freeplay

1. My downpipe is cracked right around my o2 sensor
2. My thermoswitch is broken

My idle jumps up and down drasticaly until my car warms up. It's very annoying and I am hoping to get some ideas as to what it is. Thanks in advance.

shermanyang

iTrader: (1)

don't know but thick oil is my problem...not very smart of me to run 15w50 at this time of year

Tofurky

maybe a vacuum leak?

freeplay

would it really be a vac leak if it only happens when my car is cold?

AP-Signworks1

It can be. I had a vacuum leak at the IM gasket, and it would get worse on cold days. During the summer, car idles fine most of the time. But when it got cold, the idle went all erratic and high. It would sometimes fluctuate from 1-1.5K sometimes stutter, and so on. The vacuum often read lower at idle on cold days. I replaced the gasket, problem solved.

redboost10

i had the same problem about two weeks ago over here in oregon where its been like 45 degrees all day and i had some pretty heavy stuff in there like 20w-something, and i changed it to 5w-30 and dosnt do it anymore

Distorted

I frequently had this problem(when my car ran) once i switched to DSM 450cc injectors. I think its an issure with rescaling the fuel map using the V-AFC coupled with a cold O2 sensor giving you inacurate readings while cold. If you have a A/F guage watch your values as it starts, commonly you'll see them as being exceptionally rich. This is because the standard narrow band O2 sensor doesn't get heated up to opperating temperatures before the car is started, causing it to give incorrect readins and allowing the ecu to read that as a need to dump extra fuel. Let the car warm up for 3-5 minutes and give it 1 good reve to 3000rpm and it should idle fine after that, no stutter. If you had an wideband O2 sensor that also sent the proper narrow band readings to your ECU then this would not occur, because wideband O2 sensors are commonly heated up before starting the car, still takes time. Just warm your car up right and this shouldnt happen, or rescale your fuel values. Some say its only the DSM 450's that do this, but that blastphamy.

freeplay

so if it was my intake manifold gasket, why would it only happen if it was cold? same with the oil? is it because it expands or gets smoother or what?

boostedbastard

I am not the smartest person in the world but I had that same problem out of my hatch with a b18. It ran fine with the dx ecu but when i installed the p75 it went through a fit during warm-up. Have you changed the ecu or any fuel components?

freeplay

no fuel or ecu upgrades

IMPORTant Si

sounds like a bad IAC sensor....

96IntegraRS

Are you running coolant through the throttle body??? The sensor there will cause the cold idle to fluctuate... if you have rerouted the lines to decrease air intake temps this is the result.