Electrical please help! ive tried everything! no spark from coil!
- Thread starter conigz
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- crank but no spark
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It still cranks over. I've been super busy the last week. So this holiday weekend it's time to jack it up and see if anything was disturbed during the tranny install.
Yea, I’m not sure it’s that, but those two harness connectors you had to disconnect in the previous trans effort might be the issue. These >30 year old cars can come up with interesting problems. If nothing else, you could do the clean them throughly, make sure the male pins are expanded enough to make contact, put some electrical grease on them, and retest.
rednotch
Founding Member
These cars don't need the ecu to create spark, you most likely have a grounding issue, or a signal wire voltage issue from the fuse link wires altering the pulse signal if the coil won't fire with the ecu in.. unplug the computer, have some one crank it while you verify spark. If you have spark check the conditions of the ecu grounds on the rocker by the computer should be 2 black wires, good idea to check the ecu relay at the same time your in there, its tucked up a bit on the harness. Also check the ecu ground that runs from the negative battery post to the fender apron by the starter selonid. This post has alot of the info you need to check it along with some pics on both pages. https://stangnet.com/mustang-forums/threads/help-no-spark-off-coil.736759/
View: https://www.youtube.com/watch?v=SSPtk9SAElw. He has more then a few videos showing how to check it, start with this one..
This video also shows the common problems on the EFI main harness, he pulls it out and goes threw it about mid way threw... Honestly at this point when I get cars with issues like this first thing I do is pull the main harness out, fix the 30yrs of abuse from multiple owners and throw in a new ecu relay and recap the ecu. Its no where near as hard as people make it out to be once the harness is out and its like 30mins to pull, take pics if your never.done it so you can remember where wires going on the selonid and and body grounds.
View: https://www.youtube.com/watch?v=SSPtk9SAElw. He has more then a few videos showing how to check it, start with this one..
This video also shows the common problems on the EFI main harness, he pulls it out and goes threw it about mid way threw... Honestly at this point when I get cars with issues like this first thing I do is pull the main harness out, fix the 30yrs of abuse from multiple owners and throw in a new ecu relay and recap the ecu. Its no where near as hard as people make it out to be once the harness is out and its like 30mins to pull, take pics if your never.done it so you can remember where wires going on the selonid and and body grounds.
rednotch
Founding Member
I have verified no spark with the computer out. Also I can hear the fuel pump priming with old and new computer. I have replaced everything with ignition system. Still no luck. I did go under the stang today. Everything seemed in order.
Is there a member close you that might give you a hand?
What about a local Mustang or Ford club..... I bet someone in the club would give you a hand? A new pair of eyes might spot your problem quickly...
Most people I know like to help out a fellow enthusiast keeping these cars on the road?
rednotch
Founding Member
Then you 100% have a wiring problem check the voltage on some of the 5v sensors, if any are reading low its a dead giveaway. I've bough so many cheap cars this way and its all most all ways in the main harness or injector harness when the injectors won't fire or it has no spark. Main harness is dead nuts simple to remove and go over on a work bench, injector harness just needs the upper pulled but if the injectors work I don't bother. Broken, chewed , molested wires are even fuse link corrosion is a common issue, hell the connectors are trashed on many from so many screwing with them over the years, you can buy pigtails for most.
Though it fired here without the computer? Wiring issues from the trans swap would generally cause a no crank issue from the neutral safety circuits so it generally won't trigger the selonid unless some one bypassed it, which isn't that uncommon on these cars now.
View: https://m.youtube.com/watch?v=xlKtjBzax10. You said your test light goes out while cranking, do this test with a bump switch on the selonid to jump it with the key in in the key on engine off position, it cuts outs all the neutral safety wiring so make sure its out if gear. If the test light isn't flickering on the negative side its not seeing the signal and points to the main engine harness... Most likely a chaffed wiring issue in the harness which is why I suggest pulling it to repair. These kind of issues can kill tfi's and coils pretty quickly so throwing parts at it isn't the best idea.
the Tfi ignition is pretty damn simple people don't even bother changing them with carb swaps.
View: https://m.youtube.com/watch?v=8557EepIJ8Q. Dead simple way to bench test both the coil and tfi
I wish. I have a couple guys who build up mustangs like myself
I do have a couple of guys who build up mustangs like myself. Yet..adulthood has hot us by the balls with children in sports and careers. Finding time is the hardest part. Yet you are right. A second set of eyes would be great. I'm in the country area of mid ohio. About 35 minutes north of columbus.
I did this test. I had spark. I pulled the codes also. Code 11/10. I have all the right voltage on everything. Like I said. Pulling my hair out!
This is my opinion and not based on any real mechanical training but I would say if you have power at the coil with ignition switch on but no power when cranking it's between the coil and switch, fuseable link or switch. Find the wire at the switch that should be 'hot' in start, check for power out of switch
Speak to me as I knew nothing about electrical. Which I don't by the way. My plan this weekend was to pull the whole wiring harness and look for shorts or any irregularities. I still find it odd that 2 runs after the tremic was installed it killed. Luckily about 500 ft from my house.
It still cranks though. I will try to bypass it today. Today is clean all grounds and pins and maybe bypass the neutral safety switch.
If it's cranking over with the key, clutch pushed down, then it stops cranking when you release the clutch, with key still in crank position, then the NSS is working. I believe the NSS has nothing to do with weather or not the coil is getting power.
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