I'm stumped. I swapped my s5 t2 motor trans rear etc into my 88 vert using all s4 t2 ecu, afm, boost sensor etc. when I pull out the CAS with the key on and spin it, it doesn't spark or purge fuel. Car cranks over no prob. What could make this have no spark or injector pulse?

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Also everything was pulled from the bay to be painted. I'm using the n/a s4 harness modified. The main fuse under the hood and the ecu are getting warm when I leave the key on. I literally drove the t2 donor car to the place I pulled the motor and simply placed everything in another shell. So everything worked perfect before with the exact setup.

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You need to make sure the Main Relay is working properly. W/key to on does the B/Y wires at the coils have power? Does the B/W wire w/key to on at four pin check connector next to the lead coil have 12 volts as well. And does the main battery ground have good contact w/the driver's fender as it might need some sanding down.

 

All grounds are new and tested for continuity. The B/Y wire at the coils show 12.09V. I never thought to the the B/W check connector wire I'll do that tomorrow. The bay was painted and put back together but ran perfect with the same setup in the donor car. Anything I could have forgot? I'm stumped at the moment.

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Make sure the voltages are there w/key to start as well as that is when the grounds would be stressed the most although due to the amperage required to activate the starter will pull down the voltage value of these two wires. If these wires check out okay then recheck the CAS plug and perhaps do a continuity test between the relevant pins at the ECU and the corresponding wires at the CAS plug. And make sure the Vref voltage at the TPS is 5 volts w/key to on as this wire powers up 5 engine sensors and it's vital that this voltage pans out.

 

I will get back with the test results later when I get a chance to look. Thanx again satch

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Your talking about the Br/W wire having 5V right?

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Yes.

 

Br/W wire at the tps is showing a whopping .15V, what would cause that?

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At at Vref pin 2A it's showing .55V at the ecu???

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I changed out the main relay with another known working one and no change.

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Pin 2A supplies 5 volts to the Variable Resistor, AFM, TPS, Boost Sensor and ATP so it's likely that one of these items is shorting the Vref. Unplug one item at a time and check pin 2A afterwards, when it returns to 5 volts then you know the sensor causing the trouble.

 

Once again I praise you O' HOLY SATCH! Voltage came back when I pulled the TPS wires. Cleaned the connections, plugged it back in, voltage stayed at 5V, and fired up the swap for the first time!

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Gooooooood!

 

I noticed that as I move the plug it drops voltage and comes back. Can I rewire the TPS with new wires to the ecu? How so?

Here's my interesting setup. Car is going for exterior paint next.


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Are you referring to the Emission side of the harness?

 

Nope just a random pic of the swap. I'm exited I had to share lol! The TPS wiring is bad. Do the TPS wires trace straight back to the ecu? I'd guess not... But wasn't sure, I'd like to replace the wires with new

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The TPS pigtail plugs into the Emission Harness. Were you giggling the pigtail or the Emission Harness? If you unplugged the TPS and played w/the Emission Harness as you monitored the voltage w/key to on at the Br/W wire you can possibly narrow down where the potential short is. The G/R wire runs straight to the ECU but the other two wires, one being the Vref and ground wire tap into a wire which feeds other sensors. Chances are your problem lies within the Br/W wire.

 

Yes I giggled the pig tail then it started raining so tomorrow is a new day and thanx for that info. I know right where to go now

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W/the pigtail connected to the Emission Harness, a giggling of one usually leads to a giggling of the other harness as well. Setting the meter to ohms should help isolate a potential short. A high value means a short. No key needed for this particular type of test. If the short was in the pigtail it should be easy to isolate.

 

Great info thanx!

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All is good the plug connections were shot. Traced wires back till the corrosion stopped and ran new to the TPS. 4.99V constant with no issues will giggling the wire.

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