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Join Date: May 2004
Location: Apple Hill, Ontario
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Unhappy 914 2.0lt. engine missing AGAIN

Hey everybody! Hope someone can help me out. I have a 1974 2.0lt that has an engine cough (miss) I can't get rid of. Engine coughs on acceleration and on steady rev. mostly always around 2500 to 3500 rpms and runs rough at higher rpms. I hit the gas and the car shutters and rpms drops and engine sputters. Problem seems worst when engine is warm. The car starts like a charm (don't even have to hit the gas) and idles pretty well. I can't put my finger on the problem. I adjusted the dwell, timing, and throttle switch. I suspect the switch but am not sure. This is driving me crazy. Does anyone have an idea. Could it be something real simple I haven't thought of or know about?? I would appreciate any tips or idea anyone might have. Thanks, Dominic.

Last edited by Tab914; 08-18-2004 at 05:23 PM..
Old 08-14-2004, 07:25 PM
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Sounds like the throttle position switch is worn. Recently, I had a misfire problem that was only occuring when the engine was warm and under load. At first I thought it was the throttle position switch but it turned out to be the cylinder head temp sensor. The sensor was intermittently failing when hot. I grounded the sensor cable and the engine ran great.

My recommendation is to methodically verify each of the components (fuel, ignition, wiring, etc).
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Old 08-15-2004, 08:10 AM
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Thanks Rob! I haven't checked that sensor yet but will now. This may sound silly but how did you ground it?
Old 08-15-2004, 08:49 AM
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There is a wire leading from the harness to the cylinder head temp sensor. They are joined at a connector about 6" away from the cylinder head sensor. I unplugged te connector and connected an alligator clipped jumper to it and then connected the other end of the jump to the engine case. I then test drove the car again and my symptoms were gone so I knew that this was my problem.
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Old 08-15-2004, 09:30 AM
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Thanks! Will try that after lunch and let you know.
Old 08-15-2004, 09:43 AM
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Jump it after its warm, though! Otherwise it wont start.
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Old 08-15-2004, 10:24 AM
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Hey guys! Looking at that right now and have a question. Should there be anything between the sensor and the connector to the harness? Mine has what looks like a resistor but don't know for sure. The wire to the harness is a thick black wire and the wire on this thing is a smaller white wire. Looks like something someone might have added at some point. Any idea what this is or if it should be there. I've attached a photo.
Old 08-15-2004, 11:45 AM
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Some had resistors IIRC, but I thought that only the 73 did.
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Old 08-15-2004, 11:50 AM
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Tried disconnecting and grounding but car won't start with wire disconnected. I had warmed the car up before when i again checked the timing. Do you have a trick to deal with the throttle switch aside from the adjustement that is well described here on Pelican?? Any idea what else it could be?
Old 08-15-2004, 11:57 AM
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Tried again on other side of resistor. This time car started but still got the cough and missing at the same rpm ranges and this time car actually stalled. Will try reconnecting sensor without resistor and see.
Old 08-15-2004, 12:07 PM
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Hey guys! Same results with resistor off so I just put it back on. Another thing. Idle actually tends to go up and down. Also is it normal to hear the fuel pump surging. It surges about every second and for about a second.
Old 08-15-2004, 12:31 PM
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If the engine is still missing when the cylinder head temp wire is grounded, then that's not your problem. Hook it back up as it was.

Next try disconnect the throttle position sensor wire and test drive the car again. It should run but it will be a bit sluggish. If the problem goes away, then you need a new sensor. If the problem persists, then that's not your problem either.
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Old 08-15-2004, 04:30 PM
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Thanks Rob! I'll try that as well, as soon as it stops raining here. Do you know what ground wires I should check for looseness that would cause this problem?
Old 08-15-2004, 04:37 PM
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Yes but I doubt they are your problem as a ground problem would occur at all RPMs. There are three key ground wires for the fuel injection harness. They connect to the engine case at the center of the case near the flywheel end of the engine. I recommend pulling them off, cleaning them, crimping them a smidge to make sure they have a tight fit and reinstalling, making sure all three are well attatched. .
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Old 08-15-2004, 05:19 PM
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In the engine bay or under the car? Haven't been out to check as it is raining cats and dogs here. Car is covered of course.....
Old 08-15-2004, 06:34 PM
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The grounds are inside the engine compartment, under your air cleaner. Remove the air cleaner assembly, then with the engine cover open and look down at the engine case. When you look at the throttle body/air distribution box, then shift your eyes towards the rear of the car. There is electrical ground terminal under a bolt that holds the case halves together. Its right at the center line of the car.
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Old 08-15-2004, 07:54 PM
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Thanks again Rob! Will have a look and let you know. I appreciate the help. Cheers.
Old 08-15-2004, 08:00 PM
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Old 08-16-2004, 11:09 AM
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Hey guys! Well it looks like the problem has been resolved. Here is what was done. Changed distributor cap, replaced a plug wire that looked a bit suspicious, took off throttle switch opened it and cleaned all the contacts, moved the brushes slightly off their already existing tracks so that they sweep on new line, reinstalled as per article here on Pelican. Also, and I think this is what the big problem was, I removed that resistor. After tests on either side of resistor I discovered that it was sending the wrong signal to the ECU. Then rechecked the timming and dwell, reset idle and car ran fine. Ran it up to temperature and no symptoms of the missing. Keeping my fingers crossed though and hoping that the problem is really resolved and not just temporarily. I want to thank you guys, ROB especially, MIKE and DAVE for your input and help. If you still have something you would like to add I would love to hear it. Also do you have pics of your cars. I will post one of mine. Thanks alot once again. Cheers, Dominic.
Old 08-16-2004, 02:45 PM
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The resister connected to the cylinder heat temp sensor causes your engine to run more rich across the board. I don't see how that could be causing mis-fires unless it is intermittently loosing continuity. If it did that, you would have problems.

But no matter, I'm happy you are up and running. ;-)
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Old 08-16-2004, 04:44 PM
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