Help Chasing Erratic Idle Please
10-22-2017, 07:38 AM
#21
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Thread Starter
Installed a teflon lubbed new IAC motor yesterday, TPS still set at 0.58v, fired up on the hose and it ran rough (like a dead hole(s)) blowing black smoke and idling at 1100 RPM.
From previous info. given above; with the old IAC and TPS at 0.58v it ran fine on the water, no black smoke but wouldn't stay running on the hose and idle surged on the water. Additionally when the TPS was set at 0.7v (manual value) it ran exactly how it did in my opening sentence when I fired it for the first time on the water; however, ran fine on the hose. When I brought the TPS value down to 0.58v on the water it didn't smoke, idled at 600 and purred like a kitten, now back to rough running, high idle and blowing black smoke.
ECU's get swapped next.
From previous info. given above; with the old IAC and TPS at 0.58v it ran fine on the water, no black smoke but wouldn't stay running on the hose and idle surged on the water. Additionally when the TPS was set at 0.7v (manual value) it ran exactly how it did in my opening sentence when I fired it for the first time on the water; however, ran fine on the hose. When I brought the TPS value down to 0.58v on the water it didn't smoke, idled at 600 and purred like a kitten, now back to rough running, high idle and blowing black smoke.
ECU's get swapped next.
10-22-2017, 09:53 AM
#22
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Did you check your meter for acurracy or try a different meter.
You could also hook up the the other rod and see what it's reading now.
It could definitely be the ecu.
But you don't want to be chasing your tail because you have a meter that started acting up.
You could also hook up the the other rod and see what it's reading now.
It could definitely be the ecu.
But you don't want to be chasing your tail because you have a meter that started acting up.
10-22-2017, 10:45 AM
#23
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Thread Starter
On car platforms I've seen issues with ECU's on the fritz causing intermittent issues.
10-22-2017, 06:35 PM
#24
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Thread Starter
I first confirmed the good running engine TPS is the same voltage as the erratic running unit 0.57V. I prefer to compare apples to apples but read on.....................
As promised, ATTEMPTED to swap the ECU's today and happened upon MEFI 1's with two different Model numbers. The erratic idling #16234539 and #16189069 on the other engine that has zero issue. See attached picture, they are different sizes. I stopped right there as I'm not sure whether or not they are swap-able. The #162 (erratic engine) was used by Mercruiser the #161 was not and seems to be a GM car/truck ECU (see attached picture from MEFI Burn). So now I have more questions than answers.
Should the Non-Mercruiser unit (#161) even be on a boat? Did modifications to sensors, harness, tune etc. need to be made to use in on my engine? I was afraid of swapping them and potentially cause more harm than good.
https://uniim1.shutterfly.com/ng/ser...714842/enhance
https://uniim1.shutterfly.com/ng/ser...714862/enhance
Keith
As promised, ATTEMPTED to swap the ECU's today and happened upon MEFI 1's with two different Model numbers. The erratic idling #16234539 and #16189069 on the other engine that has zero issue. See attached picture, they are different sizes. I stopped right there as I'm not sure whether or not they are swap-able. The #162 (erratic engine) was used by Mercruiser the #161 was not and seems to be a GM car/truck ECU (see attached picture from MEFI Burn). So now I have more questions than answers.
Should the Non-Mercruiser unit (#161) even be on a boat? Did modifications to sensors, harness, tune etc. need to be made to use in on my engine? I was afraid of swapping them and potentially cause more harm than good.
https://uniim1.shutterfly.com/ng/ser...714842/enhance
https://uniim1.shutterfly.com/ng/ser...714862/enhance
Keith
Last edited by Tractionless; 10-22-2017 at 06:42 PM.
10-22-2017, 07:14 PM
#25
Registered
Don't know right now but might have found the issue so long as the ECU was not re-flashed. Need to look more indepth
10-23-2017, 01:33 PM
#27
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Thread Starter
I called MEFI Burn today with the issue. They stated any of the model numbers of MEFI 1 will work but must have the correct tune installed. MB also stated the MEFI's were used in other platforms other than the marine industry. If I have to purchase another unit I'll need to ensure its loaded with the proper mapping for my engine, no matter what the model number.
Atleast I now know I can swap side to side and see if my issue goes away. Hopefully the weather will hold up to do it after work tonight. Then I'll know if I need an ECU or the problem is somewhere else in the harness in which case I'm buying a scanner.
Atleast I now know I can swap side to side and see if my issue goes away. Hopefully the weather will hold up to do it after work tonight. Then I'll know if I need an ECU or the problem is somewhere else in the harness in which case I'm buying a scanner.
10-24-2017, 07:27 AM
#28
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Thread Starter
Swapped ECu's and no change, still idling at 1100 rpm, blowing black smoke and running rough.
Switched back to original ECU, unplugged the TPS harness to tape the exposed insulation (used during testing) plugged it back into the TPS, decided to start the engine again and VIOLA; idles at 750 rpm, no smoking and not running rough! Then I blipped the throttle and right back to running rough, blowing black smoke and idling at 1100 rpm?!!?
Normally I'd assume TPS going bad; however, I've already experimented with a new TPS, set at the same base voltage as the OE unit and it had the same rough running, blowing black smoked and idling at 1100 rpm issue. See post #14. The harness side at the TPS has been tested as well, see post #13.
I feel I'm out of options and I ordered scanning software from MEFI Burn before writing this post.
Switched back to original ECU, unplugged the TPS harness to tape the exposed insulation (used during testing) plugged it back into the TPS, decided to start the engine again and VIOLA; idles at 750 rpm, no smoking and not running rough! Then I blipped the throttle and right back to running rough, blowing black smoke and idling at 1100 rpm?!!?
Normally I'd assume TPS going bad; however, I've already experimented with a new TPS, set at the same base voltage as the OE unit and it had the same rough running, blowing black smoked and idling at 1100 rpm issue. See post #14. The harness side at the TPS has been tested as well, see post #13.
I feel I'm out of options and I ordered scanning software from MEFI Burn before writing this post.
Last edited by Tractionless; 10-24-2017 at 07:41 AM.
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articfriends (05-16-2020)
10-24-2017, 08:58 AM
#30
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May have missed it...what is your fuel psi when running good vs running bad ?
