Brick wall under boost at high rpm
 

I've been reading as many other posts as I could find but have not solved my issue.

1g significantly modded running with 2g mas

Had the same setup and tune for years but this problem started occurring recently. At around 5k under boost the car falls on its face. I did a boost leak test and fixed any leak I found. Also fixed an exhaust leak and replaced the o2 sensor which was throwing a cel.

Car is tuned at 400 whp with no changes in years. I was thinking the 2g mas may have gone bad or an injector or fuel pump failing. Any suggestions are appreciated.

Re: Brick wall under boost at high rpm
 

Hit's a wall like the car bucks and feels like you got punched in the chest? Or hits a wall like power drains. The first would be fuel cut, the second could be a lot of things including knock sensor etc. Did you clear the ECU of codes after replacing sensors etc?

Re: Brick wall under boost at high rpm
 

Hit a wall like the car bucks. I didn't clear the code but the check engine light went off after I drove the car for a few minutes.

Re: Brick wall under boost at high rpm
 

That's fuel cut I'm assuming. Either injectors are not enough, fuel pump is dying, or something tune related.

Re: Brick wall under boost at high rpm
 

I had a similar issue with my car and I found out the battery tie down came off. Battery was tilting under hard acceleration, arced a spark to the frame, and completely cut ECU power and bucked every time in 1st gear.

First you need to determine the root cause. For me it was physical acceleration that wouldn't been seen on a dyno. Other things like spark blowout or fuel cut or fuel pressure decrease you can diagnose in a controlled setting like a dyno. Maybe a weak spark system could cause that. Have you replace the plugs, wires, coils, etc?

Re: Brick wall under boost at high rpm
 

I had a pretty nasty buck when I was messing with my plug gap. After being in boost for about a sec or 2 I would eat steering wheel.

Re: Brick wall under boost at high rpm
 

Tune is the same as it has been for years and no new parts have been added. Battery is tied down securely in the trunk with no possibility of arcing. Plugs are new and gapped to the same .19 they have been since the tune.

If I accelerate slowly, meaning no boost, I can get the car all the way up to redline. If I boost at all, even 10 lbs, as soon as I get around 5500 rpms the car will buck and jerk.

I swapped in some different plug wires and a coil pack to see if that would change anything and it did not.

Re: Brick wall under boost at high rpm
 

Have you checked the AFR or done any logging?

Re: Brick wall under boost at high rpm
 

Have not done any logging as I dont have a data logger. AFR is good until it starts to buck then the gauage goes nuts bouncing back and forth between good and no fuel.

Re: Brick wall under boost at high rpm
 

I'm in St Paul and available the next two days to check it out if you'd like. I can log if needed. If you have Link. Otherwise I can help figure it out in person.

Re: Brick wall under boost at high rpm
 

I don't have link, I've been using an eprom. Not sure if I'll have free time tomorrow to get to it. I appreciate the gesture.

Re: Brick wall under boost at high rpm
 

Is your AFR connected to a wide band O2 sensor? Have you check the ground wire on your fuel pump? What is your current setup?

Re: Brick wall under boost at high rpm
 

Yes it's a wideband. 50 trim, with 1000cc injectors, walboro 255, cams, built head, e85, eprom.

I will check the ground on the fuel pump.