I had a similar issue, CEL, unstable idle and almost stalling. All codes pointed to an air leak. But negative on smoke tests led to perplexed techs. Thanks to great collaboration between my dealership, tuner and a now local shop, the unlikely failure of a MAF turned out to be the issue. Apparently you can disconnect the MAF sensors and then test drive the car and if the symptoms do not persist you can assume its a bad MAF sensor.

 

I wish my problem was as simple as MAF sensors. I recently replaced mine (and I did try driving around w/ them unplugged, but it didn't alleviate the problems). RaceCo found a few more issues (bad check valves) so we will see...

 

Steamboat/Cam,

Sorry about the problems, just trying to help here: Have you considered having EVOMS flash your ECU back to stock program, at least to eliminate the tune itself as the problem? It's easy and should be free and could be done by local EVOMS retailer. Once problems solved, they could then flash you back to EVOMS program.

If all else have failed, IMHO the easiest and cheapest thing once it has become a seemingly wild goose chase is by elimination: one by one returning everything to stock, starting with the tune and the IPD plenum. Painful but hopefully you bought the car with EVOMS already on and therefore didn't pay full retail price?

Cam, I had EVOMS Stage 2 in my car previously and found out with that particular tune the software/firmware/etc. was written to raise the idle rpm from approx. 770 (stock) to 850 (EVOMS). I don't know whether the tune (vs. hardware) is causing the idle wandering in your car but it is something to check with EVOMS.

 

I picked up my car on Friday and took it to the track yesterday where it performed flawlessly. By the third run session at 1:30 PM it was 98' ambient under sunny sky's which was uncannily similar to the July day two years ago when my turbo failed, munched the motor and left me with a $50K bill. So I retired knowing I'll fight again some other day. The R-888's were left at home as the weather forecast called for heavy rains which, of course, failed to materialize. I can't say much more than the wheels look great and take up a bunch of space in the garage.

Back to the MAF's: As I posted previously, the flow rate of the sensor on Bank 1 was reading 0.200 gps less than the sensor on Bank 2 which was problematic. The driver side voltage was 1.6v and the passenger side was 1.3v. When they were both replaced, flow rates equalized and both sides read 1.1v. Fuel trims were adapting to a stoichometric mixture, a 14.7:1 ratio which is that ideal point where all the gasoline and air are completely utilized during combustion or "not too rich and not too lean". Here are a couple of good articles on the subjects since this stuff is way out of my pay grade:
http://en.wikipedia.org/wiki/Mass_flow_sensorhttp://www.obd-codes.com/faq/fuel-trims.php
http://en.wikipedia.org/wiki/Stoichiometry
Also, fwiw, the oem MAFs were $735 each and compatibility with a given vehicle can only be ensured by ordering based upon VIN number. Suncoast, for example, lists several MAFs for Porsche's ranging from $360-$1175 ($1665 retail) each so I assume there are some significant differences between types. Anyway, so far, so good as no CEL's or DTC's have reappeared in 400 miles. But, I think I'll wait another 1,500 miles or so before declaring final victory.

 

Good to hear Steamboat! Iirc, you have EVOMS turbo inlet pipes, right? Any fitment issues? Appreciate any comments on them.

 

Bogg, You are correct. My turbo has the Evoms high flow turbo inlet ducts which were installed at Evoms HQ during the rebuild. Zero issues to report so my only comment would be that they seem to serve their intended purpose just fine. Hope that helps. Best,

 

thanks. I had read that some guys bought the 996tt inlet pipes from them but they had to be modified to make them fit. I am still toying with the idea of 68vtg turbos and the Evoms inlet pipes are much cheaper than the carbon fibre CMS ones.

 

Well if you do want the evoms hoses I have a new unused set I would maybe sell for a price we were both happy with.

 

Yeah?? PM me a price shipped to Canada when you get a chance. How come you are selling them?

 

I will pm you a price no probs just pm me the zip code please.

I'm selling as I will be going a different route in the near future.

 

Just got back from RaceCo. I went up to test drive the car after the latest round of "fixes." Within forty miles I had the long term fuel trims to +32, the idle stuck at 1400 RMPs and the and "air leak" code. Still haven't found the real problem.

But that's going to be it for me, gentlemen. I've pumped $20K into this car since owning it. When it's working it's amazing, plain and simple. But I've lost the love at this point and don't have the patience to pursue the matter any further (and I've got other projects that need my attention). Given all we have done I'm sure a trip to EVOMS could get the car in proper working order but I'm just not up for it. If anyone is interested in the car please feel free to PM me.

The 911 will always have a place in my heart - it was my dream to own one since I saw Condorman as a little boy. Thanks for the good times! I'll see you guys around.

 

Okay, so I didn't give up. Ian (Evoms) and Cole (RaceCo) convinced me to give it a little more time so we did a few more rounds of troubleshooting. What ultimately seemed to help was a new / updated tune. EVOMS rewrote my tune from the ground up to make sure there were no issues. 150 miles so far and she's running great (and no ominous foreshadowings).

This is a huge step in the right direction. I wish we'd looked at the tune sooner, but on the plus side a lot of small things were replaced / repaired and I have the benefit of knowing that the car is in excellent mechanical shape.

Cam

 

I understand you being happy, but are you not somewhat irritated on evoms if it is truly their tune that is to blame for this?

 

Seems like this happens on a lot of EVOMS cars. What exactly in the "tune" caused your issues?

Steve

 

Well, I wouldn't say I'm "happy" but I'm feeling more positive. I can't say with 100% certainty that the tune is to blame (and it certainly wasn't the only issue), but it has made the biggest difference so far. For the record I think it was nice of EVOMS to redo my tune.

I'm not aware of it happening often- in most cases I know of it seems like the tune hasn't been the issue (hence the reluctance to investigate it from the start). Ian told me this:

It was interesting to me that the more RaceCo repaired the worse the car seemed to get. But if you look at it from a tuning perspective then it makes more sense.

Anyway, so far so good! That being said, I'm not sure if I will keep the car (which breaks my heart). But at least the new owner will get the car I wish I had gotten and the experience won't be tainted.

-Cam