Help Please, on the dyno and rev limiter like problem at ~4600

[johnmaster]

Same issues as here http://forum.efilive.com/showthread....ke-Symptom-GTO
except 99 silverado, cos 5 5.3l speed density, failed maf hitting a wall at 4600 where it seems to be soft limiting the spark, rpm still climbs but power holds dead flat. No maf installed on vehicle, blow through carb so it is not able to pull fuel.

[johnmaster]

Here is the tune file I am using

[johnmaster]

Thinking the way i deleted the maf may be causing the issue, Searching and can't find the details of what is needed to succesfully delete the maf without ill effects.

Spark advance #1 cylinder figure stays strong after it occurs, I would assume it would be pulling fuel as well (but haha-carb so no fuel drop out) and it climbs rpm because it can't kill enough individual sparks to hold it back so hp flatlines from 4600 and up. Feels like "torque management" after that rpm and always has, I knew it had more in it and that was a main reason I took it to the dyno. Now I can figure out why...

Would bad spark plugs cause this issue? Cracked Insulators? Here is another thread with the same issue http://www.hptuners.com/forum/showth...t=30871&page=2

[joecar]

Do you get any DTC's triggering...?

[johnmaster]

Bought new plugs, I can check for dtc's, I am sure my vehicle has a lot of them but they are mostly related to the fact that I no longer am using the fuel injection of the vehicle. I will install the plugs and go for a drive, and make sure the gap is on the tight side.

I need to remember how to work with dtc's again Since i killed all of them when I first fired it up last year I haven't had to deal with them.

[GMPX]

Hey John, got your PM at ....... 1:30am my time
The LS1 PCM doesn't cut spark for RPM limiting, it only uses throttle (if ETC) or fuel for limiting (it's been a while, but I think that is the case). It can certainly pull a lot of advance out to limit power though.

[BLK02WS6]

You need to max out B6614 - that table peaks right at the RPM you are having the issue...

[slows10]

Blow thru carb?? You mean a 4 barrel efi throttle body correct? Are you getting the maf dtcs? Can you post a log?

[johnmaster]

Yes blow through carb, fuel portion of the harness was disconnected, I'm using the pcm simply for spark and trans functions, no maf, its using a 2 bar, cos 5. Thank you for the tip on B6614, my vehicle is not etc but I will change it to see if it helps, certainly can't hurt!

[slows10]

Might as well look at B1201 if we are looking at tables you are probably not using lol. Not really the rpm range you are talking about but what the hell.