DonHood

Ok, I need some quick help here.

At WOT, my car pulls great untill I get into the upper RPM's, then it just completely falls flat on it's face. I've watched my O2 millivolts as I get on it, and they seem to vary with RPM. They start out around 920 or so when I first hammer the gas and stay that way till around 3k rpm, when they start to drop like a rock. By redline, they sometimes hit as low as 400, and it feels like it's running out of gas when this happens.

Is this my fuel pump not being able to keep up with the demands of the injectors? I tried pulling the vacuum off my FPR, and it didn't seem to help at all.

Any help would be greatly appreciated.

DonHood

Fuel filter is just a few months old, by the way.

roadrage912

get a fuel pressure gauge, it's like 30-40 bucks. hook it up to the shrader valve and run it under the hood to the windshield and close the hood easily. then drive around and watch the gauge and see what your pressure looks like. go WOT and keep it there and watch. drive at different rpms and see how it acts. then you will know.

the fuel pressure should be around 35 or a little more psi at idle and then around 43 at WOT and should stay there.

ibanez6rg

Just an FYI, O2's aren't used at WOT.

DonHood

No, they're not used for fuel calculations like they are at partial throttle, but you can still monitor them to get an idea of how rich/lean you're running.

ibanez6rg

Yea, I know that they're still read by the PCM, but they're not used. I was just stating that, that's all.

DonHood

Welp, checked fuel pressure today, and it stays around 44 all the way to redline, even under load.

Anybody have any idea what it could be now? I've got the infamous intake manifold leak in the rear, could that be causing a vacuum leak when the engine is revving high? Could it be something nice and simple like a coil, or ICM? Could I have a collapsed lifter, broken pushrod, or something else in the valvetrain?

I'm stumped.

DonHood

I sorta need to get this figured out by Friday too.

Lt1t56

I had the same problem 2 years ago, car ran great but at higher rpm started cutting out bad, my problem was the plug wires. Took me a while to figure it out because plug wires usually will miss under a load like trying to accelerate slowly at highway speeds or taking off from stops. Mine only cut out at high rpms. That was my expericnce.

DonHood

Thanks, I checked for evidence of arcing a couple weeks ago, and couldn't find any, but there could be some that I missed. I'm just gonna replace the coil to start off with, I'll take it from there if that doesn't help.

Also, in case this matters, my injector pulsewidths on both sides never get above ~9.8 or so, even at WOT. I thought you should be seeing as high as 15?