Lean at high rpm

[ALLTHECAMS]

Dynoed my car today after top end porting. Did 3 pulls and it made 383, 384 and 389 on the last pull. The graphs also dipped between 6k and 7k rpm. Before porting it made 374. Also leans out above 5k rpm so I think it's pulling timing. We checked fuel pressure and at WOT it was 40psi. Are my pumps dying?1557011356540.jpgIMG_20190504_154948035.jpg

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[Ccmano]

Yes, should be ~48-55 psi at WOT... At the risk of stating the obvious this assumes the fuel filter is good.

With the car cold, hook up a pressure gauge then simply turn on the ignition, don’t start the car. You should see 48-55 psi that way too. Another good way to test is to check the amp draw of the pumps. Good pumps draw 4-5 amps each, 8-10 amps when both pumps run. Less and your pumps are going bad. It’s nicely written up by Paul here...at post #7.

http://www.zr1.net/forum/showthread.php?p=136108

H

[ALLTHECAMS]

Ok thanks

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[Ccmano]

Based on the HP your car is modded. Curious what mods your running?
H

[ALLTHECAMS]

Originally Posted by Ccmano

Based on the HP your car is modded. Curious what mods your running?
H

OBX headers, Borla Challenge exhaust, top end porting, lightweight flywheel, Haibeck chip.

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[Ccmano]

Almost identical to mine, you should pick up some hp at the top end with the lean condition resolved.
H

[Hib Halverson]

It's a little difficult to diagnose this problem from those phone images.

Did the dyno facility give you print outs of the power and torque as well as the AFR chart? If so, can you scan them and post?

Better yet, did the shop give you the DynoJet run file? If you have the run file, please post it.

The blue and green runs demonstrate what you see when the ECM is commanding a lot of knock retard

In the other image, my comments are based on the assumption that the dotted red line is 12.5:1. If that's correct, the engine is clearly lean.

Given proper calibration and injectors, the problem could be pumps, pump pickups, fuel line restriction, fuel filter or regulator.

Has the fuel filter been changed?
Have you run all of the fuel system tests in the FSM?

[ALLTHECAMS]

Originally Posted by Hib Halverson

It's a little difficult to diagnose this problem from those phone images.

Did the dyno facility give you print outs of the power and torque as well as the AFR chart? If so, can you scan them and post?

Better yet, did the shop give you the DynoJet run file? If you have the run file, please post it.

The blue and green runs demonstrate what you see when the ECM is commanding a lot of knock retard

In the other image, my comments are based on the assumption that the dotted red line is 12.5:1. If that's correct, the engine is clearly lean.

Given proper calibration and injectors, the problem could be pumps, pump pickups, fuel line restriction, fuel filter or regulator.

Has the fuel filter been changed?
Have you run all of the fuel system tests in the FSM?

I have the printouts but not the files themselves. I will scan them later tonight. The first thing I do will be change the fuel filter. I do not have a FSM.

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[Ccmano]

The fact remains, 40psi fuel pressure at WOT doesn’t cut it. As noted it could be the fuel filter, the pumps or a restriction. Generally if the pressure regulator gives up the pressure goes to the high end. More testing is needed.
H

[ALLTHECAMS]

Didn't have much time but did some testing tonight. fuel pressure with key on engine off was barely above 10 psi :0. started the car and it was 38-40 at idle. I am going to change the filter because i am embarrassed to say I haven't done that on this car. Just one of those things I never thought of. After that Ill check pressure again.


Here are scans of my dyno sheets: