5000 RPM cutout

[christiane]

Ok, I finally got my car back together. (Fortunately the problem was not CW instead the crank trigger plate was installed incorrectly). I have re-started the engine break in procedure using 20W-30 non-synthetic motor oil. Everything appears to be going fine with the break in (only running 4 PSI of boost and not turning a lot of RPMs). The only problem that I have noticed is the car does not want to continue accelerating after 5000 RPMs. My initial thought was that the rev limiter in DSMLink was set at 5000 because it hits a wall at 5K. After checkling DSMLink the rev limiter was set at 7500 RPMs. I decided to try reving the engine with the car moving (DSMLink has a launch feature that allows for better launches) and the car revved to 7000 RPMs effortlessly. What would cause the car to not reve past 5k with the drivetrain under load? Could it be caused by bad/ fouled plugs? (The mechanic put champion copper plugs in and I thought this would be OK with only 4 PSi of boost).

Thanks for the space

 

[ddavisaf]

Have you tested for boost leaks yet?
The plugs may not be properly gapped. I would check them and see if they're at .028" like they should be. I still try and stay away from champion. I personally prefer NGK over anything else, but if they're unavailable I'll use Autolite 63's.
Part number for NGK plugs is 7131 (?), NGK BPR6ES

 

[christiane]

I have not tested for boost leaks yet, is it possible that a major boost leak could be responsible for a really crappy idle?
I have the NGK7es plugs on their way from SBR (should be delivered tomorrow). What else would cause this type of reaction aside from a boost leak/ plugs? I am starting to realize that I am going to have to go back through EVERYTHING this 'mechanic' did to my car. I should have known better than to allow anyone else to touch 'er. That'll never happen again!

 

[ddavisaf]

A minor boost leak could cause a bad idle.
For the moment I would just check those two. Depending on the results of the tests we can narrow down other possible causes. Not to mention I'm a little brain dead tonight.

 

[christiane]

Well, I got home today to use the nice weather to do some looking around on the car. First I checked the plugs they were actually Autolite 63s; however the guy that reassembled the head either did not gap the plugs at all OR he for whatever reason gapped the plugs at ~.040" to ~.050" . In addition to this the guy somehow managed to mess up the worm gear clamp on my throttle body to the point that it was not clamping. I will post back tomorrow afternoon once I replace the clamp. But I think this should solve my problem(s).

 

[ddavisaf]

That's good news. Cheap fixes are the best.