RB26 S14 cutting out under acceleration?

[Driftwurks]

I'm posting this for a friend because i'm curious as to why this is happening. My friend has a RB26 out of a R32 swapped into his S14 running off of a Haltech Platinum Pro ECU. Car turns on fine and drives fine except whenever my friend goes under acceleration (usually WOT) but it also happens during regular acceleration too, the car starts spitting and just bogs. This happens at anywhere from 3000-7000 rpm and is completely random. AFR reads around 10.5-11.2 at WOT. What are possible causes of this? Sorry if i'm not being very detailed (it's not my car I just feel bad for my friend and want to help him figure it out).

Side notes:
1000cc RC injectors
Twin turbos have been machined to larger size (T3/T4 with HKS internals)
Splitfire coil packs

If there are any details that could help you figure/troubleshoot this problem please PM or post here and I will try to get them from my friend.

[240boi115]

did your friend get a tune after his motor was swapped into his car?

[Driftwurks]

Originally Posted by 240boi115

did your friend get a tune after his motor was swapped into his car?

Sorry, I forgot to mention that! Yes, the car was tuned and the same issue was occuring on the dyno (while being tuned) and the tuner didn't figure out why either.

[AsleepAltima]

no boost leaks or vacuum leaks?

[240boi115]

maybe a boost leak^^^ or possibly a dirty throttle body. my ek9 did this and when i cleaned out the throttle body it worked magic and stopped bogging and acting up.

[Driftwurks]

Originally Posted by AsleepAltima

no boost leaks or vacuum leaks?

Not to my knowledge. I'll ask him tomorrow. Wouldn't a boost/vacuum leak cause a constant issue though? The issue my friend is experiencing is random and doesn't always occur although it is pretty often. It causes the car to go into limp mode as well. The turbos still have factory actuators as well. Don't know if that helps at all, i'm just throwing out all the info I know about the car.


More side notes:

Stock wastegate actuators
Single HKS SSQV
N1 bottom end
Factory turbo elbows

[Driftwurks]

Well, I just wanted to update this post for anyone who might experience similar issues. We noticed that when the issue occurs the tachometer drops to zero. Being that the RPMs are based off spark pulses, this indicates there is no spark when the issue occurs causing it to cut out. We are assuming it is a faulty ignitor chip and will be replacing it and see if that fixes the issue. I will post updates.

[funktown240]

Make sure that the injector corrections are correct. Low/High imp, injector latency and dead time. You can contact the manufacturer for details or if you have a flow sheet

[Driftwurks]

Originally Posted by funktown240

Make sure that the injector corrections are correct. Low/High imp, injector latency and dead time. You can contact the manufacturer for details or if you have a flow sheet

Thanks! Yes, my friend has a flow sheet for the injectors so I will let him know.

[ultimateirving]

Symptoms sound like spark break up to me, With the splitfire system im not sure why he would be seeing issues with the spark, but more than likely you will find it after the ignitor is tested. Also make sure the plugs are gapped properly, TOO wide of gap can cause blow out at higher boost
I had a stock coil pack that worked well enough to drive, but started bogging misfiring and cutting out randomly if i gave it any gas.

So, to me, that is what sounds like is happening to the RB26

[Kingtal0n]

Ive seen this before its usually plug related. try some iridium plugs brand new out of the box before you do ANYTHING else. I had a 2j give the same exact trouble and it was just plugs.

[AsleepAltima]

That doesn't explain the tach going to zero... That sounds to me like a harness ground problem.

[Kingtal0n]

Originally Posted by AsleepAltima

That doesn't explain the tach going to zero... That sounds to me like a harness ground problem.

If plugs dont fix it, then I would start thinking like this. Yes. But try plugs first IMO. I mean, yeah check the silly ground on the back of the engine.
Check if anything was painted under like by the headlights where serious grounds are. true true true

[Sileighty_85]

blowing out spark isnt gonna make the tach drop to zero all of a sudden if everything else is getting power and the engine is still rotating. It would dip a few hundred RPMS but not to Zero

Def sounds like a power loss if the tach just drops to zero all of a sudden, especially if its random. Sparks plugs arent intermittent they either work or they dont.

My S13 had a similar issue with randomly shutting off, turned out I had a bad chassis plug that a wire inside the plug corroded and broke.

For shits and gigs I would check plug gap, but Def would check harness plugs and grounds.

[Driftwurks]

Thanks for all the helpful posts guys! Also, wanted to mention that the issue is only occuring in first and second gears. I will tell him to check all the aforementioned possibilities.

[Kingtal0n]

how do you know the tach issue has anything to do with the misfire? Just because they happen at the same exact time doesn't mean they are related.

It also would depend on what kind of tach and how the tachometer is referencing rpm. If it comes right off the ECU then it could be an ECU related issue which would explain both problems.

If steve was here, he would tell you unplug the ECU and check the terminals for corrosion.

[cbcm2435]

Cam angle sensor maybe?

[Driftwurks]

Originally Posted by Kingtal0n

how do you know the tach issue has anything to do with the misfire? Just because they happen at the same exact time doesn't mean they are related.

It also would depend on what kind of tach and how the tachometer is referencing rpm. If it comes right off the ECU then it could be an ECU related issue which would explain both problems.

If steve was here, he would tell you unplug the ECU and check the terminals for corrosion.

Factory tachometer hooked up to a haltech ecu.

[91coupesr20det]

What fixed it?

[tareqelk]

I have the same problem in my 300zx I had my car tuned and still have the vg30dett motor running haltech it does the same thing you just described. It hissitates at 3k and up only on first and second gear and it does it randomly. I have no idea what it is!