7MGTE cranks, no start

MK3MKB

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I finally finished my engine swap last week. I got the car to start right up after priming the fuel system. A few days later I went to move the car, started up no problem, I went around the front to check for leaks, and the car shuts off. I cannot get the car to start back up. I've put 10 gallons of fuel in it, confirmed spark, I can hear the fuel pump, and I loosened the return line to confirm fuel to the rail. Checked for codes, only one is 51. I checked for power at the injectors, both sides of the connector have power.

Any help much appreciated.
 

Abe's 1987

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Your supra manual or auto?
Have you worked with the TPS?
Have you cleaned the AFM with anything?
Is your AC off when you start the supra?
 

MK3MKB

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Your supra manual or auto?
Have you worked with the TPS?
Have you cleaned the AFM with anything?
Is your AC off when you start the supra?
manual, but has auto ECU
I set the TPS with the throttle body off before engine was installed
I haven’t cleaned the AFM, but I had a spare so I swapped it to rule it out
A/C is off, not even plugged in right now, I have the HVAC controls and radio turned off
 

3p141592654

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I would check for spark. It will run badly without an AFM, but it should run. Look for power at the coils and igniter to start.
 

MK3MKB

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Do you have a manual or auto wiring harness?
That I’m not sure of. The clutch pedal does need to be down for it to crank. I did notice two extra two pin connectors near the back of the intake I don’t remember seeing on my NA manual harness. One gray, one white.

I would check for spark. It will run badly without an AFM, but it should run. Look for power at the coils and igniter to start.

I used an inline spark tester that lights up as the plug ignites.
 
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CajunKenny

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Try wiggling the wiring harness. Your CPS wires in particular. Just grab portions of the harness that are accessible and semi-lightly push, pull, tug, wiggle, shimmy, shake, etc...

Wouldn't be surprised if she'll fire right up!
 

MK3MKB

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Is there any significance to the colors of the plugs on the CPS or igniter? Both have green connectors and the harness is gray.
 

MK3MKB

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I pulled the CPS out and checked for continuity between the connector and each component. Wiring is good, but I can’t speak for the pickups.
 

Enraged

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The CPS wiring usually gets breaks inside the wire, on the ECU side of the connector. Lots of heat from the exhaust manifold and many years of driving just degrades it. The wiring on the CPS itself is probably fine, it's the harness side that usually cooks. Check continuity between the harness connector and the ECU connector to be sure.

I had it where it was an intermittent problem. It would run and drive fine, then I'd park and come back later, and it would just crank and crank and not start. A little wiggle, and it would work again.
 
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Clip

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set the timing pointer on 10 degrees, then set the CPS with the notch pointed at the top pickup.
Timing pointer should be at 0 degrees. Cylinder 1 should be at TDC on install. Check steps 1 and 2 on page IG-24 of the TSRM.
 

Abe's 1987

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set the timing pointer on 10 degrees, then set the CPS with the notch pointed at the top pickup.
As clip said, you'll need to set mark to 0 degrees then put system into diagnostics mode then use the cps to adjust timing. Check tsrm to set timing.
 

MK3MKB

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Timing pointer should be at 0 degrees. Cylinder 1 should be at TDC on install. Check steps 1 and 2 on page IG-24 of the TSRM.
Reset timing to zero and reinstalled CPS. Still won’t start. I didn’t think this was the issue as the injectors aren’t pulsing. They have power on both sides of the connector. When this car has the N/A engine in it the previous owner had the distributor off by 2 teeth, it had a whopping 50 degrees of timing and still started to my amazement.
 

Clip

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Reset timing to zero and reinstalled CPS. Still won’t start. I didn’t think this was the issue as the injectors aren’t pulsing. They have power on both sides of the connector. When this car has the N/A engine in it the previous owner had the distributor off by 2 teeth, it had a whopping 50 degrees of timing and still started to my amazement.
That's incredible. When I rebuilt the GE it fought me for two hours before I pulled the distributor and was one tooth off. After it was reinstalled it started right up. Sometimes I think it just feels like being stubborn.
 

MK3MKB

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I finally had time to get back to this. I'm checking out the ECU. I'm using the troubleshooting guide on the TRSM, and it says to check for voltage at terminals VC and M-REL. These terminals have 5 volts and 1.2 volts respectively. I'm beginning to wonder if my ECU is fried. Also checked resistance on injectors and they're all over the board. Ranging from 3.8-8 ohms.
 
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3p141592654

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1) with the ignition on, confirm MIL light on. That will validate power to the ECU, MREL, Vc etc.
2) crank and observe tach. If tach is moving then confirms CPS and wiring.
3) that leaves ignition and injector wiring.
 

MK3MKB

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1) with the ignition on, confirm MIL light on. That will validate power to the ECU, MREL, Vc etc.
2) crank and observe tach. If tach is moving then confirms CPS and wiring.
3) that leaves ignition and injector wiring.
1- MIL is on. I did recheck MREL, apparently I didn’t get a good connection to power probe as it now shows battery voltage.
2- Tach is bouncing
3- Terminals NO1, NO2, and NO3 have power with ignition switched on and while cranking. EO1, and EO2 have ground at all times.

I’ve also checked for power at the injector resistor and found no problem there.
 

3p141592654

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ok, good. Your ecu is almost certainly good then and that validates the CPS, igniter and wiring. I would check the coil pack connector is good and you are getting spark. I would also check if there are any stored codes after cranking.
ALso you mentioned the injectors aren't firing. That seems unlikely if the tach is bouncing but needs to be checked.
 

MK3MKB

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ok, good. Your ecu is almost certainly good then and that validates the CPS, igniter and wiring. I would check the coil pack connector is good and you are getting spark. I would also check if there are any stored codes after cranking.
ALso you mentioned the injectors aren't firing. That seems unlikely if the tach is bouncing but needs to be checked.
I have confirmed spark using an inline spark tester. I cranked the engine for 20 seconds using a stop watch (I know it calls for 15 but wanted to be sure) only code I'm getting is 51. Triple checked the tach has movement. Using a noid light in the #5 injector and it does not light up during cranking. Confirmed operation by suppling ground to no.30 terminal. I was checking the IGT and IGF terminals, they both change voltage while cranking but I can't find what they're supposed to be. Also checked STA terminal is getting 12v during cranking.
 

MK3MKB

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I got the car to start Sunday night. Typically I have a rule to always check the simple stuff fuses, grounds, etc. I didn’t follow my own rule and check the spark plugs. Only reason I even checked was because I was waiting on someone and I was killing time. Pulled #1 spark plug and it was fouled beyond return. I put a fresh set of iridium plugs in and the car fired right up. I found in researching that a test light and noid light won’t register injector pulse because it occurs so quickly. If an led light is used it will illuminate but it’s hard to catch. I didn’t try it myself, but maybe it will help the next person. 63B5E5B0-A18C-4645-967A-78CD8ABA2912.jpeg
 

Abe's 1987

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We always forget to check the basics while diagnosing. It is a bad habit i always fall victim to. Crazy a fouled up spark plug could restrict an engine from firing up. Guess the carbon was preventing the spark plug from arcing, could be wrong.
 

3p141592654

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That's a good point. Injector pulse widths during cranking are usually 3-6 ms. 6ms is pretty fast for the eye to catch. I have never used a noid light, but I assumed they were smart enough to stretch the pulselength so you can see them . I guess that is not true. So use an oscilloscope instead.