fuel cut I have no idea whats wrong. help

[Merkles]

I have no idea what is wrong with my car. My mods are listed in my profile. Here is my problem. My car rips until 15psi where I have my boost set and holds until anywhere between 4500 and 5500 rpms then hits fuel cut. I have no clue why. I ran a boost leak test and had 1 tiny leak at the throttle body but I fixed that and I changed my spark plugs and put new ones in. Any ideas?

 

[v8s_are_slow]

http://www.vfaq.com/mods/wayback/BradBauer/engine/timing.html

 

[DSM_PWR]

i dont think it works on 2g

 

[v8s_are_slow]

i dont think it works on 2g

Maybe on a 95-96 but I believe it should if you have a 98. On the 95's and 96's, the cas is on the driver side of the motor whereas the 98 is on the passenger and I "believe" it's adjustable. I won't promise that it is though. It's been awhile since I've owned a 2g. Just trying to give ideas of things to check for cause it's a lil harder to diagnois all problems over the internet. Lol. But I'm trying.

 

[BlackdOutGST]

MERKLES and DSM PWR, CHECK BOOST CONTROLLER

I HAD exact problem with mine. 16g with stock injectors and ecu. Fuel cut at about 20psi, rpms stuck at 35 to 4500, engine sputter real bad, running rich. Had a bad Manual Boost Controller. Swapped with a buddies Greddy controller and fixed it immediately. I would recommend finding a cheap one to sswap with if you don't know anyone else with a controller. It might save some hassle before doing something drastic. Good luck

 

[v8s_are_slow]

Have you guys not taken off the boost controller yet? I know I suggested it. Just dunno if you did it or not.

 

[DSM_PWR]

Thanx i really appreciate it v8.

well i did switch boost controllers but still does the same thing. although i swtiched from an ebay to a homemade.. ill try just running vacuum line to wastegate and see what that does.

and no our CAS arent adjustable

 

[v8s_are_slow]

No problem, give some feedback after you run it without the boost controller.

 

[DSM_PWR]

ran the vacuum line straight to wastegate and still does it... however my wastegate must be messed up because my wastegate use to only allow 14psi but now it let me go to 20psi... i also changed out the pcv valve

 

[v8s_are_slow]

Nah, the wastegate hole probably just needs to be ported out some. You have a freer flowing exhaust which makes it spool faster when you accelerate and isn't allowing enough of the exhaust to be able to exit the wastegate hole.

One thing you can try is taking the actuator rod off the wastegate flapper. It'll take a lot longer to spool but if you're still able to get to 20 psi, you'll know it's the wastegate hole is too small. Will also make it impossible for it to boost spike if you have the flapper disconnected. Would be interested to see how this works out for you, and wondering if the slower spool will help to prevent a sputter issue.

 

[DSM_PWR]

well i forgot to mention i dont hit 20psi till around 6krpm. it does have the slower spool. It stays around 14psi for a while then slowly goes up to 20psi.

I was however able to redline but only in 1st gear.... 2nd and 3rd always stutters around 5krp

 

[v8s_are_slow]

You're probably not sputtering in 1st because you're not flowing as much air in 1st gear. What boost level are you at when it starts sputtering? Have you noticed? Also, what octane? I may have already asked but do you know if your timing is getting pulled? Do you know?

 

[DSM_PWR]

Well its weird. Usually around 20psi BUT say im pushing 14psi.. it will hold 14psi then around 6krpm it will sputter..

And no its not pulling timing. Im running a 50/50 mix of 93 oct and e85.. e85 has had great results as far as running higher boost without knock/timing being pulled.

 

[DSM_PWR]

The only thing i can think of is that i have a bad GM MAF. is there any way to check them rather than buy another one and hope for the best??

 

[v8s_are_slow]

Well, I doubt it's the maf cause it's only doing it at a certain rpm. Even with a lower boost, so I'm not thinking it's an airflow issue. I'm still leaning towards a spark issue if anything. Not sure how good those plug wires are.

 

[sniperelite]

Ya guys I am still thinking that it has to be an issue with spark. If your engine is breaking up at higher RPM's, the majority of the time it is something to do with spark, that is why people revving to the moon usually go with a COP setup because it is better for running higher RPM's. If you have already changed your plugs and wires to the correct ones, it has to be the coil pack that is bad... That is my guess

 

[DSM_PWR]

Yea i just changed the plugs and wires last week... i was also told to try runnin a smaller gap.. something like .22-.26?? is that a good idea..

 

[v8s_are_slow]

Just because they're new doesn't mean they're good. What kind of wires again? Bosch or something? Wondering what they look like. There's definately some cheap brands out there. You can try a a smaller gap but don't see you needing it. Heck, .028 is already a pretty small gap and if your ignition system is up to par, there shouldn't be a reason to have to decrease it.

 

[Merkles]

I got another set of wires again today and also moved my MBC pressure source a little closer to the compressor housing then poooof like magic it was fixed. The car is running great now, def pulls harder and feels like its running strong. I'm guessing the new set of wires I bought before were sh*t right out of the box. Anyways thank you everyone for your help. Now we just need to help DSM PWR.

 

[v8s_are_slow]

Glad one of you guys got it fixed. Just one more to go.

 

[DSM_PWR]

yea i got the bosch.. i always ran these and the car ran fine before.. im thinking it could be the coilpack

any recommendation on what wires to get?? hey merkles what kind of wires did you get??

 

[Merkles]

I am running Bosch Wires. I had them before and they were great for alone time, the replacement set I got were garbage and the new set I got work perfect. Its weird

 

[Merkles]

Well it did it again today on the way to work. Maybe the spark plug wires were not the issue. Anyways I have a Perrin Boost Controller in the mail to replace my home depot boost controller. (It needed to be replaced anyways) We will see if that does it.

 

[Merkles]

DSM PWR when is the last time you changed your battery?

 

[Merkles]

I got a new battery and she runs perfect now. My old battery was almost 2 years old, still had 2 months of warranty left on it from advanced auto, so I took it in and they swapped it out for free for me. Can't beat that. Ill post back in a couple days and let you know if its still holding up fine.

 

[v8s_are_slow]

Good to hear. Keep us posted. As for me, I'll be racing tomorrow night. New turbo and stuff so excited to see how I do.