Thread: High jumpy idle after new turbo isntall - 500-4500rpm - video

So the great news is that I finally got the car started after about 10 weeks (thanks Daryl aka dphillips). The bad news is that I have a problem that didn't exist prior to the upgrade.

The short story on the upgrade. I had a t25 setup on the car, and upgraded to a gt2860rs. Everything that needed to be upgraded was. Running JWT ECU.

The problem is the idle is controlling itself. The idle jumps between 500-4500rpm, and doesn't stop, it just keeps fluctuating. Never had this problem on the old setup. However, numerous things were removed. All emissions equipment were removed. So a few questions.

1. Do I need to keep the solenoid plugged in where the EGR was, or will that not affect anything (other than throwing a code)?

2. Do I need to keep the Carbon Canister solenoid plugged in, or will that not affect anything (other than throwing a code)?

3. I searched and read through a lot of threads, but most idle issues are not like mine (so high). Should I still try and adjust base idle? Or will I be unable to because of the jumpiness?

4. New z32 MAF wired incorrectly?

Here is a video of the idle (only 2.2mb). Whats interesting is, there is no vacuum reading at the low idle, but normal vacuum reading on the high idle. The boost line is shared with the AFPR line.

www.kpapartments.com/high_idle.wmv

After this much time without the car, I am dying to get this thing back on the road. I absolutely need to get this figured out in the next few days, as I will be back in school, and need to get the car running properly. So any advice is appreciated.

Here are a few pics of the new setup.

Just an update. I got the DVM on the TPS this morning. It was waaaay off (1v). So I got that adjusted properly. The car is behaving better than the video. The new behavior is about 1100rpm idle, jumping to 3000rpm idle, then drops to 2000rpm and sits for about 3 seconds, then back to 1100rpm.

What would be the next adjustment?

Also, the vacuum reading is still strange. I am not seeing vacuum at 1100rpm, but I see normal vacuum (-12 with S4 cams) when it revs up. Here is my vacuum setup.

afpr and boost gauge one nipple.
wastegate to another nipple.
boost controller to another nipple.
All other nipples capped off.

You have a massive vacuum leak then or your vac line isnt in a very good spot. Did you move it around from where you had it previously.

Its looks like you put some jdm intake runners on, is this the case?

Where are you feeding your vac gauge off of. You should be off on of the ports behind the throttle body on the plenum. Not off one of the two bottom ports that attach to the throttle body itself. This could cause that little to no vac reading until velocity in the intake is picked up from the revs raising up.

I would definetly search for a leak somewhere. It seems to be the only proper cause for something like that.

As far as the sensors are concerned. The only one you need to leave plugged in depending on what emissions your car came with is the EGR temp sensor, but if it doesnt have California emmissions on it then you can unplug them all without issues. Thats how mine is and ive never had a check engine light on.

Thanks Ashton. Let me address some of your questions.

Its looks like you put some jdm intake runners on, is this the case?
When I purchased the car, a newer JDM engine was swapped in. However it had EGR and AIV on it. They were removed.

Where are you feeding your vac gauge off of.
The gauge is t-ed into the afpr line, which is right behind the throttle body.
Not off one of the two bottom ports that attach to the throttle body itself.

I would definetly search for a leak somewhere. It seems to be the only proper cause for something like that.
I have my boost controller going to a bottom port right now. The BOV goes to a line after the TB. Should I just T the boost controller in to the same line as the BOV, and cap off the two ports under the TB?

As far as the sensors are concerned. The only one you need to leave plugged in depending on what emissions your car came with is the EGR temp sensor, but if it doesnt have California emmissions on it then you can unplug them all without issues. Thats how mine is and ive never had a check engine light on.
So I should plug the sensor/solenoid back in at the end of the injector harness? The carbon canister solenoid can be removed completely and capped off?

I will look for any other leaks. Its a brand new IC pipe setup, and everything looks tight. But I will mess around with the vacuum lines and a few things and see what comes of it.

I moved some vacuum lines around, got the recirc welded on and hooked up. Cleaned the maf and plugs, regrounded the maf. Tried setting base idle in timing mode, but near impossible to do since its acting so poorly.

So with the TPS plugged in, the car idles around 1200, and fluctuates to 2000rpm. When its unplugged, it pegs itself at 3250rpm. Any thoughts? Very frustrated right now. Thanks,

I'm convinced you have a serious vacuum leak somewhere, but without being there in person I couldn't begin to help you find it.

Maybe remove the air filter and tape up the air intake and then start the thing up and listen for the leak? Just throwing a crazy idea out there...

Here is a new video with the idle situation as it stands. I just dont know where a vacuum leak could be. I have gone over everything a million times

I get the feeling like it's only dropping the idle because you've corrected the TPS reading. When you did that, the ECU knows now that you don't have the throttle pressed any, so it's running into the fuel over-run cut limit which is around 2k rpm. If you slightly open the throttle to overcome that setting I bet the idle would go right back up to 4.5k or something. That's a lot of air. That's not some small leak.

Try taking the filter off and taping over the air intake right in front of the MAF. Or put a plastic bag over the filter to choke it. Then start the car and rev it. You should be able to hear where the air is rushing in.

Ok, I will give that a try.