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.

 

[Lonnie gandee]

Maybe change the plugs..... It sounds dumb but mine runs like crap up top on wore out plugs.

 

[Kickin Asphalt]

I couldnt figure it out either but when I changed to a hotter plug (ngk BPR8es) it stopped the problem. If it's running rich you might have a small pinhole boost leak also.

 

[herblove]

So you guy are saying try different plugs. I run NGK 1 range cooler plugs. Right now the stock range NGK's are in it and I have problems with both.

 

[Lonnie gandee]

I doubt your running less than 15psi, so i wouldnt bother with 6's at all.

Its winter time here in ohio, so i run 8's at 20 psi.

U should at least buy a set of brand new 7's... It the easiest thing to try.

And do u have an upgraded turbo?? Maybe ## 14b turbo is out of wind up there @6200.

 

[herblove]

Yeah I dont think it the plugs. I have replaced with new 7's and the same thing happens. I should be able to rev to 6200 rpm on a stock head. Yes boost is at 25 psi on a GT-12.

 

[Kickin Asphalt]

Try a boost leak test, I'm still guessing its a small leak. Does it back fire at all?

 

[Rex2342]

Whats the gap set to on the plugs? It sounds like your breaking up. Have you tried to tune it out? What about a boost leak test?

 

[herblove]

Sorry have not had time to work on the car. I am in the process of doing a boost leak test and have found I have a major leak around the intake mani area. I will fix this and let you guys know the results.

 

[fourreGsixty3]

I couldnt figure it out either but when I changed to a hotter plug (ngk BPR8es) it stopped the problem. If it's running rich you might have a small pinhole boost leak also.

BPR8es' are colder plugs not hotter.

To the OP:

What kind of management do you have? Are you seeing any kind of detonation? The overly rich mixture is probably from the boost leak at the intake manifold that you found.

If you are seeing detonation, the ECU is most likely dumping fuel, and retarding the timing.

 

[herblove]

I am using AEM EMS. I have had it tuned and no one seem to know what is causing it. It was tuned by a respected tuning on the east coast. I did a boost leak test and my pcv valve was leaking. I just finish driving and it still is doing it. To go on what some one said. It seems like it is breaking up. Plugs gap at 028 NGK 7's. We though it was to much oil psi to the head so I ported the oil filter housing and still nothing. I just cant get in my mind that the dual springs are not holding up at 6200 rpmsWTF. So what else could it be. Someone said sensors. What sensors. My coolant sensor for the AC is not plugged in (dont need right now) Thats all.

 

[herblove]

during my drive I watched the boost and A/F wideband gauge and nothing changed as if there was no problem when the car broke up

 

[turboglenn]

HAve you trie new plug wires. WHne my car did that it was in need of good wires. Went magnecore and haven't had it happen since.

 

[herblove]

wires and COP and it still happens

 

[turboglenn]

I am using AEM EMS. I have had it tuned and no one seem to know what is causing it. It was tuned by a respected tuning on the east coast. I did a boost leak test and my pcv valve was leaking. I just finish driving and it still is doing it. To go on what some one said. It seems like it is breaking up. Plugs gap at 028 NGK 7's. We though it was to much oil psi to the head so I ported the oil filter housing and still nothing. I just cant get in my mind that the dual springs are not holding up at 6200 rpmsWTF. So what else could it be. Someone said sensors. What sensors. My coolant sensor for the AC is not plugged in (dont need right now) Thats all.

Now that i think about it.

I remember when the first one's came out, we had that same problem at a shop clled import autosports where i was doing fab and tuning work. We had several of them that wouldn't rev much past 6. We got some support from The guy who brought it over from europe when it was still the GEMS and there was something we had to do with either the signal modification or a resistor some where. That's been at least 6 years ago so i can't remember what it actually was now. Try getting on the AEM forums and see if you find anything.

But these cars did it from the get go, if yours has just recently started this it could be something else.

 

[herblove]

Now that i think about it.

I remember when the first one's came out, we had that same problem at a shop clled import autosports where i was doing fab and tuning work. We had several of them that wouldn't rev much past 6. We got some support from The guy who brought it over from europe when it was still the GEMS and there was something we had to do with either the signal modification or a resistor some where. That's been at least 6 years ago so i can't remember what it actually was now. Try getting on the AEM forums and see if you find anything.

But these cars did it from the get go, if yours has just recently started this it could be something else.

Turboglenn that is interesting because when I was on the factory ECU and MAF-t I had no problems. I wonder if it has something to do with the way the AEM EMS is hooked up. I think that my tuner would know of such a thing. My tuner didnt hook up my EMS he just try to tune it.

 

[turboglenn]

I would say go search teh AEM orums, if no answers found there, call AEM tech support. If you can talk to Jason Siebles ( the somewhat "inventor" or guy who originally marketed it to AEM and imported it from the european GEMS system)

 

[xtreme-elements]

check your ecu... i had problems like this about a month after i installed 3" gm maf and maft trans 16 g turbo turbo chargers mani and 550 injectors... i started at the basics then ended up checking the caps in the ecu and sure enough blown cap

 

[herblove]

Well I have talked to some machine shops and they all say it sounds like a lifter problem. Has anyone had problems with the lifters. I have the revised 3g lifters by the way.

 

[BooostedAWD]

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.

From the sound of it.. I'd say we have a very similar problem.
If I find out anything, I'll let you know:
http://www.dsmtuners.com/forums/problem-diagnosis/276467-weird-misfire-cant-figure-out.html



Speaking of lifter problems.. I have 3G lifters also.
I've heard rockers can pop off allowing this to happen.. I haven't had the chance to check mine yet.
But the thing about this, is that I don't have the AEM EMS.

 

[turboglenn]

Have you called AEM or checked their forums yet? Like i said, we had a few units do that and it was all somehting that either had to hook up or be set differently in the triggers. It's been too many years to remember exactly what it was now days though

 

[herblove]

From the sound of it.. I'd say we have a very similar problem.
If I find out anything, I'll let you know:
http://www.dsmtuners.com/forums/problem-diagnosis/276467-weird-misfire-cant-figure-out.html



Speaking of lifter problems.. I have 3G lifters also.
I've heard rockers can pop off allowing this to happen.. I haven't had the chance to check mine yet.
But the thing about this, is that I don't have the AEM EMS.

I have just read your post and it sounds like we my have the same problem. If you fix let me know how and I will do likewise. I don't think the aem is the problem. I am leaning more onto something in the head is out of wrack.

 

[turboglenn]

I'm telling you from experience that the AEM will do this EXACT thing if something is out of whack on the trigger setup. You can believe me and call AEM and see if they have notes on it, or just keep wondering Jason Siebles at AEM was teh one who told us what to change to get the one's that we had doing this to work correctly.

 

[BooostedAWD]

I have just read your post and it sounds like we my have the same problem. If you fix let me know how and I will do likewise. I don't think the aem is the problem. I am leaning more onto something in the head is out of wrack.

Thanks. I have dual springs also...
I was also reading on another forum that this exact problem happened when a guy with Web Dual Springs and popped off the valve cover and saw that 2 of his outer springs were broken in half.
He said that this happened to him twice. He explained that it was because he hadn't let the car warm up to running temp before driving it. (I know I have been guilty of this a couple times).

Although I hope thats not the case for both of us.
I plan to pop off the valve cover tomorrow.. I'll let you know what I find.

In the same forum, another DSMer had a problem with the intake manifold gasket had a huge chunk missing. He was describing the same problem. It's another option..

Good luck.

 

[GVR4592]

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