R34 GTR - Misfire/Stuttering

[NAB 8]

R34 GTR - Misfire/Stuttering

 

Hey guys,

Over the past couple of months I have noticed an increase in misfires while coming on boost/just before boost. Initially it was mild yet when it happened the 4WD and A-LSD error lights would toggle on in most cases. Now every time the car is driven I experience the misfire.

The coil packs and spark plugs were swapped out for new ones just under a year ago so my initial thought was that it could not be them. Boost is also very inconsistent in when and what boost it hits. I also noticed that in 2nd gear for example, there is barely any boost (0.4-0.5 bar) before 4.5k rpm and then at around 5k it hits really hard (1 bar) and causes the car to jolt suddenly. I do know that the stock turbos currently installed are in poor shape having a whining noise so I wasn't sure if that had anything to do with the problem but I am planning to swap the turbos out next week hopefully.

Has anyone had something similiar or know of a fix?

Thanks, Nick.

 

Edited April 24, 2017 by NAB 8

[JGTC]

Have had similar issues in the past, whistling/whining sounds coming from the turbo can be bent/chipped fins or just faulty/split vacuum hoses, both can cause issues with the AFMs which in turn can cause the car to run funny.

Before removing parts, take it to your tuner, have them perform a 'check up' on the dyno, where they can hook it up and diagnose before removing anything as well as a smoke test to test all the vacuum hoses/lines,  faulty turbos can deliver inconsistent air causing issues with the AFMs which can cause the car to overboost, spike or miss.  

Best thing to do start cheap by doing a smoke test then move on to the dyno in a controlled environment to diagnose before spending money fixing unknown issues.

Edited April 24, 2017 by squareznboxez

[NAB 8]

On 2017-4-25 at 0:39 AM, squareznboxez said:

Have had similar issues in the past.....

Thank you for the reply. That does make sense now that I think about it . I will get in contact with a tuner within the week coming and I have had air leaks in the past so I will make sure to inspect the whole system properly.

Again cheers for the help, Nick.