Exhaust smell through A/C at idle, any ideas?
 

Hello,

I have a 90 2+2 with Auto Climate Control. I've noticed an exhaust smell or engine fumes entering via the A/C vents.

I had the exhast system checked, and it was OK. No leaks. The car runs fine. Good pick-up, smooth idle, etc.

I verified the smell is entering the A/C by shutting off the A/C during idling. No fumes enter the cabin if the A/C is off.

I've seen references that may indicate that the AIV could cause fumes to enter the cabin via the A/C. T/F? and How?

I seen another reference that said to check the hood seal. Makes sense. The seal is there, and looks good.

It should be noted, that I can NOT smell any fumes near the intake vents at the base of the windshield. So, how else is it entering.

Any ideas on this problem would be greatly appreciated.
Thank you

Re: Exhaust smell through A/C at idle, any ideas?
 

Try to disconnect the AIV actuator valve and see if it helps. If it does, the AIVs could have gotten clogged... I'm guessing here because I can't remember what's the schematics for the AIV system, but it does sound logical. The AIV system takes air from the intake and puts some in the exhaust. If it doesn't work right, the exhaust could get into the intake I guess.

Disconnecting the AIV actuator is really simple. Right next to the battery there's a little T-shape connector on the air tubing. Disconnect the inlet hose (the bottom one) and you will hear hissing, but the AIVs will stop working since they won't have any air suction to activate them.

Alternatively, look at diagrams to locate the AIV solenoid valve and disconnect it's electrical connector.

I've disconnected my AIVs that way and I drive like it for two years now. My AIVs were gurgling and instead of fixing them I just ditched the whole system.

Good luck!

Re: Exhaust smell through A/C at idle, any ideas?
 

Do you have the AC set to recirculate? Might be an easy fix.

Adam
1996 300Z TT

Re: Exhaust smell through A/C at idle, any ideas?
 

Hmmm, this one is stumping me, Im gonna go do some research and see if I can't come up with a possible answer.

Adam
1996 300Z TT

Re: Exhaust smell through A/C at idle, any ideas?
 

Ok, back with a little more info. I don't know how it relates to the AC, but here are some possible culprits that you haven't mentioned that I would take a look at.

It sounds like your fuel mixture is too rich, and thats making your exhaust smell all the worse. So here are a couple things.

1) easiest: Check your Air Filter. I can't imagine that this is the thing, but its too easy not to just check. Clean it, or buy a new one and check it out. If it still stinks its obviously not the culprit.

2) Check your fuel pressure regulator. Don't ask me why its just what I am seeing as the main cause of what your describing. (I think this is your problem, oddly enough)

3) If its niether of those two, check your fuel injuection sensor. Thats another one ive found to cause exhaust smell in the cabin.

Hope that was some help,
Adam
1996 300Z TT

Re: Exhaust smell through A/C at idle, any ideas?
 

Here's an update:

Recirc doesn't seem to help. Their may be another problem there (not so concerned, right now).

However, I disconnected the vacuum from the AIV actuater. The smell is gone. No trace of exhaust or any fumes in the A/C.

I wish someone could explain how exhast fumes can get into the A/C via the AIV's..

Now the question is should I complety remove the AIVs (cap off the lines from the CAT), or just leave them there the way they are (disconnected from their vacuum lines.).

You mentioned running rich. Based on residue at the tail pipe I can tell that its running rich. I'll have have that checked. That still doesn't explain why disconnecting the AIV prevents the the fumes from entering the cabin. If fact, if I understand their purpose it should make things worst. Aren't they supposed to supply more air to the CAT during idle to burn off excess fuel. If so, it would seem that with them disconnected there would be more unburned fuel the CAT,

I don't understand why the A/C intake has anything to do with the exhaust air intake...

Thanks for you responses. I have those items checked.
AN

Re: Exhaust smell through A/C at idle, any ideas?
 

Hi,

congrats. Leave the AIVs, it's too much hassle to take them out of the car physically. Just leave them disconnected, but not by disconnecting the vacuum hose, but by disconnecting the electrical connector. You don't want a loose vacuum hose in your engine bay (so that flies and crap could fall in it).

If you're running rich, you should get an AFC to tune that.

Re: Exhaust smell through A/C at idle, any ideas?
 

I should have mentioned that I plugged the vacuum line at the actuator. I left the two lines to the AIVs disconnected.

OK, I'll bite.. What is an AFC?