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Join Date: Jul 2005
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2.0 Idle Seeking problem

Hey everyone, I am new to this site and after viewing alot of the posts I decided to consult you since everyone here seems very helpful.

I am assisting a friend in repairing his 2.0 75 914 with EFI and we are at an impasse.

The main problem is idle, when started it idle seeks, going up and down very rythmically.

I assumed vacuum leak and did some checking. Heres what I found.

He had some sort of issue that filled the air filter box and intake manifold with tons of oil (apparently he over filled the crankcase with over 3 extra qts of oil -if note more)

We drained the oil and started trouble shooting.

- the Smog system was removed and there are various block off plates everywhere.

- what i know to be the air injector ports on the motor next to the plugs are not connected (since it was desmogged) and he is missing one of the injectors all together. What is a good replacement to block off the hole he has there? could that cause the idle problem ?

- his pressure sensor for the EFI system is bad (will not hold a vacuum either by hand pump or by sucking on it) have searched for a replacement but they are VERY pricey from what i have seen.

He wants to go to a single carb setup in the efforts of cost....i know that is a frowned upon thing but he really has no money if the pressure sensor is gonna cost 800-1100$ (you know where they are cheaper?)

What do you guys recommend as a path for trouble shooting the idle seeking and getting this fine auto up and running.

Also does anyone have a diagram of the vacuum system as it should appear now with all the smog equipment removed. I cant locate one and that would help me trouble shoot.
Thanks
Old 07-30-2005, 05:49 PM
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The MPS is the single largest determiner of mixture in the system. If it's bad, the engine will not run right. If it leaks down like that, it's bad. They are very expensive new, some places offer rebuilt ones for less but they aren't necessarily as good as new ones.

Hunting idle like that is often a sign of a lean mixture. A broken MPS diaphragm would probably make the mixture go rich, so chances are there is other stuff going on as well.

Some of the 75-76 cars had a smog pump, which pushed fresh air into the exhaust ports. If the air injectors are not plugged up, then you have major exhaust leaks--I would expect you could hear them and feel them. You can unscrew the air injector and screw in a plug with the same threads; I believe that a valve adjusting lug actually does have the same size threads. (Might be the early adjuster only? Not sure.) I'm not sure what kinds of idle problems/driveability problems would be caused by having exhaust leaks into the engine bay, but I don't think they'd be very good. They will tend to erode the head where the leaks are coming through...

The single-carb setup is about the worst possible way to get air and fuel into the motor. If you go carbs, duals are the only way to go. Not overly cheap, but the singles just don't work well on our engines. (If you can find a way to heat them up, then maybe...)

To understand just about all that is known about the D-jetronic fuel injection at this point in time, see:
http://members.rennlist.com/pbanders .

--DD
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Old 07-30-2005, 10:13 PM
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here is a pic of the 73-74 hose layout.
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Old 07-31-2005, 06:54 AM
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Thanks, is that the same diagram as the 75 2.0?
Old 07-31-2005, 08:38 AM
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Mostly, yes. Line-drawings are available elsewhere on this site--check the front page for "EFI Hose diagrams". The vacuum hoses are pretty much the same on the 75-76 2.0 as they are on the 73-74 2.0 (except if you have a smog pump or EGR on the car), and the fuel lines from the tank up to the engine bay are pretty much the same as the 75 1.8 diagram.

--DD
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Old 07-31-2005, 06:50 PM
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