[JST1FIX]

I have a 19 SS 1LE M6 with K&N CAI, Soler ported 95mm/100mm effective TB, MSD intake, Katech ported GM heads, GPI LT-NFC cam.

I had it dyno and driveability tuned by a trusted local shop and it ran well. But, after driving it home it developed a surge at idle from 800 to 1200 RPM. It would also drastically drop RPM when pushing in the clutch to come to a stop and then recover. Long story short, I have taken it back three times to the tuner, and everytime he is able to adjust the torque settings so that it works well again. But, every time after bringing it home it starts the same surging and sometimes stalls when pushing the clutch in to stop. I even disconnected the battery and did a relearn which worked until I left it sit in the garage for 6 hours and drove it again and it was all back to acting up. I did spray ether around the intake and TB checking for leaks and had no change in idle. It will straighten out and idle eventually, but when driving it goes right back to the problems. Any ideas?

[ctrlz]

Is the tuner road testing the car? it sounds like you have a vacuum leak that is coming and going as parts shift around. I would guess intake, as there have been multiple reports of leaks around MSD intakes here.

[Mark114]

It could also be an air leak in the PCV system. That caused surging with my car.

[ctrlz]

Make sure all the gaps closed when you torqued the intake:
https://www.camaro6.com/forums/showp...67&postcount=9

[radz28]

Have you tried Soler's TB relearn?

[Megahurtz]

just a wild guess without a datalog

[ctrlz]

Originally Posted by Megahurtz

just a wild guess without a datalog

yeah, like a lot of threads here.
I would not go back to the tuner until I figured out what went wrong. Three times and the guy can't fix it does not speak well for his diagnostic skills. And the tuner should have the tools to get data while driving the car.

[JST1FIX]

Originally Posted by ctrlz

Is the tuner road testing the car? it sounds like you have a vacuum leak that is coming and going as parts shift around. I would guess intake, as there have been multiple reports of leaks around MSD intakes here.

Yes, I actually rode around with him while he was tuning. He would get it straightened out, and it's almost like it relearns the problem. Like I said, I did check for leaks around the intake manifold and CAI with starting fluid and got no fluctuation in idle. I would think if it had a vacuum leak it would be constant.

[JST1FIX]

Originally Posted by radz28

Have you tried Soler's TB relearn?

I have not. I will look into that. Thanks.

[JST1FIX]

Originally Posted by Mark114

It could also be an air leak in the PCV system. That caused surging with my car.

That's a good point. I will check into that also. I don't understand why it would clear up with tuning and then seem to relearn the issue though.

[ctrlz]

Originally Posted by JST1FIX

That's a good point. I will check into that also. I don't understand why it would clear up with tuning and then seem to relearn the issue though.

I would try tugging and pulling on the intake and the connected plumbing while the car is idling.
The tuner should be able to see what is going on to cause the car to surge. It is surging based on data it is getting from the sensors. If it is going lean (like form a vacuum leak), you should be able to see that on the O2 sensors and the fuel trims.
This doesn't sound electrical or fuel related. There are enough threads here on these MSD intakes with leaks that make me keep suspecting that as the problem.