skullandbones

Hi,

I have a Cobra replica with all Mustang running gear: diff, spindles, rack, engine, trans, computer, etc......

The reason I came here is that you have a technical forum for 5.0s. The other forums I'm on don't discuss engine stuff exclusively. Sometimes, you get decent advice but not consistent. Now that mine is running and I have app 1K on it, I want to tune and discover ways to improve the performance.

My 5.0 is mildly modified: Holley Systemax EFI, 24 lb injectors/MAF, 75mm throttle body, GT40p heads (ported), E cam, BBK 4x4 headers to side pipes, Crane rocker rollers, cold air system to fender well, alum fly wheel. The PCM is from a 92 GT.

My question is: what will cause an intermittent surge +/- 1K rpms? I just replaced upper intake gasket and throttle body gaskets and checked for vacuum leaks. At times, it idles perfectly and lopes like it should. This is my first experience with a FSB and EFI so I am thinking that I may have a computer issue but the problem is on and off so it's hard to get a handle on it.

Thanks in advance,

WEK.

88 orangepeel notch

Have you done a search on this forum? There have been a ton of threads already posted that explain the order if chasing down the surge. Good luck

skullandbones

I didn't think of it being such a common issue so I didn't search. But I will now.

Thanks for the heads up!

WEK.

skullandbones

So I did a search and found a few possibilities.

I think the code 67 could be the culprit but I will have to check that out.

The only other thing I can think of is the memory being wiped out every time I cut the engine off due to the battery cut off switch. That is an easy fix.

Thanks, WEK.