Lambda Dwell not swinging

[eseethal]

Maybe someone can help here - the DeLorean runs perfectly fine, warm, cold everything, milage, but that concerns me:

When measuring dwell for the Lambda the needle is not swinging - see video here: https://photos.app.goo.gl/wUoPmnPb2eQxKTGg7
When I actuate the WOT switch the needle goes a little to the left (seen in the video)
When I ground the cable to the Lambda the needle very slowly goes almost to the left (not shown in the video)
I have replaced the Lambda probe but that did not change anything
I measure the dwell from the diagnostic plug orange cable and ground
The frequency valve buzzes, when I disconnect it, the engine RPMs react a little


I can perfecly live with this condition as the car runs fine, but as a mechanic I always want to get to the bottom of things :-)
Any hints here what can cause this behaviour?

thanks..............Eugen

[David T]

Either;
You did not hook up the dwell meter correctly,
Your dwell meter is not working,
Or you don't have the meter set up right.

Connect to a GOOD clean ground and check the connection to the Lambda wire. It sounds like the Lambda system is functioning so you should be getting better readings.

[AugustneverEnds]

Perhaps it's not going into closed loop. You stated you replaced the lambda (oxygen) probe so it's probably not that. Check the lambda ECU behind the driver's seat for loose connections or poor grounds. If you are able try swapping the ECU with a known good unit.

[Ron]

Maybe someone can help here - the DeLorean runs perfectly fine, warm, cold everything, milage, but that concerns me:

When measuring dwell for the Lambda the needle is not swinging - see video here: https://photos.app.goo.gl/wUoPmnPb2eQxKTGg7
When I actuate the WOT switch the needle goes a little to the left (seen in the video)
When I ground the cable to the Lambda the needle very slowly goes almost to the left (not shown in the video)
I have replaced the Lambda probe but that did not change anything
I measure the dwell from the diagnostic plug orange cable and ground
The frequency valve buzzes, when I disconnect it, the engine RPMs react a little


I can perfecly live with this condition as the car runs fine, but as a mechanic I always want to get to the bottom of things :-)
Any hints here what can cause this behaviour?

thanks..............EugenIt sounds like the O2 sensor is not connected/bad (even though new).
Did you try applying 1.5V to its lead (see WS Manual D:04:15, 5.)?

+1 Nick.

[eseethal]

Thanks for your help here! Sorry for the late reply - I did not get the notification messages from the forum.
I will check the Lambda unit, but have no spare one to replace it.
The dwell meter should work, I remember having used this before on the DeLorean. The ground also is good. It reacts to the WOT switch. When I ground the Lambda wire the needle of the dwell meter goes to the left side slowly. Next time I will try the 1,5 V battery test.

thanks, greetings from Austria..........Eugen

[Michael]

Make sure that O2 sensor is a Bosch and not some cheap part. I have back to back vids with brand new China junk vs. Bosch and the difference is obvious.

[eseethal]

Thanks, yes, it is from delorean.eu - they have the right parts. And the not-swinging was with the previous lambda sensor too.

[QUOTE=Michael;276189]Make sure that O2 sensor is a Bosch and not some cheap part. I have back to back vids with brand new China junk vs. Bosch and the difference is obvious.[/QUOTE

[mark w]

Your Freq valve is buzzing....continuously or on/off?

the meter reading tells me continuous.

sometimes if the base mixture is too far off- lean or rich, the system cant adjust, and it stays at one value.

[eseethal]

Thanks, the valve is continously buzzing. The mixture I measured with a CO-tester and a Wideband Lambda should be correct. The car runs fine, the fuel consumption is also o.k :-)

[poidog]

Thanks, yes, it is from delorean.eu - they have the right parts. And the not-swinging was with the previous lambda sensor too.


delorean EU carries chinese junk O2/Lambda probe... the same one that DMC houston carries. I just recently put a new one in from DMC and it failed in less then 3 months, same symptoms as you, it would not swing and stick at 45 degrees open loop. I put in a new Bosch 02 prob and it is working normal now and swinging properly. Replace the O2 probe with a bosch unit and I bet money on it that it solves your problem.

Make sure you have your meter connected properly - the orange wire connector that would go to the diagnostic plug and use the engine hook or AC bracket as a grounding point.

[Timeless]

delorean EU carries chinese junk O2/Lambda probe... the same one that DMC houston carries. I just recently put a new one in from DMC and it failed in less then 3 months, same symptoms as you, it would not swing and stick at 45 degrees open loop. I put in a new Bosch 02 prob and it is working normal now and swinging properly. Replace the O2 probe with a bosch unit and I bet money on it that it solves your problem.
FWIW I replaced my 02 earlier this year with a BSOCH unit from DPI and it's working well.

[Bitsyncmaster]

Thanks, the valve is continously buzzing. The mixture I measured with a CO-tester and a Wideband Lambda should be correct. The car runs fine, the fuel consumption is also o.k :-)

If your wideband showed normal 14.7 AFR (1.00 lambda) and your dwell reading on the FV is holding the minimum value then you probably just need to adjust the mixture screw.

[eseethal]

Oh, interesting! Thanks for the info! That really could be the cause! I will try the Bosch sensor!

thanks..........Eugen

[eseethal]

Thanks for all the help here! I finally replaced the LAMBDA ECU with a new unit and now the needle swings again as it should be :-)
best wishes, greetings from Austria...........Eugen