Cleaning KE-Jetronic ECM/ECU [1986 560SL]
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Hi. I recently introduced myself and 'Sadie' to the forum.
(Backstory)
She was designated a gross-polluter by the state of California due to CO and HC. She had a rough seesaw idle. We had a smoke-down and found some big vacuum leaks introducing a lot of false air, and culminating a lean misfire.
Replaced
O2 sensor was set full rich, didn't respond or read. O2 sensor was rusted in. Had it cut out by a local exhaust guy and re-bung'd. Didn't see the anticipated mixture improvement.
Popped out the ECU, and EC-eeEw..
Was hoping someone had a recommended cleaning procedure, or tell me to not bother and get another. I took a peek inside and looks like it could be worse. I dont see corrosion beyond the pins. The harness worries me a bit. After careful study, I will disassemble the ECU sandwich unless someone smarter than me stops me.
Lastly, I saw and was inspired by the epic write-up:
www.benzworld.org
by @Myndex (mad props 🤘) , but didn't find a pinout for the KE-Jet (004 545 40 32) here. I found the attached elsewhere. Any advice and/or pinout confirmation would be appreciated.
*edit - fixed pinout attachment to non-transparent bg
*edit - confirmed - not correct pin allocation below
(Backstory)
She was designated a gross-polluter by the state of California due to CO and HC. She had a rough seesaw idle. We had a smoke-down and found some big vacuum leaks introducing a lot of false air, and culminating a lean misfire.
Replaced
- Vac line to transmission modulator which was split
- both breather hoses to injector caps
O2 sensor was set full rich, didn't respond or read. O2 sensor was rusted in. Had it cut out by a local exhaust guy and re-bung'd. Didn't see the anticipated mixture improvement.
Popped out the ECU, and EC-eeEw..
Was hoping someone had a recommended cleaning procedure, or tell me to not bother and get another. I took a peek inside and looks like it could be worse. I dont see corrosion beyond the pins. The harness worries me a bit. After careful study, I will disassemble the ECU sandwich unless someone smarter than me stops me.
Lastly, I saw and was inspired by the epic write-up:
Inside the ECM
Inside the Engine Control Module, aka ECM or ECU. This relates specifically to the ECU for the 1980 450SL, however, I suspect it is very similar (if not identical) to 380SLs (1981 thru 1985), as the wiring diagrams indicate the same pinouts and connections. The 560SL however uses a very...
www.benzworld.org
by @Myndex (mad props 🤘) , but didn't find a pinout for the KE-Jet (004 545 40 32) here. I found the attached elsewhere. Any advice and/or pinout confirmation would be appreciated.
*edit - fixed pinout attachment to non-transparent bg
*edit - confirmed - not correct pin allocation below
Attachments
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Upon looking inside, it looks pretty clean. I think the plan is to focus on the terminals:
- canned air
- gentle copper wire brushing to loosen debris (being careful not to scratch terminals)
- canned air
- CRC 5103 Quick Dry electronic cleaner
- canned air
- DeoxIT
- gentle swab
- canned air
Attachments
After the first pass, it's a big improvement, but not down to the metal as I had hoped. I didn't have a copper brush so worked it with horsehair. Probably better to start less aggressively anyway, and more as needed. I think I'll reapply the DeoxIT and leave it to see if any improvement.
My next idea is a Vinegar/Salt solution. Maybe pack cotton around the terminals and let it soak for a while, checking ever 30 min for improvement. Then, neutralize with water/baking soda.
Lastly, could get some micro files, but didn't want to damage the surface of the terminals, but looking at them, I believe that ship has sailed.
My next idea is a Vinegar/Salt solution. Maybe pack cotton around the terminals and let it soak for a while, checking ever 30 min for improvement. Then, neutralize with water/baking soda.
Lastly, could get some micro files, but didn't want to damage the surface of the terminals, but looking at them, I believe that ship has sailed.
Attachments
Okay.. I found a brass brush and went at the pins, intermittently rinsing the pins with the Quick Dry electronic cleaner, following immediately with canned air over the circuitboard to blow out any overspray. I reapplied the DeoxIT and let set for an hour. Cleaned the well out with horsehair brush, hit it again with the air and called it good. I'm pretty happy with the result. I reinstalled the ECU and went for a drive. Definitely running a lot better than yesterday. I'll spend some time tomorrow on the mixture and see where we're at with emissions. Fingers crossed 🤞
Attachments
Thanks! I wasn't sure what I was up against. The day before I topped up to 16 gal Chevron 91 +Techron. Added a bottle of CRC, and put 125 mi on the clock up Hwy 1, along the coast and down through the redwoods. Gave it the "Italian tune-up" regularly bringing her up to 4,500 rpm, making the KE-jet work. We bonded.
It was her maiden voyage. First time I really drove her since I got her 3 weeks prior. Took her down to 1/8th tank. Then filled her with 89. I read conflicting info on which gas would be best to pass smog. Even read a scientific/technical paper titled "Effect of E85 on Tailpipe Emissions from Light-Duty Vehicles". Left her running when awaiting my turn at the Smog shop (about 30 minutes), and crossed the fingers. I have to admit being pretty shocked when she burned cleaner than a Prius.
I'm super-grateful for all the amazing wisdom in this community. Without it, taking on this car at my skill level would have felt impossible.
Special thanks to @H.D. for sharing amazing knowledge and @isthisdave for aggregating so much great info. I can't wait to give back.
I run premium always as I hear the ethanol isn’t good for the fuel lines. For how much I drive in a year it’s not a financial burden. The wife’s car takes premium too (Subaru Outback 3L) and that starts to put a dent in the beer fund as we drive it 99% of the time.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
Yeah. I've read that ethanol itself isn't bad, but it's too expensive for fuel companies to remove all the water from it. Water in excess in the fuel lines can certainly cause corrosion when stored for longer periods of time.
Methanol and aluminum definitely don't get along.
Methanol and aluminum definitely don't get along.
@H.D. - To @MBGraham 's point, to not hijack the 107 Service Manual thread, ECU discussions may be more on-topic here. I'll ping you if I make headway on the Arduino test unit project if you're interested.
I did find the attached Pin allocation and diagram for the '88 560SL, and don't want to unintentionally send you on a fool's errand. Also if the pin allocations are buried in the electrical section of the service manuals, that's good enough for me. I have just yet to find them. I certainly don't mind doing the work.
@bereng - H.D.s on-board ke-jet test unit thread
www.benzworld.org
I did find the attached Pin allocation and diagram for the '88 560SL, and don't want to unintentionally send you on a fool's errand. Also if the pin allocations are buried in the electrical section of the service manuals, that's good enough for me. I have just yet to find them. I certainly don't mind doing the work.
@bereng - H.D.s on-board ke-jet test unit thread
On-board KE-Jetronic test device
I‘d like to introduce a simple self-built on-board test device that provides diagnostic information (mainly) about the KE-Jetronic fuel injection system anytime … while driving or parking. … Makes detecting or narrowing down problems a lot easier, especially if they occur intermittently. …...
www.benzworld.org
Has anyone ever heard of Sea Foam? The local auto shop people highly recommended this additive when I was looking for an engine/injector cleaner but it's a bit different from most. The instructions on the bottle recommend that half the contents go into the gas tank and the other half go into the oil. Apparently it takes 200+/- miles for the lower engine cleaner to work after which an oil change is suggested. Presumably the full gas tank is adequate for the injectors etc.
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