Multiple Cylinder Misfire P0300

[phoondie]

I have a 1998 GSX that is having the multiple cylinder misfire when cruising between 70-MPH. I have replaced the plug wires with NGK ones and replaced the plugs with NGK stock temp ones. The only mod that I have done is install a Fidanza aluminum flywheel and 2.1 clutch disk. I started receiving the code shortly after that. This has been happening for the past 9K miles and is getting really anoying. If I put the clutch in and let it drop to idle it will stop for awhile then come back. If I vary the throttle a lot when cruising at 70 it also helps it from happening. Any ideas/help would be greatly appreciated.

Thanks

 

[Spln_Hrd]

Check compression, ignition timing, did you gap the plugs?

Whenever I have a customers car with a missfire I put it on an osilliscope so if your not getting anywhere with it I would suggest taking it to a mechanic should only take one hour of him checking stuff, which would cost $60 here.

 

[phoondie]

yup, gapped the plugs correctly, the compression is good, and I have not checked the timing. I guess I was wondering if the lightened flywheel would cause any of this. Also I have tried to keep it at a steady RPM in lower gears that equaled the RPM at 70 and 80, this would not trip the misfire situation. It only happens at speed not rpm. figure that out. makes no sense to me. thanks for the response I will get the timing checked out. Let me know if you guys have any more thoughts on what I just posted to add to the original.

 

[twicks69]

http://www.dsmtuners.com/forums/showthread.php?t=242628

Please read post #15 regarding your problem.

I had it a few years back, and it ended up being a mixture of ignition coils, cam angle sensor and crank angle sensor. All were replaced around the same time.

Unfortunately, there is no definitive answer; just things to check and make sure that they are still within tolerences.

I would first off check the cam angle sensor, and the camshaft seal on that side -- as it may likely be leaking and may be affecting the signal the cam angle sensor is recieving.

Next would be the ignition coils; get your hands on another set, and check it.

Finally, the crank angle sensor is the hardest to get to, and requires the timing covers removed to get to it.

 

[phoondie]

thanks for the link to the other post. I will look into all that and see what happens. I also heard that it could be air leaking by the throttle body. Don't know how much water that holds though. Thanks again.

 

[PieEyedPiper]

Welcome to the club!

I too, started getting the P0300 code while cruising on the highway the DAY after I had my Spec Stage 2+ clutch installed.

I've:
-tested coils
-tested wires
-replaced plugs
-installed a grounding kit
-tested injectors
-replaced CAS (cam angle sensor)

All with no solution in sight.

I really think this has something to do with the clutch install because you (the OP) and I aren't the only 7bolt guys to get this code (relentlessly) right after a clutch job.
but since theres nothing to really do about that if that is the cause, I will continue my testing and probably replace my CPS (crank position sensor) next. I just hate throwing parts at a problem.

 

[phoondie]

That is exactly why I posted this question. I started to throw money/parts at it then thought what if what I am doing does not fix the problem. I could put my coil overs on for the amount this is going to be if I just keep on throwing things at it. I wish you luck. and thanks for the insight.

 

[dave99gst]

P0300

 

[PieEyedPiper]

Anyone have any luck with this yet?

This winter TPS, IAC and CPS are on my list. I'll let you know what I find.
But to be honest, seeing that this coincides (sometimes) with a clutch install (I had my rear main done too, would it matter?) it seems that CPS is probable but isn't that on the entire opposite side of the engine?
Just talking out loud.. trying to figure out what/if the clutch really has anything to do with this.

Also, there is a cam seal by the CAS, correct? Perhaps changing that seal would help, there is a bit of oil inside the CAS housing. I've heard there should not be.. but it seems impossible not to if you've taken one apart before.
But I'll add it to my list.

 

[twicks69]

Funny enough, this problem happened right after a clutch install in my car in January 2003, when I was leaving his shop. i thought he broke something...but it was just the dumb car.

 

[Hoodeclipse]

I was wondering if this issue has been resolved or not? Like phoondie I also have the exact problem with my 99 gsx after installing a 3.2 clutch and a 8lb flywheel from fidanza. I have checked all the basics wires, plugs, tested coil pack etc.

 

[clockworktoy]

Talk about thread revival, but Hoodeclipse check check your cam angle sensor and while your at it do a good ol C walk check. That was the culprit behind my random missfire problem.

 

[Hoodeclipse]

Thanx my dude I'll try that out and let u know I'm takin it to the shop to get some other things checked out and I'll have them look at that.

 

[TheyCallMe Tim]

Check the coilpacks. A P0300 code is a random/multiple misfire. Very rarely will multiple plug wires go out at the same time. See if you can get access to a professional grade (I prefer SnapOn) scanner that will tell you which cylinders it's counting the misses on. My guess would be a bad coil or ignition control module, I've had the ICM go out on my Camaro before and it threw the same code.

 

[vanilla gorilla]

Wow. What a freakin coincidence. I parked my car for a while because of a destroyed clutch. I then installed a fidanza 3.2 clutch and fidanza flywheel. Test drove it, then went the next day and got it inspected. Ran good, next day, the code came up and the car hasnt been running right since. Varys by speed. Does it at 80mph, then i can ####y foot it to get past 80..then it does it again around 100-110. Man I'm pissed. I checked for crank walk when I was doing my clutch install.

 

[SethA]

I have the same problem after a PTT twin disk install. There are numerous p0300 threads. There is not one specific cure. Some people had bad ECUs, some people had flakey MASs, some people had bad coils/ignitors. I don't know how many of these came after a new flywheel.

As was already said this often occures after doing a light flywheel on a 7 bolt. There was a suggestion in one that the crank harmonics are magnified by the reduction in inertia the lightened flywheel. Perhaps a weak crank position sensor is thrown off by the new harmonics?

I have changed my CAS and that didn't work. I think I will just bite the bullet and replace my CPS. Has anyone with this issue replaced their CPS and still got the P0300?

Seth

 

[ARPtunner67]

have you checked your crankshaft sensing blade for proper position, you must make sure it isn't touching against he crankshaft position sensor. also verify for propper timing. 2g 7bolt engines suffer from crankwalk that could move the crankshaft sensing blade. the primary reason that crankwalk happens is cause of the push and pull from the clutch it self. by changing it to a higher clamp force clutch it is gonna speed up the crankwalk problem. just my two cents from the experience I have building 4g63 engines.

 

[asexton6969]

Hope this may help.

 

[xlMcMlx DsM]

Multiple misfires are USUALLY fuel related, as if there was a fuel delivery problem, it would affect all cylinders, and not just one. One cylinder misfires are usually ignition related.

 

[vanilla gorilla]

Well, I just wanted to post to say that I fixed my problem.
The first thing I tryed was the cam angle sensor, which did nothing, which makes sense because if I'm correct, the CAS only controls advance/retard.
So I changed my Crank position sensor, and that did the trick, which makes sense because the crank sensor is what controls the firing....if im not mistaken.

I hope this helps anyone else that has a speed-dependent P0300....crank sensor

 

[PieEyedPiper]

Good news that you solved your situation! I also appreciate that you documented your success.
Did you happen to check end play while you're in there? Did you end up doing a full timing job to get to the CPS?

 

[vanilla gorilla]

Good news that you solved your situation! I also appreciate that you documented your success.
Did you happen to check end play while you're in there? Did you end up doing a full timing job to get to the CPS?

I didnt check endplay no. My engine isnt walked yet. And in order to change the CPS I had to take off the T-belt, which isnt a big deal. Take off the serpentine belts, then waterpump pully. Then remove the crank pulley. Yank off the timing cover. Undo the timing belt tensioner pulley. Remove the hydraulic tensioner and reset it. Take off the t belt. Swap the sensors. Put the tensioner back on. Put the belt back on, then the cover and serpentine system....done

 

[SethA]

Thank you for replying about your fix. I guess I need to quit procrastinating and do the CPS.

Seth

 

[Hoodeclipse]

alright so i finally got around to fixin my car and my problem was that the timing was off by a tooth so if you are havin this problem go get the timing checked