JBRPerformance666

Whats the most peak power anyone has been able to squeeze out of a 4088/rb26 combo running e85 or pump? Trying to decide if the loss of response / increase in lag can be offset by the gains.

Both ideas make sense but one thing I tried was disconnecting the turbo compressor from the intercooler so the engine would run without any boost at all. Still the exact same proplem. Also ive checked the fuel pressure with a gauge while on the dyno, not fuel pump or pickup related as the pressure in the rail does not drop.

the sensors are also all functioning and displaying valid parameters on the ecu interface.

Hi guys thanks for the time. It sure is an interesting one! The ignitor module is no longer in place, LS1 coils have an ignitor built in. All have been replaced. Dwell time on coils is supposed to be 3.2ms @ 13.8v. Ive altered the ecu as low as 2ms right up to 5.5 and it makes no difference to the issue. Prior to the misfire a wideband afr was fitting approx 1 month beforehand. And yes, happens in all gears on dyno and all gears ive tried on the road.

Hi Thanks to anyone who has taken the time to think about my cars issue. Below are the mods done to my car in a little more detail but firstly im asking if anyone has experienced a similar issue to me and what you have done to resolve it. Secondly if anyone has any suggestions on the next step in the process then im also interested to hear it! My car has developed a misfire, actually its more like a hard cut rev limiter at about 5200rpm if under load. At idle or lighter load it can rev higher. The wideband indicates the AFR is not changing when the problem starts. The plugs all look fine. Fuel pressure is available (checked while under load on dyno). Symptoms are the same no matter what gear its in. Already Tried: Checking Plugs, replaced, and gapped them progressively tighter until getting as low as 0.3. Replaced with Iridium plugs at .8, then refit new copper at .6 - No change. New Coil Packs - No Change New Leads - No change New injectors - No Change New Crank Angle Sensor (checked with timing light to top dead) - No change Disconected turbo compressor from intake to test with no boost. - no change Some more details about the car. built motor, T04Z Turbo - no maf sensors Haltech Platinum 2000 Ls1 Coilpacks huge fuel system Im sure ive left out some key info however ill come back and add anything the moment i remember it.