got-a-ls1

iTrader: (12)

so i was having this issue today at the track.. when i tried to do back to back runs the car would DENY me lol...

Basically i would start my run go through first gear fine. Between shifts when i would let off the throttle the motor obviously went to vacuum... when i would shift into 2nd and give it gas there was nothing there, no throttle response at all. Looked at the logs and when it showed tps 100% in 2nd it also showed like 20kpa on the map wtf... it would take 2-3 seconds and it would come out of it..

obviously with the throttle open the motor cant be seeing a vacuum like that. So is it possible for a map sensor to stick?? I cant see the vacuum with 100% tps being realistic and it would only do it during the shift when the motor saw vacuum.. the map seems to work fine otherwise... nice smooth curves with boost ramping up and everything..

It would only have this problem when trying to do consecutive runs. If i let it cool off for 30-45 minutes i could do a pass no problem. i mean i maxxed out the 2 bar today so a 3 bar is in order but id like to make sure this is just a bad map sensor and not something else. 99% sure it has to be a bad map?? the sensor is the standard cobalt 2 bar map

got-a-ls1

iTrader: (12)

got-a-ls1

iTrader: (12)

any ideas of anything else that could cause this before i go and change the map sensor?

NoGo

iTrader: (2)

Looks like you had a healthy amount of KR on that run. Any concern there?

I would think that a vacuum MAP reading while under boost would really underfuel the car - I'm guessing the car sounded like it practically shut off when you hit the gas?

What is your actual timing doing when you get back into it....that flatline at 16 deg looks like an error.

got-a-ls1

iTrader: (12)

i had race gas in the tank on that run.. i was chasing what i believed to be phantom knock, which is why i commanded the 16 degrees from the vcm controls. it would even show knock at 12 degrees timing. thinking maybe the sensor are just to sensitive.. but i dont want to change the values

you can see by the injector pulse width its dumping no fuel. its like i just shut it off. it

NoGo

iTrader: (2)

If that is truly your timing, then I agree. Throttle goes down, no gas added.

Being you are SD, there are only a few things that could cause that, the MAP being a big part of it.

So, I'm in agreement. I would go after the MAP sensor.

got-a-ls1

iTrader: (12)

i think i nailed down the problem. i believe the map sensor is reporting correctly. found a small hole in my silicone 90 that i had stuck on the turbo to point it down under the radiator... i think the reason this is only happening between gears is because when i let off the gas the BOV opens, turbo is still crankin and moving air.. well i imagine with a open bov and a cranking turbo the amount of air the compressor is going to move is going to increase dramatically for that split second. when it did it would suck shut the elbow and when i would go to get back on the gas it would still be sucked shut against the compressor inlet.. Also explains why the 30 minute cool down would allow me to complete a pass as with the hood open and elbow cooling off it wouldnt suck shut. anyways pics worth a 1000 words. silicone was very hot, huge vacuum made a neat little hole

got-a-ls1

iTrader: (12)

and on the inside you can see where it was sucking shut haha