And its a real pain in the *** to figure out!
http://www.ls1tech.com/forums/showth...4&page=1&pp=20

I don't know how to explain this better then once my car is warmed up it will not rev past 2,500+ RPM's while driving. When the car idles its completely fine. It happens in all gears and at all speeds in the RPM range above 2,500. I took a video if it to help people who haven't seen my car. If the car is still cold I can run it to red line without any problems but maybe a few more minutes down the road it becomes intolerable to drive.

The car is a 1995 Z28 M6 with a CC306 and worked heads, & a stock short-block. I am currently running stock 24# injectors with a newly installed Racetronix 255 fuel pump. I have Racetronix 38# injectors but I'm waiting to install them until I have the computer re-tuned by MadZ28.

-I have this feeling that its fuel or ignition related because I figure if it was ignition I would notice it even at idle but the car runs just fine at idle and only breaks up when the car is at operation temps.
-The plugs are fouled which would indicate it running rich.
-I swapped computers with a friend and the problem was still there.
-Its very hard to get a Dyno tune in my area. I have to travel real far to places that I have no experience with.
-I have to still get a Fuel pressure gauge on the car before i find out my pressure.
-I swapped on 3 Blaster Coils w/ ICM's on and tested them with a multi-meter and all read correct.
-I unplugged the 02 sensors, and the car idled fine and drove fine when cold, ran the same when it warmed up. I even reset the computer twice to clear any codes.
-The 02's are AC Delco that I bought new in October.
-Its been like this since the first day I had the car running back in October





Just incase:
Engine:
-Comp Cams CC306 (230/244 .544/.576 112 lsa)
-Comp Magnum 1.52RR
-Comp .0072 Chromemoly Push-Rods
-Comp 977 spring
-Comp Ti +.050 retainers/seats/locks
-ARP 7/16 studs
-561 casting heads flowed @ 255cfm @ .500 lift
*54cc Chambers
-ARP Head Bolts
-Racetronix 255lbhr Fuel Pump & Hot-Wire kit
-Stock 24# Injectors (Have Racetronix 38's waiting)
-GMPP HV Oil-Pump
-Lunati Double Roller Timing Chain
-Port Matched LT1 Intake with Ported Runners
-GMPP EGR Block-Off plates
-Enlarged Throttle Body Opening (sized for 58mm throttle body)
-Stock ported Throttle Body
-K&N FIPK2 Cold Air Intake
-Trick-Flow Hard Intake Elbow
-Rk Sport Air-Foil
-March Under-Drive Pulleys (Crank & Alt)
-Summit Opti
-MSD Blaster Pack
-Taylor 8mm Thunderbolt Wires
-NGKTR55 Spark Plugs
-160* Thermostat
-Meizer Electric Water Pump
-!A/C 1LE A/C Delete Pulley
-!AIR/EGR
-Throttle Body ByPass
-MADZ28 Tune

Exhaust:
Pacesetter 1 3/4 Long Tube headers
Pacesetter Off-Road Y-pipe
-Magnaflow 3" Cat-Back Exhaust
-QTP 3" Electric Cut-Out

 

Coolant temp sensor?

 

Maybe your tranny is slipping and can't hold the power over 2500? You say it's fine at idle, so if you put it in Park or Neutral can you rev up to 6K?

 

Sound like the cat may have melted down. Once it starts acting up look under the car and see if the cat id glowing on you. The parts places around here "loan" tools so maybe you can see if they have a fuel pressure gauge.

 

Thats what I thought until i saw he had longtubes / offroad Y :O

 

it pretty sure its your maf. unplug it and see if there is a diff. or swap with your friend.

 

Sounds to me like you need to put a stock TB back on.JMHO

 

Why? I dunno. I know that you are at open loop when you first start up and no feed back from your 02s until you are cruising. So you then start using the 02s for feedback. And when you punch it you are in open loop again, but since you can't even get to that point, I would guess that you are not getting enough air, which means there must be a restriction in the actual intake (TB) or your MAF is reading too much air when it is not getting that air and your are running too rich expecially as you approach 2500 rpm.

So either your ported TB is somehow boogered or your MAF sensor is boogered. On the other hand, maybe I'm crazy.

 

opti blew up

 

just a fyi the lift on the cc306 is .544/.576 with 1.6 rockers, with your setup the lift would be .517/.547 with 1.52 rockers

 

Build up on the points probably isn't good. Neither is a burned up optical sensor shield.




I got a replacement through Summit & I'm about to order a Delteq system. The MAF is fine, I have 3 of them laying around, 1 screened & 2 unscreened and they all worked on friends cars and my own.

 

Well I guess I know now where to look next, been having the same exact problems you had and have been trying to figure out what the problem is because I just replaced my opti because it was dying on me and ended up having new problems. Also since I was replacing the opti put in new plugs, wires, water pump, coil, fuel filter, had the ICM checked, tested the IAC, O2s, made sure there was no fireworks with the new plugs, checked the cat and everything else I could think of.

Then I watched your video and bam, same exact problem, getting the same exact sound and retarded timing that your experiencing, so gonna look at the opti again, guess it isnt such a surprise that it might be bad even though its new.