I thought I fixed it...

[labcoatmonkey]

Hey yall, Im just hurtn because I just put my plenum back on after cleaning it out and polishing it. I also cleaned EVERY connection possible to the engine. Well I started her up and she idled at around 1500rpm even when the temp was at full operational. Now the issue is, once I rev the engine while its warm, it starts to lose idle and becomes erratic until it stabilizes itself. This only happens when the car is fully warmed. Could it have something to do with the VTC, because I was shipped the wrong springs and the sprockets still rattle? Im just really frustrated because I cannot find the source of the problem

[alright2020]

i would think its your idle air control valve... or you have a vacuum leak somewhere. both plugs are pluged into the IACV? all vacuum hoses plugged in tight? did you delete anything while the plenum was off? hook a vacuum gauge up to it and see what it reads and go from there

[labcoatmonkey]

Sorry i forgot to mention, the idle control valve seems to check out fine, i doublechecked every connection. Coils are all firing, injectors are good. If unmetered air was to be getting in wouldnt the car just stall or idle very low? Im going to pressurize the intake tomorrow and see if there might be a leak somewere. I took it to two different mechanics who "specialize" in nissan, 240sx etc. and one said its my CAS and I need to adjust my valves . So i took it to another mechanic and he said I should change the idle valve and adjust the screw, which i did a million times, yet the problem persists. Its getting to the point were I want to crack my scull against the motor. . Anyone ever have an issue with the VTC causing an irratic idle at operating temp?

[Ace2cool]

IIRC, the VTC soleniod malfuntioning will throw an ECU code. You should try pulling the codes from the ECU. Here is a good writeup on that.

[labcoatmonkey]

I wish I had a code... it gives me 55

[Ace2cool]

The only thing left that I could possibly think of would be the IACV. Not necessarily the screw or the connector, but the valve itself. Try Robo's writeup, found Here.

My Subaru was doing the exact same thing, so I located my IACV on the Subie and sprayed a pretty generous amount down the hose, and it runs like no other now. I mean, it's worth a shot, and you probably have some WD-40 laying around.

[Zwicked]

I'd say vacuum leak because (I'm guessing) you didn't have that idle issue before you pulled the plenum. Did you use a new Nissan gasket for the plenum?If it's erratic, the IACV is likely working as the ECU is trying to correct the idle. Doing a boost leak test as you are going to do is the best solution.Changing the VTC springs in most cases will not correct the noise. The VTC's internals wear out and then they need to be replaced or changed to an adjustable cam gear.

[labcoatmonkey]

Thanks for the replies guys, Im going to try spraying into the air regulator assemblies and definately the vac/boost leak test. Actually I did have the idle issue before the pull, but now its a little more stable since (since the clean up i assume), and all the gaskets were replaced.

[labcoatmonkey]

btw zwicked dont take this in offence but in my eyes u seem like Spock of the Z32 world... very logical and methodical in every post haha. I wish u lived around my area, Id probably bother ya once in a wile with my car when ur gettin ur coffe in the morning :