99 Altima Idle Pulsing Up and Down

[aznissanaltima]

This is driving me nuts! Any help is appreciated

When idling, My Altima pulses constantly from about 1100 to 2000 rpm. It gets a little better with the AC on and when it's cold.

It seems to run fine other than that, and it's not throwing any codes.I took the IAC off and cleaned it, no change. But - shouldn't there be a spring in the IAC? Mine didn't have one, nothing in there but the plunger.

Could that be the problem? Any ideas?

[Dansmaxima]

I'm having the same problem with my 2001 maxima. I swapped out my iac with a junkyard one. New was $275--junkyard was whole throttle body for $150. The only spring on my iac was between the plunger and body, built in. I hope to find my answer here, maybe MAFS or other components causing this... good luck!

[aznissanaltima]

Thanks for the reply. I've seen similar problems on here, but no real answer for the cause, just some (hopefully) educated guesses.

Mine has no spring at all inside the IAC, so it makes me wonder if that's the problem. I disconnected the plug and the pulsing continues with no change, so my guess is that it's either mechanical - like a missing spring - or it's something else entirely. Maybe the MAFS or CTS....

[3Q Jay]

my soft recall of the IACV on the ka24de (at least my '95) is that the spring was on the outside--between the solenoid and the end cup that goes on the lower plenum. again, just going by memory from a few years back.

check for vacc leaks.check EGR (not only does the diaphragm need to pulse at warm 1800 rpm, but all passages must be cleaned to spotless.how dirty was the inside of the plenum? you might still have some clogs.MAF cleaning wouldn't hurt. 'mist' the element with CRC lectramotive. apply stabilant-22, or at least some dielectric on the connector pins to MAF.

what is fuel pressure?

[aznissanaltima]

Well, I guess I'll never know what caused it now. I had to go to the hospital last month with a burst appendix, and then while going to the doctor for a followup visit, an Explorer pulled out in front of me and totalled my Altima.

After seeing all the threads on here about idling problems, I don't know if I'll get another one, will have to think about it a bit

Anyhow, thanks to everyone who offered advice. I just wish I could have gotten it figured out and posted it here so someone else wouldn't have to go through all of the aggravation.

Later.

Bob