I did some reading on this forum from users having similar problems. Please read on and see if anyone can offer any insight.

Having cleaned the MAF wires and replaced the coil wire, I took the car out for a spin.

It was misfiring big-time right off the bat for the first 10 mins or so of operation, or until it got good and hot. But once it got warmed up it did run smoothly/normally.

I took it out onto the highway for a little high RPM, non-WOT testing, to see if it would still run rough up top. Sure and begorrah, as soon as I got above 4500 I could feel it starting to miss again, although not nearly as violently as it would at WOT.

I suspect a POS opticrap, plug wires or plugs (or all of the above). Opti and wires are < 2 yrs old, and have about 45,000km on both (replaced at the same time). Delco platinum plugs are about 3 weeks old and have about 4,000km on them.

To recap, so far in the last week I've

Replaced:
- 2x O2 sensors
- TPS
- fuel filter
- ported MAF for stock MAF
- coil wire

Cleaned:
- MAF wires inside MAF

Tried:
- 90,000 coil for my 200,000+km coil (introduced cold misfire)
swapped back my old high mileage coil, still have cold misfire now
- ran a tank of GM injector cleaner thru

Adjusted:
- mid-pipe away from cross member, to remove constant rattling (possible source of knock retard)

I will take it out later and get a TTS data log to see what the PCM thinks is going on.

Any advice is much appreciated.

Mike...

 

Is your car tuned for the hotcam? If not, then I would bet $$ that it is either just a bad opti, or perhaps even a vacuum leak. Check for those before you buy a new opti.

 

The car is PCMForLess tuned for the hot cam.

 

If its untuned Im sure the cam is causing a certain amount of missfires... I would still say your OPTI has taken a dump...

Rule #1 for LT1 cars.....Replace the water pump and opti while doing a cam swap... Its $300 and peace of mind in case of things like this.

Later,
Jason Coffman

 

A couple of possible issues as i see it.
I could be wrong (for all of those Nay Sayers that Inevitably Come around). THIS IS JUST MY OPINION!

I would say top of the list is Opti Spark. The Opti is actually a two peice problem. it could be an issue with the cap & rotor (very common, and in my experiance, even in NEW opti's) or the optical portion (a little less likely but still possible). You might want to consider the upgrade to the Vented Opti. But if you have that money, do yourself the favor of buying the Dyna Spark Opti. 3 of my friends have bought them, and they spent about as much money on theirs as i did converting to the regular vented opti last year. They are all having great luck with theirs and i wish i had gone that route. But that is not to say that my conversion didnt go well. Infact, it went quite well. Not one problem with the opti (that i know of) yet.

Next: The cam timing, while it might seem like something that is hard to screw up, it really can cause the issues that you are discribing. If all else fails this "might" be your problem.

Next: Wires And/Or Plugs. Put your car in the garage at night, and run the car with all of the lights off on the car & off in the garage. what you want is to have there be as much darkness as possible under the hood of the car while it is running. When this has been accomplished. With the car running, look at the wires. What you might see will be faint, but you might see the wires or the plugs arching. This will look like little lighting bolts hitting the block. I know this sounds crazy, but trust me, i have found more than one set of bad wires this way.

Hope this helps.

 

I have some experience in cam swaps, and electrical issues.

XXV, has described his issue well and in detail.

I drove the car on Sat., and it most definately felt like something a bad O2 would do, but those were changed. I suspect the wire, and even the coil wire (coil wire changed).

 

I didnt know you had Bryan Herder tune your car!
After you figure out your issue, what ever it is.



(ONCE AGAIN, MY OPINION)

Buy LT1 Edit and learn to tune the car yourself.

Bryan Herder (PCMforLess), (ONCE AGAIN, MY OPINION) is not a good programmer . There is NO SUBSTITUTE for tuning a car in person. With LT1 edit & a good education in how it works ( re: the LT1 Edit Mailing list ) you can tune your car to a degree the Bryan Could NEVER do through the mail.

Hope this Helps!

Knowledge is Power!

 

PCM for less tuning.....HMMM.....drove my freinds 396 LT1 with PCM for less tuning.....Horrible . My god was it one of the most painfull feelings a poor car running like that. After some LT1 edit with a good dyno tuner all is well now with the 396 and drives with decent manners

 

Can you give me some info on this Dyna Spark opti? I did a little searching and found nothing that looked related (all seemed to point to Harley ignition parts).

As for the PCMForLess program, a friend of mine w/a 1995 Z/28 bought the program. He and I have the exact same mods, with his being an A4, mine being an M6. I copied all the tables and values from his program to a copy of my stock program and uploaded. Not exactly honest, but I'm sure I'm not the only person to do it.

I've been messing about w/LT1Edit for a couple of yrs now, mostly with regard to fuel (before the cam swap), and have also parsed through the LT1Edit archives from time to time.

I will 2x check the plug wires in my garage tonight, in total darkness.

Thanks,

Mike...

 

Dyna Spark:

http://www.dynotech-eng.com/dynaspark.htm

Lt1 Edit:

http://www.ttspowersystems.com

Learn it, Love it. No one says it. But TTS Data Master is the singal most necessary tool in diagnosis of an issue with your car (IMOP). Most of the guys on the LT1 Edit list have it, they can tell you how best to use it.

Bryan Herder uses things that are (IMOP) seekey and wrong . (I really dont want to get into it, because there are some people on this board that are so in love with him that they would kill to keep his name clean, and that is a fight i really dont want to have) Tune the car yourself. I have the exact same car as a friend of mine, and his has WAY different issues than mine. (IMOP) NO TWO cars a alike, regardless of the mods. They dont live the same life, and they dont die the same way.

Learn more, log every trip, even if its to the store. Like i said, Knowledge is power!

 

Evl, or anyone else who is interested, I took a log of my car this afternoon and have posted it here:
http://www.solvnt.ca/CarShots/Logs/. Note you must have TTS to view the log file.

While poking around under the hood, I did manage to find a loose header bolt, which I gave a good crank to.

Thanks for your help so far, and the links earlier.

Mike...

 

I am having issues with my PCMFORLESS programming right now. I know its hard to do a mail order tune. 30* of timing at idle is way to much for my 11.8:1 cc306'd motor, I get 2-3* of KR at idle.(running 50/50 mix of 101 octane & 91 octane), yes I have confirmed its real knock. Once I adjusted it to 24* at idle , I get no KR at all.
No more PCMFORLESS or any mailorder tune from now on.

 

In Bryans defense I think he is a very good programmer. The problem is that no single car reacts the same to the same mods. It would be almost impossible to get a car tuned proper through mail order tunning. But for those of us that can't afford dyno tunning or to tune it ourselves, its a good alternative. I know you weren't trying to flame bryan in any way but this is to my opinion.

Aaron

 

O2 sensors burned?
You CERTAIN the timing chain is lined up?
Even with stock tuning your car should run pretty decently.

Ryan

 

fireman,
no offense, but isn't that exactly why you would get the unliimited email updates for a setup that exotic? I don't know your setup exactly or how you did your tuning (mail/email) or if you did get updates.