Idle issue after heads/cam
03-16-2018, 06:01 PM
#1
Idle issue after heads/cam I just finished up a heads and cam swap with a dls2 intake and the 85mm Maf. I'll start out by saying it's not fully tuned. I had my guy come by and install a quick tune for the new 42lb injectors so I could start it up. Hes coming by this weekend to finish but there's a weird issue.
When I start the car it'll idle for a few minutes until it starts to warm up then it'll start stumbling and then dies. When I start it back up I have to give it a little throttle so it'll stay around 1000. Without moving my foot it starts to bounce around between 1100 and 800 rpms. I realise the tune will help but is there anything I should double check that might cause this before we start working on it with the wideband?
Thanks
When I start the car it'll idle for a few minutes until it starts to warm up then it'll start stumbling and then dies. When I start it back up I have to give it a little throttle so it'll stay around 1000. Without moving my foot it starts to bounce around between 1100 and 800 rpms. I realise the tune will help but is there anything I should double check that might cause this before we start working on it with the wideband?
Thanks
Last edited by jaxcam02; 03-16-2018 at 06:11 PM.
03-16-2018, 06:59 PM
#4
TECH Fanatic
You just changed all the vacuum properties for your engine. If it was stock before, it was making great vacuum at idle. Bigger aftermarket cams/heads are going to idle with much less vacuum, like a lot less. You also changed your compression values, again, because of the cam.
You just need a tune. Don't sweat it. It's perfectly normal for it to do that, and idle like crap. If you feel the need to do anything before tuning it, you can open the TB about 1/4 turn at a time and see if that helps. Make sure you reset it each time. It needs more air, plain and simple, due to the reduced airflow at idle, i.e. lack of vacuum. And of course, a tune, which will involve those same adjustments, in addition to fuel and spark.
You just need a tune. Don't sweat it. It's perfectly normal for it to do that, and idle like crap. If you feel the need to do anything before tuning it, you can open the TB about 1/4 turn at a time and see if that helps. Make sure you reset it each time. It needs more air, plain and simple, due to the reduced airflow at idle, i.e. lack of vacuum. And of course, a tune, which will involve those same adjustments, in addition to fuel and spark.
03-17-2018, 12:45 PM
#7
You probably need to open the throttle blade some and do a TPS/IAC reset. DONT drill a bigger hole in the T/B.
You want your IAC counts around 30 at a hot idle.
Log your TPS%, IAC counts and desired idle.
The RAF table probably needs more air too but adjusting the T/B blade should get it idling unless your cam is huge.
You want your IAC counts around 30 at a hot idle.
Log your TPS%, IAC counts and desired idle.
The RAF table probably needs more air too but adjusting the T/B blade should get it idling unless your cam is huge.
Trending Topics
03-17-2018, 08:44 PM
#8
You probably need to open the throttle blade some and do a TPS/IAC reset. DONT drill a bigger hole in the T/B.
You want your IAC counts around 30 at a hot idle.
Log your TPS%, IAC counts and desired idle.
The RAF table probably needs more air too but adjusting the T/B blade should get it idling unless your cam is huge.
You want your IAC counts around 30 at a hot idle.
Log your TPS%, IAC counts and desired idle.
The RAF table probably needs more air too but adjusting the T/B blade should get it idling unless your cam is huge.
Yea I adjusted the screw a bit and it's idling much easier. We're going to finish the tune tomorrow. I shall report tomorrow with results.
