Thread: Idle surge causes?

Originally Posted by CrazyGuy03

Wow. Didn't see that coming.... Zero fcks given now. Good luck!

X2. could f ing care less. have fun with your messed up build. if your lucky you didnt just piss everyone else off.

Originally Posted by GTPChristopher

Wow! I was just simply stating that I was looking for advice, not criticism. Why is it that you know it all, but can't offer me simple advice Scotty? There's much reward in being humble, maybe one day you'll learn this. I've been taking pics of my entire build, and wanted to do a full build post. I have the exact opposite of a "sloppy mess", I just wanted to post everything when it's driveable. Sucks that I've put over $12,000 into everything to be belittled over an idle surge. Not saying, just saying.

maybe you should have documented your build while you did it, so you could of had help...but your to good for that crap lol

12 g's, what you f ing smoking over there? send me 5 bucks worth will ya.

how about instead of snarking at him let's be a little more analytical in the approach.

let's ask "how does the PCM set the P0300 code?" it looks for excess oxygen in the exhaust stream and knowns which cylinder fired when it saw the lean condition. (remember, a misfiring cylinder will have *excess* oxygen and read lean to the O2 sensor, not rich, because the unburned fuel did not consume the oxygen in the cylinder). If its a random misfire on all cylinders then the cam could absolutely explain the P0300 code, you have enough overlap on each cylinder that some fresh air is getting into the exhaust and the PCM interprets it as a misfire.

what causes surge? the PCM is cycling the IAC valve in response to *something* because it thinks the mixture is wrong (i.e., O2 readings are not responding as expected) for the given RPM, MAFF, and IPW. Vacuum leak can cause a lean condition, PCM blasts the IAC closed to richen up, then it's too rich, so it opens it again, etc.

taking both of these together: check for obvious and non-obvious vacuum leaks. all hoses, MAFf sensor gasket, EGR tube. Even injector O rings. make sure the O2 sensor wiring is not being rubbed or burned. Make sure the O2 is in the right place and is getting hot enough. then try a new O2 sensor.

Does it surge on P/N only? What happens when you drop it in gear?

My car is doing the same thing as his. The surging only occurs in P and N.

Figured it out. On my car, the vac line to the evap system had a huge hole causing a terrible vac leak

Originally Posted by BoostedPontiac

Figured it out. On my car, the vac line to the evap system had a huge hole causing a terrible vac leak

ding ding ding lol not a tune issue for sure on your car.

I've heard about using the 1/8th hole
in the throttle plate for North Star throttle bodies helps the iac hunting

why not just delete all the evap codes and cap off the port for it on the tb. did that like 3 years ago now.

It was bugging the hell out of me. One minute it was fine, the next minute it fluctuated like a Mofo.

What about the line that goes to the venturi bucket? Cap that off too?

i took the purge solenoid off and the line for it just hangs out back there open to air with no fvcks given lol all 12 codes iirc are deleted.

i had evap codes due to a large leak, so instead if fixing it i deleted it all. i later found the filler vent tube was rotted and fell off. im sure that was the issue. ive since fixed that cause i was smelling gas from it, why it was found, you smell gas you start to look for things.