ogamer777
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- Joined
- May 22, 2016
1982 244 Ti stock K Jet
I am having some troubles with my air fuel mixture, and an intermittent rough idle. The car is stock k jet fuel injection and bosch ignition system. I was looking for the test ports in order to check and adjust the dwell angles as necessary, but they are not in the normal location, near the battery and driver's side fender.
In addition to that, I believe something is faulty with the frequency valve in the fuel distributor system. The car will intermittently idle rough due to too much fuel, 10.0 on the AFR gauge, then seemingly random, the idle smooths out and air fuel ratio return to around normal.
I ran a few tests to try to figure out what is going on:
When the car is fully warmed up:
Idle: 900
AFR: 13.6-13.8
Narrowband O2 voltage reading: .45V
After running the engine at 2000RPM for ~30 seconds and returning to idle:
Idle: 900
AFR: 13.6-13.8
O2 voltage: .46V
Cold start with multimeter hooked up: (Waiting for car to cool down, maybe tomorrow)
Idle:800-1100
AFR:10.5-11.0
O2 voltage open-loop: .390V
O2 voltage closed-loop: .63V - .73V?
Time to reach closed loop: 10:00min?
When I started the car with the multimeter hooked up, the engine idle very poorly and extremely rich. I could hear the frequency valve through the windshield and doors closed and windows up. Pressed the gas 15% - 20% to see what would happen and the car ran worse, misfiring, and the frequency valve got louder. So I undid the red lead from the multimeter and started the car and it started just fine.
Here is a log of how the engine acted upon a cold start after sitting for a few hours.
A.F.R .... | NB O2 V | I d l e | Time
-----------------------------------------------
10.5-11.0 | .390V | 8-1100 | 0:30sec
10.5-11.0 | .395V | 8-1100 | 2:00min
10.5-11.0 | .397V | 8-1100 | 4:00min
10.5-11.0 | .400V | 8-1100 | 6:20min
At this point I took the engine to 2000RPM for about 30 seconds, the O2 sensor voltage and AFR remained the same once the engine returned to idle.
10.5-11.0 | .410V | 8-1100 | 8:20min
At 10:00 my multimeter shut off, and after a few seconds, the idle smoothed out and AFR increased.
13.7-14.0 | .420V | 900 | 10:30min
I let the engine idle for a bit and the numbers were all about the same.
I will do another test run tomorrow morning after the engine sits overnight.
Following conducting these tests warm, I discovered that when I had the test probe attached to the narrowband o2 power, the idle would smooth out and the o2 volts would read .43V, and then 1-3 seconds after removing the test probe, the idle would surge between 700-900. When the idle dipped to the lowest, around 700, I quickly got the test probe back on the o2 wire and saw it read .34V then quickly jumped back to .43V.
The same thing happened upon cold start, just at richer AFR.
I removed the CI relay and that caused the mixture to lean out, plugged back in and idle and AFR returned back to "normal".
I've replaced 99% of all the stock vacuum lines and intake hoses. Still getting 11MPG with mixed city/hwy driving.
Any helpful suggestion are welcome as I am out of ideas at this point. I've been futzing with the car for 9 hours straight.
I am having some troubles with my air fuel mixture, and an intermittent rough idle. The car is stock k jet fuel injection and bosch ignition system. I was looking for the test ports in order to check and adjust the dwell angles as necessary, but they are not in the normal location, near the battery and driver's side fender.
In addition to that, I believe something is faulty with the frequency valve in the fuel distributor system. The car will intermittently idle rough due to too much fuel, 10.0 on the AFR gauge, then seemingly random, the idle smooths out and air fuel ratio return to around normal.
I ran a few tests to try to figure out what is going on:
When the car is fully warmed up:
Idle: 900
AFR: 13.6-13.8
Narrowband O2 voltage reading: .45V
After running the engine at 2000RPM for ~30 seconds and returning to idle:
Idle: 900
AFR: 13.6-13.8
O2 voltage: .46V
Cold start with multimeter hooked up: (Waiting for car to cool down, maybe tomorrow)
Idle:800-1100
AFR:10.5-11.0
O2 voltage open-loop: .390V
O2 voltage closed-loop: .63V - .73V?
Time to reach closed loop: 10:00min?
When I started the car with the multimeter hooked up, the engine idle very poorly and extremely rich. I could hear the frequency valve through the windshield and doors closed and windows up. Pressed the gas 15% - 20% to see what would happen and the car ran worse, misfiring, and the frequency valve got louder. So I undid the red lead from the multimeter and started the car and it started just fine.
Here is a log of how the engine acted upon a cold start after sitting for a few hours.
A.F.R .... | NB O2 V | I d l e | Time
-----------------------------------------------
10.5-11.0 | .390V | 8-1100 | 0:30sec
10.5-11.0 | .395V | 8-1100 | 2:00min
10.5-11.0 | .397V | 8-1100 | 4:00min
10.5-11.0 | .400V | 8-1100 | 6:20min
At this point I took the engine to 2000RPM for about 30 seconds, the O2 sensor voltage and AFR remained the same once the engine returned to idle.
10.5-11.0 | .410V | 8-1100 | 8:20min
At 10:00 my multimeter shut off, and after a few seconds, the idle smoothed out and AFR increased.
13.7-14.0 | .420V | 900 | 10:30min
I let the engine idle for a bit and the numbers were all about the same.
I will do another test run tomorrow morning after the engine sits overnight.
Following conducting these tests warm, I discovered that when I had the test probe attached to the narrowband o2 power, the idle would smooth out and the o2 volts would read .43V, and then 1-3 seconds after removing the test probe, the idle would surge between 700-900. When the idle dipped to the lowest, around 700, I quickly got the test probe back on the o2 wire and saw it read .34V then quickly jumped back to .43V.
The same thing happened upon cold start, just at richer AFR.
I removed the CI relay and that caused the mixture to lean out, plugged back in and idle and AFR returned back to "normal".
I've replaced 99% of all the stock vacuum lines and intake hoses. Still getting 11MPG with mixed city/hwy driving.
Any helpful suggestion are welcome as I am out of ideas at this point. I've been futzing with the car for 9 hours straight.
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