RPM limitation questions

[WickEdSix98]

I was having problems with my car not wanting to rev beyond 6550-6600 and I thought it was weak valvesprings and the type of lifters I was running. I just got done putting some Manley 150# springs and OE-R lifters in the car, and it still does the same. I have the fuel cut-off set at 7000 and the RPM threshold at 7000. Is there another field I'm missing thats preventing the engine from revving higher? The car is tuned SD in a 98 auto F-body. TIA.
-Lance

[viper04af]

I was having problems with my car not wanting to rev beyond 6550-6600 and I thought it was weak valvesprings and the type of lifters I was running. I just got done putting some Manley 150# springs and OE-R lifters in the car, and it still does the same. I have the fuel cut-off set at 7000 and the RPM threshold at 7000. Is there another field I'm missing thats preventing the engine from revving higher? The car is tuned SD in a 98 auto F-body. TIA.
-Lance

err RPM vs gear maybe?

[WickEdSix98]

Sorry to bring the thread back up but I'm still having the problem and don't know why. I've looked all through the tune and cannot seem to find a possible cause.

[Russ K]

Post your tune file.

Russ Kemp

[WickEdSix98]

I'll do that tonight, thanks.

[WickEdSix98]

Its a little later than I said, but here's my tune. TIA

[S2H]

Its a little later than I said, but here's my tune. TIA

File Failed Validation Check....
try to reupload it again

[Bill@HPTuners]

File Failed Validation Check....
try to reupload it again

werd, 20kb is not a .hpt file.

[WickEdSix98]

how do I make it smaller? Thats the exact tune that I upload into my car.

[S2H]

its not smaller...
re read the file from your PCM...
upload it...
it should be closer to 450+ or 1000+
pcm uses 512 or 1024 files...
compressed and encrypted by hpt they show up as slightly smaller

a 98 TA F Body should be 512(minus a few because of compression/encryption)

[LNorton]

Lance,

Just Checked my hpt files and they are all 467KB on the dot. So look for it to be around that.

[LNorton]

I will also let you guys know this weekend if I am having the same problem. We are finally going to have enough injector to turn it that hard and I plan on shifting the car at 6700, so I will post up a tune and scan after we run the car.

[WickEdSix98]

Here ya'll go...for some reason the other file was messed up which is strange because its the exact tune thats in my car right now.

[Bill@HPTuners]

Please post a scan of you hitting the limiter, be sure to log injector pulse width & spark advance along with the other normal parameters you'd be logging as this will help determine if its an actual rev limiter.

[WickEdSix98]

You can see in that scan that it started flat-lining at the top end of the run at 6266RPM. If the track was longer the flat line would have been longer. You can feel when it does this in the car because it just stops pulling. I know its not a rev limiter because I rev it higher than that on the shifts. But anything over 6500-6600ish, it won't rev.

The Sealy scan shows better. Since that track outting, I've got better springs, lifters, and a bigger cam but I'm running in 5000' air instead of 1500'.

[WickEdSix98]

Here is the scan I meant to post above from last weekend.

[Bill@HPTuners]

well it aint a fuel or spark cut.

[LNorton]

Only got to make one run tonight due to rain, but we also saw the same problem in that we cant turn it past 6500. I know it shouldnt be in the valvetrain because we set this thing up to spin 6800.

Mind you we dont have a WB yet, but on the run dead at 6500 the O2 sensors show a major lean spot. The car also had a lean pop at all three shifts which were 6700/6500/6500.

When i got back to the trailer I tried to take it past 6500 with 5 different PE tables, and a ton of fuel, just to see if that was the problem, and each time it does the same thing. Right at 6500 it pops and wont turn any further. To me it has to be a fuel/spark problem, but it doesnt show in the tune file.

The only thing I figure is that the factory computer reverts to its own tables, or just wont let the thing turn any harder because it doesnt know any better. Seems logical when the tables only go to 6400...

Is this a limitation that we can overcome? or are we stuck with having to go to an aftermarket PCM to turn 7000 in the future.

I know of a stock eliminator that is turning these motors 7000+ with a FAST system.

[viper04af]

TTT

i'm trying to help another guy and car is doing the same thing

[Bill@HPTuners]

viper04af please start a new thread with the vehicles info, scanner log & .hpl file your working with.

Thanks,
bill