MAKES NO SENSE!!!!!

cherokeetrinity · Sep 22, 2009

i went today and got new cap, rotor, and wires, came home, put it in time TDC, put everything together, im getting spark, im getting fuel, its perfectly in time but i am getting nothing!! i did run a KOEO test and i accidentally hooked the wrong wire into the wrong plug, could i have burnt up the ECU?? any thoughts on whats going on??

liljoe07 · Sep 22, 2009

You probably burnt the ECM up. Quick test would be to test the voltage at the SIGRTN on the Self Test connector, Key on, see if it has close to 5v volts or so.

cherokeetrinity · Sep 22, 2009

if i did burn up the ecm would it still be possible for me to get spark? and fuel?

liljoe07 · Sep 22, 2009

Yep, still get spark and Fuel.

The circuit that frys, is the Sourced ground circuit for most of the sensors. If its got an open, then the sensors go haywire(kinda). If you have 5v or so, youll have to open the ECM up and look for a burnt spot, then solder a wire in its spot, then check your connections with a Voltmeter on Ohms/continuity.

cherokeetrinity · Sep 22, 2009

i did take a reading from my tps and it read .47 volts but a couple of days ago i set it to .99. i wouldnt think it would move on its own. i set it back to .99 volts and nothing changed, it still wouldnt fire...... one more thing,if i did burn up the ecu then it probably isnt firing the injectors or what?? just curious, im learning as i go

1987stangman · Sep 22, 2009

liljoe07 said:
You probably burnt the ECM up. Quick test would be to test the voltage at the SIGRTN on the Self Test connector, Key on, see if it has close to 5v volts or so.

Never heard of anyone frying an ECU hooking up the TEST port wrong... I've been tinkering with EFI Mustangs for a LONG time. Sounds like your scaring the guy to me..

You said "TDC", give us some background! Did you just do a tune up or was the engine running prior to the cap, rotor, and plug change? You may just have the firing order wron or. if you removed the dizzy and reinstalled the timing could just be out. Sounds like an easy fix to me.

liljoe07 · Sep 22, 2009

1987stangman said:
Never heard of anyone frying an ECU hooking up the TEST port wrong... I've been tinkering with EFI Mustangs for a LONG time. Sounds like your scaring the guy to me..

Yeah, Im just scaring the guy because it fun to make guys do alot extra work. Do you know me.....Didnt think so.....

Ever seen what happens when the Hood light terminal is used when trying to pull codes.........Do you know what 12v blast does to the SIGRTN? It frys the SIGRTN trace off the board. Period end of discussion. I gave him an easy test to try. SIGRTN to ground with volt meter. If voltage is around 5v, its more than likely a burnt trace. Easy fix.

liljoe07 · Sep 22, 2009

cherokeetrinity said:
i did take a reading from my tps and it read .47 volts but a couple of days ago i set it to .99. i wouldnt think it would move on its own. i set it back to .99 volts and nothing changed, it still wouldnt fire...... one more thing,if i did burn up the ecu then it probably isnt firing the injectors or what?? just curious, im learning as i go

Not the TPS. the SIGRTN. It one of the wires on the Test port. Its listed below. Either way it will still spark, and I have seen them run this way. It takes about 3 minutes to do. Key on, Red Volt meter lead to SIGRTN and Black Volt meter lead to ground. Should be very very little voltage. If its in the 5v range, you need to inspect the ECM board. Its more common than you think. No biggie, **** happens.

View attachment 244800

liljoe07 · Sep 22, 2009

You did make sure you stabed the Distributor on the Compression stroke right?

cherokeetrinity · Sep 23, 2009

ya the dizzy is in the right place. i KNOW for a fact that its the correct firing order i checked it three times.

liljoe07 · Sep 23, 2009

Posted via Mobile Device

Verify the injectors have power at the red wire. Then make sure the injectors are actually pulsing.

liljoe07 · Sep 23, 2009

Posted via Mobile Device

On top of that, you still need to check and see if the ECM was actually damaged. I don't know how you hooked the Test Port, but if the Hood light terminal was used, then its a good possibility.

You may get away with running a KOEO(correctly) self test and see if a slue of codes show up. Or just test the SIGRTN wire for voltage like I said earlier. Do this first. Then worry about the no start issue.

cherokeetrinity · Sep 23, 2009

ok, i disconnected the ECU and seen on the actual ECU itself there is a pin, the 3RD one from the top left and it is shorter than all the rest, about a quarter inch or so, is that supposed to be like that??

cherokeetrinity · Sep 23, 2009

one question, does my mass air sesor have to be hooked up for the car to run right?

liljoe07 · Sep 23, 2009

Which one is it from the Picture above. Notice where the small tabs on bottom are.

On a Side note, why is the ECM out? You could have tested it while it was plugged in.

liljoe07 · Sep 23, 2009

cherokeetrinity said:
one question, does my mass air sesor have to be hooked up for the car to run right?

Yes, absolutely.

mustangman9812 · Sep 23, 2009

cherokeetrinity said:
one question, does my mass air sesor have to be hooked up for the car to run right?

Ummm Yes Correct

cherokeetrinity · Sep 23, 2009

i have alot of sensors unhooked cause i was told they are not neccessary for the vehicle to run, the H.E.G.O sensor is unhooked, and the EGR ( its plugged off), the A/C plug., the barometric pressure sensor, the oxygen sensors, theres a couple more but i cant quite remember, also, just a few minutes ago i took off the valve cover, made sure both valves were closed, made sure it was at TDC, the rotor is one number one plug, i am running the 137..... firing order, the same order as the ECU, the ECU is good, its reading almost nothing through the signal return, the TPS is reading a steady .98, the injecters are getting 13.64V with just the key on and not running, when i turn it over it reads almost a steady 10.67V. i am at a loss, i am half tempted to burn the damn thing!!!@!!!!!!!!!, i am going now to get some contact cleaner to clean the ten pin connectors for the injector harness..... one more thing, would the iac sensor cause it to not start when perfectly in time?? i wouldnt think so but im not really speaking from too much experience, i know that the motor has the 137... firinhg order, and i know that for the 90 gt they only put one motor in it, that motor was the 5.0 H.O and the firing order was 137... EVERYTHING is good!! what the hell is going on!!! the only thing that i can conclude is that the injectors are not pulsing, what would make it do that?? the ECU is good, i just removed it and completely inspected it, no burnt leads at all, and the signal return test is good, ****IN ****!!!!!

cherokeetrinity · Sep 23, 2009

i forgot one thing, ...... when i take the firing order and change it to the 154... it will fire up and run REALLY weird!! why would it run on the wrong firing order and not the right one????

liljoe07 · Sep 23, 2009

LOL......

You need those sensors. The HEGO's need to be pluged in. The ECT, ACT, Baro, mass air, TPS, probably some more Im forgeting.

This is a mess

MAKES NO SENSE!!!!!

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