[Jamieebeau]

Hey everyone,

I know I'm not the first to ask about an RB misfiring and I won't be the last, but from my searching, I can't find anyone posting similar symptoms. Basically I bought this RB25det R34 GTT last year (2022) from a guy that had just driven it about 3200km (the car is at 195xxx KM). He said the misfire had been happening for awhile before that. The car looks to have a few basic mods, but they were all done by the first owner. The guy I bought it off was definitely not a guy car, so he knew nothing about it. It has things like an Apexi AVCR boost controller, turbo timer, HKS intercooler, HKS SSQV blow-off and other small things.

What is happening is a serious misfire. So far I have; Replaced spark plugs, replaced coil packs and coil loom, fixed all boost leaks, replaced the blow off valve and run a few injector cleaners. I'll list the symptoms below

• The misfire doesn't happen all the time. Maybe 40-60% of the time
• It's more common at lower RPM. It ALMOST always goes away when running at over 3500RPM
• It will 100% go away over 4500RPM
• Some days it'll run 2 hours without misfiring once
• Some days it'll misfire from the moment it turns on
• There seems to be a connection to the car coming on boost and the misfire going away, however this isn't consistent
• There seem to be a connection to the temperature of the air?? The hotter the day is, the longer it normally takes for the car to start misfiring, but again, it's not very consistent
• The misfire varies in terms of severity. Some days it's a small tick, other days it'll totally stall the car and prevent the car from accelerating at low RPM
• The car is running 16PSI and I can't verify the car was ever tuned appropriately to run this boost

Any suggestions would be greatly appreciated!!

 

[Tricky-Ricky]

Sounds like a closed loop problem, so I would be looking at the lambda sensor, also the ECU coolant temp sensor although the symptoms you describe don't point directly to this, also a possible MAF problem.

 

[Jamieebeau]

Sounds like a closed loop problem, so I would be looking at the lambda sensor, also the ECU coolant temp sensor although the symptoms you describe don't point directly to this, also a possible MAF problem.

Lambda sensor, as in the O2 sensor?

 

[ms33]

Pertaining to the MAF problem, the internal solder joints are known to fail. Just need re-soldering.

 

[Tricky-Ricky]

Lambda sensor, as in the O2 sensor?

Yes!

 

[Mike Rotchburns]

Hey everyone,

I know I'm not the first to ask about an RB misfiring and I won't be the last, but from my searching, I can't find anyone posting similar symptoms. Basically I bought this RB25det R34 GTT last year (2022) from a guy that had just driven it about 3200km (the car is at 195xxx KM). He said the misfire had been happening for awhile before that. The car looks to have a few basic mods, but they were all done by the first owner. The guy I bought it off was definitely not a guy car, so he knew nothing about it. It has things like an Apexi AVCR boost controller, turbo timer, HKS intercooler, HKS SSQV blow-off and other small things.

What is happening is a serious misfire. So far I have; Replaced spark plugs, replaced coil packs and coil loom, fixed all boost leaks, replaced the blow off valve and run a few injector cleaners. I'll list the symptoms below

• The misfire doesn't happen all the time. Maybe 40-60% of the time
• It's more common at lower RPM. It ALMOST always goes away when running at over 3500RPM
• It will 100% go away over 4500RPM
• Some days it'll run 2 hours without misfiring once
• Some days it'll misfire from the moment it turns on
• There seems to be a connection to the car coming on boost and the misfire going away, however this isn't consistent
• There seem to be a connection to the temperature of the air?? The hotter the day is, the longer it normally takes for the car to start misfiring, but again, it's not very consistent
• The misfire varies in terms of severity. Some days it's a small tick, other days it'll totally stall the car and prevent the car from accelerating at low RPM
• The car is running 16PSI and I can't verify the car was ever tuned appropriately to run this boost

Any suggestions would be greatly appreciated!!

without being able to get my hands and eyes on it, maybe CAS. back when i was doing alot of Z32s a majority of the time, random multiple missfires were a bad CAS.

 

[ms33]

https://www.google.com/url?sa=t&sou...sQFnoECDAQAQ&usg=AOvVaw1wrU-98NS3W_LpWgVad64S

[/URL]

 

[Mike Rotchburns]

Can't open link

 

[xtremetofu]

I would try maf clean first doubt anyone’s cleaned it in years on most of our rides.

 

[ulyssesmeads]

ask too