Cammed 4.8 Won't rev past 5700 RPM's!!!! Why??
10-07-2005, 07:34 PM
#1
Cammed 4.8 Won't rev past 5700 RPM's!!!! Why??
Ok, this is ------ me of entirely, no one can seem to find the problem. Mods are in the sig, Had my truck dyno tuned the other day with the 01 LS6 cam and all the better power they could dyno tune out of it was 230 RWHP at 5500 RPM's. Does this sound right? Anyways, after crying my way home thinking I was going to put out 250 RWHP with that cam and mods in sig, I went WOT in 1st gear to give 'er hell and the tach flung up to 5700 RPM's and then cut out like it was shutting fuel off. Tried again in 2nd, same thing. Went back to Doug Rippie Motosports and told him what was going on. He double checked and sure enough the rev limiter was set to 7000 RPM's as I had requested. He tried putting it up to 9000 and I went for a test drive, did the same damn thing. We then thought something was wrong with the PCM so we tried another PCM with an entirely new tune. Not even the same BIN file. Tried it out after another hours worth of building the tune and it still cuts out at 5700 RPM's. Now I'm like WTF, and doug is totally baffled. He thinks the fuel injectors cannot supply enough fuel to the motor, I have a feeling it's still in the tuning. I don't know what to think anymore. Try another tuner? Apparently Doug is giving up, he said he called some of his tuner buddies and they have no idea what's going on. So I guess this thread is two things, why only 230 RWHP and why can I not go higher than 5700 RPM's, opinions please!!!! Do I need to buy HP tuners myself and just do the ------ thing on my own?
Last edited by Crash Dummy; 10-09-2005 at 09:27 AM.
10-07-2005, 07:37 PM
#2
One more thing, check this **** out. I disconnected the MAF after he "tuned" it and it goes like a mother effer!!! Why would this be? And why wouldn't he have tuned around the MAF if having it connected screws with the timing tables so much? I just may have to go MAFless and get myself into the world of tuning.
10-07-2005, 07:40 PM
#3
damn... so with the maf unplugged it'll do what it should do? that little pos should just be called the MF... bc thts what it is, a mother f*cker. There is a way to tune around it... you can actually get rid of it.. called speed density mode. Idk why you would have that problem tho.. def something in the tune
10-07-2005, 07:58 PM
#5
oh... i wonder whats causing it to still cut off at that rpm tho. This is jesse tuning all this for you? I think his tunes dont realie on the maf as much as a stock one does... his is more tps reliable. Does it throw any codes with the maf unplugged? and did you specfically tune for the maf to be deleted?
10-07-2005, 09:12 PM
#7
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Originally Posted by Rhino79
Did you change your springs?
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10-07-2005, 10:13 PM
#9
Originally Posted by SSlow 4.8
oh... i wonder whats causing it to still cut off at that rpm tho. This is jesse tuning all this for you? I think his tunes dont realie on the maf as much as a stock one does... his is more tps reliable. Does it throw any codes with the maf unplugged? and did you specfically tune for the maf to be deleted?
Jesse had done the original tune and then I brought it over to Doug Rippie motorsports to get a Dyno done, all it was putting out was 210 peak RWHP at 5200 in stock form with Jesse's tune. The tune was running a 11.9:! AFR. Doug talked me into getting a dyno tune and said there's nothing better....... Well, I did the LS6 cam swap, changed out with new LS6 springs as well and brought it back. After tuning the best Doug could tune out of my truck was 230 RWHP. "Only a 20 RWHP increase??!!"
I thought the cam alone would bring close to 30 RWHP and tune would enhance that. After all was said and done I was thinking I was going to be sitting at 240-250 RWHP. Does that sound reasonable? Anyways I'm just not a happy camper right now because I know there's a lot more in the truck and no one can seem to bring the power out in it. I feel like I got suckered into the DRM tune that doesn't work worth ---- and Doug cannot seem to find out a way past the 5700 cutoff problems.
Last edited by Crash Dummy; 10-09-2005 at 09:30 AM.
10-07-2005, 10:22 PM
#10
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Originally Posted by 2xLS1
There is a separate table for ETC fuel cut off. Are you sure the tuner changed that table too? Easy to miss if you are used to dealing with cable operated throttles.
can be very very helpful on tunning and cant complain he made mine run hella better