Need help MSD MC-4 cutting out

[healter skelter]

I should have sent my coils and plug wires when my box went in to msd for testing.I am going to build new wires and try all of the other things you guys are suggesting first and if no luck I will try new coils.It rained all weekend hope to go next week and try.

Thanks again Ron.

 

[Thomas800]

Hi Ron. So did you make any headway this weekend? You probably already checked, but how are your valve clearances. Any chance you've got some tight ones that get worse once the motor is heat soaked?

 

[healter skelter]

Hi Tom it rained again this weekend, it gives me more time to change things out.I never checked valve clearance, for how it is acting it sure seems like ignition.What do you think about the stator? It checks out OK. Maybe when it starts working its building up heat and fails?I am going to swap it out also.My fingers are crossed, the rocky's are coming up fast.

 

[Thomas800]

Darn Rain. I forgot to mention that we borrowed a new trigger plate to try on our car, so we will have a plate to try on yours at the Rocky's if you haven't found the problem yet. The stator shouldn't have any effect unless it is not charging the battery or possibly pulling it down. I can bring a spare stator down if you want.

 

[healter skelter]

I'm going to swap out stators with my brothers sled tonight and I have new wires on and I will let you know if things get better. But the are calling for servere thounder showers tonight.Hoping things get cleared up for the Rocky Mt nationals we have been getting rain every weekend last 3 weeks this will make it 4

 

[healter skelter]

Went last night and same old B.S. On second run came back to pits and hooked up cool cart and played around it. Seems like it will rev up to 5000rpm then hit a rev limiter setting.That is what it does on the return lane every pass.I am woundering if it is doing this on the passes when the rpm drops and picks up.It seems to cut out to 5000rpm then revs up and cuts out to 5000rpm and revs up.But third pass I let the sled sit for 3hrs and tried it. It should of run like a first pass after 3 hrs but right at the burn out it ran like crap and had to scrap the run.Is mike on the right track with some kind of setting?Not in the programing but it getting some kind of signal for a rev limit.I am booking it in on a dyno in 2 weeks and going through it.

 

[nothinbutansrx]

You may want to check the main power wire and ground for the msd. If you are powering it through the key switch, you should change it to a relay activated by the key switch instead. Solid power to the msd is very crutial.

 

[rxrider]

nothinbutansrx - welcome to the site

 

[healter skelter]

Hi nothinbutansrx I do have the main power and ground direct to battery and the smaller red (ignition switch) to a toggle switch.Are you running a msd also?And what kind of sled and setup.

 

[nothinbutansrx]

I did the wiring for fastsleds rx1 turbo, and he's running an mc4. Battery size and condition is very critical, just because it says 12v it doesn't mean it has any current draw capability. I would check the battery with a load tester. Are you using the burnout and/or the launch wires (blue and light blue off the top of my head)? I would disconnect both temp and try to make a pass. If any stray voltage is hitting either wire it would hold you right at where its set. Do you have any datalogging and what is it showing?
here's a link to how I've got his setup
http://www.f150online.com/galleries/pic ... anum=10664
http://www.f150online.com/galleries/pic ... anum=10664

 

[healter skelter]

Nice work, I wish mine looked like that.My battery is a new 18 amp hr stock battery.And I am using the blue launch wire and tried disconnecting it and no diff.My next step is to run it on a dyno a see if I can spot anything as it is running.Tom you still coming down next weekend ,I owe you a hotdog.

 

[Thomas800]

I'm coming down Thurday. Did you get a chance to leak the motor when it's hot? If not, we have our leakdown tester, comp tester, etc.