legacycentral bbs

I'll put the summary here, the original post is below.

Issue: No fire, no spark or fuel, no activity from the green connectors, and no CEL.

Fix: The large, 0.47 ohm resistor, 2W, in the JECS EJ20G (6K) ECU was fried, disabling any sub-12V power feeds including the CEL, various sensors and solenoids, the fuel pump circuit, and the ignitor circuit. Replaced the 2W with a 5W unit from Radio Shack. This replacement is a tad larger, but fits and is a bit more robust. All systems back to 100%.


Long time, but I couldn't stay away.

But I think this one just might cause me to go bald!

91 SS, 5MT. Has a "6K" ECU in it. Paperwork I found in the car suggests its a 440 RobTune, but there are no markings on the case nor chip. Has TD05 and gray side-feeds.

Also has a twin ignitor, 4-2 channel conversion(poorly spliced and taped up under the dash).

The issue is a no-spark. The CEL also doesnt come on, nor do I hear the FP.

Working from the FSM, Checked all the power feeds to the ECU plug (back-probed), all check fine. All grounds are good. CEL wire seems to putput 12V with KOEO, and i pulled the dash to check the bulb and it still works.

Since this looks like a factory 6K ECU, shouldn't the CEL come on and the FP/solenoids cycle with D-check mode (they don't)?

There looks to be an OBD2 to USB adapter wired to the SSM port, I'll see if ECUTuner or ECUFlash can communicate with it...

How did you check for spark? Have you checked for fuel? Get a fuel pressure tester inline? Compression check? Did it run after you got the car or are you getting it non-running? Maybe there is a kill switch somewhere disabling the ignition or the fuel pump.

Received it non-running.

Spark check was with plug-style tester and timing light-on-wire.

Fuel pump in non-op.

There IS a mysterious rocker switch and quick-off switch on the center console, but aside from the hacked-in 4-to-2 channel ignition converter, there's nothing attached to the ECU/Ignition wiring. And I get power to all 3 power wires at the ECU.

I'm starting to lean toward a dead ECU as no CEL, no fuel pump prime (or activity with the green-connectors) nor any activity from the solenoids.

Update:

Confirmed that there is no 5V feed to TPS, MAP or any other sub-12V feeds. All power to the ECU from ignition, and the ECU is not commanding the CEL on. I DO get a 12V feed to the MAF and CTS for some reason...

Double checked with my FreeSSM, JECScan via my SSM1 cable and no response from the ECU (unable to read).

So I cracked open the ECU and the ONLY evidence I could find was a hot-spotted resistor. Says 0.47 ohm on it, ohms out at nearly 50k. Maybe a problem, huh? Probably caused by the P.O having the board mounted upside-DOWN in the case.

New resistor is on order, let's hope this is it.

Sounds like you're on to something.

Update:

Stopped by RadioShack (yes, there are still some around) and picked-up a new 0.47, 5W resistor. Granted, it's overkill from the 2W unit, but it'd work. Little bigger, but what the hell.

Slap it on, button it up, plug it in, and WHAM. Fuel pump primes, I hear several more solenoids click, but still no CEL.

Plug in the SSM cable, fire-up JECScan.... and it's alive! ECU ID 744017. Closest thing on the list is 744014 (V2 STi). Might have to find a copy of EvoScan, but it reads TPS voltage, Baro pressure and CTS correctly.

Was about to try and crank, but I heard a fuel injector start hissing after several key cycles to prime the fuel. Dammnit.

Will update once I get those seals in.

I can get you a copy of evoscan that's had the baud rate modified to datalog properly with an ej20g ecu.

kimokalihi wrote:I can get you a copy of evoscan that's had the baud rate modified to datalog properly with an ej20g ecu.

That would be most helpful!

Good news! Since I don't know my right from left, the CEL DOES actually light up! Was looking on the wrong side of the dash.

But got a new seal for the injector, buttoned up, and SHE LIVES!

Lifters are a bit ticky, and I think old gas has it running so/so, but she idles and no CEL.

Now it's on to rehabbing the brakes so she'll stop from all this go!

Awesome fix! I love it when it's that simple.

Awesome work!