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1998 mustang gt 4.6l sohc no spark from coil

249 Views 3 Replies 2 Participants Last post by  Cobrajet67
It cranks great wont start. Narrowed it down to no signal to coil packs. All grounds and wires have been checked and are good. Obd2 connects buts has no codes. Reads live data like rpms and temperature but no codes. It has fuel at the rails but the plugs are dry as a bone. Not sure if related but no dash back lights. I'm not sure but I suspect the ecm not sending the coils signals..so that would mean it's bad,but how come I can connect to it and read live data. What do yall think.
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How do you know for a fact that you have nothing going to the coils?
How do you know that you have proper fuel pressure at the rail?
Is your antitheft light on or blinking?
What is your fuel pressure?
You likely don't have injector ground pulse if the plugs are dry. You should check the injector connectors when cranking to see if a ground is turning on/off to each injector.
This seems like a PATS issue but if it were then you should get a code. No codes tells me that either you have a communication issue between the PCM and the cluster or your PCM is likely the problem. If you've verified that the PATS is functioning normally and you have proper fuel pressure art the rail then maybe pull out your PCM and your cluster and send them out to an automotive module repair service. Automotive Circuit Solutions, Autoecm, Upfix, and Module Master are places worth considering. They'll test the PCM and cluster and if needed then repair them as well.
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Thank you for your response... i wanted to keep it brief and to the point but I been at this for some time now. I've unplugged the ecm and tested the wires from the crank sensor and the cam sensor. Both connectors for the coils. They all check out. Used a fuel pressure gage and that checked out. The injectors got power but are not getting triggered like you said. To test pats I got a copy of the key made with no chip and it does what it's supposed to. It blinks fast if you use the wrong key. I've opened the ecm and looked for damage. It looks good in my opinion..as in not melted chewed or covered in corrosion. Thank you for the info about having these things tested. My dumb azz forgot to mention a couple things..the ecm had a power force chip piggy backed on it. Can't find any info on that online. I've tried it with and without the chip and nothing. Something that I thought was weird when this problem first started is that after cranking it a few times the battery obviously drains and the engine cranked slower but it would try to start better than when the battery was fully charged. It actually ran once....like **** but it ran. But as soon as I gave it slight bit of gas it died. Recently it has stopped even attempting to start like it used to. The rpm barely moves to 2 or 300 rpms when cranking too now too. I'm going to go over everything and anything else I can think off and them I'm going to check out those repair places. Sorry for the book I just wrote. I really appreciate your help.

Update - Not running yet though…
When this first no start first happened I noticed one the the times I cranked it that the radiator fan would come on after I stopped cranking. Oddly enough when I unplugged the ecm and turn the key to the on position the radiator fan also comes on. Does this mean that the ecm has been failing or has it been losing power. Also with a test light I get flashing from the injector when cranking. I've also read about a ground strap somewhere behind the engine that goes to the fire wall but I have not seen one. The only grounds I know of are the ones on each side of the radiator core support. The block. One strap from the block to the body. The one by the ecm. I'm sure theirs is more but those were the only ones that seemed relevant to my situation. Today I hooked up to the obd2 and looked at the rpm while I wS cranking and it went to 172 or there abouts. Not sure what that means. Also when I crank it over it looks like the rpm needle lags before it moves. When it does move it does not move far. If anybody has anything to add that I should check or test please let me know. Any help is greatly appreciated.
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It cranks great wont start. Narrowed it down to no signal to coil packs. All grounds and wires have been checked and are good. Obd2 connects buts has no codes. Reads live data like rpms and temperature but no codes. It has fuel at the rails but the plugs are dry as a bone. Not sure if related but no dash back lights. I'm not sure but I suspect the ecm not sending the coils signals..so that would mean it's bad,but how come I can connect to it and read live data. What do yall think.
Thank you for your response... i wanted to keep it brief and to the point but I been at this for some time now. I've unplugged the ecm and tested the wires from the crank sensor and the cam sensor. Both connectors for the coils. They all check out. Used a fuel pressure gage and that checked out. The injectors got power but are not getting triggered like you said. To test pats I got a copy of the key made with no chip and it does what it's supposed to. It blinks fast if you use the wrong key. I've opened the ecm and looked for damage. It looks good in my opinion..as in not melted chewed or covered in corrosion. Thank you for the info about having these things tested. My dumb azz forgot to mention a couple things..the ecm had a power force chip piggy backed on it. Can't find any info on that online. I've tried it with and without the chip and nothing. Something that I thought was weird when this problem first started is that after cranking it a few times the battery obviously drains and the engine cranked slower but it would try to start better than when the battery was fully charged. It actually ran once....like **** but it ran. But as soon as I gave it slight bit of gas it died. Recently it has stopped even attempting to start like it used to. The rpm barely moves to 2 or 300 rpms when cranking too now too. I'm going to go over everything and anything else I can think off and them I'm going to check out those repair places. Sorry for the book I just wrote. I really appreciate your help.

Update - Not running yet though…
When this first no start first happened I noticed one the the times I cranked it that the radiator fan would come on after I stopped cranking. Oddly enough when I unplugged the ecm and turn the key to the on position the radiator fan also comes on. Does this mean that the ecm has been failing or has it been losing power. Also with a test light I get flashing from the injector when cranking. I've also read about a ground strap somewhere behind the engine that goes to the fire wall but I have not seen one. The only grounds I know of are the ones on each side of the radiator core support. The block. One strap from the block to the body. The one by the ecm. I'm sure theirs is more but those were the only ones that seemed relevant to my situation. Today I hooked up to the obd2 and looked at the rpm while I wS cranking and it went to 172 or there abouts. Not sure what that means. Also when I crank it over it looks like the rpm needle lags before it moves. When it does move it does not move far. If anybody has anything to add that I should check or test please let me know. Any help is greatly appreciated.
What is the fuel psi at after turning the ignition to on and do you hear the pump prime?
You seem to indicate that you checked continuity in the crank and cam sensor circuits to the PCM and the coil circuits if I understand your description correctly.
I would replace the CCRM(constant control relay module) since this contains the PCM relay, FPDM relay, cooling fan relay, and A/C clutch relay. It's a common cause for electrical issues in your generation of Mustang: What is a Mustang CCRM? - LMR.com
You said that you weren't getting injector pulse but now you are?
The aftermarket chip could have caused a problem. A bad PCM can manifest itself in many different ways and can have only one thing malfunction in it, multiple things malfunction, or be completely dead.
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