J30 VTC--possible problem

[Ken Park]

I have been trying to figure out what this stumbling problem is with a friend's 95 J30. We have cleaned out the AAC valve, cleaned the MAF, replaced the PCV valves, and it still has a stumble/hesistation after the car is warmed up only. When it is cold it runs great. His cousin told him that the VTC solenoid could be going bad. Anybody ever heard of this?

[yodawill2000]

Knock sensor ??If no check engine light comes on that would be my best guess.

[Ken Park]

When I used my laptop and software on his car once I did see a knock sensor stored code.

[yodawill2000]

Well there you go !!When they get old and cracked they will do just that.Run great till the engine warms up.Then it retards the snot out of the engine with a false knock code.

[misfit6794]

I had the same exact problem with mine. I think it had something to do with the egr tubes being completely clogged. Could also be an injector, since when the cars cold its putting a little more fuel into the engine to warm it up, but once warmed the injector isn't pushing aenough gas through. What you can do is to pull the connector for each coil pack to see what cylinder has the misfire. My guess is a fuel injector.

[yodawill2000]

That would throw a CEL though ,,, Wouldnt it ?

[gr8scott72]

That would throw a CEL though ,,, Wouldnt it ?

Yes, and yes (EGR and misfire)

[Ken Park]

Well there you go !!When they get old and cracked they will do just that.Run great till the engine warms up.Then it retards the snot out of the engine with a false knock code.

I assume this will not throw a code every time then. Where is the knock sensor (s) on this engine?

[yodawill2000]

Thats the bad news ..Its under the Lower plenum.Some here have relocated it instead of pulling the upper and lower plenums . (Big Job)Do a search and you should find the procedure.

[gr8scott72]

Thats the bad news ..Its under the Lower plenum.Some here have relocated it instead of pulling the upper and lower plenums . (Big Job)Do a search and you should find the procedure.

I'd push my car off a cliff before I replaced the knock sensor. Def look into relocating it instead of replacing it.

[yodawill2000]

Let me know when your about to push that T off a cliff Scott. I'll come take it of your hands .. hehe

[gr8scott72]

Let me know when your about to push that T off a cliff Scott. I'll come take it of your hands .. hehe

All is good with it right now, but I'll let you know before I do that. Course, I don't know of any good cliffs around here. lol

[Q45tech]

VVT solenoids and CAS are common old age problems on J30/300zx.