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Discussion Starter #1
Ok,

So last week I installed one of Kris's 4r70w's and Alans 4000 stall converter.

I drove the car pretty much directly to Carlisle 6 hours each way after installing the trans.

Everything was great, I drove the car all weekend, it deffinitely needs a retune, but its very driveable and a ton of fun.

So I drove the car home six hours yesterday, and parked it and let it sit.

This morning I started it up, and let it warm up, I was going to take it somewhere.

I back it out of the driveway then slowly pull away.

At this point the car is fully warmed up, everything is good.

Then the car started bucking at anything over 3500 rpms.

I thought the motor was pinging and I panicked like crazy and pretty much idled it home.

So, I thought that maybe I got some trash in the fuel filter, and I cursed the station in rochester that I bought gas at.

So I installed a new motorcraft fuel filter, and I mixed up about a gallon of xylene with about half a bottle of Marvels Mystery oil.

I started the car up and everything seemed normal, i revved it a bit in park, and the engine runs fine, it wasn't pinging at all.

Hmm, ok so I wasted a little time changing a fuel filter that was new and had no blockage anyways but no big deal.

I take the car back out, and its missing totally intermittently. Sometimes it will pull strong, other times it will sort of make a "purring, chattering" sound over 3500 rpms.

I checked the fluid, everything looks fine, it might be overfilled by like 1/4-1/2 a quart but nothing major.

The fluid is red, no metal nothing weird. I did notice that the dipstick was super super hot, it burned my hand when i grabbed it, which I was surprised about.

The car has a 28k cooler on it, and a magnefine. THe radiator cooler is completely out of the picture, and I checked all the lines for kinks or blockage and everything looks good and new and fluid is flowing properly.

So anyways I take it back out again, just trying to figure out what is wrong with it.

The 1-2 shift deffinitely needs a tune, it feels like you are letting out a clutch on a fivespeed, it flares a bit. But it has done this since I installed the trans, so it was "normal".

Sometimes over 3500rpms it will make the purring sound and i get a vibration. Its tough to describe the sound it makes, its sort of like rolling an R off your tounge. The second it starts doing this i get off the throttle I don't want to break anything.

Whats weird is that its totally random. Sometimes the car will run perfect A1, then sometimes it will stumble really bad. When it first happened I thought there was something that had come apart in the cat converter and it was blocking the exhaust.

Ok so now after really thinking about it, I think one of the wires on the trans harness might be loose, or something is grounding out on something. But that doesn't make sense, it only misses at around 3000-3500 rpms.

I got ahold of lonnie (thanks man), and he told me that he could take a crack at tuning the converter, but right now I deffinitely have a problem that has nothing to do with the tune.

Right now i'm just super frustrated, i'm going to wash the fuel smell off my hands, put a cover on the car and let it sit for about a week until i feel like messing with it again.

Any help or advice, I'd really appriciate it.

I'm also thinking of cleaning the mass air flow sensor, or o2 sensors, but the problem is so random that neither of those would make sense. The car is tuned up totally, the plugs are like brand new.

The plug wires are OEM equipment from 1996, that just occurred to me.

Ok, i'm done thinking.
 

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Discussion Starter #2
it only misses under load, so its not the plug wires. I can rev it in park and it runs fine and never misses. Its not the o2 sensors or any tuneup related part (wires, maf, etc)
 

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Actually I've seen quite a lot of 4.6 wires miss only under load. Usually you can hold the motor against the footbrake and duplicate it. I don't know if you've ever replaced the wires, but the ones I put on there when Sebastian had it here were the original factory wires from my car.

Let me ask you about the flare you're feeling. Does it just feel about like the trans slips right before it shifts? If so, this is the converter going into modulated slip for the upshift. I only notice it with real loose converters like this. The amount of modulated slip can be limited in the EEC.
 

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Discussion Starter #4
kdanner said:
Actually I've seen quite a lot of 4.6 wires miss only under load. Usually you can hold the motor against the footbrake and duplicate it. I don't know if you've ever replaced the wires, but the ones I put on there when Sebastian had it here were the original factory wires from my car.

Let me ask you about the flare you're feeling. Does it just feel about like the trans slips right before it shifts? If so, this is the converter going into modulated slip for the upshift. I only notice it with real loose converters like this. The amount of modulated slip can be limited in the EEC.
I'll get a set of plugwires ordered tomorrow. Just the regular 8mm ones from the dealer. Yep, the wires say 1996 on them, so I figured they were that old. My theory was that it was only missing up high so it couldn't be plugwires, but thats probably just bull**** spewing in my head.

Yes the shift feels exactly like what you described.

Thanks man.

JH
 

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Discussion Starter #5
Put the plug wires on it, and it runs excellent.

Yeah its alot of fun, I can see myself in handcuffs a few times this summer.

The next move is to get the ecc tweaked a little bit, then start hunting for fbodies and c5's.
 
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