ChaseTruck
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Have you tried the IAC reset procedure I linked earlier?
Terrible Idle After Major Service (1 Viewer)
- Thread starter TriaxialBulls
- Start date
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Once I put it all back together with a new OEM part. Boom. All was good. The CEL was gone for good. Or burned out. Lol
- Thread starter
- #44
That’s a good idea, I’ll do that today and then if it doesn’t seem to have that affect I’ll go through the procedure @ChaseTruck posted. If that still doesn’t fix it, my next step would be to take the plenum off and inspect/replace all the vacuum lines and valves under there, although I won’t be able to do that for at least a couple weeks.
I took the tube off yesterday and didn’t see any cracks, nor did I ever feel or hear it sucking in air from around there.
- Thread starter
- #45
Also I’m still not throwing any codes which is really weird to me. If there was a huge vacuum leak somewhere, I’d expect it to be running super lean and therefore be throwing codes from the O2 sensors at least. With that said I STILL think it’s a vacuum leak lol
- Thread starter
- #46
Alright, back again with another update.
The truck actually was idling okay today, but I’d also been playing with the throttle cable to get it to artificially idle higher so I could finish my coolant flush process I was in the middle of. I tried unplugging the IAC valve as suggested by @fjbj40 and here’s how it acted upon warm startup:
IAC Unplugged Idle
So it seems like the IAC is working in some capacity at least. However the oscillation in the revs still leads me to suspect a vacuum leak.
The truck actually was idling okay today, but I’d also been playing with the throttle cable to get it to artificially idle higher so I could finish my coolant flush process I was in the middle of. I tried unplugging the IAC valve as suggested by @fjbj40 and here’s how it acted upon warm startup:
IAC Unplugged Idle
So it seems like the IAC is working in some capacity at least. However the oscillation in the revs still leads me to suspect a vacuum leak.
I had the exact same idle as you after doing the HG, deleting PAIR, and deleting EGR on my '93. It improved after coming to temp, and was definitely drivable, but it drove me crazy having an issue like that after doing so much work. After going through the PO's service records, I noticed one wherein the PO had complained of a bad idle on cold start, and the shop recommended changing the IAC because it was likely "sticking." Cleaning the IAC/TB, following everything in the FSM, and scouring these forums for a cheap fix did no good. I decided to bite the bullet on a new one, installed it yesterday, and my idle issue is fixed.
No idea whether that's your issue, but that's what worked for me.
No idea whether that's your issue, but that's what worked for me.
- Thread starter
- #48
Alright guys, I wanted to update this thread. So I did actually find a vacuum leak on my engine; there was a small section of the valve cover that was bowed out (I don't know why) and allowing air to come in. Unfortunately, this vacuum going through the valve cover had the side effect of pushing a bunch of oil up into my TB and intake, so that's a bummer. Once I took the whole valve cover BACK off and fixed it, the engine idled pretty well. I also advanced the base timing to 7 degrees BTDC.
However, it still has some idle quirks. When I put the trans into gear, the RPMs drop to around 400 and the truck becomes very shaky. I thought the RPMs were supposed to increase when you put it in gear? Could this be something with my kickdown cable needing adjustment?
However, it still has some idle quirks. When I put the trans into gear, the RPMs drop to around 400 and the truck becomes very shaky. I thought the RPMs were supposed to increase when you put it in gear? Could this be something with my kickdown cable needing adjustment?
Did you ever get this situated? Once I replaced my IAC, it idled OK for a while, but then went back to the same old same old. Still testing for vacuum leaks.
Hey Everyone,
I had no P0100 or P0110 before I had Valve cover gasket, spark plugs were replaced and EGR cleaned. I had EGR codes before, but they have gone out since the cleaning.
But since the Valve cover gasket and EGR cleaning, some vacuum hoses were connected/disconnected in the process, now I am getting MAF sensor circuit, intake temperature sensor code, and O2 sensor codes. none came before the above mentioned service, but are now coming immediately after the service, making me thing they all can't fail all the sudden, but something happened like vacuum leak or the valve cover gasket isn't seated properly. I am good at fiddling with mechanical things and electrical things, but have not played much with vacuum side of things in the cars. so have a very little understanding of how vacuum things work and why are they used in the cars. as oppose to electrical and other mechanical solutions.
so, if someone suspects as me that my expensive MAF sensor and O2 sensors all the sudden didn't go out during the service, if you can guide me through how to find what the real culprit is for my P0100, P0110 and O2 sensor codes?
what conditions has to occur for MAF, intake temp, and O2 sensor all to start to complain at the same time?
car runs okay, I feel it's a bit under powered, has a little rough idle, but it's a new to me car, so perhaps the power is normal for this engine. I been also traveling in the mountains of Colombia, so not the easiest terrain.
Thanks for any guidance.
