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502 mpi running on 4 cylinders > 502 mpi running on 4 cylinders
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502 mpi running on 4 cylinders

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Old 05-05-2013, 04:30 PM
  #21
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Originally Posted by sutphen 30 View Post
check to see if theres at least 12v at the injector w/ the key on.then we'll go from there.
Will do thank you for the help I apreciate all the help you guys have given me
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Old 05-05-2013, 08:31 PM
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had a 95 272 that went into limp mode when outdrive iol was low. just a thought could it be somthing along those lines?
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Old 05-06-2013, 02:37 AM
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I had the exact problem with my 350 mag mpg. Ended up being one of the injectors shorting the driver in the ecu out. After many days of trouble shooting I started engine on hose and started unplugging injectors and once I got to the bad one engine went to running on 7 cylinders. Once plugged back in it went to missing all for 1,7,4,6. Once that was figured out I replaced all injectors.
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Old 05-06-2013, 08:36 AM
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Originally Posted by gerg g. View Post
had a 95 272 that went into limp mode when outdrive iol was low. just a thought could it be somthing along those lines?
My resivor is low so this could be the problem...I hope it's that easy
But I do see a wire going back to the ECM...would that tell the ECM go go into limp mode if my drive oil resivor was low?
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Old 05-06-2013, 02:45 PM
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like mentioned,,if one of the injectors have a low ohme reading it will tell the quad driver in the ecu to shout them off..unplug them and ohme them all out,,i think they should be around 12.3 tp 13.2 ohmes cold..
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Old 05-06-2013, 11:59 PM
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If you lost those 4 injectors, then more than likely either there is a break in the blue or green(whichever goes to the bad injectors) wire going to the injectors, or the driver in the ecm is bad. You can check with a noid light at the injectors. Unplug all 4 of them and check each one. As mentioned, also check the ohms of each injector. They should be about 12.2-12.3 ohms. The pink wire is 12+ volt. It should have power since all of the injectors are tied together and 4 are working, so i don't think that is your problem.

If you don't have a noid light, you can use an analog voltmeter. It's easier to see what's going on with an analog instead of a digital meter.
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Old 05-07-2013, 09:06 AM
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Just for an update I took each injector connector and turned it over till I found what injector wasn't working...I disconnected cylinder 4 connector and it started running on 7 plugged it back in and back to 4

I then pluged the noid into the connector and pulses just fine so I ordered a new oem injector

But another issue is I pulled the dipstick and the oil has turned a hazy brown milky color? Moisture or water in oil? Just changed the oil on Saturday with valvoline 20-50 vr1 racing oil
I never had this happen
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Old 05-07-2013, 08:42 PM
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well the badly running engine is sucking water back in.I'd wait till you get it running right.
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Old 05-08-2013, 08:48 AM
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Yeah that's what I was thinking
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Old 05-11-2013, 01:27 AM
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I had the same problem with my last boat (1994 454 Mag EFI--385hp). Only running on 4 cylinders. Tested EVERYTHING and it was finally determined that my ECU was bad. Replaced it and good as new. If replacing your injector doesnt do the trick you might want to consider a new ECM (buy one used on OSO for a couple hundred).
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