Car just Dies !!! Help

[jhertel]

Hello. Buddies car has been running for about a month. LS1 with turbo . We have been getting closer with tune
thinking we are close enough to bring to a dyno. All of a sudden, this problem showed up. It justs shuts off when
it starts to build boost. WE used to rev to 6000 and 8lbs boost and Afr was rich but safe . Now look at the log. Frame 475 then 476. inj duty-pulse fall off. Map drops. Throttle pos the same until he lifts because it stumbles then dies. Fuel pressure
falls in less then a sec. Argh. Checked all fuel pump wiring. Not sure what happens first. Car dies , pump shuts off or pump
shuts off then car dies? Really hard on mtr trying to figure this out. Log and Cfg. Please look and any Ideas for us.

[2xLS1]

Why is your MAP sensor reading 44.7 kPa with engine not running? (rpm = 0)

[jhertel]

Weird isn't it! Could the map sensor be causing all of this? This thing ran pretty good for a month. Car runs fine until it goes into boost.
Fuel pressure has me worried also. Why would it drop so fast? I thought the pump runs for a little while even if the can dies. 2 Sec?

[jhertel]

Using 200 and 10.33 offset

[mowton]

Need to post a copy of the tune. Any DTC's? Could be reduced engine power except timing stays up? Connections to MAP or electrical. With key on and engine off, what does the MAP read?

Ed M

[jhertel]

No codes thrown. I will ask him to check Map. Weird it ran good for so long. Even went back a few tunes to see if some software glitch but same problem. He lives 60 miles from me so I have not seen the car since this started. Just trying to get some ideas and a plan so when I can get to the car we can make some progress.

[jhertel]

I guess He has to crank it a while before it restarts then all is fine again. Looks like it happens around 147-155 KPA.
Just noticed on the tune PO106 DTC is disabled. Should I enable it to see if it throws a code?

[jhertel]

Ok. Finally made it to the car, It is throwing a code p1635. 5 volt. We are also using the egr 5 v for the FP sensor. So thinking
either the map is going to ground at around 145-147 kpa and pulling the volts down causing the Fuel pressure to appear as it is dropping
or we have other wiring probs. You can see map reads weird right after 147kpa. also. Happens every time at that boost range. No other time.
Wiring looks ok. Car ran good for a month than $hit. Anybody see this with a MAP before? I ordered a cobalt 12615136 but we live in the sticks so
3-4 days out. Can I put the 1 bar map back in and just change the Linear and offset back to 1 bar or do I have to revert the OS to 1 bar.
Don't want to do that as all of my VE timing tables are very old on my 1 bar OS. Just want to see if we can get over 4000 rpms to rule out any other prob. IE see if Fuel press stays up. We have a WB so we can watch AFR and I can rape the PE table to keep it close. Just don't want to wait 4 days and then it still has the same prob with new Map.
THanks

[jhertel]

Update. Installed new Cobalt MAP. Yep. Problem gone. Go figure. He had a cheap 2bar map off of E-bay. I wont mention the seller but they sell
injectors also. Lesson learned. Bad MAP pulled down 5V bus and made it appear that we lost Fuel pressure causing the bogging-killing of the engine. So after a week of chasing a fake fueling problem we can now think about Dyno time and POWER CRUISE USA.
Thanks to the two guys that posted for us.
CYA

[mowton]

Update. Installed new Cobalt MAP. Yep. Problem gone. Go figure. He had a cheap 2bar map off of E-bay. I wont mention the seller but they sell
injectors also. Lesson learned. Bad MAP pulled down 5V bus and made it appear that we lost Fuel pressure causing the bogging-killing of the engine. So after a week of chasing a fake fueling problem we can now think about Dyno time and POWER CRUISE USA.
Thanks to the two guys that posted for us.
CYA

Thanks for the follow-up and divulging the cure. We all will add that to our little tuning books

Ed M