Code 14, rough idling, misfiring sub 2000 rpm, Fixed. Odd issue. Options

[stephen_lee]

OK guys. I bought a 1995 ST recently. its always idled rough when warm, but when i first start it, it runs fine. well lately its gotten worse so i replaced the WHOLE dizzy w/ a known good one, plugs/wires(new toyoa), and throttle body. Helped for awhile then the issue returned. It got steadily worse till tonight where it completely died on me while driving. wouldnt start. no spark at all.. i swapped dizzys out again and it reverted back to the original random misfires.

Replaced:

• Dizzy
• Plugs
• Wires
• PCV valve
• IAC
• TPS

So i checked the CEL codes and i pulled a code 14: Ignition Signal - no IGF signal to ECU 4 times in succesion.
Not the ignitor, cant be since 2 had the same issue.
i wiggled the wiring around and no changes.
Resetting the ECU helps for about 20 min.
Wiring or the ECU is the only other things i can think of unless there's something i missed.

Any suggestions?

This post has been edited by stephen_lee: Jul 30, 2009 - 1:55 PM

[Spider77]

K, im staring at this big ol book. Word for word here...Open or short in IGF (ignition confirmation signal.....to the ECM) or IGT (ignition signal....to the igniter) / Igniter / ECM. You could check for opens/shorts in the harness/connector on your ECM, but that probly wont be that fun. Probly the lease paingful would be to check the igniter connector and body ground (9-14 v) or the ignition coil (primary resistance cold: 0.36-0.55 ohms, hot .45-.65 / secondary cold 9.0-15.4k ohms, hot 11.4-18.1k ohms)

[stephen_lee]

K, im staring at this big ol book. Word for word here...Open or short in IGF (ignition confirmation signal.....to the ECM) or IGT (ignition signal....to the igniter) / Igniter / ECM. You could check for opens/shorts in the harness/connector on your ECM, but that probly wont be that fun. Probly the lease paingful would be to check the igniter connector and body ground (9-14 v) or the ignition coil (primary resistance cold: 0.36-0.55 ohms, hot .45-.65 / secondary cold 9.0-15.4k ohms, hot 11.4-18.1k ohms)

Yes, I know. I was staring at the BGB too. I molested, poked, tested, and shook that harness to the point that I was afraid that I would damage the harness lol. The Dizzy(and all ignition components) was fine I know, I tested them, too. And after weeks of looking I finally found my issue. THE INJECTOR HARNESSES WERE SWITCHED AROUND. Cyl #'s 1 && 2 were switched around. The 7a does NOT use sequential injection, it fires TWO injectors at once, cyls # 1&3, then cyls # 2&4. So that caused the low RPM random misfires, bad MPG, and just rough running in general, yet at higher RPMs (above 1600-2000 RPM) it felt like it was running fine. SO my assumption is that since the fuel wasn't being sucked into the cyls the ECU expected, it evaporated and was sucked into the other cyls, causing the random misfires, and then the ECU had to over compensate to get the affected cyls(or average A/F) to the right A/F ratio, causing poor MPG.