Hello everyone, ill start off by listing the mods, 2.4l 4g64 with evo 8 head. 6266 dbb gen 2 turbo. spark tech coil on plug, 2150cc injectors, single walbro 450 intake rewired. s3 cams build head, on e85. my car as of now is not derivable. i can get it to start up in the garage and i have to keep my foot on the throttle to keep it running but very randomly it goes rich about 12 AFR's and with a scan tool hooked up its running -12.5 on the short term fuel trim, then once it goes into closed loop it will try to correct it self and the AFR's go back to 14.7 and the short term furl trim goes back to -5 to 5. the weird thing is when it wants to stall i notice on the AFR gauge that it goes fuel lean for a second as it try to stall, sometimes it will stall other times it will stumble and catch itself. i have no engine light or anything like that. The really weird part is when i take off the spark tech coils and put the stock coils back on the car will not start. it will only crank and that is it. which makes no sense to me where it seems to be a fuel issue and not a spark issue. if anyone has any input that would be great. i would really like to hook up a fuel pressure gauge while its running and see if the pressure dips down when this issue seems to be happening but unsure how to do so with the stock fuel lines and rail.

 

Sounds like it needs tuned. And maybe the BISS turned out a bit.

 

car has been tuned in the past and nothing has changed sense. car started acting up a couple days after I got home from the shoutout in ohio. i just drove there did not race.

 

If the car still gets into boost and drives well, other than the idle issue, it's not a fuel pressure issue.

It's weird it won't start with stock coils.

What MAP sensor is in the car?

 

as i stated in the original post, the car does not drive and get into boost. it starts to buck me around as soon as i try to drive. I tried to drive it around my sub last night and if i left it in first gear it would kinda be fine but still cuts out and jerks the car around. i do have a twin dick clutch so i think that is why it bucks as hard as it does. as for the map sensor its on a omni 4 bar.

 

The post only says it doesn't idle.

I've so many omni 4 bars go bad, that is where I would start.

 

As previous guys pointed out, start from the omni bar and go on from there. I had a stalling issue and eventually was the TPS. At lower rpm and cruising, the TPS was showing 0% throttle, causing the engine to stall. Eventually, it was the wires that were going to the TPS. Also the idle valve probably must be checked also including the biss screw. It is weird that the sensor cannot hold the idle rpms steady and without needing to hold your foot on the pedal in order to avoid shutting the engine

 

The first line after mod list says " my car as of now is not derivable" but i was thinking either the map sensor or the cam position sensor maybe going out causing it to stop firing the injectors for a second. i am getting my injectors cleaned as on now just to make sure and its starting to become winter over here in MI so i like to get all the e85 out. but i will see if someone local has a 4 bar map sensor that i can swap out real quick. thank you!

 

My snap on scanner shows the TPS moving accurately on scan tool data. it could be the bliss screw but i cant drive the car so i don't believe it is that other wise i would just have an idle issue. but i will look farther into the TPS/IAC/MAP sensors.

 

Injectors don't suddenly act like this. Find someone to let you borrow a known good map sensor.

 

I have gotten a video of what is happening. I will post it here.

 

I posted the video of what is happening with the car onto youtube to be a little easier, here is the link. NOTE: as soon as i try and drive it it will try to shut off and do what it is doing in this video.

 

Still having this issue. Any ideas?! Any help would be appreciated

 

I had a similar issue, was boost leak in bov & biss screw was off a couple of turns. Start w/ boost leak test & biss screw or just buy a new map sensor.....

 

I've tested with another map sensor, still does the same thing. Messed with bliss screw a tad didn't change anything. I will do a boost leak test tonight after work. on speed density im pretty sure even with a boost leak it should not random shut off like that or at all but ill check.