I had the msd ignition installed on my truck (6A module mounted to firewall above intake, blaster coil, cap and rotor, Ford 9mm wires gapped at .50, timing set at 12* btdc) and now it misses when taking off from idle and when driving at low rpm's. It's worse between 1000 and about 1700 rpms. When sitting still in drive the idle is perfect, no low rpm stumble at all. When it's floored the engine is perfect. It's the taking off from a stop and not flooring it and cruising speed. It was real bad at 45 mph and in overdrive. When I took it out of overdrive, the rpm's were higher and the miss wasn't as bad. Still there at times but not as bad. Also, when this occurs, the tach jumps like crazy.

Other engine mods are full Bassani exhaust and bbk 56mm throttle body

Please, any ideas would be appreciated! I'm heading for vacation Saturday and towing a pop up camper!!

Thanks,

Jason
87 XLT 302 AOD

 

Hey just putting out the first thing that comes to mind here, are you sure the cap is on correctly and not turned around as well as the wires being on in the correct order? Can't hurt to look at it just to be sure. Good luck....

 

Yeah..that part is right. I'm kinda thinking there are maybe 2 plug wires that are arcing at times. The strange thing is it'll idle great in gear at a stop light and run strong when I floor it. It's the idle in park and low rpm crusing speed where is sputters, the tach jumps and the whole truck just starts jerking.

 

take of your IAC and clean it , also check for codes incase something is wrong. you might also disconnect your battery for 15mins. then reconnect and drive for 45mins so the ecu can relearn what you have done.
you did pull the spout connector out when you timed it correct?

 

The IAC should be pretty dang clean. It's less than a year old plus I did look at it when I installed the new TB a couple months back. All the MSD work is being done by my mechanic...I didn't have time to install the new ignition system prior to leaving on vacation this saturday. He did pull the spout when doing the timing and the code is 44...Thermactor. Yeah...the worse possible one! Strange thing is that is ran fine prior to the MSD install. But I guess the higher voltage is just really magnifying the problem? I called MSD and they said it sounds like a lean fuel condition but the truck smells like it's running too rich. Another Thermactor clue. I'm getting desperate now...almost 48 hours away from when I was planning on leaving for vacation!

 

i would still take it off an clean it with tb cleaner.

the plugs should have been gapped to .55 as well. what plugs did he install?might have the shop check your fuel pressure as well.

 

Plugs were gapped at .50 but would that cause this problem? Plugs were Autolite copper core. What about the TFI module? Think it could be that? That was replaced about 2 years ago.

 

the tfi could very well be part of the problem. good call and worth a try

 

Well, my mechanic has tested each sensor that comes into play with the thermacter and they all test good. He talked with another mech who had a very similar problem and it turned out to be the upper plenum intake gasket so he pulled the upper plenum off and has the new gasket and will install that in the morning and see if that solves it. He did say there was one spot on the old gasket that looked bad so I'm hoping this will solve the problem. He stayed out there until 9pm working on it for me. Once he gets this figured out, I'll have to bring my grill up there and grill them boys some steaks!!

 

Big daddy , i had trouble with plug wires as mentioned in a previous thread . I installed the bassani uncoated and had a one plug wire bad ---Hope this helps. I ended up installing the the accel 8.8 300plus wires and it solved my problem TR

 

Well the upper intake gasket was replaced and didn't change anything! The mechanic just told me it's running very rich and he cannot find anything to lean it out. I told him if he can't fix it, just make sure it's driveable. Bucking, missing or not...I'm going on vacation tomorrow towing my pop up camper! It's only an hour drive on the interstate so if I can't keep it in drive at 55 running smooth, I'll take the back roads. I'll just take my tools with me and I'll work on it more there.

 

a bad o2 sensor , or fuel pressure regulator could cause a rich condition

 

Let us know what you find out. Still having the same problem. I thought it could be the o2 sensor also. I am not able to pull codes for mine.

 

Okay...the low rpm stumble/miss is still there and the truck is running very rich. I've replaced the o2 sensor, ect and tried replacing the map sensor. My mechanic 'found' a map sensor in his shop that plugged in and the truck runs better with that one rather than the one on the truck. So not knowing if that truly was a good one, I bought a new one and the truck barely runs at all with the new one. I'm taking it back over to his shop tomorrow so he can look at it some more. The only code present is 44...thermactor system.

I'm still not convinced the new MSD ignition isn't the culprit. There were no problems like this prior to the MSD install. We checked all the connections, even replaced the plugs which were brand new and nothing. I don't have my instructions here, but is there a way to unplug the MSD 6A Module and see if the problem goes away?

Any help would again be appreciated! I'm about ready to drive this beast into the lake out back!!

Thanks,

Jason
87 XLT 302 AOD

 

Talked to an instructor at UTI. He said to check the pickup in the dizzy, they tend to go bad.

Chris