Pyzik

Hello, I need some help with my problem that I'm experiencing at high rpm on every gear except when car is in neutral , or clutch pushed in. Seems that the engine struggles to pull at 4500 rpm . My coils look original, if that matters. Also using Bosch plugs ( stock ones I bolieve. Running 56psi fuel for the v4 porken chip .. Would a spark plug gap matter? Maf ohms? A/f? Please help as I wasn't able to red line my 928 for months!

Jim M.

Fuel filter clean?
Fuel pressure at high RPM?
Cats plugged?
Ignition wires in good condition?

Temekun

Did you get the Chips with the no lift shift option? I think that if you have it but its not connected that may rev limit it. Ken will have to weigh in.

Tim

IcemanG17

In the immortal words of Jim Bailey... "the single best way to improve the performance of your 928 is to make sure its performing 100%"

Yours isn't....plain and simple....there is a significant issue in play that is severely reducing your performance..... fuel filter, pump....spark plugs-wires-dist-rotor-computer so many variables that Kens chips can't answer for...... Ken designed his chips for a 100% running car....your isn't even close....we need more info to help you fix it....

Pyzik

I went thru some receipts to check dates and : nology spark plug wires ,spark plugs, fuel filter were replaced 11/10 then about 5 months ago I bought Bosch plugs, but never changed the gap from what is came per adjusted. Fuel pump is original, had the maf rebuild couple months ago and I set it to 382ohms,

Pyzik

What kind of info would be helpful?

John Speake

Check you have a good vacuum at the pipe going to the EZ-F ECU... about 21"Hg at idle.

Pyzik

I checked today and at idle it was 19

John Speake

Not low enough to suggest that it's a good suspect for the problem.

SteveG

If that means you did not check the gap, you should.

Did you check the items Jim M suggested? I can't tell from your description, but a weak signal (could be wire or connectors) from coil was causing a similar condition for me.

PorKen

Did you check the cam timing? (I don't recall.)

One or both sides a tooth off will make it run poorly.

Randy V

Pull what?

Pyzik

It's been snowing for last couple weeks and I don't have a garage so I wasn't able to check the things Jim suggested , this Saturday looks like if will be sunny so I will do some work.

Pyzik

Randy V, the cars acceleration slows down when the engine gets to 4500 rpm and till red line doesn't accelerate as it should , maybe I can record a video of the techometer when it happens .