ECMlink 1g 1990 with ECMLink only connects when running

[zcopp]

Hello!

I've bought an ECMLink V3 for a 1990 M/T car from a known running car and have installed it on my 1990 M/T GSX. The car starts up reasonably OK.

However, there is a very odd issue with the ECMLink it's self. If the car is put into IGN-ON, I cannot connect to ECMLink. If I start the car, I can then connect to ECMLink and it works as expected. I can then make updates and save them or stream live data. When the engine stops, the streaming data will stay on for 6 seconds, at which point the MPI relay clicks off and the EMCLink connection immediately dies. If I kill the engine and switch it back to the IGN-ON position, the ECMlink connection stays on... but it eventually dies ~25 seconds later. It seems to "fritz" out at about 20 seconds then drops completely by 25 seconds.

I've tried multiple laptops with the same result. Cant connect in IGN-ON unless the car is running or in that post-running state.

I've also checked IGN-ON power at ECU 102, 103, and 110. 12v and 110 loses power if ignition goes to off. I've also checked the MPI relays 4 and 5 (12v hot back to ECU and other things...) and everything seems to be in order there.

I have set the ECMLink to run the fuel pump on IGN-ON instead of the short prime; it IS running so I'm pretty sure the ECU is powered as expected and at least functioning. Obviously as well because the car starts and runs, reacts to ECMLink live changes, etc...

I also did troubleshooting on the diagnostic ports. Pin 10 showed 3.5 volts as expected on a 1990. pin 12 has continuity to ground. Pin 1 is supposed to "fluctuate" but it seems to hang out at .013 volts at IGN-ON. I'm using a fluke multimeter on DC voltage to check that; this is the only thing that seems slightly "off". I would be all over this however it connects just fine when the engine is running... so I'm at a loss!

Anyone experienced this before? Car's pretty stock and I'm not tracking any major wiring hacks in the ECU harness area....

Sources:
ECMLink troubleshooting:

connectionproblem [ECMTuning - wiki]

www.ecmtuning.com

ECU Pinout:

Visual Frequently Answered Questions - Home Page

MPI pinout:

:: Project Zero G :: - Wiring Information

 

[steve]

I've also checked IGN-ON power at ECU 102, 103, and 110. 12v and 110 loses power if ignition goes to off. I've also checked the MPI relays 4 and 5 (12v hot back to ECU and other things...) and everything seems to be in order there.

I'm not sure what you mean when you say "12v and 110 loses power if ignition goes to off." Pin 110 is the signal telling the ECU the ignition is on so I would expect it to only have battery voltage when the ignition switch is in the ON or START positions but what did you mean when you say 12v loses power?

Pin 103 must have battery voltage all the time. It's unswitched power to the ECU.

Pins 102 and 103 should have power for as long as the ignition switch is in the ON or START positions and for roughly 6 seconds or so after you turn the ignition off. It's during that time that the ECU does it's housekeeping before it turns the MPI relay off.

By extension the MPI relay should get activated when you first turn the ignition switch on and stay activated until the timeout after you turn it off. https://www.dsmtuners.com/threads/1g-basic-ecu-mpi-relay-circuit-function.435961/

What does the CEL do when you first turn the ignition on and ECMLink can't connect?

Are you sure there isn't a turbo timer or alarm sticking it's nose in here?

 

[zcopp]

Hey Steve, thanks for the reply!

102, 103, and 110 have power as expected if it's in IGN-ON (with 103 always being powered...). I may have misspoken about the 110. I'll triple check 110s behavior when the MPI timer runs down since the MPI timeout insta-drops an existing connection, I feel like it may be related...

The CEL comes on when going into IGN-ON then turns off after a few seconds. If I have the "run fuel pump when key on" setting enabled, the fuel pump runs as expected and the MPI makes its clicks on IGN-On so, aside from not being able to connect via the laptop in Key on engine off, everything seems to be working.

I dont see a turbo timer or alarm hacked in there but I'll go double-check. As far as I can tell, everything is getting power when it should be.

I also noticed someone appears to have had the same issue on the ECMLink forum but it went unresolved: https://www.ecmtuning.com/forums/showthread.php?t=90015&highlight=connect

V/r
Z

 

[1990TSIAWDTALON]

I have had this issue on a 1990 TSI, but it isn't always. Only occasionally does it happen and I do the same as you, once its running it connects. 90% of the time though, no issues and I just figured it was another DSM "gremlin".
Watching this thread close!

 

[zcopp]

I have had this issue on a 1990 TSI, but it isn't always. Only occasionally does it happen and I do the same as you, once its running it connects. 90% of the time though, no issues and I just figured it was another DSM "gremlin".
Watching this thread close!

yeah, we need to do a flash and there's not really a good way to do this. I have a 2nd 90 ECU that I'm tempted to get set up so I can see if its the ECU or the car... but it'd need an EEPROM conversion and all that jazz. Hopefully it's just something dumb that I can figure out!!!

 

[steve]

I also did troubleshooting on the diagnostic ports. Pin 10 showed 3.5 volts as expected on a 1990. pin 12 has continuity to ground. Pin 1 is supposed to "fluctuate" but it seems to hang out at .013 volts at IGN-ON. I'm using a fluke multimeter on DC voltage to check that; this is the only thing that seems slightly "off". I would be all over this however it connects just fine when the engine is running... so I'm at a loss!

Pin 1 not pulsing may be due to ECMLink if you have the Lock comm in ECMLink mode on the Misc tab selected. Also it won't pulse if you had pin 10 grounded with or without ECMLink.

It's been a long time since I really looked into the oddities of the 1990 ECU so I'm likely missing something.

 

[zcopp]

yeah, now that you mention it, it was on lock comms. I'll probably unlock comms and check to see if it pulses.

 

[1990TSIAWDTALON]

@steve is such a wise man. The forum is so lucky to have you hang out here!