Random Missing

[giant noob]

I had a shop swap a six bolt into my 2g by a DSM shop. Once i got the car back it idled over 2000rpm at start up and would randomly rev the engine between 600-3000rpm. It also would lose power and stutter if the car was driven at a constant rpm over 2000 (usually on the freeway) for about a min, but it doesn't always do this (all i have to do is push the clutch in and let the rpm drop to below 1000 to have the stuttering go away). I told the shop and they said it was probably boost leak, due to a bad throttle body. I had them replace the throttle body. when i got the car back nothing had changed. I got kinda fed up with the shop and decided to deal with it later. It is now later. Any ideas will help.

 

[jim95redgsx]

With a 6 bolt swap, you're obviously running a 1G CAS. This will result in false misfires. http://www.dsmtuners.com/threads/po300-code-like-clockwork.481913/#post-153445000

The idle surge is a different problem. There is too much air getting into the engine at idle. This results in a too high idle speed. The ECU will then cut off fuel until the RPM's drop. Then it starts all over again. This can be caused by many things but most likely is a vacuum/boost leak at or after the throttle body.

It could also be caused by the IAC, FIAC, throttle body or intake manifold gaskets or a too tight throttle cable.

Jim

 

[giant noob]

Wow, thanks for the info. Ill try this stuff this weekend.

 

[bmxfelon420]

The easiest non hack way to fix the random misfires is to just get ECMlink and disable random misfire detection. Otherwise you have to wire a potentiometer to fool the baro input into disabling the misfire detection routine, which is a half assed way to do it, if you ask me. Plus, ECMlink is probably the first thing anyone should buy anyways in terms of upgrades.

 

[giant noob]

Im just looking for the cheapest fix so i can sell a reliable running car.[DOUBLEPOST=1417930097][/DOUBLEPOST]Is there a way of converting the car back to a 2g cas or do i need to wire in a resistor.

 

[bmxfelon420]

A cheap way? Not really. This would be the best way to do it: http://kiggly-racing.com/all/6-bolt-crank-trigger-sensor.html

Otherwise, you have to run the potentiometer. Is your car missing the MDP sensor? I believe thats what it wires into.

 

[95GSTowner]

+1 to what these guys said above. For idle issue my 1st guess would be IAC. Check your injector seals as well. Also, ecmlink v3 is the way to go when fixing the random misfire problem. With my 6-bolt swap, I'm running a black 1G cam angle sensor (Hall effect) and I still got random misfire until I installed ECMlink.