poormxdad

Gents,

I'm at VIR right now. My first session today went fine. In the second session, the temps were a little higher, but still cooler than my last event. I saw mid-9 AFRs at WOT, coolant about 210, and the car wouldn't pull above about 6500 with the AFR that low. I've checked for boost and vacuum leaks--tightened every clamp--but I won't get back out for almost an hour. I was at Dominion Raceway two weeks ago. Ambient was easily 15 degrees warmer, probably more. Not a cloud in the sky and not a bit of shade. The pavement was so hot it was uncomfortable to stand in one spot. I could not get the car to cool down much between events. I saw coolant temps reaching 225 and would have to slow the pace down to drop the temps. But, I never had the rich AFR issue, which is why I was thinking it might be something that has changed, like a loose clamp.

The AFR at idle after she gets warm is right at 14.5 or so. At less than WOT, I don't seem to have an issue.

Thought I'd ask the experts if they had any ideas. Thanks in advance...

aidandj

iTrader: (5)

Post tune and log.

OGRacing

iTrader: (1)

is your air filter exposed to fast moving air? if no then i have no idea. #notAengineGuy

poormxdad

Here's my tune.
I did not get a log, dammit. There's nothing on the card. I have another session, but I also have to drive her home.
I've got a Racing Beat fiberglass shroud that seals the air filter from the engine compartment heat. It gets air from under the driver's side headlight. Essentially, from the wheel well.
It was worse this last session, the sub-10 AFRs coming at a lower rpm. I also saw 217 coolant temp. I'm using a GM intake air sensor. If the sensor was reading cooler than it really is, that would effect the whole rpm and boost range, wouldn't it? I

afm

iTrader: (3)

You only have 3% EGO authority so it's not like it's compensating much elsewhere. Check the IAT reading and see if the wiring is okay?

Gotta see the humor in poormxdad being too rich

poormxdad

Here's a log file. I did one lap.

I made sure there was nothing stopping airflow under the headlight. I also tightened the supercharger belt. I did not have this problem two weeks ago, and it was hotter then. Something must have changed/died/failed..

Any help would be greatly appreciated.

Thanks,

poormxdad

I went in to TunerStudio OFFLINE and clicked on Tools, Calibrate Thermistor Tables. There's nothing there. It doesn't even indicate which sensor I'm using. Is that correct? I seem to remember that the values aren't stored in TS, but then I'm getting old, and I'm no tuning expert. I can't get my money back for tomorrow's track time, so I'd be willing to try almost anything. I'm just concerned there could be something going on that I'm making worse by driving her. She needs to get me home.

Thanks,

Savington

iTrader: (31)

Last time this happened to me with very similar AFRs, it was an IAT sensor failure.

poormxdad

If I go to NAPA or Advance Auto, what do I ask for?

poormxdad

What an asspain. Every parts employee wants to know what vehicle it came out of. I don't know that, but I had part numbers. The first place said they had the AC Delco part, but it wasn't anything like what I have when I finally got there and opened the box. Took almost two hours to find one of those in South Boston VA, and I'm not sure it fixed the problem.

Any other ideas?

Thanks,

poormxdad

She's supposed to be making 9 pounds of boost. I'm only seeing about 7. I added some Rotrex Traction Fluid. It was on the low side, but not anything heinous. I checked all the clamps. I took it out this morning and did a couple of laps. It was cooler, but she seemed fine. Went out for a full session and came off with an exhaust leak. The EGR valve fitting (which was plugged) cracked nearly off. I pulled it off once it cooled. The only thing that makes it worse is I took three days off. But hey, I'm still at VIR. I just hope my beer can/RTV/hose clamp patch can get me home.

My wife said "It was not meant to be". I want to find out why.

poormxdad

I think this is an interesting story.

I couldn't figure out why I lost two pounds of boost, and was consequently running rich. This is my first forced induction car and I'm just not that smart a tuner. A fine young man at the track looked at my log file and suggested pulling 7% or 1 AFR of fuel at WOT and see what happens. The car ran much better, but still didn't go above about 7 pounds of boost. Should be at 9. That cracked EGR fitting in the story above required a homebrew fix to get me home, and then removal of the header for welding. Since I had the header out, I decided to pull the cat. Melted and separated inside. Clogged like Hillary's soul. The car was trying to tell me what was wrong.

I love MIatas.

Andre94R

It's surprising that the boost would be less, on a positive displacement it usually goes up.

poormxdad

Andre,

I've done some more research and would have to agree. Everything I've read shows that clogging up the exhaust would increase boost. If it's just a coincidence I need to play the lottery. And, that means I still haven't figured out what's wrong. I've checked all the hoses and tubes and vacuum lines to the best of my ability, but I have not pulled the nosecone to check the intercooler for leaks. There is no damage to the intercooler anywhere I can actually see. I don't hear anything out of the ordinary that would indicate a leak (hole) somewhere. The car still feels very strong on the low end, but I really haven't had an opportunity to get it to WOT on I-64 for more than a couple of seconds...

So if my car was tuned on a much cooler day, with lower humidity and higher pressure, could that make a two pound difference in boost?

Thanks.

Andre94R

It would have to have been very cold and the intercooler would have to have been fairly inefficient to lose 2 psi.

I see slightly more boost in the winter with my FFS.

kamel6k

I Would say you need to be more agressive on your MAT air density correction.