Car won't rev past 5000rpm.
 

I just got home from Mosport, I was at a PCA DE this weekend. My 86 944 Turbo will not rev past 5K. It starts to stumble and misfire at exactly 5k.

Ihave replaced:

Cap and rotor
Plugs(2 sets)
wires
Ignition Coil

I have looked over the wiring 100's of times, seems ok.

The car is running a Rogue DME and M-tune. It is currently running very, very rich. AFR gauge is showing 10-1 at WOT. Idles well and pulls nice to 5K
Engine compression and leakdown numbers are well within spec.
Stock K26-6 Turbo has been rebuilt by evergreen
All the grounds have been cleaned
No boost or vacuum leaks after multiple tests
all vaccum lines/hoses have been replaced.
FQS switch is set to pull as much fuel as possible(Rogue DME)
Car has a S2 transaxle(not sure if speed signal would mess things up)
Car seems better when first driving and would get worse as the track session went on.
bypass valve is a billet unit from lindsey


I tried the 3 bar FPR, no luck. Runs better on the stock 2.5
I was able to turn the boost up to 16 lbs to compensate for the lack of revs but obviously I'd like to figure this out.

I don't even know where to look or what to do at this point.

Megasquirt is looking awfully tempting at this point...

Please help. :banghead:

Here is a thread regarding issues with running rich with an M-Tune.

https://rennlist.com/forums/944-turb...ll-around.html

You've checked everything i'd recommend.
Clean the MAF sensor?

It sounds to me like you have the same issue I have with my car. M-tune and Rogue DME. There is an issue with your KLR and the Rogue DME. If you switch the board as a quick test only to NA the car should run normally.....HOWEVER WARNING.....the knock detection will be bypassed.

I have to send my board off to FTech9 to have it fixed/modified. I posted my issues a few years ago as my car would not run properly when the switch on the DME was set to turbo mode. Mine would not rev up at all or allow any boost. It did run on NA mode.

Unfortunately I was not aware of the knock bypass and my engine detonated and I lost piston # 4. My car may have been more sensitive being a 3.0L and a ton of mods to the car. I am going to be shipping off my board shortly to FTech9.

The car boosts great and revs to 5K with no issue. It;s too rich but it pulls fine. Hitting 5K it starts to misfire everytime. I am wondering if the fueling tables get super rich at 5K and the ignition cant light the too rich mixture.

Hotter range plugs helped a little as did high octane fuel. It still misfired but not as bad.

I've contacted Joshua at Rogue again, hoping for a replacement chip or a DME tuner. Failing that I will go megasquirt.

I don't have m tune but I would be curious to know what the timing looks like. Can you check timing with mtune? Any chance you are running an adjustable cam gear that may have loosened? My thought were a hotter plug and higher octane fuel are a crutch for either a poor coil or a timing issue. Scope your ignition pattern if possible. I would also think a poor grounding ignition cycle may be an issue.

Timing is set within the chip(tables) and I have no access to them. I'm not sure what the timing looks like. I wish I had a DME tuner.
No adjustable cam gear so no chance of that.
Coil is brand new. Ran the same on the old coil.
Grounding could be an issue but I can't see it happening at exactly 5000rpm every single time.
Plugs look great, nice and tan. I really think I'm flooding the cylinders with fuel beyond 5k and its causing major misfires/backfires but that type of behaviour points to an ignition issue.

I'm stumped.

Hey Darren! That sounds great. I'm looking into getting the A-Tune to start and glad to see there's still support from Joshua et al.