repair info system.
FOR TEST EQUIPMENT A VACUMN GAUGE AND A GOOD VOLT/OHM METER AND A ALL DATA diy ONLINE SUB.
The all data has repair flow charts for your code.
Go threw them and they will lead you to your problem.

And last thing a old paper clip to jumper pins A and B codes.

[pete44]

Update again:

Took it to a shop today and after 1/2 hour (and $35) they said it was an EGR problem...Mechanic said they just worked on a truck like mine and it ended up being HEAVY DEPOSITS in the throttle body area. He quoted me $600 to clean out throttle body..So, like most of us here I said thanks and went home and started out with a new PVC (it was clogged heavily) and cleaned out vacuum lines to carb from PVC. Tomorrow or better yet this weekend (if weather permits I will pull EGR and clean it and all other vacuum lines that need it) and while I am at it look into throttle body and shop vac it out..Mechanic did say this can be a "can of worms" the more you take it apart meaning SUT...Interesting though I mentioned the oil leak started same time my problem happened and he said "yeah, that happens with everything clogged up" otherwords oil being "pushed" out of seals..no aspiration..You know, funny thing is my oil pressure has been "higher than normal" since this has happened..Maybe he is making since in a way..Will keep you updated.


Pete

[MT-2500]

Originally Posted by pete44

Update again:

Took it to a shop today and after 1/2 hour (and $35) they said it was an EGR problem...Mechanic said they just worked on a truck like mine and it ended up being HEAVY DEPOSITS in the throttle body area. He quoted me $600 to clean out throttle body..So, like most of us here I said thanks and went home and started out with a new PVC (it was clogged heavily) and cleaned out vacuum lines to carb from PVC. Tomorrow or better yet this weekend (if weather permits I will pull EGR and clean it and all other vacuum lines that need it) and while I am at it look into throttle body and shop vac it out..Mechanic did say this can be a "can of worms" the more you take it apart meaning SUT...Interesting though I mentioned the oil leak started same time my problem happened and he said "yeah, that happens with everything clogged up" otherwords oil being "pushed" out of seals..no aspiration..You know, funny thing is my oil pressure has been "higher than normal" since this has happened..Maybe he is making since in a way..Will keep you updated.


Pete

He quoted me $600 to clean out throttle body.
600$ Was he wearing a mask? Like the masked bandit?
A tooth brush and a can of carb/throttle body cleaner and 15 minutes work will give you that 600$ clean up.
5$ for cleaner and 15 minutes work = 2395$ hr labor there.
Also.
Throttle body deposits will give you a higher tps reading not low.

Get a repair flow chart for the tps sensor code.
And go all of the way threw it.

On the egr valve do some proper testing and inspection of EGR valve passages.
And confirm EGR valve is working right like opening and closing good.

[j cAT]

with the shops findings I agree on this can turn into a big mess..

your engine has a poorly maintained engine oil/crankcase system.

the PCV needs checking every year.. replacing this is required every 2 years when the vehicle does stop and go traffic..this valve can wear out or get plugged up by not changing the oil in the proper time/mileage.

vacuum lines need replacing not cleaning..................

Intake manifold could be plugged up ..this would require in some cases removal and acid wash...using a stiff wire and a shop vac you can try to open it up..throttle body will need to be removed to open this passageway..if plugged..


poor idle is PCV #1...then other components..measure engine vacuum WITH A GUAGE , and then start replacing hoses see what you get after ..

with the engine running at idle place a piece of paper over the oil fill hole...it should be sucking in....not blowing out ...blowing out means crankcase pressure and this is a bad PCV/VENT system...

this is why it leaked oil .

[pete44]

I agree..The engine in this truck is not original. I had a "rebuilt" one put in around 200,000 miles..It now has 280,000 miles..Shop man made a point by saying the engine rebuild place SHOULD have cleaned out the intake and throttle body.I change my oil every 5,000 miles..So point being said I will replace the EGR and the EGR solenoid. If no fix , I will be prepared to take apart and clean..( after my old car is ready for the road)This truck is a daily driver 36 miles a day to work...I changed all vacuum lines already. Wish me luck and again thanks to everyone!

Pete

[j cAT]

Originally Posted by pete44

I agree..The engine in this truck is not original. I had a "rebuilt" one put in around 200,000 miles..It now has 280,000 miles..Shop man made a point by saying the engine rebuild place SHOULD have cleaned out the intake and throttle body.I change my oil every 5,000 miles..So point being said I will replace the EGR and the EGR solenoid. If no fix , I will be prepared to take apart and clean..( after my old car is ready for the road)This truck is a daily driver 36 miles a day to work...I changed all vacuum lines already. Wish me luck and again thanks to everyone!

Pete

If you use dino oil , the oil and filter should be replaced at 4000miles max...also don't use fram filters and only drain the engine oil when hot at the normal operating temp. allow time for total oil drain ..with 80,000 on this engine and the PCV being plugged the oil is not being maintained correctly...could also be the thermostat is not allowing the engine to run at the correct temp..too cold will do it...