p0300(yes another one(possibly resolved))

[Airsign89]

Hello all:
So this may be a long thread, so those that have short attention spans, please skip. I got my car ready for winter a month and a half ago and then the weather in michigan didn't turn, ie no snow and the such, so I ran the car every week or so and about three weeks ago the idle got somewhat erratic and a ISC code came up, thus I changed the ISC, it seemed to fix the problem but I don't daily drive it, so issues aren't as pronounced. Two days ago I went to Ann Arbor, MI to pick up some parts and on my way home I merged onto the highway and hit the gas about 100% through part of second gear and part of third gear and when I shifted to fourth the car fell completely on its face: the exhaust sounded as if only three cylinders were firing(It sounded like my second 420a engine before the rod bolt broke and a rod went through the block, yes, a mess); power was non-existent(although I was only at about 10% throttle position), and so I limped about a quarter mile to the next exit and parked it.
As an aside I recently lent another dsm'r my logger and wideband because I thought I had no use for them for a bit.
So I start to go through all of the electrical plugs in the engine bay: CAS(cam angle sensor); ignitor coil; plug wires and every other electrical plug that is reachable within the engine bay and checked the oil dipstick several times to see if I saw any bits of metal in it, and after the car had cooled for an hour I checked to see if I saw any traces of oil in the coolant...nothing. I seriously thought I had melted or bent some exhaust valves(I never smelled gas from the exhaust at idle or otherwise, though.)
So after an hour I felt brave enough to start the car and it immediately started and idled pretty much like it had when I bought it, so I began my trek home and when I got off I75 at 9 mile I remembered I didn't have my logger, so I stopped at the murray's/oreilly's and used their scanner which revealed a....P03000 code!
I limped it to my house and yesterday did most of what everyone says to do-for cheap-when you get this code:I did a boost leak test and found a major leak near the throttle body(when I did the ISC), so I pulled the entire assembly and seeing as the gaskets were metal, I added rtv black in a thin line on both gaskets and tightened them to spec. I had ngk br7's from last summer when I was running more boost, so put those in; I checked the plug wire ends and they seemed fine, I checked all the fluids and anything that would seem mandatory for the problem and reset the computer and the car has run...fine, for a the last day or so.
My questions are: When does the random misfire code usually show up: full throttle; half throttle or just anytime the problem is present? Also, is it a bad idea to give the car full throttle? Will the problem show up via a blown block? I have about 50 miles on it and am waiting for the code to throw again.
Thank you guys very much,
Matt

 

[PieEyedPiper]

For me, this is classic P0300.

There are at least two varieties, even three, but I've yet to confirm that in person. The Multiple Random Misfire condition on 2gb's that do not have a 6-bolt swap is usually present at nominal hwy rpm, say ~3k or so. This code can be debilitating, even dangerous when driving in heavy traffic at 70mph. I have a few questions regarding your car. When did the car start doing this? Was it only once? Did the previous owner experience this? When was the clutch work done? Have you been inside the tranny?

I realize that's a bit of a barrage, but it's relevant. What's also relevant to me is that you are employing a SPEC clutch. Funny how I had a SPEC Stage 2+ when I was plagued by the P0300 and then all of a sudden when I swapped clutches my problem hasn't resurfaced 3 or 4 years later. However it was also assembled by a v8 "performance transmission" shop that decided the best course of action was to take 9 hours to do the clutch swap by NOT dropping the crossmember and some how pulling the tranny out from the backside?? Whatever, those guys were idiots and I always suspected that they cut my flywheel with runout. I've never measured it but I still have it so I can still check it. I've since switched to a 11lbs. chromoly. I hate it and love it

Where this is all going is that, apparently, balance is a major contributor to the p0300. Numerous cases of the p0300 have coincided with a recent clutch swap. Most of which were not using the "regular" ACT setup, but, instead they appeared to be using other varieties such as SPEC units or others. That's not to say ACT has the ultimate in quality control, they have more documented failures than anyone, but it seems balance is not their weakness.
I suspect that slightly out of balance components are causing the CAS/CPS to produce signals that are out of the specified range, triggering the p0300 code that delivers that wonderful running on two cylinders feeling.

-Hint, you can alleviate the symptoms by putting in the clutch, pulling back to neutral, allowing rpms to drop to idle and then throwing it back in 5th. Worked for me every time. I had to suffer on a 40mile daily commutes on hwy 101 here in CA for a couple years. It was only a 35min drive but I'd often recieve a nice jolt of p0300 as many as 5 times, one way.

-The Random Misfire usually shows up at constant part-throttle
-It is only bad to give the car full throttle when you are currently experiencing p0300.
-A blown block is a much larger problem than a p0300.

If this is the scenario I think it is, no amount of plug, wires or coil swapping will remedy the issue.

 

[Airsign89]

Thanks for the reply pieeyedpiper. To answer your questions, its only occured once, the PO never mentioned it, the clutch work was done, I believe, about 5k miles ago and I've not been in the tranny yet. I say yet because after work today I'm pulling the t-case to get off my oil pan to reseal it. Since the first time it threw that code I've put about 150 miles on it and it hasn't come up again. I was wondering if you think ES motor mounts would exagerate the issue as I have a front/back combo I was gonna throw on tonight. Oh and thanks for the clutch in, nuetral trick.

 

[PieEyedPiper]

Motor mounts very well could have an impact on this - but I wouldn't let it stop me. I have all 4 filled with urethane that gives my passengers a good little vibe and I don't, and didn't have issues relating to that when I only had 2 filled.

I believe this is a clutch/flywheel balance problem. There is a documented correlation between people who experience the p0300 and who have recently had their clutch replaced. It seems that some level of unbalance causes the issue - though I have no definitive proof.

If it is, indeed, a clutch issue then I'm sure you can imagine what must be done. Other solutions that I know of actually relate to a different problem. It doesn't hurt to cross them out first, as their easier and much cheaper to diagnose and fix.

I gotta run, but I'll try to amend this post in the near future.

 

[Airsign89]

thanks again PieEyedPiper for the response, I hope what your saying is not true, but seeing as how you went through a situation that was nearly the same I might, once the car is back on the road after the winter season, take it to TRE. They're just a stones throw from me, well so is Shep, and have them replace the spec if my problem persists. Oh, and the oil pan is a pain to take off the first time around...just finally got done last night after nearly 8 hours of work.

 

[PieEyedPiper]

Before you sweat it too much, it has only happened once. Sure, it's likely to show up again at some point but when this is bad, and I mean real bad, you can hardly make it a mile before the car stutters and craps out on the highway. Sounds like you're not there and I won't say "yet" since I don't know if the problem can progress the same way something like a small tear becomes a large tear.

Test your alternator, your battery, your CAS (clean it, too), your coils, wires and plugs. Use a multimeter. All but the wires and plugs are other suspected causes. But I still believe that if your car is in otherwise good working order that this is caused by an imbalance on the clutch side that is being detected by the CPS or CPS/CAS combo.

I'll cross my fingers for you.


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Wait, it took 8 hours to get it off or you worked for 8 hours and THEN took it off..?

Also, don't freak out too much like I mentioned above. If this isn't happening to you everyday, several times, you might even have a hard time getting a shop to reproduce the problem. In my opinion, the best you can hope for is that the condition is liveable or you have your eyes on a new clutch setup (flywheel too) and you're dying to get dirty.

 

[Airsign89]

PieEyedPiper, yeah the car is in great condition other than this, and I have just parked it for the remainder of the ####-storm that we call winter in Michigan. I did install the motor mount inserts, replaced the tranny fluid with redline mt-90, topped the gas off, and as I said earlier resealed the oil pan. What I had meant by the "8 hours of work" , was that it took me that long to take off the downpipe, t-case, axle carrier bolts(?), oil pan, cleaning surfaces and then reversing the process. So about 4 hours to take off, four hours to put back on.
I am very thankful for intelligent and concise people like yourself in the community, so please continue your good work!
Thanks,
Matthew