Was driving on the freeway last night, got into boost and heard a loud pop... car reved and shut off.

Trying to restart the car, it wants to instantly rev so I shut it right off. Turbo starts spooling car wants to take off.

First checked to make sure the throttle wasnt stuck. Then the throttle position sensor, its getting normal readings and fluctuates fine.

Looking at the MAP, its reading a constant 101kPAs with the key on (not running) and also when starting. Which is obviously very high. Unplugged the MAP, it dropped to 14kPA... no surge on start up, but also obviously wouldnt run.

Im also getting a Crank position sensor code, but i think thats from the awkward startup.

ECU let me access it, pulled my tune, no errors, so i think its ok.

So, im thinking its the MAP sensor. Just havent ever really heard of a MAP sensor just going bad... Any other ideas would be greatly appreciated.


Aftermarket MAP, SD tune.

 

Wat map u running?

 

Reach behind the intake and see if anything is loose. May have popped something out?

 

Im using a GM style 3bar map. Doesnt have any part numbers or anything (says 1007F05), but its re-located off the intake. stock one is still in place, harness was extended and new MAP is remounted. Its been on the car for several years.

Also, in theory if it was on the intake and popped off... it would read less kPA, not more.


Guess ill just order a new one. Cant think of anything else being wrong... less the ECU is messed up, but being able to access it kinda tells me its ok.

 

Isn't ~100kpa essentially atmospheric pressure? Anything less is vacuum, anymore is boost. So typically when you key on, engine off, it reads whatever the atmospheric pressure is.

 

sounds like you have a vacuum leak

 

Thats what I was thinking....a VERY large one. How much PSI you running? Stock plastic intake? I think you blew a hole in it somewhere judging by you saying it made a loud pop. And a large vacuum leak will cause the car to rev up. I'd pull the intake and check it out. It's an easy enough job.

EDIT: Re-read a few things in the thread...def check where the stock MAP is if you havn't yet. It may have blown out of the hole and that will make a pretty large vacuum leak.

 

vacuum leak? 100kPA is more air pressure then a stock f body would have at max rpm (atleast here in Vegas) its about 3-5lbs of boost on my car. So its definitely not a leak... And a leak wouldn't cause the car to rev violently like it does, I've had tons of leaks. Lol

 

I had to come back an appologise... it was a vacuum leak. lol








A VERY VERY big vacuum leak. Most time when ive had leaks, it didnt really matter just made the turbo laggy and wouldnt go full boost. Guess its a little different then the MAP is shot off the back, oil pressure sensor broke, cam sensor plug broke... haha.

I guess 22psi is too much for the ls6 intake.

 

yea boost leak before the throttle body is very different from a vaccum leak. LOL and a piece of intake missing is just that and essentially is a wide open throttle haha

 

Yes!!! I kinda got one!!!!

 

There are other methods to get inside the intake to port it. Lol