I should have looked at your sig. That's really good info- thank you!

Haha, no. My Vette doesn't have a wing

 

I had two new intercoolers installed. RaceCo double checked everything for leaks, test drove it over a hundred miles and said it was ready to go! I made it about 25 miles before I was back where I started. Air leak, CEL, same codes. Back it went.

I'll give it one more shot. but I think I'm about ready to throw in the towel.

 

Jeez I feel bad this is happening, but at least you still have your humor.

 

I feel sort of bad too. Based on the cost of my last repair it costs me $200/mile to drive this thing (not counting gas or counseling).

 

Cam,
My story, which is quite similar to yours, continues as well. Last week after running 400+ miles CEL free, the light reappeared and threw 3 DTC's (lean bank 1, lean bank 2 and air leak) when hooked to my scanner. In addition, the idle got hung at 1200-1400 rpm a couple of times which was a first for me. After I erased the codes, they have not returned in 150+ miles, the idle returned to normal and the car is running great.

The guys at 3Zero3 Motorsports in Denver are flummoxed. They have been over every connection and replaced the hose clamps with t-bolt clamps wherever they would fit. Smoke tests remain negative. One would think that IF there is an air leak, simply restarting the car and erasing the code would not fix it. Ergo, perhaps there ISN'T an air leak. Similarly, one wouldn't think that the software (tune) would arbitrarily change every few hundred miles either which has us thinking that perhaps a sensor, one or both of the MAFs, may be intermittently failing and transmitting bogus data resulting in DTCs to be erroneously thrown. The MAFs have been recently cleaned and seem to test out fine but like your shop, Evoms and all the rest, we are running out of ideas. So, my car goes in on Thursday and will have remanufactured MAFs installed (saving about $600 compared to new ones) and we'll see where that gets us. It will also be smoke tested just to make sure but I"m pretty sure they've gotten all the leaks. The good news, I suppose, is the car is running great and I can clear the codes and CEL with my $100 scanner in about 30 seconds. I'll keep you posted if the MAFs have a beneficial effect. Good luck to all of us. Best,

 

Well at least you made it 400 miles! Those are the same codes I'm getting. I have the idle issue too (always have).

You're right - resetting the car shouldn't fix an air leak. And the tune shouldn't change either.

Just out of curiosity what pressure are you guys testing at? These cars build up to about 24 pounds of boost. Do you pay attention to your long term fuel trims? Mine rise and rise until the car gives up (around +32%). But until they hit the top end the car runs okay.

What kind of MAF sensors are you putting in that thing? New ones don't cost anywhere near $600. I just put in new MAF sensors. I don't think that's going to be the issue, but keep me posted.

You certainly seem to be taking it all in stride. I'm not planning on taking it much longer myself...

 

I have to believe that there's a rational explanation for these symptoms; we just haven't found it yet. Usually I get 300-400 miles before a recurrence but I've gone as long as 1,700 miles this summer. What's up with that? If anyone has any other ideas, I'd love to hear/see them!

I don't know what pressure they test at but I'll check. When the last CEL appeared, I was just toodling out of a gas station under zero boost and going about 40 mph. Nothing high pressure about that.

Also will inquire about the LTFT. I can't monitor that with my scanner - not a Durametric - so I don't know how they trend. I wonder if your high readings could be a result of bogus data from a sensor?

What type of MAFs have you installed? Replacement units from Suncoast are $400-$500 each compared to remanufactured at ~$180. I found some new oem ones on Amazon for about $200 but the shop said they were incompatible with my vehicle. I guess I'm willing to roll the dice for a few hundred bucks but I'm getting tired of parting with $1,000 bills......

It's all very frustrating. On a happy note, my R-888's and OZ wheels shipped today from Tirerack!! Onward!

 

You will have to excuse my ignorance, I am new to the ownership of my 997 evt700. I have had multiple problems with the car (none of which I can blame on any one person or company). A lot of tuners have had hands on my car and so i have had to rely on process of elimination to fix my cars issues.

One problem I came across was with the boost recirculation valves. I had leak tested the system and found no leaks. Every time I drove the car I would get symptoms of a boost leak but it would be intermittent. I decided to take out the brv's and found not only were the O-ring's split and pinched (the ones that seal the brv to the inside of the turbo) but the lube used to grease the piston had become dirty and was very sticky. I cleaned them, greased them and replaced the O-rings and my boost leak problems are gone.

Other issues continued so I took a friends advise and went with a protomotive mafless tune and that fixed a huge host of issues. My biggest problem now is the horrible fuel we have here in California. My car wants 100+ octane to run well in sport mode. With what is available here in Ca I'm thinking my only good option is to go e85.

Try servicing the brv's. It is very easy and inexpensive thing to check.

 

v10nut,
Thanks for your response. Although we've been down the BRV road before, perhaps it's worth another look. Do you know if you were running the oem valves or the Evoms product? Another mechanic has suggested the same thing and BRV's would be a lot easier to fix than some of the other alternatives we are considering.

If I can ask, what other issues were you facing that led you to the Protomotive tune? Thanks,

 

They are the evoms bov's. The nice thing about them is that they are easy to service. I will post about the rest when I have some time.

 

I am fairly sure my maf sensor was the main reason for my car running so poorly. The issues started in sport mode. Under wot the car would buck and the power would come and go. Then the car started to do that in standard mode. In sport mode it began backfiring and the power level felt like I had blown a boost hose completely off. It idled ok but anytime I got on the throttle the car would jump and buck and sputter. As soon as I did the mafless tune the car was better in every way. Cold start was much smoother and the car drove much better during the warm up period. All issues in regular driving mode vanished. Sport mode still gave be some strange jumps and loss in power depending on the rpm. Out of frustration I decided to try some torco octane booster and that did it. All power issues were gone and the car has way more power than it did previously. Unfortunately for my wallet my heads and cam viper is still faster than my porsche so I am really considering going to e85. I really need my turbo to be a beast! I guess its an illness.

 

v10nut, thanks for the info. Question:

So did you get a CEL when you were having this issue? If yes do you recall what the codes were?

 

The car never gave me a cel which I found odd.

 

My car went into the shop today. They will pull the BRV's even though like v10nut they vacuum test fine. My car has slipped into limp mode on two occasions without throwing a CEL but does throw a DTC (air leak) on the scanner. My shop guys, UTPorsche's and Evoms are all collaborating on this at this point in time. There certainly are enough car brains involved but this is proving to be a tough one to figure out. More as it becomes available........

 

Well, it appears that the mass airflow sensors are failing. The shop observed a 0.2 gram/second flow differential side to side (should be 0.0) which is about a 15% variance from normal or more than enough to cause intermittent gremlins. Anyway, we'll replace with Porsche oem parts as Porsche individually calibrates the flow meters for the housings they reside in. A bit more expensive but after all we've been through, more than worth it if it fixes the problem.

Also the shop pulled the diverter valves which were fine and conducted another smoke test which revealed no air leaks. Hopefully we're getting close to resolution. Off to the track this weekend where I can try the new R-888's!