Sometimes I get caught in traffic and the car starts idling funny after a while of not moving much. The temperatures in Canada are like pretty cold (no snow yet, thank god) and the temperature gauge is still horizontal so I don't think its a temperature problem although I could be wrong since im not really a car person.

Basically, it drops jumps from 0.8-0.9 to 0.4-0.5 continuously until I make it move for a decent stretch where it then stables at 0.9 again. I also notice that the boost gauge drops from -11 to -7 PSI in tandom with the drops in the revs. So boost goes up slightly as revs drop slightly.

Turning lights on/off and fans etc doesn't have a noticable affect. Any ideas what it could be or if its something I should worry about? The car never died but next year in the summer I'm worried its a temperature problem. Hopefully its something basic. List of engine mods follows...

rebuilt engine with street port and 3mm apex seals
upgraded Bully clutch
Walbro 255lph fuel pump
dual filter K&N intake with heat sheild
3'' down pipe and 3'' cat back exhaust
Pettit ecu

thewird

 

Does it only happen when your foot is on the clutch?

 

What RPM is the occuring?

Sounds like you are talking about idle hunting. If you are not mechanically inclined it will be hard for you to do anything about it. The only thing I might recommend is check under hood to see if you notice any vacuum lines that are disconnected. Also try and see if the Idle Speed Controller is plugged in. Its behind the UIM.

Who built and installed your motor? Is the Pettit ECU setup for the street port and larger fuel pump?

 

It happens with both. I tried a bunch of things and the only thing that affects the RPMs is hitting the gas or clutch+1st gear which raise the rpms by about 0.1.

I mentioned the RPM's in the post. Mazdee's Performance shop did all the work. The car boosts fine except sometimes it does 9-10 PSI instead of 13 PSI, not sure what causes the difference in boost there.

thewird

 

Where?

Must be loosing my eye sight from being on here too much lately...

 

If you are running a full exhaust (i.e no airpump) with the Pettit ECU, you usually need to raise the idle a little higher to around 1100 rpms for it to be smooth. What rpms is your car idling at now?

 

It idles at 0.9-1k RPM when its fully warmed up and not stuck in really bad traffic.

thewird

 

Hehe. So thats what you meant. We refer to that as 900 to 1,000 RPM.

 

Sorry, I just assumed people would know what I was talking about >.<.

thewird

 

thewird,

I would try setting the idle to about 1100 rpms and see if that makes a difference. The problem is the Pettit ECU is not a programmable ECU so it can't account for the airpump being removed. Therefore, to counter-act the lumpy idle effects without the airpump, you generally need to raise the idle up.

For me, anything below 1100 rpms the car just seemed to keep hunting.

 

Well, i'm not sure if the airpump was removed or not and I didn't mention it in the post so either you misread or you know something I don't which is probably the case because I'm a car noob.

Anyway, how would I go about increasing the idle rpms? It only does it when im stuck in stop and go rush hour traffic.

thewird

 

bump

 

That was my mistake. I mistook your exhaust setup to mean a midpipe was installed. However, this does bring up a good thing to check which would be AC fuse. Does your AC work well? The airpump and AC share the same fuse so if its blown, you can have some idle issues (just as if the airpump isn't working).

 

Well, its winter so I don't think there would be a proper way to test it. If you think raising the idle might help, please tell me how to raise it. Thanks.

thewird

 

My drivetrain is all stock other than downpipe and catback. In the winter time (cold outside air temps) I've always noticed when stopped that my idle hunts back and forth a little bit. No sputtering or anything, but a loping that is only present when it's cold outside. I've always suspected the IAT sensor but have never bothered.

 

So I should wait until the summer then to see if it still does it? Thanks.

thewird

 

If the car is not stalling, I would.