Ford Mustang Forums banner
1 - 20 of 56 Posts

·
Registered
Joined
·
23 Posts
Discussion Starter · #1 ·
Hi all. First time I’ve ever posted on one of these forums and I’m only doing this because I’m not sure where else to go for help. Over the winter I built a 400horse n/a 306. Msd 6al box is the only electrical add on to the ignition I’ve done other than a tune (chip). I drove the car in the colder weather and had no issues but now it’s starting to heat up I can only drive the car for about 30-40 min before I heat soak something in the engine bay causing a misfire that starts small then becomes very bad after a while. When I pull up to a stop light the car will surge at idle then fall on its face. It will always refire and I pedal it to keep it going. I let it sit for a few hours come back fire it up and it’s as though nothing ever happened. Runs great! I’ve swapped out the icm. Put in the old distributor (oem) did have an msd distibutor. Put the old coil back in and changed all my coolant temp sensors. I’m lost. Have no clue what it could be. Car runs about 180* on the coolant side but when it hits 190 is normally when this starts. Any help is greatly appreciated! Sorry for such a long write up!
 

·
Registered
Joined
·
2,241 Posts
Oem distributor is superior to any other distributor. Please list what parts you have installed on your engine. If it truly makes 400hp, the stock fuel injectors are not going to be sufficient for sure. Did you tune it after the upgrades or before? Who tuned it?
 

·
Registered
Joined
·
23 Posts
Discussion Starter · #3 ·
Oem distributor is superior to any other distributor. Please list what parts you have installed on your engine. If it truly makes 400hp, the stock fuel injectors are not going to be sufficient for sure. Did you tune it after the upgrades or before? Who tuned it?
Rodeheavers in mason town pa tuned it. All he does is obd 1 fords. The car is running trickflow 42lbs injectors wise I domed pistons 190cfm 11r trickflow heads 58cc combustion chamber trickflow r intake 12-1 compression. 90mm tb with matching mass air meter. Obviously I ditched the egr system and long tubes x pipe with side exits. (Fuel lines are all wrapped) The car was tuned after I built it. It’s running the stock computer just chipped. I just unplugged my msd box and that’s not it either. The tach jumps all over the place only when it starts missing. I thought it could be a vapor lock. But race fuel I would think shouldn’t vapor lock and the fuel pressure hasn’t changed at all which leads me to believe it’s not vapor locking.
 

·
Registered
Joined
·
23 Posts
Discussion Starter · #4 ·
Rodeheavers in mason town pa tuned it. All he does is obd 1 fords. The car is running trickflow 42lbs injectors wise I domed pistons 190cfm 11r trickflow heads 58cc combustion chamber trickflow r intake 12-1 compression. 90mm tb with matching mass air meter. Obviously I ditched the egr system and long tubes x pipe with side exits. (Fuel lines are all wrapped) The car was tuned after I built it. It’s running the stock computer just chipped. I just unplugged my msd box and that’s not it either. The tach jumps all over the place only when it starts missing. I thought it could be a vapor lock. But race fuel I would think shouldn’t vapor lock and the fuel pressure hasn’t changed at all which leads me to believe it’s not vapor locking.
Also have a custom cam. Off the top of my head I forget the specs
 

·
Registered
Joined
·
2,241 Posts
If the tach is jumping around i would suspect either the tfi or the pip in the dizzy. It could also be a wiring issue or grounding of the ignition signal. If it happens with both distributors, my first thought would be the TFI module but it's possible it's the pickup... The ones in aftermarket distributors are usually not great and old Ford units do fail. Mine would have problems restarting and would occasionally die on me. It was the PIP in the distributor. Do you by chance have a spare TFI? The TFI is much less likely to fail in the 94/95 because it's remote mounted but they do fail, often intermittently then they just fail. The video i posted below is great for troubleshooting the ignition system but it won't really be helpful unless you have a no start issue. If you find it's the pickup, get a motorcraft du50 pickup and rebuild your oem distributor.

 

·
Registered
Joined
·
23 Posts
Discussion Starter · #6 ·
If the tach is jumping around i would suspect either the tfi or the pip in the dizzy. It could also be a wiring issue or grounding of the ignition signal. If it happens with both distributors, my first thought would be the TFI module but it's possible it's the pickup... The ones in aftermarket distributors are usually not great and old Ford units do fail. Mine would have problems restarting and would occasionally die on me. It was the PIP in the distributor. Do you by chance have a spare TFI? The TFI is much less likely to fail in the 94/95 because it's remote mounted but they do fail, often intermittently then they just fail. The video i posted below is great for troubleshooting the ignition system but it won't really be helpful unless you have a no start issue. If you find it's the pickup, get a motorcraft du50 pickup and rebuild your oem distributor.

I’ve thrown 2 too modules at it so far. I do have a spare. Might just try swapping it next time see if a fresh(cool) one might do it? Could be worth a shot. I thought it was the pip in the dizzy too but with two separate distributors and the oem is a known good distributor. It never failed me before. Which is why I’m so confused. Thank you for the video any help is worth it at this point ready to put my head through a wall 😅
 

·
Registered
Joined
·
2,241 Posts
have you pulled codes? Can you take a video of the tach jumping around so we can get a better understanding of what you're seeing?
 

·
Registered
Joined
·
2,241 Posts
My Spark Disappeared products should always be suspected. Make sure you get a cap with brass leads if it's MSD.
 

·
Registered
Joined
·
2,241 Posts
Even though the box that new Msd cap and rotor kits come with say "all brass terminals" it's the nickel coating they put over the brass that causes the misfiring issues.
I've wondered why they do that.
 

·
Registered
Joined
·
1,315 Posts
I don't know they didn't used to do it and it ruined their reputation and I don't know how they pass quality control. They are lacking extensive testing in their quality control department that's for sure because one of mine took a couple drives to start missing. Didn't do it the first test drive. But after it started missing didn't go away till I replaced it.
 

·
Registered
Joined
·
1,228 Posts
Had a set of plug wires cause similar issues. With the lights out in the garage, I could see the arcs jumping from the wires to the headers. This also caused my tach to jump around. Probably not your issue, but at least its easy and free to test.
 

·
Registered
Joined
·
23 Posts
Discussion Starter · #14 ·
Alright. I’ll try and take a video next night I get a chance and upload it. I’ll replace the cap because it is msd but the rotor is factory. I appreciate the feedback guys. I’ll get back to you guys soon!
 

·
Registered
Joined
·
1,315 Posts
Alright. I’ll try and take a video next night I get a chance and upload it. I’ll replace the cap because it is msd but the rotor is factory. I appreciate the feedback guys. I’ll get back to you guys soon!
That is another issue. You need to match the cap manufacturer to the rotor manufacturer. The clearances and tolerances vary from brand to brand. I'd get a whole cap and rotor kit. One with all brass terminals that is not MSD brand.
 

·
Registered
Joined
·
4,288 Posts
Just to be crystal clear, you are talking about the surging and stalling when you come to a stop?

if so, that is 100% poor tune.

a real misfire would be present throughout the entire rpm range,regardless of temperature.

FYI there’s no such thing as a “matching MAF”, the injector data must be entered correctly into the tune, as well as the MAF transfer function.

again, surging is not a misfire. You described surging & stalling. Correct?
 

·
Registered
Joined
·
23 Posts
Discussion Starter · #17 ·
Just to be crystal clear, you are talking about the surging and stalling when you come to a stop?

if so, that is 100% poor tune.

a real misfire would be present throughout the entire rpm range,regardless of temperature.

FYI there’s no such thing as a “matching MAF”, the injector data must be entered correctly into the tune, as well as the MAF transfer function.

again, surging is not a misfire. You described surging & stalling. Correct?
I do have a matched MAF and No the car doesnt start surging at idle until it has already started misfiring when driving. It is very strange. It will misfire for a good amount of time before surging at idle. It only surges because I think it’s trying to keep itself from stalling? It is definetely a misfire. But when I come to a stop after it’s been misfiring it will surge then stall. Surge probably 2-3 times then fall on its face.
 

·
Registered
Joined
·
23 Posts
Discussion Starter · #18 ·
I do have a matched MAF and No the car doesnt start surging at idle until it has already started misfiring when driving. It is very strange. It will misfire for a good amount of time before surging at idle. It only surges because I think it’s trying to keep itself from stalling? It is definetely a misfire. But when I come to a stop after it’s been misfiring it will surge then stall. Surge probably 2-3 times then fall on its face.
Yes the misfire starts out around 3500rpm but within 2-3 more minutes of driving I will notice it anywhere from 1500-7500 rpm and it seems random at that point definetely not a single cylinder miss.
 

·
Registered
Joined
·
1,315 Posts
O'Reilly's has the Accel cap and rotor kits in stock for around $40 if your out and about today. Had real good luck with those as well as many of my friends and customers after I came across this MSD defective cap dilemma.
 
1 - 20 of 56 Posts
Top