5.0 Long shot Question

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Nov 30, 2010 | 11:26 AM

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From: Palm Beach Co. Fl.

5.0 Long shot Question

I,m pulling a EFI 5.0 out of a 86 merc wagon. I was removing connectors,and vac hoses one at a time to see if it would make any difference. All was going well until I put in some FI cleaner in the gas[more than I should have 3/4 bottle into 5 gal] and plugged a couple of vac lines. the next day it started ,but it would idle rough and when put in gear it would lunge with the rough idle but would run strong when I put my foot into it. Now it seems to be getting worse could it possibly be the FI cleaner or what? I know this is a long shot question I just hope someone can help me out Dennis

Nov 30, 2010 | 12:00 PM

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From: Palm Beach Co. Fl.

I went back and unplugged all the vac lines and that was the problem I'm new to this but I always thought that vac leaks could make a engine run rough. The vac lines were comming off the intake maniflod where I can't see where do they go to? Dennis

Nov 30, 2010 | 03:55 PM

xlt4wd90

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From: SoCal

If the engine runs better with a vacuum leak, then it's running too rich. It's possible that it's running in a limp-home mode, with minimal computer control. The EFI engines need most of the stuff that's connected to the engine in order to work properly, especially a vacuum line between the intake manifold and the MAP sensor. The 86 EFI systems use speed-density to infer air flow, and the air density is calculated using manifold absolute pressure.

Try to hook up all the lines correctly if you can. Otherwise, it's hard to get the EEC to work properly.