stilov

So, my car has been running very well lately. Once the temp warmed up...occasionally the idle would hunt at first crank ever so slightly (Only I would notice)

I left my car sitting since Friday morning, started it up last night, idle seemed significantly worse, drove to the store (about 1.5 miles way) Got back in the car, fired right up, then idle went really choppy. CEL light came on, slowly drove home.

Pulled out the durametric

P1518
Porsche fault code 404 - DVE control range

P0638
Porsche fault code 402 - DVE fault: position deviation

P1504
Porsche fault code 410 - DVE fault: necessary intake air position


Recorded codes, cleared them, then car wont start...just turns over (like a car that ran out of gas would) Disconnect the battery and the car will fire up, but just once.

Side notes: Put the car on a dyno two weeks ago with race tune. I flashed back to street tune on last Friday morning. Really only drove it to work and back since. Tried unplugging MAF to see if it made a difference...not really.

Ideas? Thanks guys!

Kevinmacd

It sounds like the drive by wire control circuit

stilov

Ya it looks like most of it point to something with throttle body.

Replace it?

rmc1148

Never heard of a throttle body stopping a car from starting but I have not had much experience with drive by wire.

neanicu

Clean it

neanicu

What's the throttle plate opening at idle? In percentage...

stilov

Not sure...it wont stay running now. Turns over but doesn't fire.

neanicu

Do you have an OBD2 scanner with Live Data capabilities? Put the key on and look for that PID.
I don't remember exactly right now,but if the throttle plate is open for more than 2% you are dealing with a dirty throttle plate.

Macster

Before you do anything else try an E-Gas adaptation.

Check the owners manual for the steps. From memory with the key off and keep your foot off the pedal -- throughout the procedure -- then turn the key on but do not attempt to start the engine.

Wait 60 seconds. Turn the key off. Wait 10 seconds. The adaptation has been done.

After you do this you can read out the fault memory to see if any codes are present. If they are then you'll have to post them.

Another thing you can do is perform the adaptation as detailed in the owners manual then switch on the ignition (again) wait one minute, then actuate the accelerator pedal then switch off the ignition and wait 10 seconds. Then read out the fault memory.

stilov

adaptation done and it runs again...ran smooth for a while

P1518 came back and I watched the live data from the throttle spec, and plate angle

Running well on cold start was 1100-1200 rpm and was at 2.4% then once warm, idle settled to about 800 at 1.9 ish %

Then it started blipping again and the spec throttle angle would jump from 0.4 to about 2. Almost like I was blipping the throttle slightly, but wasn't.

So I only have p1518 and it seems to be the hunting/blipping

neanicu

I've checked on mine. I have a steady 0.6% at idle. Yours is surging.

stilov

Right. I'm going to do a pressure test but I've got to buy a new air hose for my compressor.

I fired it up again and let it run for about 10 min and it idled well.

I was thinking either throttle body or vac leak, however after researching and testing. I'm leaning towards throttle body. If it was a vac leak, I'd think the problem would be more consistent.

neanicu

If it was a significant vacuum leak you would see it in your fuel trims.

stilov

Good call. The lambda stayed steady right about 1.00 but when I would purposely blip the throttle they'd drop to around .94ish. So no real rich issues.

neanicu

I suggest to start with the basics before tearing deeper into it. You said you had a tune but reversed back to stock. The problem started right after. Maybe something went wrong in that process...just thinking here...