Spark jumping

[1slow95]

Absolutely, regarding keeping the wires separated (kind of an induction crossfire). The racers in here can tell which two wires in particular are notorious for it (IIRC, there was even a TSB for it on foxes, and I cannot think of why the TSB would not apply to us since we have the same basic components and packaging). I know that Rick91GT knows which two wires are known to crossfire (and Paul and the others probably do too. I never dealt with it so the info went in one ear and out the other).

I think I mentioned before that I've used fuel line to sheathe plug wires for diagnostics. And it does work to help find a crossfire! I'd buy a few feet of fuel line, slit it lengthwise and slide it over the wires where you think there could be an issue. I can think of NO ignition that can permeate a plug wire's insulation and go through the wall of fuel-line to create a short.

It's just something that's real cheap and easy to do - if fixes the issue, you know your wires are bad. With those expensive wires you run, it sucks buying some in hopes that it fixes the issue (but you're much more affluent than I, so it might not be worth your time to hose around with the kind of crap I end up doing. ).

Good luck Mike.

More affluent! Hahaha! I highly doubt that. I just have a "slightly" different budget than you. BTW, I just finished paying off the loan I had to take out to finish my engine project.

If I could get away with cheap wires, I would use them. I had a set of cheap FMS wires to start with, but one of the boots caught on fire after about 5 minutes.

Would Napa carry carry the fuel line? Cause they're only 5 minutes from my house.

 

[HISSIN50]

Any old parts store will have fuel line and it's about a buck a foot. It doesnt even matter if it's fuel line or not - just some rubber line to go around the wire is all you need.

I'll have you know I once diagnosed and fixed a spark jump issue shadetree style. On another car, the coil pack for cylinder one was jumping spark to the fuel rail.
After a quick survey of available items to use as an 'insulating block', the heel of an old sandal worked quite well. Point is, there's no need to be extravagant. I happen to keep 3-5' of most sizes of fuel and vac line on-hand for quick fixes. And I go to this pile of hose when I need to work on something like you're working on.

Grady, thanks for the wire info! Mike, I'd start with those two wires, given Grady's help.

I have to say that I'm sure you do very well in your career, considering the excellent advice you have given me in the past.

 

[1slow95]

:SNSign:

I'm off to tear into it in a few minutes. I'll let you guys what I come up with later tonight. Thanks again everyone.


I do very well in my career, but I don't get paid very well. I'm happy with it tho, and I like this area. I could easily make double the $$$ in someplace like Columbus, but I'm happy right where I'm at.

 

[True 5.0]

Why couldn't it be the Crane ignition box? I assume it has some sort of rev-limiter built in. Maybe it's faulty.

 

[1slow95]

I bypassed the Crane ignition box and it's still missing. That's one of the first things I tried.

Well, I have about 3 feet of fuel line on my wires and it's still missing, but not quite as bad. Unfortunately I gave away my old set of plug wires, so I'm stealing a couple of my brother's wires to try replacing those 2 possibly damaged wires. If that doesn't help, I'll change all the plugs next. More updates later.

 

[1slow95]

Replacing the two wires didn't help at all. They're old Motorsport wires(stock replacements I think), so I don't know if they would even work right with my setup....I changed the plugs but that didn't help either. So up to this point I've changed the coil, plugs, a couple wires, and hopefully eliminated all random sparking. I also mounted the TFI since it was just zip tied on. What's next? Distributor cap and rotor?

I talked to a friend of mine tonight and he suggested that it could be the x-pipe scavenging causing what feels and sounds like a slight miss. He said his car does it do, and he has almost the exact same setup as me. I can see that being part of the problem, but it does feel like it still has an actual miss every now and then.

Anyways, I need to get the high rpm miss figured out so I can head back to the track. I noticed all my old plugs were kind of white, which would mean it's a little lean right? I fixed an exhaust leak that was right in front of the O2 sensor, would that make the car run leaner? If so, could that cause a high rpm miss? I'm still running the stock FPR, but I can buy an adjustable one if you guys think it will help. It's been on my list of things to buy for the last year or two anyways.

Also, I noticed the distributor cap and rotor have a little play in them. They're almost new, they came with the MSD distributor. At one point I changed them both to try to fix the idle, but it didn't help so I took them right back off.


Something else I'll add. Almost a year ago to the day I had a rocker work it's way loose. I adjusted all the rockers after that. I can't remember if the high rpm miss started after that or several months later. I *think* it was a couple months later.

What about the TPS? I had it set at .94 volts I think, and I adjusted the idle stop screw at one point so it could be over 1V now.

 

[True 5.0]

Something else I'll add. Almost a year ago to the day I had a rocker work it's way loose. I adjusted all the rockers after that. I can't remember if the high rpm miss started after that or several months later. I *think* it was a couple months later.

What about the TPS? I had it set at .94 volts I think, and I adjusted the idle stop screw at one point so it could be over 1V now.

This is not an idle set screw. There is an idle air bypass screw built into the TB. It's under a plastic cover on the stock TB. I doubt that this is your high RPM miss, but you can easily test it out. Set your TPS back to <1V and see what happens.

A more likely problem will be a rocker set too tight causing valve float at higher RPM's. I know it's a big PITA to adjust them so I'd like to hear what others think on this first.

 

[1slow95]

Fox TB = Idle set screw. I didn't think it would be the problem, but I just thought I would throw it out there.

I honestly can't remember running the car hard after adjusting the rockers. I remember I (accidentally) took it well past 6000 and thats when the rocker came loose. After that I can't remember driving it much until about 2-3 months later when I know the problem was there.

 

[1slow95]

Any other opinions before I adjust the rockers again?

 

[final5-0]

Any other opinions before I adjust the rockers again?

How much preload did you use when you last did the adjustment?

Grady

 

[1slow95]

How much preload did you use when you last did the adjustment?

Grady

I used the method on FTI's website which says to go 1/2 to 3/4 turn past zero lash I think. I think I went 3/4 this time but I can't remember for sure.

 

[final5-0]

I used the method on FTI's website which says to go 1/2 to 3/4 turn past zero lash I think. I think I went 3/4 this time but I can't remember for sure.

As you know, the lifters can pump up at high rpm.

It is possible if you went a bit far with one, you might be holding a valve off
its seat by just the slightest amount at those elevated rpm's or maybe one
is seating but with reduced pressure that prohibits a good seal

It certainly won't hurt to run em all again.

Grady

 

[1slow95]

I remember two of them felt weird when I went the extra half turn or so, like they were already tight. I did them again before I put everything back together, but it was the same both times. Also, I either didn't run the engine before doing, or didn't run it long. Should I let it run for a few minutes before I start to make sure the lifters have oil in them?

After I thought about it all day, I remember going 1/4 farther than I did initially. But I still can't remember what I set them at. I'm thinking it was 1/2 turn, not 3/4 turn....I'll try setting them all back to 1/4 turn. It was noisier that way, but it ran better....If that is my problem

 

[final5-0]

I remember two of them felt weird when I went the extra half turn or so, like they were already tight. I did them again before I put everything back together, but it was the same both times. Also, I either didn't run the engine before doing, or didn't run it long. Should I let it run for a few minutes before I start to make sure the lifters have oil in them?

After I thought about it all day, I remember going 1/4 farther than I did initially. But I still can't remember what I set them at. I'm thinking it was 1/2 turn, not 3/4 turn....I'll try setting them all back to 1/4 turn. It was noisier that way, but it ran better....If that is my problem

I don't worry if they are pumped up or not. When my motor was down and I had my first opportunity to look at these roller lifters, I depressed several of them to see how much effort it took to start the pre load process.

I found it was easier on those with less oil but never the less ... It did take enough effort that I could tell what was what even with those not pumped.

I came to the conclusion that they did not seem any different than the older flat tappit style

If you wanna fire it up for a short bit to pump em up .......
I can't see how it is gonna hurt anything at all if you do

As a general rule of thumb

looser is better for high end performance
but
also a bit more click it tee clackee

I went to a total of 3/8 of a turn with my stud mount Scorpions

1/4 of a turn with the nut ... then snug up the lock
then
1/8 more with both nut and lock for a good-n-tite final value

Sounds a bit like a sewing machine
but with the hood down ... its not all that noticeable

Heck .. when we were kids hangin out at the track ..........
we ran em at 1/8 of a turn and found a tad more et
but
they were noisy

Hope it helps

If it don't ... you'll have peace of mind ... they are right on the money

Grady

 

[1slow95]

1/4 to 3/8 it is! I'll work on that some night this week, whenever I get motivated. The nice thing about my car is I only have to remove the air intake pipe to get both valve covers off

 

[1slow95]

Time to update this thread since I've made some progress. I adjusted the rockers(after I spent an hour trying to get the motor to turn over...It helps if it's not in gear ) and the car seems to have a little more power but it didn't fix any problems. I changed the header/manifold gaskets, didn't help. I fixed the two messed up plug wires, but again I didn't notice a change. Then I removed the O2 sensors and that did help. It's running pretty smooth now at cruising speeds, but it needs re tuned to fix some bucking issues.

But I'm still getting that high RPM miss. I'm thinking it's the PIP/stator or the TFI module. I can "borrow" a TFI from one of our several stangs if that could be the problem.