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924martinirossi · Posted: Tue May 13, 2003 4:32 pm Post subject: Hunting at Idle

My car has been having some rather small problems with the idle staying at the correct setting. Yesterday the car started to idle from 1k - 1.2k just going up and down about every two seconds. Also sometimes when I would start the car I noticed that the tach would jump up and down. And finaly the car cut out while driving, however it restarted quickly.

Today I started it up and it died before I got out of the driveway. What I found was about 2vdc on terminal 15 of the coil, it should be a miniumn of 5. When I disconnected the Ignition Control Unit (ICU) the voltage went up to battery voltage. All wires and the coil pass the required tests and are good.

Anyone have a spare ICU to send me for a 81 931?

Fairchild p/n 211-905-351
Lucas p/n DAB400
Bosch p/n BIM 137
Porsche p/n 191.905.351A

Michael

Smoothie · Posted: Tue May 13, 2003 11:14 pm Post subject:

This sounds like it could be a mild case of the flakey 12 pin DITC connector problem. I'd try an unplug-replug on that connector.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

924martinirossi · Posted: Thu May 15, 2003 2:06 am Post subject:

Just checked the connector of the DITC all looks good. Still no spark, tach signal or fuel pump relay action.

Michael

Jim d · Joined: 02 Jul 2019 Posts: 12 Location: Syracuse, NY

kondzi · Joined: 02 Jul 2018 Posts: 494 Location: Poland/EU

Maybe faulty crankshaft position sensor? Do you have access to scope (best) or multimeter (set to AC) to see if the sensor produces alternating Signal?
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded)

Fifty50Plus · Posted: Sun Jun 05, 2022 6:36 am Post subject:

It's an NA? No crank sensor then.
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1979 924 NA race car H-Prod SCCA
1982 924 NA race car - Sold
1981 924 Turbo sold
1982 924 Turbo sold
1972 911 E race car - traded for Cayenne Diesel
1975 914 1.8 Building for H-Prod SCCA

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2595 Location: MI

Slow/lazy O2 sensor?

Use a dwell meter in 4cyl mode and see what duty cycle the frequency valve is running at, oscillating, hunting..
Black wire on test port drivers side fender well near firewall..

Or you could just unplug the O2 sensor and see if it stops hunting..
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80 Turbo - Slightly Modified