Posts: 4,808
My VIN: 3937
When you said "shuddering", it made me think of what happens when you get the engine wet and a spark plug well has water in it. Assuming there's something else at play here though. Check to see that your spark plug wires are all clipped in properly anyway.
Could you post a video or some pictures of the engine bay with the cover/louvres raised? Maybe one of us will spot something out of place for you.
Sept. 81, auto, black interior
Location: Leonardtown, MD
Posts: 9,006
My VIN: 03572
I did not see or hear anything out of the ordinary on your video.
Location: Vancouver, BC
Posts: 3,385
My VIN: thirty two 'o five
Club(s): (PNDC)
I couldn't get sound but the idle looked fine.Originally Posted by Bitsyncmaster
If the WOT switch and unplugging the FV did nothing to affect idle i bet his car is tuned to run open loop.
Dave
Here, somewhere.
Location: Northern NJ
Posts: 8,581
My VIN: 10757 1st place Concourse 1998
Which raises the question, "Was the Lambda system working BEFORE this problem?". We don't know. Sounds like it wasn't. Maybe you suddenly developed a vacuum leak? Is the plug there over the mixture screw? First order of business would be to get the frequency valve to buzz. Then check the duty cycle and if necessary adjust the mixture screw.
David Teitelbaum
Location: Vancouver, BC
Posts: 3,385
My VIN: thirty two 'o five
Club(s): (PNDC)
I think you're right
Dave
Here, somewhere.
Location: Sudbury, ON, Canada
Posts: 46
My VIN: 11633 (and formerly 3133)
Well, I thought it was buzzing all along, but it turned out to be the idle speed regulator humming!
I can't seem to get it to buzz by turning key to 2. Zero voltage going to either pin on its connector.
But... When the engine is running it gets just over 14V on one pin and the other fluctuates up to 2V.
When I pull the Lambda ECU connector I see that it is receiving no power until the engine is actually running (13.9V).
Location: Leonardtown, MD
Posts: 9,006
My VIN: 03572
The lambda relay gets turned on my the RPM relay. So just like the fuel pump, the lambda system only gets power when the engine is running.
You need to get a dwell or duty cycle meter onto the FV to verify your mixture is set correctly.
Location: Northern NJ
Posts: 8,581
My VIN: 10757 1st place Concourse 1998
For troubleshooting purposes refer to D:04:12 for a simplified schematic of the wiring of the Lambda system. A good place to start would be the ECU module. Pull the plug and verify power, grounds, switching and wiring. Also refer to D:04:15 5 A-E. By applying power (1.5 DCV) or grounding the O2 sensor lead you should see the correct values on your dwell meter. Read the system repair notes, specifically #3 to power the Lambda system for testing purposes. The Lambda system isn't going to work till you can make it do what it says under "Pulse Ratios #5 A-E. If you can force the readings but it won't fluctuate as it should under A, the O2 sensor is probably no good.
David Teitelbaum
Location: Sudbury, ON, Canada
Posts: 46
My VIN: 11633 (and formerly 3133)
It wouldn't be like me to find an issue that is causing a symptom so I'm sure you are right... It likely wasn't working and was tuned to run open loop without bothering to physically disconnect anything. There is a plug above mixture screw. I'm probably chasing my tail going down the Lambda route.
Location: Sudbury, ON, Canada
Posts: 46
My VIN: 11633 (and formerly 3133)
You can only hear the issue. It's a seemingly completely random fluctuation, not all all like seeking. I'm editing together an updated video with some driving. Should illustrate things better.
It's so intermittent and random that it must be electrical. I can pull away from a stop with no trouble whatsoever and at the very next one, less than a minute away, I can barely get moving, then the next fine again.
The hotter the engine gets, the worse/more pronounced it seems to be. In fact, when I took it out just now to shoot the video, at first I thought that something I had done had fixed it, but it just got progressively worse the further I went.
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Dave M vin 03572
