high rpm miss-tery......

[Jim Nilsen]

I am still fighting with my high rpm miss. I swapped out my ignition box and still have the problem. I have gone thru the fuel system and only found the fuel filters to be only the part that affected my starting and idle and now it is gone and only left with the distributor or possibly the valve springs as the culprit. It has been thought to have to be in the ignition from most people who have heard it.

I am looking for info on what others have done to their dual sync distributors when they found them faulty other than sending it back to Accel. I can't see any visual problems other than the shaft diameter seems to be small enough to let the rotor be a bit loose. I have siliconed the rotor in place mostly eliminating it as a problem. What else should I look for?

I have also been given the thought that it could be valve springs getting weak, I have beehive springs and wonder if anyone has had similar symtoms with valve springs. I don't have a pressure tester that can do them on the car and am looking for one to borrow if possible?

I have until thursday to get this figured out or I am going to Putnam Park as is .

I did get out today and the engine made it to 5800 rpm once but mostly only to 5200 rpm before it sounds like it is hitting the rev limiter. This is driving me nuts.


I am going to reprogram the distributor just to see if it is a fluke that it went out of sync with the ecu as a last ditch resort in that scenario.

I did check all of my plug wires for resistance and they all came up good at less than 100 ohms.

Other than the high rpm miss the car runs and sounds great so it seems it would be reasonable to rule out the ecu as the problem, but ya never know?

I am going to win this round of the battle sooner or later but I am sure hoping for sooner.

Thanks for any help

[LS6 Tommy]

What kind of coil do you have & if it's external, is it mounted laying on it's side or standing up? Many coils are oil filled & laying them down casues them to overheat. Then you get all kinds of weird missfires.

Tommy

[Jim Nilsen]

What kind of coil do you have & if it's external, is it mounted laying on it's side or standing up? Many coils are oil filled & laying them down casues them to overheat. Then you get all kinds of weird missfires.

Tommy

I have an accel coil and it is standing up like it is supposed to be. The engine wants to run up higher and does sometimes but it doesn't make it to 6800 rpm where the rev limiter is set like it has done for 1000's of miles before. The coil doesn't get hot where it is at and the engine misses when it is hot or warm. I never rev it up when the oil temp is cold.

Thanks for the heads up. maybe I will find another coil and try it just for grins.

[Jim Nilsen]

The problem may have just reared its ugly little head.

I decided to order up a new distributor today because the one in the car has always been a little on the suspicious side of working. It had been gone over by Accel way back when the system didn't want to rev over 3500 rpm. Everything was good for 7000 plus miles and then the backfire happened and that is when the miss started.

I was out driving tonight to see how high it would rev while datalogging it . I could see what was going on with the rpm and it just wasn't going to go over 5700 rpm and was dropping down to 4700 rpm several times, then it happened, the code 72 came up and told me what was going on. The cam and crank sensor was the decscribed problem.

I almost feel happy to finally have something definate to go on. It is not what I wanted to see but with the new distributor coming in tommorow and the possiblity of fixing it on my birthday so I can see the red shift lights on my racepak light up it may be a really good present to myself.

I still don't know positively if it is the whole problem yet and with all I have been thru I stopped getting my hopes up for perfect when working on the efi.

So if you can all think positive for me and the gods of the RPM are with me I will have a car that can see the shift light of day.

Fingers crossed !!!!!!!!

[Jim Nilsen]

The new distibutor is so different than the old that you have to wonder how they missed the boat. The wires are bigger to the pickups, there is an o ring on the rotor shaft to hold it better, the tolerances on the shaft are way better, and the housing even looks better.

So far the revs seems to be there while stationary. We will see what it does tommorow when I get it out on the road.

This thread can be moved to the efi section for future reference.

One would never think that the way parts are made today and the machines that make them and test them that there should ever be parts made like the 1st distributor was made. But thats the way it is these days.

I'm keeping my fingers crossed and hope it works better and longer than the last one.

When I see redline and hit the rev limiter I will be all smiles again.

Putnam Park here I come.

went out his morning and all is better and it is a relief to finally get back to other things that need to get done.