Topic

I everyone,
A couple of weeks ago I brang my tf160 to a workshop that had the T4 to see whether he could get rid of my engine light that was on from the beginning. We didn't find anything but he made some adjustment to the air intake I guess saying that it was way too high or something according to the T4. The result was the engine reving too high when not in gear. It was 1000rpm instead of the usual 800rpm. But I first thought it was supposed to be that way until today it started reving at 1500 rpm in neutral. And eventually when restarting it again and again it would drop at 800rpm or 1000rpm. I also noticed that the idle wasn't stable at all, it's like someone was lightly reving it.
Here are the live data indicated by my pscan if it can help.

Do you have any idea how I can undone this with the pscan or another way ? Or maybe is it something else ?
Thanks for your help

Kelvin

It is probably a sticking IVAC or an air leak some where on the inlet manifold.

Try resetting the stepper motor. Also check what step the stepper motor is on. It is shown on your pscan readout somewhere.

Thanks for your answers
I did the reset, seems to work but the engine is like hesitating when I stop the car it stays at 1200 rpm for 1sec and then drop at 1000 rpm. Some improvement !
By the way what is the stepper motor David ?

Alright I just googled what the iacv or stepper motor is, I understand now.
I will check that with my pscan tomorrow and I'll come back to you
Cheers

From your photo you can see your idle error is 307 rpm which suggests that the stepper motor is sitting on too high a step.
I believe a warm engine should show step 25 or 26.
Check this pdf from cairnsys showing mems3 data.
https://www.the-t-bar.com/forum/attachment/26489

Here are the data I collected with my pscan when engine warmed up.
I'm going to reset it one more time to see what changes

After the second reset here's what I've got.
Thought ?

The first set- the throttle butterfly is slightly open at 11 degrees, but the step is 22. The idle is too high
The second set - the throttle angle is in the closed idle position at 4 degrees but the step is 8. The idle speed is slightly low but close to normal.

That is a truly confusing set of results.

Ideally, the up to temp. idle speed should be 875 and the step 25 or 26. The throttle angle should be 4.7 -5 degrees at idle.
I think you can disregard the first set of results, so looking at the second set it appears that the step is too low. Normally you would screw in the idle adjustment screw to raise the idle, and then wait. The stepper motor would probably drop the idle speed again and you would readjust and wait. Repeat until the idle stayed at 875 for at least 5 minutes.

However I think you need to check that your throttle butterfly is opening and closing freely. Is the cable moving freely. Also, as James mentioned earlier the stepper/IACV may be gummed up. You can remove it and clean with carb cleaner spray..
Check for air leaks

I took it the worchop this afternoon, it seems there is no air leak and that the butterfly is moving freely. According to him it just needs to be adjusted with the T4.
I'll give you the feedback when he is done
Thanks again !