Rev Limiter Feel At 2K RPM/Boost
Rev Limiter Feel At 2K RPM/Boost 1999 Camaro
Stock engine
Huron single turbo (5 psi WG spring)
Deka 60lbs.
Walbro 255 (58 psi at idle)
GM 2 bar MAP
BR7EF plugs (.028 gap)
I just finished getting this put together. It has a base tune, trying to datalog for needed adjustments. It accelerates well at part throttle, wideband showing 12-13AFR. When trying to go above part throttle, it feels like a rev limiter is being activated as soon as boost is seen. It sputters and won't accelerate. Vacuum/boost gauge shows 0.0PSI when the issue starts. When going freeway speeds around 2,000 RPMs, going WOT will cause the RPMs to drop to around 1,000 with the rev limiter feel. AFR is around 9 during this. I checked the plugs after 100 miles and they are very black. I think I also smell some gas in the oil. If I hold WOT long enough, every once in a while, it will suddenly accelerate hard over 2,000 RPMs and build boost. Could this be a tune issue or are there other things I should be looking for?
Stock engine
Huron single turbo (5 psi WG spring)
Deka 60lbs.
Walbro 255 (58 psi at idle)
GM 2 bar MAP
BR7EF plugs (.028 gap)
I just finished getting this put together. It has a base tune, trying to datalog for needed adjustments. It accelerates well at part throttle, wideband showing 12-13AFR. When trying to go above part throttle, it feels like a rev limiter is being activated as soon as boost is seen. It sputters and won't accelerate. Vacuum/boost gauge shows 0.0PSI when the issue starts. When going freeway speeds around 2,000 RPMs, going WOT will cause the RPMs to drop to around 1,000 with the rev limiter feel. AFR is around 9 during this. I checked the plugs after 100 miles and they are very black. I think I also smell some gas in the oil. If I hold WOT long enough, every once in a while, it will suddenly accelerate hard over 2,000 RPMs and build boost. Could this be a tune issue or are there other things I should be looking for?
Last edited by MC Ray; Apr 6, 2025 at 08:09 PM.
TECH Fanatic
Joined: Jul 2022
Posts: 1,041
Likes: 392
From: Alaska
What is battery voltage while driving ?
Consider that a TR6 spark plug is more suited to LOW boost street use.
Possible weak coils ?
What is dwell time ?
Describe your fuel system in more detail: feed from tank, filter, regulator location, return.
What is fuel pressure at ZERO manifold VACUUM- is it equal to your stated 58 PSI static pressure ?
You are EITHER running out of fuel, or running out of spark... black wet plugs imply a SPARK issue.
Consider that a TR6 spark plug is more suited to LOW boost street use.
Possible weak coils ?
What is dwell time ?
Describe your fuel system in more detail: feed from tank, filter, regulator location, return.
What is fuel pressure at ZERO manifold VACUUM- is it equal to your stated 58 PSI static pressure ?
You are EITHER running out of fuel, or running out of spark... black wet plugs imply a SPARK issue.
Start over from scratch with that tune and hope you have not completely washed out your ring seal in the cylinders. There are plenty of issues, but the main one is that you have not updated your injector data for the 60lb injectors that flow over twice as much as stock. The good news is that I doubt there are any mosquitos left alive near you.
edit-- When you do the necessary oil change before attempting to run the engine any more, save the oil. It may have enough gas in it to use as 2 stroke fuel.
edit-- When you do the necessary oil change before attempting to run the engine any more, save the oil. It may have enough gas in it to use as 2 stroke fuel.
Last edited by gametech; Apr 7, 2025 at 01:01 AM.
If this is on a stock tune, I bet your going very fat on fuel. you are running twice the injector as stock, hence when you hold WOT long enough for the turbo to light, it leans out and makes power.
No need to speculate. He posted the tune and a log. There are spots showing .51 lambda, and so much fuel is being dumped in that 60lb injectors are showing over 80% IDC at 4lbs of boost and 4000rpm.
