URGENT - Recurring misfiring / stuttering problem with RB25DE engine.

[SilverR33GTS25]

URGENT - Recurring misfiring / stuttering problem with RB25DE engine.

Hi to all at SAU Community,

 

I own a 1994 R33 Skyline GST25 automatic with the series 1 RB25DE engine, which is the non-turbo engine. In the seven or so years I have owned the car, it's rarely given me a problem of any sort. I run the car on BP Premium Unleaded 95.

 

In the last 18 months I have started driving the car more often due to work reasons, about 4 times a week, and covering a lot more distance, although most of it is freeway driving. About 2 months ago, I started having a problem with the engine sometimes stuttering and misfiring. It seemed like it was running on 5 cylinders. The spark plugs had been changed a bit over 12 months before that (NGK Platinum plugs) , so it was doubtful it was the plugs, they should last 80,000-100,000 kms, and the car had not even done 20,000 kms in that time.

 

The local mechanic looked at it, could not find anything wrong, just 1-2 plugs needed a clean. He cleaned all the plugs and told me to see how it went for a little while. The car ran like a dream, punchier and more dynamic. All was fine for a while, and now in the last 2 weeks the problem returned, although not as bad as before. It seems to run fine after starting and then idling in park or neutral. Once shifted into drive and idling, or backing in reverse, the problem then appears - misfiring and mild kicking / stuttering. It goes away once back in drive and the car is travelling. It will re-appear when stopping at lights and idling in drive, and also when giving it some throttle while driving, or going up a hill. 

 

It all seemed to start after getting fuel at a Shell service station that I had not used before, and only went there out of necessity, so naturally at first I thought it was just bad fuel.

 

The problem continued, so back for another visit to the same mechanic. This time I'm getting told that spark plug no. 3 was rusty, meaning water was getting to it, and that a compression test indicated the beginning stages of a crack in the head gasket between the 2nd and 3rd cylinders. I'm told the car is still drivable, and changing the head gasket was not needed any time soon, but it would gradually get worse. 

 

While there, I had a new set of performance ignition coil packs put in, as well as a new fuel filter. No improvement. :s

 

My brother used to be a mechanic, and did his own inspection, and did not find symptoms of a cracked head gasket. Further opinions from 1-2 other retired mechanics agreed. So we are now considering bad advice or dishonesty from the mechanic who worked on the car. My brother poured a bottle of injector cleaner fluid, and also some basic stuff like topping the engine oil, and flushing the radiator with coolant. It actually runs better, but the problem is still there. He is now telling me I should get new spark plugs, especially since I have new coil packs, and to upgrade to Iridium plugs.

 

I am not rushing into buying new plugs just yet, as the current set of Platinum plugs have done a bit over 20,000 kms. Two different suppliers have told me in the last week that they should last 80,000-100,000 kms as said before.

 

MY QUESTION - Has anyone else experienced this or a similar problem, and what could the most likely cause be??? I've heard a range of causes ranging from bad fuel residue, to a cracked head gasket, depending on who you listen to.

 

Any help would be appreciated. Thanks. George. 

[zebra]

CHANGE THE PLUGS!!!

 

You can't "clean" iridium plugs

 

throw some copper plugs in, check them in a couple of weeks, If 3 is rusty or coated in coolant than it is head off. Or spend a few hundred bucks on a wrecker motor.

[Aqua]

My car had misfire/running on 5 cyclinders during idle, and also hesitation/stuttering/whatever you call it at mid rpm or when it was trying to come on boost earlier this year.

The misfire was due to blockage in injectors (I run E85 and occasionally BP/Shell 98). Mechanic cleaned all the injectors and problem solved.

However still having the hestitation during mid rpm. Mech did all the mechanical checks and couldn't find anything so deemed it has to be electronic problems. So I replaced my old splitfire with brand new ones and bought brand new OEM loom. Problem solved.

From my researches, spark plugs, injectors, fuel systems, coilpacks are the common issues. So you are on the right track, just need to track it down I guess.

Although the platinum plugs SHOULD last 100k kms but they still have a chance to get faulty before that. As per @zebra, getting some cheap copper plugs to check wouldn't hurt.

Hopefully this helps.