Hard Boost run issues

[Tom]

+1 on everything John said. Might as well check for blink codes while you're at it I'd also check the TPS (at the DME/KLR connectors) in case it or its connector is sending whacky signals. If it told the DME the throttle was closed under boost, it may have shut off the injectors in fuel overrun mode; and if it is telling the KLR your foot is to the floor when it isn't, it could trigger the WOT signal when you're not at WOT. And quadruple check all your wiring connections. If the ignition really did cut out randomly, or of if the MAF is sending rich signals, wiring is always on the list (ask me how I know....). But, yes, happy to look at your KLR if you want. I can even put it in my car, but if the problem is intermittent and infrequent, that may not tell us much.

p.s., I assume your Rogue stuff has been running fine for a long time, such that this isn't one of the drivability issues that afflicted those systems in the post-Josh world?

[Fejjj951]

Okay.

I have some things to look at now.

I have been jammed up with business the last couple of days and will be heading out of town Friday morning so hope to get to the car next week. Thank you for helping me out guys!

[Tom]

Any progress?

[Fejjj951]

Any progress?

I did drive the car last weekend and did some hard boost runs. I was hoping to duplicate what happened previously so I could check the voltage on B and C but it ran normal EXCEPT twice under full boost in 5th gear, I experienced fluttering around 4K RPM. A little ways further down the road I was able to boost normally in 5th.

[Tom]

Any progress?

I did drive the car last weekend and did some hard boost runs. I was hoping to duplicate what happened previously so I could check the voltage on B and C but it ran normal EXCEPT twice under full boost in 5th gear, I experienced fluttering around 4K RPM. A little ways further down the road I was able to boost normally in 5th.

No guarantees, but that sounds like a classic example of a weak spark on these cars. Under heavy sustained load (high gear, full boost) the spark isn't strong enough and the car stumbles a bit. Unless everything is pretty darn new (like less than a year old) I'd put in a fresh set of BPR7ES plugs gapped to .26; new Clewett wires, Bosch cap and rotor, and I bet that goes away. My car pushes the limits but I need to replace the plugs and wires at least every couple years. The wires are an often overlooked part of the equation that can absolutely lead to weak spark. Ask me how I know. I have tried nearly all the wires out there and love the Clewett's. He'll customize them too as needed, and sells them for peanuts compared to anything approaching their quality.

[cda951]

All of this led me to go with standalone engine management (VEMS) which allowed me to easily adapt a wasted spark ignition system, which allows for proper spark plug gaps (0.032") and the ignition system keeping up with 19 PSI boost (though 14.7 PSI is the norm for my setup, high boost is for fun ).

Everything is a compromise, one just has to pick and choose what to compromise, especially if smog compliance in CA is an issue.

[Fejjj951]

Any progress?

I did drive the car last weekend and did some hard boost runs. I was hoping to duplicate what happened previously so I could check the voltage on B and C but it ran normal EXCEPT twice under full boost in 5th gear, I experienced fluttering around 4K RPM. A little ways further down the road I was able to boost normally in 5th.

No guarantees, but that sounds like a classic example of a weak spark on these cars. Under heavy sustained load (high gear, full boost) the spark isn't strong enough and the car stumbles a bit. Unless everything is pretty darn new (like less than a year old) I'd put in a fresh set of BPR7ES plugs gapped to .26; new Clewett wires, Bosch cap and rotor, and I bet that goes away. My car pushes the limits but I need to replace the plugs and wires at least every couple years. The wires are an often overlooked part of the equation that can absolutely lead to weak spark. Ask me how I know. I have tried nearly all the wires out there and love the Clewett's. He'll customize them too as needed, and sells them for peanuts compared to anything approaching their quality.

I agree with your assessment Tom. It makes sense in light of what I originally posted. I have also noticed the my AFR at idle has been dithering between 14.6-15.4 which is higher than what I normally see. Just wondering if it also might be a FPR issue.

Also, I did pick up a known good KLR that I plan on swapping as soon as it stops raining here. I have been so busy building an ark I haven’t had much time for the car.

[Fejjj951]

All of this led me to go with standalone engine management (VEMS) which allowed me to easily adapt a wasted spark ignition system, which allows for proper spark plug gaps (0.032") and the ignition system keeping up with 19 PSI boost (though 14.7 PSI is the norm for my setup, high boost is for fun ).

Everything is a compromise, one just has to pick and choose what to compromise, especially if smog compliance in CA is an issue.

Understood.

I have a MAXXECU setup waiting on completion of the harness and then can get rid of the existing harness.

[Fejjj951]

I have not been able to replicate the ignition cut followed by the pig rich condition.

However, the last few times I drove the car I am seeing rich AFR’s under part throttle (12.5-13.5) and WOT 10.8-11. I cleaned the MAF sensor with CRC and checked all vacuum connections. I also ordered new spark plugs.

[Tom]

How frustrating that must be. Seems like every time you post it's a totally different set of symptoms. How close are you to installing the new ECU and harness? There may be more than one thing going on there.

Is it rich at idle or does it stick close to 14.7? If 14.7, that would at least tell you the wideband isn't just inaccurate. Did you ever check the WOT signal to see if it is stuck in the on position? (That would not explain being rich under WOT though.) Check Fuel Pressure?

All this started out of the blue on a car that had none of these problems before, right? Some of the Rogue MAF systems (especially from LR) had mapping issues, but you'd know that as soon as you install it if that's the problem.

Vacuum leaks would make you lean when off boost and rich when on boost.