Hey, babywag - thanks for the followup. Have verified that i've got a 1227747 ECM, and over the last couple weekends, i've been able to clean up the wiring (more on that below), and have seen voltages rise as measured by the ECM as changes were made; moving from ~12.5V (logs showed
ranges 12.2V-12.8V) to a high of 14.2V now. With all that, i still feel like i'm missing something here - voltages measured by multimeter show consistently higher by .2-.4V than what the ECM reports for Battery Voltage, and while the engine is running better than it ever has, we still have the base issue of hesitation at cold start, intermittent dying when going into gear, and high speed backfire when letting off the throttle at 70mph, coasting to 60, and getting back in it. Right now, am focused on getting the wiring fixed, and raising the battery voltage measured by
the ECM as high as possible.
Can you verify that voltages reported by the ECM match what you see when measured w/a multimeter?
When measuring battery voltage w/engine stopped & running, i see nearly no voltage drop between battery voltage tested w/a multimeter and whatever terminal i'm testing at the ECM, but the ECM reports .2V-.4V less than that. Am wondering if i've got a bad connection in the ECM harness
connector?
For example,
------------------- Engine ----Engine -----Measured per ECM
------------------- Stopped --Running ----& shown in logs
------------------- ---------- ---------- -----------------------
Battery Voltage 12.5 ------ 14.5-14.6 - 14.1-14.2
ECM Pin A6 ----- 12.5 ------ 14.45
ECM Pin B1 ----- 12.5 ------ 14.45
ECM Pin C16 --- 12.5 ------ 14.45
Over the last couple weeks, i've broken apart the wiring harnesses (factory & EFI) & run voltage drop tests, finding a myriad of bad splices/ connections along the way. As part of that, ive cleaned battery terminals, cleaned all the grounds i could find, found and connected a previously
unconnected 'green' 12-ga ground wire that was connected to the negative battery post - stuffed in the headlight hole. All of this got me from ~12.5V measured at the ECM to ~13.2.
After reading & re-reading your posts, and talking to AFI & Bill_USN1 on binderplanet, i worked my way to the ECM itself, the main relay & fuel pump relay & began cleaning connections there with DeoxIT D100 contact cleaner. Corrosion was pretty amazing, as evident from the bubbling. That's when i found a major cause of voltage drop - the ECM fuse. The mix of corrosion & cracked connection was responsible for ~1V.
Cracked fuse
Battery voltage as reported by ECM jumped from 13.2 to 14.2, after cleaning ECM & relay connections and replacing the cracked fuse.
DeoxIT D100 electrical contact cleaner
i've also uploaded the latest set of data logs, would appreciate your taking a look & see if anything jumps out. One thing i notice in the logs is voltage drops the longer the engine runs... So far, i'm only driving it in a 6-10 mile loop that includes in-town & highway driving, so am wondering how far it would continue to drop if i drove longer/further?
Right now, the ECM is in mounted in a box under the hood, on the driver's fender where the rear window washer bottle should be. Given the hacked up nature of the EFI harness, am planning on getting a new one & moving the ECM to inside the Jeep - wanted to get it running properly first.
Wondering: could engine heat be affecting measured voltage?
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