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Engine wont rev to redline under load


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1990 Eagle Talon with VR4 PNP, running E85 and 2200cc injectors. 

Car refuses to rev past 7k under load. Car can free rev to my set 8100 rpm limit. Under load the car feels like it is hitting soft cut and the car just back fires. Have thrown in 4 different sets of spark plugs gapped all the way down to .18 and no difference has been made. 

The car has no boost or vacuum leaks. It holds 26 psi strong all day. Fuel pressure is being logged and rising 1:1 with boost so fuel is not an issue. The stock ignitions on these cars can easily handle 700+ hp and 40+ pounds of boost. At 20psi this car is barely cresting 400whp and I shouldnt have to gap the plugs this low.

I have chased down every mechanical issue possible, replaced the entire ignition system, new cam angle sensor, new fuel pump, cleaned the injectors and nothing.

Attached is my current calibration and a log.

Hopefully something sticks out because I don't think spending a thousand bucks to put ign-1a's and convert the car to sequential ignition is going to do anything but mask some other problem.

 

pat more timing.pclr Log 2020-06-23 8;50;27 pm.llg

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Doesn't look to be any trigger errors logged, but your TPS is going to 110% and your differential fuel pressure does drop under boost  but only by 4psi or so and it looks like you've tuned around that.

No sure if having a TPS reading over 100 would impact anything otherwise.  Cant see any limits being triggered in your log.

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As JMP says there are no limiters or trigger issues in your log.  I would lean towards it being a lack of ignition energy.

I used to play with Evo's and VR4' a lot 20 years ago, the stock ign system is not as good as you suggest.  We used to get be able to get to about 25psi with stock ignition but that was with small plug gaps and petrol based fuel.  With E85 and another 20 years of age on many of these components you are probably going to struggle.  The ignitor's are very limiting, from memory 7A is all they can do.  We could get a bit more out of them by using a better ignitor with the stock coils or a MSD DIS 2 with the stock coils.

With your commanded dwell of 5ms I think you will be exceeding the ignitors current limit by a long way so you may get a better result down at a more normal 3 or 3.5ms.    But if that doesnt help I think you will need to upgrade the ignition system.

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