Why I cant rev pass 6200 rpms

[herblove]

My car will not run right if I rev pass 6200rpms. It will start to sound like it has dropped a cylinder and runs rich. This will last about 20 seconds then it will be back to normal. My timing is correct and I have dual springs in the head. I have also ported the oil filter housing to relieve pressure to the head. Can anyone throw out some good ideals why I am having this problem. I mean 6200 rpms is not that high to have problems.

 

[turboglenn]

Post your AEM cal file. Does the problem occur in every gear? Does it feel the same as hitting the rev limiter?

+1 maybe i can get the files from teh cars we had issues with to compare things ( they were also DSM's and one nissan )

 

[BooostedAWD]

Herblove,

I've figured out my problem.
One of the outer valve springs on the intake side if cylinder #3 had broken right in half!
I suggest taking off the valve cover and examining each spring carefully..

When I moved the cams with 2 17mm wrenches, and the lobe wasn't touching the rockers, I was able to spin the spring around with my fingers.

Well, I guess thats better than buying a new eprom ecu.. Still scary though.. if that little spring fails, thats my engine

anyways, I'm glad I found my problem.

Good luck.

 

[herblove]

Herblove,

I've figured out my problem.
One of the outer valve springs on the intake side if cylinder #3 had broken right in half!
I suggest taking off the valve cover and examining each spring carefully..

When I moved the cams with 2 17mm wrenches, and the lobe wasn't touching the rockers, I was able to spin the spring around with my fingers.

Well, I guess thats better than buying a new eprom ecu.. Still scary though.. if that little spring fails, thats my engine

anyways, I'm glad I found my problem.

Good luck.

Glad you found the problem. Do you have stock springs? I found out last night that I can rev pass 6200 rpm if I am not in boost. I rev to 6800 rpm in second gear and didn't have any problem at all as long as I was not underboost or heavy throttle. So I think that my problem is not with the head. I mean if I can rev like that not under boost the head is still seeing the same stress (Right). I did a boost leak test and didnt get pass the pcv vavle as far as a leak. I not thinking boost leak because my gauge hold steady and A/F is normal through out my runs. I dont want to pull the valve cover cause now I think it something else.

 

[herblove]

BoostedAWD I read your profile and it says you have dual spring also. I think if that was my problem it would break up at 6200 even w/out it being under boost.

 

[fourreGsixty3]

Why not just pop the VC off, and just check incase. I wont take more then an hour, and you can be 100% that its not your problem. Instead of says" Well I dont think thats my problem" and start looking other places, and it could be your problem.

 

[BooostedAWD]

BoostedAWD I read your profile and it says you have dual spring also. I think if that was my problem it would break up at 6200 even w/out it being under boost.

It would be good to check just in case.. but yes, I see your point.
I was not able to rev over 6200.. at all.. in neutral, WOT, 1/2 Throttle.. couldn't do it.

But it's worth it just to check so you can cross some things off your list.

So it only misfires under boost?
You're running 25 psi on a gt-12? Thats a lot of boost. It almost sounds like it could be spark blow-out. I'd try turning down the boost some to see if it helps.
Any kind of knock showing up when it misfires?

 

[GVR4592]

Let's see that cal file. I've seen this happen a lot with AEM equipped vehicles and in most cases it's a really easy fix.

 

[herblove]

Why not just pop the VC off, and just check incase.

You are right I just pulled my VC and checked and for sure it was a damn spring. I was just sure it couldn't be that. I mean they are dual springs and the motor hadn't even had 10,000 miles on it yet. Thank guys from all your insight. BooostedAWD and fourreGsixty3

 

[herblove]

What would cause the spring to break. I have crane cams and dual springs.

 

[bori18]

Once you fix the problem let me know if it was the cause..... also ngk makes 9s wich you might like to try they cost the same as the 7s and 8s and they make a big difference on big boost only problems is they foul easy in cold weather start up

 

[herblove]

Once you fix the problem let me know if it was the cause..... also ngk makes 9s wich you might like to try they cost the same as the 7s and 8s and they make a big difference on big boost only problems is they foul easy in cold weather start up

I change to ngk 9's today it seem to help a little but when I looked under the valve cover I found that one of my springs was broke on the exh side one cyclinder one. Still like to know why it would break. Head is fairly new.