RB25 misfiring and spluttering on acceleration

[Azj]

Hi guys,

I have a series 1 r33 running spitfire coils, 1250cc injectors, walbro 460 fuel pump, gtx3076r and an Apexi fc. 

 

The car DOESNT struggle on start up/Idle, but splutters and struggles to accelerate. After 15mins or so of driving, the car suddenly runs as normal and runs like a champ. 

 

The problem all started within one day- I drove the car in the morning and it ran fine and then came back to it 2 hours after of parking and the problem started. Hasn't gotten worse or any better.

I have checked the spark plugs, they all look fine.

 

Is it a coilpack problem? 

Ecu problem? 

Sensor problem? As it runs like shit until normal engine temp. 

 

Thanks a a million guys,

Any help is much appreciated.

[Cowboy1600]

Sounds like maybe the cold start map is rooted?  Could be related to a sensor, I imagine a temp sensor.

I'm a f**king genius, I know.

Or I have no idea what the hell I'm talking about.  I'll let you decide.

Actually, i just found this - http://www.skylineowners.com/forum/21-tuning-technical-questions/217142-r33-gtst-starting-problems-help-please.html - it explains how to test the coolant temp sensor (wasn't the issue in his case).

 

[Azj]

@Cowboy1600  Thanks man, I'll definitely consider what you suggested. I'm hoping that it isn't ECU related because I can't afford a tune!

Can anyone suggest any other possible causes? As I said it misfires pretty bad until the engine is warm (or after 15 or so mins of driving).

Thanks!

[admS15]

If the car ran fine then all of a sudden it started playing up, it isn't tune related. I'm with cowboy and suggesting a sensor. Probably coolant sensor, I believe there is a couple of them, not 100% sure. Do you have a hand controller for the power fc? If you do, you could check what the sensors are reading and if anything looks suspect.

[KiwiRS4T]

There are two coolant sensors. the one with one wire goes to the gauge so won't be a factor. The one with two wires goes to the ecu. Try pulling the wires off . if it cold starts ok its definitely the sensor as without it the ecu will use a back up map but if its dodgy it will mess with things. 

[Azj]

Thanks for the responses everyone. But a bit of an update; drove it again today and it misfired until completely warm, where it would then normally stop misfiring once warm, but today I also noticed a slight misfire whilst driving once the car was completely warm as well? The misfire when warm is irregular but seems to be on partial throttle, but full throttle it doesnt misfire  Still a coolant sensor problem possibly? Thoughts? 

Edited July 21, 2016 by Azj

[Cowboy1600]

I'd hazard a guess that your plugs are now dirty. It's running hella rich when cold and the plugs are fouled.

 

[KiwiRS4T]

3 hours ago, Azj said:

Thanks for the responses everyone. But a bit of an update; drove it again today and it misfired until completely warm, where it would then normally stop misfiring once warm, but today I also noticed a slight misfire whilst driving once the car was completely warm as well? The misfire when warm is irregular but seems to be on partial throttle, but full throttle it doesnt misfire  Still a coolant sensor problem possibly? Thoughts? 

What's the point of sharing my thoughts if you just ignore them? Pull the wires off the sensor - 2 second job as above. If it doesn't make any difference its a two second job to put them back!!!

[Azj]

@KiwiRS4T Sorry mate, I wasn't ignoring what you said but was just updating what had happened. I'll give it a crack tonight and report back but cheers for the support and help everyone!

[V28VX37]

Could be a million reasons, the RB loves to keep you guessing. My experiences here, can be used as a bit of a checklist: 

Anyway mine ended up being a busted CAS so it broke down past 4000rpm, yours sounds a little different.

[Azj]

UPDATE: So I pulled the coolant temp sensor out (to the ECU) and the car ran fine as it should with no misfiring. I put it back in and started the car again and seemed to rev/idle as normal as well with no misfire? Is it possible that the sensor just needed to be unplugged then plugged back in? And reset itself or something? Also, I pulled out the spark plugs and they are pretty black and look like they could do with replacement plugs.

@V28VX37  Thanks for your reply man- I'll have a look at your post if the problem persists.

Edited July 24, 2016 by Azj

[Dose Pipe Sutututu]

You have a powerfc with a hand controller.

Look at the water temp

[89CAL]

Id pull the plug off the coolant temp sensor (ecu) and clean the contacts. Continue to drive and see if it is better. I would hazard a guess its more likely you have partially cleaned the contacts by removing and then re-installing the plug if the problem seems to have fixed itself. The ECU merely reacts to what the coolant sensor is telling it so there is no 're-setable' element to it

[hardsteppa]

^^^ there you go. +1 for the 'cleaning contacts' by unplugging/replugging.

[Azj]

Hey guys..just a bit of an update;

Ended up taking it back to my tuner and we diagnosed that an injector was faulty and replaced it. After this, the car seemed to run fine when you weren't hitting it hard, but when I did, 1st gear would break up badly (only 1st) and every other gear didnt feel like it was hitting full boost (I don't have a boost gauge). This all happened for about a week then the misfiring during sedate driving happened all of a sudden again.

Took it back and we diagnosed another faulty injector and replaced it. I got the car back today and it doesn't misfire when driving sedately, but 1st gear still breaks up hard and it doesn't feel like its hitting full boost in the other gears. 

Is the next step replacing coilpacks? What else could be the root of the problem from other peoples experiences,

Thanks a million guys.

[Jaffarr]

Coilpack or ignitor

[msammut]

Hi Aaron

 just looked at the FSM page EN-139 states

Perform CONSULT active test mode
( Increasing "FUEL INJECTION" item) or
enrich mixture by disconnecting engine
temperature sensor connector and
inserting a 600 Ohm resistance after warming up the engine. )

Nissan suggest that insufficient fuel pressure could cause misfire on acceleration.

Has fuel pressure been checked? Have you an after market fuel pressure regulator or Stock? need to check that the regulator is working correctly also.

Lots of other checks that should be done on pages EN-139 - EN-142 before changing parts by guessing.

Michael.

Edited August 31, 2016 by msammut

[Azj]

Sorry for the late reply but cheers for the response Michael- although the fuel pressure is fine on the FPR. 

So now the car isn't missing as it was after replacing the coilpack loom.

Though the car is DEFINITELY  still down on power, and sometimes splutters briefly then pulls when you get on boost around 4500rpm and full throttle (again, the pull isn't as hard as what it used to be).

 

Tuner seems to think it's not the splitfire coilpacks after testing, all Injectors have been replaced, I've checked the coolant temp sensors, O2 sensors etc but yet no avail.

 

Can anyone suggest anything else? 

 

Thanks a million guys.