Idle problem with 3.6 engine

[PcarPhil]

Originally Posted by shahram

Scott, I have exactly the same problem.

shahram - My '88 911 w/ '97 3.6 euro Varioram engine is a new to me car and the idle issue is one that I'm actively investigating.

I too have a Wong chip and a 1400 RPM idle. This chip was installed when I started my high idle troubleshooting. During the process I swapped in the Cyntex chip I also have which gives a 1200 RPM idle. Still too high. So I swapped back in the Wong chip to continue troubleshooting.

Originally Posted by shahram

ISV Trick wont work for me. the ECU kicks it back to 1400 no matter how I rotate or disconnect the ISV.

Same here, mostly. I can uplug the ISV and set the idle wherever I want (currently set at 950 RPM unplugged) however as soon as I plug the ISV back in the ECU sets the idle at 1400 (Wong) or 1200 (Cyntex). I tried leaving the ISV unplugged however this causes stalling issues.

I have a few questions for you:

Have you spoke with Steve Wong about the 1400 RPM idle?

Have you performed the idle adaptation that's mentioned in the Wong chip installation instructions?

"Disconnect power from the DME by removing it and wait till the memory clears. Then try reconnecting it and follow the procedure to turn on the key for 3 minutes without turning on the engine, then turn on the car for 3 minutes and allow it to idle. Then turn off and repeat three times, so that the idle potentiometer readings adapt to the DME, so it learns the idle position readings, part throttle, and full throttle."

What is the part number on your Wong chip and what is the part number on your DME?

Mine is p/n 993.98.EU.678 for the Wong chip and the DME is 993.618.124.04 / 0 261 203 675.

My next few steps for troubleshooting this issue are:

- Complete idle adaptation. I performed the above procedure a few days ago however I haven't had a chance to drive the car to see if it made a difference. I especially want to make a few drive cycles before doing any additional troubleshooting.

- Wire in an OBD port into DME harness. Check codes and verify engine is running idle code at idle.

Originally Posted by shahram

Does anybody know that the Idle RPM can just be set to 800 in the ECU/Chip?

I don't think you'll want to do that as I think you'll encounter stalling due to the lightweight flywheel. I'm thinking 950 RPM is my target idle speed.

I'll keep you updated on my troubleshooting. I may end up asking you if I could borrow your stock DME chip (I don't have one) to see if it produces the same 1300 RPM on my engine.

[john walker's workshop]

Originally Posted by bigchillcar

don't use carb cleaner, but buy some brake cleaner and pray around your intake area and listen for the sound of the engine rpm increasing...that would indicate a leak. brake cleaner is more volatile then air, so you'd expect an increase.
ryan

brake cleaner produces phosgene gas when it goes through and engine.

[PcarPhil]

Originally Posted by Kaefer

My next few steps for troubleshooting this issue are:

- Complete idle adaptation. I performed the above procedure a few days ago however I haven't had a chance to drive the car to see if it made a difference. I especially want to make a few drive cycles before doing any additional troubleshooting.

- Wire in an OBD port into DME harness. Check codes and verify engine is running idle code at idle.

A quick update - I've performed the idle adaptation and now I have a few drive cycles on the car. With the currently installed Steve Wong chip the car seems to idle around 1200 RPM (down from 1400 with this chip). I haven't tried the Cyntex chip again along with an idle adaptation.

While this is an improvement I'd really like to try and get the idle around 950-1000 or so.

I'll keep everyone updated on any additional progress I make...

[PcarPhil]

Another update - I let the car sit with battery disconnected for a few days, then reconnected the battery and performed another idle adaptation. Now the idle seems to be normal for a 3.6 Varioram engine with lightweight flywheel.

Basically when driving the car and coming to a stop the engine drops to 1050 RPM for 10 seconds or so, then it drops down to 950 RPM. This works for me...

If anything changes I'll let everyone know however the idle problem seems to be fixed.