Weird sparking issues/power loss

[pnosker]

I was driving today and above 2800 RPM there was the sound of like a spark jumping. The car didn't run well at all up there. Below 2800 RPM there was severely reduced power. I recently changed to NGK plugs due to my DASC (copper plugs) so could they be bad already? Is this even a possible symptom of bad plugs? I scanned the car and had a Cyl 3 misfire.

[MPWR]

For sparking, I expect that the wires are more likely to be the problem than the plugs- especially if the plugs are relatively new.

[pnosker]

The plugs probably have about 3-4k on them but my car is hard on plugs... my wires should be ok. Magnecor 8.5mm and they looked good to me.

[pnosker]

So the sparking was fine all along. After playing around with it a little more today I think the timing chain jumped. I think some valves might have been bent . Looks like my S44 build project will have to be put on hold now, but at least I have all the top end parts I will probably need.

[pdxmotorhead]

Ouch....

It never happens when you have all the cool parts witing in the garage does it??

Dave

[tiFreak]

that sucks, hopefully it won't be down for too long

[xxxJohnBoyxxx]

That sucks. Hope it's something small like just the chain or maybe even something even easier

[pnosker]

Upon further analysis... (lol), the chain looks ok. There doesn't seem to be any valve damage either as compression is ok (not great but ok). The cylinders were between 120-130 psi each. A little low but who cares since it was still putting down 235 rwhp. If I don't have to use the spare motor for this I will definitely do the motor rebuild soon because I want some great compression again.

Though there is reason to be happy. The ti hit almost exactly 100k since the DASC was put on. It pushed 10+ psi almost its whole life! That's some good longevity.

Plugs are now fouled, so getting some iridiums to put in for now. Still trying to figure this damn thing out! Hopefully it isn't too bad though.

[xxxJohnBoyxxx]

That's better news. Broken rocker not broke all the way? DISA valve damaged and ubstructing? Maybe chain jumped and that's why the compression is low on all?? What was you base line compression?

Just throwing out ideas nothing I can pin down. I'm Bummed for you but remember the fast ones always break and I think you had one of the top 3 fastest I-4's daily driven on the board

[pnosker]

No DISA valve (DASC still), chain is taught and no play so probably not that. I got the car with 125k on it, 140k now. I never tested this motor before but my last motor had 145-155 psi in each cylinder.

The good news is that fuel is getting in OK, spark is OK... so gotta work from there.

[xxxJohnBoyxxx]

Originally Posted by pnosker

No DISA valve (DASC still), chain is taught and no play so probably not that. I got the car with 125k on it, 140k now. I never tested this motor before but my last motor had 145-155 psi in each cylinder.

The good news is that fuel is getting in OK, spark is OK... so gotta work from there.

I think I always had around 155 psi when cranked with the TB open on my stock M44 motor with 173,000 miles on it. No issues on core when turned in. I know they can vary from gauge, battery and starter. The most important is that the psi are close together within 10% of each other or it needs a rebuild. Even better is leak down which I use instead of compression tests.

My opinion