Resolved 2G crank but no spark frustration

[avaien]

My car is a 99 GSX w/ECMLink and a 6bolt swap. I have changed almost everything on this car and went to fire it up, the car cranks but I do not have any spark.

After checking a lot of wires, pin 82 on my ECU shows ground on my power probe. As I understand this should be the ignition 12v power that ultimately goes to the coils. I traced that whole wire circuit from the PTU > coils > VSS > fuel pump relay > blue plug behind radio to end up with the ground still coming from the ECU pin.

I swapped in my 99 black box ECU and it does not read ground on pin 82. Do I need to keep inspecting from the ECU > ignition switch?

PS. I thought I had fixed it problem when unplugging stuff and was getting 6.1v on pin 3 at the PTU, which is it's 12v source.

 

[steve]

I'm not sure you're reading the diagrams correctly. Pin 3 on the PTU is a black wire to ground. Pin 6 is a black/white wire that is connected to the ignition switch IG1 output.
You should see battery voltage there when the ignition switch is in the RUN or START position. This wire also is connected to Pin 3 of the Coils, Pin 82 on the ECU, and Pins 3 and 4 on the Fuel Pump relay.

The car will crank until the battery dies if the ECU isn't running. You need to get constant battery voltage to pin 3 and 4 of the MPI relay and to Pins 12 and 25 of the ECU when the Ignition switch is in the RUN or START via ECU pin 82. You also need constant battery voltage on ECU pin 80. That comes from fuse 11 (room).

The basic test that this is working is you get the CEL light turning on for 5 seconds when you turn the ignition on, the factory boost gauge goes to it's zero point until you start cranking, and returns to the zero point when you start and about 10 seconds after you turn the ignition off the MPI relay clicks off.

 

[avaien]

Thanks! Sorry I did speak incorrectly, it is Pin 6 on the PTU and not 3. I plugged the blue connector behind the radio back in, that the IG1 wire travels through and also found the body ground back there was cracked so fixed that. Now I have voltage besides ecu Pin 12 and 25 since the ecu is not connected.

 

[steve]

Now I have voltage besides ecu Pin 12 and 25 since the ecu is not connected.

That's strange. With the ECU disconnected the MPI relay should not be turning on so nothing should reach ECU pins 12 and 25. It's the ECU that turns the MPI relay on by pulling the Blue/Green wire from ECU pin 38 to pin 2 of the MPI relay to ground in response for the ECU seeing battery voltage on ECU pin 82.

 

[avaien]

That's strange. With the ECU disconnected the MPI relay should not be turning on so nothing should reach ECU pins 12 and 25. It's the ECU that turns the MPI relay on by pulling the Blue/Grey wire from ECU pin 38 to pin 2 of the MPI relay to ground in response for the ECU seeing battery voltage on ECU pin 82.

What I meant was there is no voltage at ECU Pin 12 and 25. No ecu in the car. I did finally get voltage at IG1 switch all the way to ecu Pin 82. I believe I have the MPI relay in that state.

I showed what I said to my dad at the shop and he was confused. My brain gets ahead of my communication, appreciate you.

 

[avaien]

I put it all back together and still no spark. I do have voltage at the Coil Pack plug, the black/white wire when I turn the key.

 

[steve]

Since you have ECMLink, take a log and post it using the add photos button. Start the log before you run the starter so we can see what your sensors are reporting and we can see what the battery voltage does. Try to log everything to begin so we can check them.

 

[avaien]

Yesterday my Ecmlink wouldn't connect, and then it did. Today it wouldn't again... working on it.

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looking at https://www.dsmtuners.com/threads/obdii-port-pinouts.122243/

"Pin 1 Yellow to ECU pin 56 (Diagnostic Mode)
Pin 4 Black to Ground #5
Pin 5 Black/White to Ground #5
Pin 7 Pink to ECU pin 62 (Diagnostic K-Line)
Pin 14 Yellow/White to ECU pin 86 (Vehicle Speed Sensor)
Pin 16 Red/Black to ECU pin 80 (Backup +12v Power)

Pin 9 black/blue to ETACS-ECU pin 14
Pin 13 yellow/black to Auto Cruise-ECU pin 24 (cruise)
Pin 12 yellow/black to SRS-ECU pin 11 (SRS)

Pin 6 Yellow-Red to TCU pin 9 (ATX Diagnostic)"

 

[steve]

I'm not surprised and finding out if it worked was part of the reason I asked, given you never confirmed that the ECU was running as posted in #2 above.

 

[avaien]

I'm not surprised and finding out if it worked was part of the reason I asked, given you never confirmed that the ECU was running as posted in #2 above.

OK I did the basic test. First, I do not have a CEL light on, I have brake, battery, oil, seat belt flashes and anti lock. Second the vacuum gauge doesn't move at all. The MPI relay, clicks off after almost 10 seconds.

PTU Pin 6 is Black/White. Voltage when RUN.
Coil Pin 3 is Black/White. Voltage when RUN.

MPI Relay, If I am looking into the relay w/ the connector pointed away, I have Pin 3 and Pin 4 on the bottom and they are Red/Black. Both have constant voltage.
Pin 1 is R and Pin 2 is Blue. Pin 2 has constant voltage until I move the key to RUN. Then Pin 2 loses voltage, and Pin 1 gains voltage.

Ecu Pin 12 and Pin 25 are both Red. No voltage until RUN/START, and they keep the voltage when turned off until the relay clicks off.
Ecu Pin 82 is Black/White. No voltage until RUN/START. Loses voltage immediately when key is turned off.
Ecu Pin 80 has constant voltage all the time.

 

[avaien]

I feel like I am just missing something. Was just reading your thread again, https://www.dsmtuners.com/threads/2g-basic-ecu-mfi-mpi-relay-circuit-function.497188/
"Shortly after battery voltage shows up on ECU pins 12 and 25 the reset circuit in the ECU wakes the ECU up, the CEL will come on for about 5 seconds and then turn off, the boost gauge will display 0 (Stock ECU software on turbo cars) and the ISC on the throttle body will move in and out to rehome."

I get 12v to the ECU Pins 12 and 25 but no CEL.

"
Yes that is where it is. CEL is on pin 36 of ECU (green/red wire) on a 16 pin connector (B-54). If you ground it the CEL should light with key to "ON" (pull connector to be ECU safe although if you can't, it should also work and be ok).

Gary"

I just checked ECU Pin 36. When I turn the key to ON, it grounds itself for about 5 seconds, which is what the test was trying to do. Maybe the car alarm, wire, bulb? I'll start looking

 

[avaien]

OK I found a white connector behind the radio not all the way in. Now I have my CEL on the dash for 5 seconds with key turn.

 

[steve]

Can you get a log now?

 

[avaien]

Cool! I finally got it. I still had difficulty with my laptop connection actively going in and out. I replaced the obd2 leads and connector and it seems good now. This is my first time really using the software, I did the initial setup and speed density setup last year. I added as many raw values to capture as it would allow me.

 

[steve]

Log shows that it's seeing the START signal and that the battery voltage is dropping like it's cranking but there isn't any RPM signals. Check the Crank and Cam sensors next.

Are you running 2100 cc injectors on gas?

 

[avaien]

Log showes that it's seeing the START signal and that the battery voltage is dropping like it's cranking but there isn't any RPM signals. Check the Crank and Cam sensors next.

Are you running 2100 cc injectors on gas?

Thanks, will do that today. Yes there is 93octane in the car right now with the 2100cc injectors. I have 750cc or the stock injectors in the cabinet, and I can get e85 fuel up the street. I have a GM flex fuel sensor installed.

I have the Sheridan 1G-in-a-2G CAM angle sensor adapter harness. I pulled the connector at my 1g CAS and tested 4.9V, 12V, to ground, 4.9V across the 4 pin connector. I tested both end pins while cranking, both stayed at 4.9V during key START

I think I now check my 1g CAS

 

[avaien]

I sharpened a probe and stuck it into the CAS connector while the key is ON. Blue wire on Pin 1 is 3.5V ON and 3.5V-4.0V when START. Black wire on Pin 4 is 3.5V when ON and 2.4V-3.0V when START. The Black/Red wire Pin 3 is 11V when ON and 3.4V when START.

I aligned the engine to TDC and pulled the CAS. Looks like it was backwards to me. I attached pics. I rotated it and put it back in. Tried to START the car but did not start. Pulled Plug Wire 1 and put a spark plug in it and saw no spark still. I ran a log and it still had no RPM.

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[steve]

Which version of that cable do you have?

And yes, that 's 180 out.

 

[avaien]

Whoa I think you nailed it! I don't have that cable. I searched my email and in 2020 I ordered the RRE cable, I also told them my car is a 1999 in that order. But I have since changed ECUs to 1995 ECU running ECMLink.

I searched my ECMLink emails just to make sure I didn't order one. And they said this when sending the ECU back, "We'll also modify the ECU for direct compatibility with your 1G CAS."

1999 car, 1995 ECU ECMLink, 1g black top CAS, 6 bolt block, 2g head.

Is this still the correct wiring? Do the injector trigger wires need to be switched? I am going back to look at the cable.

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[avaien]

I sharpened a probe and stuck it into the CAS connector while the key is ON. Blue wire on Pin 1 is 3.5V ON and 3.5V-4.0V when START. Black wire on Pin 4 is 3.5V when ON and 2.4V-3.0V when START. The Black/Red wire Pin 3 is 11V when ON and 3.4V when START.

I was looking at these results on my notepad from the CAS and CPS Testing, in comparison to the harness wiring diagram, my Pin 1, blue wire to the CAS connector and Pin 4, black wire to the CPS voltages look swapped.

EDIT: I was thinking on the drive home, those voltages were from when it was upside down anyway. I can't wait to figure this out, back at it tomorrow.

 

[steve]

I sharpened a probe and stuck it into the CAS connector while the key is ON. Blue wire on Pin 1 is 3.5V ON and 3.5V-4.0V when START. Black wire on Pin 4 is 3.5V when ON and 2.4V-3.0V when START. The Black/Red wire Pin 3 is 11V when ON and 3.4V when START.

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Looking at the 1G black top CAS here you see the white wire on pin 1, the smaller black on pin 2, the thicker red on pin 3 and the thicker black on pin 4. Some voltage between 0 and 5v on pin 1, perhaps nothing on pin 2 depending on if you are using the 2G crank sensor signal otherwise the same as pin 1, battery voltage on pin 3 and nothing (ground) on pin 4. That doesn't sound like what you measured. As the the sensor rotates the voltages on pin 1 and 2 toggle between 0 and 5v.

I expect the difference in a cable for a 95/96 and a 97-99 is the length of the legs of the cable since on a 2Ga both sensors are on the timing belt side and on a 2Gb the crank in on the TB side but the cam is on the trans side like the 1G CAS is, not the pinout. The RRE diagram replaces both the 2G cam and crank sensors with the signals from the 1G CAS.

What always seem to throw people off if which pin is which. Depending on how your looking at a connector the ends swap.

 

[avaien]

OK, I used the physical "bump" on the connector at Pin 1 to orient myself. My Blue wire Pin 1 is closer to the firewall, and all Black wire Pin 4 closer to radiator. My Black/Yellow wire on Pin 2 went to ground all the time. Looks like my Pin 2 and Pin 4 are not reading correct.

I need to get to this I think

Pin 1 - CAM > ECU Pin 88
Pin 2 - CRANK > ECU Pin 89
Pin 3 - 3-12V > MPI
Pin 4 > ground body

 

[avaien]

It tried to start! I cranked it a few times and it sputtered up, before I could touch the gas it died. I did get a log!

EDIT: What I did was swap Pin 2 and Pin 4 on my CAS connector.

EDIT AGAIN: I just tried to start it again and gave it a couple tried and some gas, I could lightly rev it and it died. I am so excited.

RESOLVED: I had 4 issues I fixed to get my spark

1. A white harness connector behind the radio, fixing that connection gave me my CEL.
2. My OBD2 diagnostic port was not making consistent connection.
3. 1g CAS was incorrectly installed upside down
4. Engine harness CAS connector, I swapped Pin 2 and Pin 4.
EXTRA 5. Car fired spark now, rough idle. I backed out the BISS and the car kept itself on and I am going to start working on the idle.

 

[steve]

Great. Charge the battery before trying again.

Let see a picture of what the cable at the CAS looks like now.

 

[avaien]

Charging the battery now. I messed with the whole harness a lot, to get to this point, so it is all just my mistakes. Appreciate the guidance. Here is the cable at the CAS.

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