VIP Maxima

what causes high idle after cleaning the TB? during cold starts my rpm goes up to 1400-1500 instead of 1100-1200 and when car is fully warm in gear, it sits right at 1k instead of 750-800 and when in neutral it sits lower than usual at 500 rpm.

where is the screw and how do i fix the high idle? also what is the normal RPM for auto tranny. should i adjust it when engine is cold or after the engine is fully warm ?!

thanks in advance

99 SE-L

Ye i got the same quistion i was messing wiht my IDLE CONTROL VALVE NOW AT A STOP LIGHT IT IDELES AS ABOUT 1 I HATE IT HOW DO I FIX>>

lilaclucymaxima

iTrader: (16)

adjust the screw near your accelerator cable

maxmiles

There is a plastic screw under a black cap on the IACV. It is sorta reccesed(sp?) in the hole like a set screw.
Set it warm. There is a procedure in the svc manual on which sensor to unplug first.
as I recall you shut off the car after warming it up, unplug the TPS and restart the engine. This may turn on the check engine light but it will go out after a couple days, or erase the code by taking the batt cable off for 10 min.

VIP Maxima

is that it? ^

if not then please show me on one of these 2 pics

Maximeltman

iTrader: (11)

no thats a fuel regulator for the fuel's pressure. just adjust the cables like the way you adjust the handbrakes on a bmx.

Vlasic

iTrader: (13)

clean the IAC and PCV valves first and then if the idle is still not right start adjusting the throttle cabels, THEN the black plastic screw on the IAC valve.

Julchen

I'm giving all the idle threads a bump this morning so that, hopefully, someone more experienced can give us some good advice.

96 stillen max> how will the throttle cables cause a high idle. Are you assuming they are too tight.

I would also like to know why you should have to adjust the idle after you clean the TB and IACV? I don't understand why you should have to mess with the settings at all. The idle should be poor before you clean these components, and then improve afterwords. But the settings shouldn't have to be messed with.

I DID successfully lower my idle yesterday by disconnecting the TPS and backing out the set screw on the throttle body. See my thread here:

http://www.forums.maxima.org/showthr...=1#post3454552

Greg

Julchen

Also, something to consider is air leaks. I used to own an '85 Saab and it had lots of idle problems. They were caused by 1) the IACV, and 2) air leaks in the intake system. The problem was that the idle was controlled in part by the MAF sensor measuring airflow across itself, but if air leaks were present downstream from the MAF, the engine was actually taking in more air the the MAF thought it was taking in, and the idle increase (or worse, hunted, which would really drive me crazy).

I don't know if maximas have a similar phenomina if there are air or vacuum leaks, but I would strongly urge everyone to make sure all the intake components, including vacuum hoses, PCV grommets, vacuum grommets at the brake booster and intake, etc., etc., are very TIGHT, and leak free. Its just a preliminary theory, but perhaps as these cars age, plastic gets brittle and rubber gets hard, these idle problems will continue to crop up.

GregS
'95 Max, 118k

Vlasic

iTrader: (13)

the throttle cables can cause the idle to be to high, but not too low. if your idle is sometimes too high and then sometimes too low, or it is always hunting, then it is most likely a problem with the IAC, PCV and or the EGR valves. cleaning these should set your idle back to normal...i did for me.


also, a hunting idle can be a TPS problem. clean the valves first and if its still acting up, test the TPS. there is a thread about it in the how-tos.

njmaxseltd

iTrader: (19)

The proper way to adjust the idle speed on 95 - 99 is as follows:

Warm the engine up to operating temp, at leaset a 15 min. drive.
Shut engine off and disconnect the TPS.
Restart the car, the CEL should NOT be on.
Adjust the idle speed to ~650 RPMs, neutral, no accessories on.
Turn engine off and reconnect the TPS.
Restart engine, if the idle speed is not correct adjust it using the IACV bypass adjustment screw to approx 700 - 750 RPM.

You need to set the default idle speed at the throttle body first, then adjust the IAVC only if necessary to correctly set your idle speed.

VIP Maxima

thanks, just what i was looking for except i have no clue what TPS is ?! is it seen in one of the pix i posted?

Vlasic

iTrader: (13)

if you look in the pics you posted. the TPS is the one with that red and grey connector next to the TB.

Julchen

I guess I'm still suspicous about my car because 1) I never had a problem until I cleaned the throttle body, and 2) I had to back my set screw out so much to get the idle down to 700rpm with the TPS unplugged. I had to back it out so much that the throttle actuators don't even touch the set screw anymore. Somehow this just doesn't seem right, and even after backing it out that much the idle only went down to 700rpm (not 650 or lower).

Again, can anyone give me more detail on diagnosing and cleaning the EGR valve?

Thanks,

Greg

crazy97

iTrader: (1)

You need to screw it IN to get the idle down

VIP Maxima

oh i see, do i unplug both connectors?

njmaxseltd

iTrader: (19)

Something isn't right. Seems like you have air getting into the intake after the throttle plate. EGR would give you a very rough idle if it were leaking, I don't think thats your problem. The IACV valve might be letting in to much air for some reason at the default closed position or you have a vacuum leak somewhere. You should be able to stall the engine by closing the throttle plate with the adjustment screw at the throttle body while the TPS is disconnected. There's excessive air entering your intake plennum from someplace.

crazy97

iTrader: (1)

Yes, otherwise you will never get your idle down.

bennny

what can a intake leak do ?