3.2 Idle question Please HELP!!!

ThePointman · ThePointman's Garage

What would generally cause the idle to be low and rough most of the time but then pur around 950 randomly when warm? Most of the time my idle sits at around 550 but occasionally goes to 950 or so when warm then back to rough and 550 again. Any ideas?

I have had the alternator rebuilt, valves adjusted, plugs replaced, dist cap and rotor replaced, plugs wires will be replaced when they arrive. I also cleaned the ICV as per the post located here.

Could this still be an alternator (voltage reg) problem? The voltage across the battery is a steady 13.7 volts. This rough idle is driving me crazy .. sometimes when I come to a stop the idle dips like its gonna stall then pulls back up to 550 and rough. I only use premium 92 octane fuel. I am also going to have the fuel filter replaced and the air filter too even though it looks fine. I am running out of things to replace. Any help would be greatly appreciated :-)

MotoSook · 02-08-2006, 08:01 PM

Could be the idle air control valve. Run a search..it's been dicussed lots of times.

don911 · don911's Garage

This is a long shot but I had somewhat similar idle issues once. My issue turned out to be the connector that goes into the air meter. When I plugged the connector in, two of the contacts were pushed out. Everything looked fine but when the connector was off, you could see two contacts not in line with the others. This caused a really bad a/f mixture.

Jason Cullen · 08:31 PM

You are not alone, sounds like the Air Control Unit.

My 85 has an aftermarket unit, I'm switching back to stock and adding a chip.

I have the exact same operating issues.

It sounds like a Air/Fuel mixture as Don mentioned. This causes the running issues, you need to get that dialed in.

Good Luck - 3.2 Carreras are wonderful cars.

Thank you,
Jason

scottb · 02-09-2006, 01:14 AM

When was the last time you checked your mixture? You might be running rich.

ThePointman · ThePointman's Garage

Quote:

Originally posted by scottb
When was the last time you checked your mixture? You might be running rich.

I have never checked my mixture. It does seem to be going through too much fuel runs a little groggy unitl you hit about 3500 then it screams like a banshee. I suppose you need some sort of special unit to test the mixture?

Rot 911 · 02-09-2006, 07:06 AM

Quote:

Originally posted by ThePointman
runs a little groggy unitl you hit about 3500 then it screams like a banshee.

That is how a typical 3.2 that hasn't been modified runs. Comes on cam around 3K rpm.

88911coupe · 02-09-2006, 07:08 AM

Somewhere back in my feeble brain I seem to recall this could be tied to the O2 sensor. You might try disconnecting it but don't leave it that way...I think Motronic 3.2's are not supposed to be run long without it connected.

scottb · 02-09-2006, 07:08 AM

Quote:

Originally posted by ThePointman
I suppose you need some sort of special unit to test the mixture?

Frankly, I just took mine to my to my mechanic. He adjusted the mixture, and when I got it back the idle was perfect.

dentist90 · dentist90's Garage

Hey Marc, buddy! (Pointman)

A common culprit for wonky idle is a vacuum leak... trying to find it (if it exists) is another problem. My 84 3.2 has similar issues, except the idle dips to stall level after lifting the throttle until it is full warm. Then it seems to settle around 800 rpm. I am going to clean the ICV this spring.
As per your problem... I noticed with mine that when I take off the oil filler cap the idle surges and sounds a bit rough. When i cover the filler neck with the palm of my hand it smooths out again. Try this just to see if it's something as simple as a bad seal on your filler cap. That's about the easiest vac leak to repair.
Otherwise it may be time to get vacuum checked out and see if there is a leak somewhere?

ZOA NOM · ZOA NOM's Garage

Airflow Meter probably has worn grooves on the potentiometer that provides the airflow reference voltage to the DME.

ThePointman · ThePointman's Garage

Quote:

Originally posted by dentist90
Hey Marc, buddy! (Pointman)

A common culprit for wonky idle is a vacuum leak... trying to find it (if it exists) is another problem. My 84 3.2 has similar issues, except the idle dips to stall level after lifting the throttle until it is full warm. Then it seems to settle around 800 rpm. I am going to clean the ICV this spring.
As per your problem... I noticed with mine that when I take off the oil filler cap the idle surges and sounds a bit rough. When i cover the filler neck with the palm of my hand it smooths out again. Try this just to see if it's something as simple as a bad seal on your filler cap. That's about the easiest vac leak to repair.
Otherwise it may be time to get vacuum checked out and see if there is a leak somewhere?

Well that is a good thought. She is going in for a fresh coat of paint tomorrow so I will have to look for leaks when she comes home. Plus I am installing a cat by-pass and will leave the O2 sensor unplugged at first to see what that does. This is just very annoying because when it idles around 900 it is smooth and purs ... when it idles around 550 it stumbles, sounds and feels terrible. And I am very tuned to the physical and audible response from the car, thus any of the fore mentioned irritates me to no end ... Thanks for the tips Derek. Hey hows the weather in 100 mile these days?

Nine9six · Nine9six's Garage

How old is your o2 sensor? I replaced mine and it cured the idle hunting problem.

ThePointman · ThePointman's Garage

Quote:

Originally posted by Nine9six
How old is your o2 sensor? I replaced mine and it cured the idle hunting problem.

Not sure I have only had the car since Oct 18th of last year. The idle just started to hunt one in a while to go with the 550rpm low idle that has been occurring for some time.