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Im tuning a 99 Jeep XJ with a 6.0l LS engine swap, 36lb injectors, 90mm DBC throttle, mild cam and th400 tranny. I calibrated MAP and adjusted all thats needed to get it idiling and running good. No MAF. I set the rev limiter at 7000rmp and Resum at 6995rpm. Part throttle and before hitting rev limiter all runs great. No more than 3% error on MAP table, good timing, no knock. As soon as I hit rev limiter, engine dies. Fuel doesnt resum at the 6995rpm set point. I checked the tune, but cant find anything missing. I ran the scanner, but it all looks good until it hits 7000rpm. Im using HP Tuners. I have tuned multiple vehicles similar to this one with no issues like this. ECU is a Stock 411 Gm. Any ideas what might cause the engine to die? Can the ECU be bad amd cause this issue and still run great everywhere else?
Am i correct in taking it that the engine has a hard limiter?
Do you mean the engine completely loses power and you have to restart it, or do you mean you are expecting it to immediately resume and it isn't?
You may have set it too close to get a clean differentiation - try dropping to, say, 6750 for resuming and see what affect that has, if it's working correctly, bring it up in 50 rpm steps until you're happy with it.
If there's an option, you find it better to have a soft limit a "x" rpm and a hard limit 100 rpm, or so, above it.
Yeah it has a hard limiter, it cuts fuel. No options for soft limiter.
When 7000rpm is reached at WOT fuel gets cut off and engine dies, its like I switched the engine off (key off). I have to stop the vehicle and restart it, engine comes back on with no issues and idles great.
I actually tried dropping Resume RPM to 6950, 6900 and 6800 but it makes no difference. As soon as it hits 7000rpm, engine dies.
As long as I dont hit that 7000rpm, it runs great. Idles great and has a lot of power. I know someone people might say to just stay off the limiter, but while drag racing in sand and trying to shift that th400, it bounces of limiter once or twice before it shifts. At least thats what the other vehicles I have tuned do. This is the first time I have this issue.
engine rpm limiter cut time set to 2 seconds instead of 0.2 seconds so it stalls out on you when it hits the limiter? do you have a timeout anything like that at all?
Yeah, when it hits the rev limiter it stalls. I dropped the limiter to 4000rpm and revved it while in neutral and it stalled as well. From what I can see, its cutting fuel when hitting rev limiter, but its not resuming at the set rpm.