74 2.0L, Running Very Rich, owner quite confused, need diagnostic help |
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74 2.0L, Running Very Rich, owner quite confused, need diagnostic help |
drumsticks2112 |
Sep 20 2009, 12:56 PM
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#21
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Newbie Group: Members Posts: 7 Joined: 29-October 08 From: New London Member No.: 9,704 Region Association: Upper MidWest |
Car fires without a problem, but idles quite rough, and runs very rich, so much so that when the it settles down to normal idles, it floods out. MPS was replaced with a used but tested one recently. When it was last running ( a year ago) it ran a little rich, but nothing like this.
As of now, the CHT is not connected. When it is connected, the RPMs jump up to 4000 and stay there. When the CHT is bypassed with direct grounding of the harness, the results are the same as with the sensor being disconnected. I have no reason to suspect the injectors, FPR, Decel Valve, or the MPS. Any and all advice is welcome. -Todd |
CHAZT54 |
Sep 23 2009, 12:41 PM
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#22
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CHAZT54 Group: Members Posts: 19 Joined: 29-December 08 From: New London, Wisconsin Member No.: 9,878 Region Association: Upper MidWest |
I am working with drumsticks on this car and have done the following in the last 24 hrs to track down the source of this problem;
I replaced the vac. hose going to the MPS - there seemed to be good vaccum on the MPS end of the hose when running and connecting it to the MPS while running had minimal effect- still flooding out. At the same time I connected the hd temp sensor lead to the inj. harness lead which makes the eng race immediately without moving the throttle body flap. ALSO - grounding the hd temp lead from the brain had NO effect. I am beginning to think we are barking up the wrong tree. This car ran pretty good a year ago, albeit a little rich, without the hd temp sensor being hooked up. In the process of restoring the car over the winter, we removed the throttle body and intake tubes for cleaning and painting and then re-assembled with new gaskets. No other EFI components were disturbed. The throttle valve sensor was recalibrated upon assembly. As stated before, the eng. fires right up but the plugs eventually drown in gasoline at idle. I have not yet checked the fuel pressure - possible source of the problem? We are frustrated and open to any and all advice. CHAZT54 |
Dave_Darling |
Sep 23 2009, 08:51 PM
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#23
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914 Idiot Group: Members Posts: 15,048 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
...At the same time I connected the hd temp sensor lead to the inj. harness lead which makes the eng race immediately without moving the throttle body flap. That's a big red flag to me! If the RPMs went over 2K or so, you have a vacuum leak. A pretty large one, in fact. Advanced timing can also raise your idle RPM, but only a smallish amount. Air leaks are the cause of almost all instances where the RPMs climb with the throttle still shut. Find the leak and fix it. Then start figuring the rest of this stuff out. Do you have any hoses that go straight from the air cleaner to the manifold? You should not. --DD |
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