Intermittent miss...

[Boydster]

could it possibly be a weak fuel pump causing it? have you checked fuel pressure?

Thanks, No 11. Fuel pump has been in there for quite a few years, but I have an adjustable regulator and it's set at 40 with vac removed and plugged. I would think a weak pump would make it run bad all the time and not be causing a hard miss.

Know how a V8 will run all-around rough when a cylinder is totally dead? It's not a miss like that... it's a hard miss like the timing is way off. Just sitting in the driveway and idling, you can hear / see / feel it skip a beat every once in a while (no rhyme, reason or fixed tempo to it) and if revved to about 2000 rpm, the engine is like Rrrrrrrrr Rrrrrrrrrrrrrrrr Rrrrrr Rrrrrrrrrrrr Rrrrrrrrrrrrr Rrrrrrrr Rrrrrrrrrrrrrrrrrrrrrrrrrrr Rrr Rrrr Rrrrrrrr Rrrrrrrrrrrrr.... wow, that made me feel stupid doing engine noises on a forum. Maybe I should do a video.

 

[Noobz347]

Maybe I should do a video.

Ok, but the video should be of you mimicking the noise so that we don't miss what you're talking about.

 

[Boydster]

hahaha.... not gonna happen, man. I dont have enuf trophy points to get away with that.

 

[Noobz347]

hahaha.... not gonna happen, man. I dont have enuf trophy points to get away with that.

... and this is the VERY reason why.

 

[Boydster]

Checked the shielding of the ignition wiring today. From the open end of it near the TFI / spout connector to battery neg... .5 ohm. No problem there...

Computer will be here tomorrow. I'm not real confident that this'll fix it, but I'm starting to hit a dead end...

 

[Noobz347]

Worn gear on the dizzy. That been checked? How about a stretched (old) timing chain?

 

[Boydster]

Worn gear on the dizzy. That been checked? How about a stretched (old) timing chain?

New MSD Pro Billet dizzy, new Ford timing chain during the rebuild. Gear on dizzy looked fine when I pulled it to change the PIP.

 

[Noobz347]

New MSD Pro Billet dizzy

SCORE!!!!! You got the OEM dizzy??? Swap it in and see if that clears it up!

 

[Boydster]

No, I don't have the OEM. Tore it apart to make a pre-oiler.

If the A9p doesn't do it today, I'll try a new dizzy next. Although since I already replaced all the electronics in it, I don't know what in the MSD could be causing this... misalignment between the cap and rotor? And why would it be intermittent?

Not questioning your help, Noobz, just wondering why. I'm an aircraft mechanic... it's in my nature.

At least I have another angle to attack...

 

[Noobz347]

No, I don't have the OEM. Tore it apart to make a pre-oiler.

If the A9p doesn't do it today, I'll try a new dizzy next. Although since I already replaced all the electronics in it, I don't know what in the MSD could be causing this... misalignment between the cap and rotor? And why would it be intermittent?

Not questioning your help, Noobz, just wondering why. I'm an aircraft mechanic... it's in my nature.

At least I have another angle to attack...

I'm not sure why either and I wouldn't head out and dump money into the possibility either. After market distributors for Fox's seem to be problematic. The MSD (whether earned or not) seems to be the poster child. Personally, I've never owned one. I've always used the OEM dizzy but check here: http://www.stangnet.com/mustang-for...let-distributors-garbage.851499/#post-8564097

For troubleshooting purposes, I would see if I could get my hands on an OEM dizzy.

 

[Dmarstroker]

i am having similar issues to mine as well. I have an accell dizzy though. Ive replaced almost everything you listed. Gets frustrating real quick.

 

[Boydster]

i am having similar issues to mine as well. I have an accell dizzy though. Ive replaced almost everything you listed. Gets frustrating real quick.

Yeah, it does get frustrating. Stay tuned as I either figure this thing out or start parting out my car...

 

[Noobz347]

Yeah, it does get frustrating. Stay tuned as I either figure this thing out or start parting out my car...

Watch you start parting out the car and find a steel wool hair or something in some electronic part as you box it for shipping.

 

[Boydster]

Watch you start parting out the car and find a steel wool hair or something in some electronic part as you box it for shipping.

It would kill me to part her out... I've owned it since new.

 

[Noobz347]

It would kill me to part her out... I've owned it since new.

Yeah... I'll chock that up into the, "Not an option" column.

3 months ago, I'd have been able to drop a dizzy into a box and send it to you.

Might be worth putting an APB out to see if anyone has one to loan/sell for troubleshooting.

 

[Boydster]

Yeah... I'll chock that up into the, "Not an option" column.

3 months ago, I'd have been able to drop a dizzy into a box and send it to you.

Might be worth putting an APB out to see if anyone has one to loan/sell for troubleshooting.

Thanks for the thought. I considered the APB idea myself... watch me work!

 

[Boydster]

Rebuilt A9P installed, no help. Seems to run better overall, but still has the miss. Started instantly. Got a $10 bid in on a used Ford dizzy, auction closes tonight.

Does anyone think the MAF meter could cause this? I wouldn't think so. I'm running a used C&L 73 that I got off CList, has the correct 24 tube for my injectors, no related codes... just wondering out loud.

While I had the A9P out, I checked the ground and it's clean and tight. Comp pins were all in place and clean.

 

[Noobz347]

Could just disconnect the MAF and see if you still have the miss.

 

[txstang84]

Rebuilt A9P installed, no help. Seems to run better overall, but still has the miss. Started instantly. Got a $10 bid in on a used Ford dizzy, auction closes tonight.

Does anyone think the MAF meter could cause this? I wouldn't think so. I'm running a used C&L 73 that I got off CList, has the correct 24 tube for my injectors, no related codes... just wondering out loud.

While I had the A9P out, I checked the ground and it's clean and tight. Comp pins were all in place and clean.

just thinking out loud myself here, I had a 73mm C&L and I never had a days fuss with it. But, I guess if there's a dirty contact in the connector, it could do that nonsense...momentary glitch? The wires all shoot good right? Did you win that $10 dizzy?

Oh, noticed your an aircraft mechanic, same here...we have problems with oily cannon plugs on accessory drive gearboxes all the time...causes no engine rotation faults during startup pretty frequent. Gotta love lowest bidder parts...

 

[Boydster]

But with the MAF disconnected, it'll run like crap, right?

Tx, what do ya work on? I'm on 757-200 and 767-300ER freighters right now. Been with Big Brown about 23 years now.

Yeah, oily plugs, especially on these modern engines with 2-channel FADEC...

The $10 dizzy still has an hour and a half to go...