Engine Jerking 2k Revs -1984 911 Carrera
04-15-2021, 06:07 AM
#1
Engine Jerking 2k Revs -1984 911 Carrera
Hi, hope everyone is well. Any help would be much appreciated.
I have an 1984 911 cab
The car drives pretty well and I'm happy with it except when I'm accelerating through revs 1.8-2.2k the car will start jerking back and forward a little..... I go past 2.2k revs and the car drives well and also below 1.9k revs.
I have had the injectors cleaned and reconditioned, new filters, New HT leads, 1x new rotar arm and 1x new distributer cap and this has not fixed it.
Any other thoughts what it could be?
Many Thanks,
Alex
I have an 1984 911 cab
The car drives pretty well and I'm happy with it except when I'm accelerating through revs 1.8-2.2k the car will start jerking back and forward a little..... I go past 2.2k revs and the car drives well and also below 1.9k revs.
I have had the injectors cleaned and reconditioned, new filters, New HT leads, 1x new rotar arm and 1x new distributer cap and this has not fixed it.
Any other thoughts what it could be?
Many Thanks,
Alex
04-15-2021, 01:38 PM
#2
Burning Brakes
For a while, I had a problem that may be similar on my '85. It turned out to be engine-air-flow related, rather than directly RPM. It was the Air Flow Meter (AFM).
That is a known issue on these cars. You should be able to search on it to find troubleshooting methods. The simplest one to explain is to measure resistance across the correct two pins in the connector and ensure that it is monotonic with no dropouts or jumps as you move the flap through its range of motion. Or maybe you need to apply voltage and measure voltage, I don't exactly remember, but the main thing is to have the signal be smooth throughout the range.
You may have a worn spot at the same place you are having trouble. As you move through that, the resistance may jump, confusing the DME, but once you get through it, on to higher air flows, you're fine again.
That is a known issue on these cars. You should be able to search on it to find troubleshooting methods. The simplest one to explain is to measure resistance across the correct two pins in the connector and ensure that it is monotonic with no dropouts or jumps as you move the flap through its range of motion. Or maybe you need to apply voltage and measure voltage, I don't exactly remember, but the main thing is to have the signal be smooth throughout the range.
You may have a worn spot at the same place you are having trouble. As you move through that, the resistance may jump, confusing the DME, but once you get through it, on to higher air flows, you're fine again.
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alexdbwilliams (04-16-2021)
