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!

 

If car fires up after battery disconnect and then will not after first start its probably DME related or maybe intermittent fuel pump/relay issue.

 

dme related...that doesn't sound good.

Should I try re flashing the map?

 

I would go back to tune you had last when running well and see what happens.

 

Maybe bad gas. Injectors. Fuel pump on the way out. You can swap tune and see. But I don't think that will change, maybe ecu

 

I'm with what's the last thing you did and then also in a connected way how good an idea is it to switch files back and forth on a 10 + year old ecu or does that not ever matter?

Its something to consider..maybe

Nasty sounding codes. Good luck w it....

 

e gas adaptation made it run again...easy enough. p1518 came back, although intermittent...hunting idle. Sort of like light throttle stabs.

I'm leaning towards TB based on diagnosis procedures and watching live data from durametric.

 

Interesting that the tb would act up so quickly sounds more like the MAF or vac leak sounds like you have a handle on it at least.

 

I'm going to do a pressure test first...I need to go buy a new hose for my compressor.

That way I can rule it out...it does seem like a vac leak, but watching how through the durametric...you can see where all the sudden the throttle will stab, and show higher voltage. When its running smoothly, the value shows much closer to zero.

I thought MAF too, but the 1518 code according to Porsche diagnosis, points to throttle actuation. And I unplugged the MAF and tried that...no real change when I unplugged it. Assuming it was bad and caused the problem, I would at least think I'd get a higher smooth idle.

Oh and fuel trims are fine too, along with MAF voltage.

Ya, I'll fix it...its funny, this is the first "issue" I've had with the car really. Its been one of the better cars I've owned.

 

There is a post by wross996tt that lists diagnosing 1518 code may help. I used search but I'm an idiot with computers or I would have linked.

 

Pressure test revealed large vac leak of a Jose coming off the tb. No cels back yet.

Just an update.

 

please go put in a new maf and "if" it solves the issues?, then you don't have to say.. though admittedly those are more ominous codes than a faulty maf might suggest. But If it works? Unplugging it to determine if its working, as it should, is not enough.

You'd be amazed, ( as I am continually ) as to how important the integrity of the few "sensors" this car has are to its overall health and smooth running efficiency..particularly if tuned etc

 

That should narrow it down considerably lol.

 

A little update...the 1518 came back but with a 1515 this time (after driving a couple days) The idle felt a lot better though.
I decided the steps I'd take were clean the TB (the 1515 was saying the throttle body wasn't closing fast enough)
Then if that didn't work...replace the TB. Last night I pulled the y pipe and attempted to clean it.

I ended up pulling it off and compared it to the other TB I had...
LOL