Frequency valve not buzzing

[stevie67cars]

Hi,

I am working at an early Automatic DeLorean (900's) which is having trouble under load. It will start (not as quickly as I would like) and idle ok, also rev with miminal splutter while in P or N, but seems to get very bogged down when you try to drive it or place it under any load. If you back off the accelerator pedal a bit, it will improve slightly and can be driven but it is not right.

After speaking to someone in the know I determined that the frequency valve is not buzzing or working at all. This car has a cat and when I disconnected the lamda sensor as per my friends suggestion to force the system into default, the frequency valve still did not buzz.

It appears to be the correct relay in the lamda/fuel relay with 5 pins (Bosch).

Any suggestions as to what I might try next?
Should I be getting 12v at the frequency valve?
Does this sound like it would cause the symptoms I am describing?

Any help greatly appreciated.

By the way, I have my 82 manual DeLorean beside me too should I need to do any comparisons or swaps.

Stephen

[David T]

Remove and replace the plug on the Feq valve several times. Sometimes that is all you have to do. Check that the black wire from the plug is connected to ground. If it is still isn't running check that you are getting power to the Lambda ECU.
David Teitelbaum

[sdg3205]

Try Dave's suggestion first and also double check that one of the pins in the relay socket hasn't back out. That will cause the FV to become inoperable.

[axh174]

Hi,

I am working at an early Automatic DeLorean (900's) which is having trouble under load. It will start (not as quickly as I would like) and idle ok, also rev with miminal splutter while in P or N, but seems to get very bogged down when you try to drive it or place it under any load. If you back off the accelerator pedal a bit, it will improve slightly and can be driven but it is not right.

After speaking to someone in the know I determined that the frequency valve is not buzzing or working at all. This car has a cat and when I disconnected the lamda sensor as per my friends suggestion to force the system into default, the frequency valve still did not buzz.

It appears to be the correct relay in the lamda/fuel relay with 5 pins (Bosch).

Any suggestions as to what I might try next?
Should I be getting 12v at the frequency valve?
Does this sound like it would cause the symptoms I am describing?

Any help greatly appreciated.

By the way, I have my 82 manual DeLorean beside me too should I need to do any comparisons or swaps.

Stephen

Hi Stephen,

The symptoms you are describing sound nearly exactly like what happened to me once. The pins on the frequency valve connector were corroded on 2234 and the freqeuncy valve was not buzzing. I checked all the relevant connections from the relay/fusebox area and found nothing wrong, but as soon as I checked the frequency valve connector itself the problem was pretty evident. Popping the plug on and off, as suggested by Dave, will often get you going, but if you have some serious corrosion buildup you may want to consider some sort of contact cleaner as a long-term solution.

And I do believe you are supposed to be getting 12V at the valve, yes (hopefully someone will correct me if I'm wrong).

Another problem might be that your enrinchment is set so high or low that the frequency valve simply doesn't respond, but in that case you'd have other/additional symptoms.

[Bitsyncmaster]

Yes you should be getting 12 volts (engine running) on one pin to the FV. The other pin is driven to ground (square wave) by the lambda ECU. Make sure the lambda relay is the correct unit. One of the standard relays if installed in the lambda socket would cause no FV operation. I've also seen the RPM relay fail and cause no lambda power.

[stevie67cars]

Cheers guys, thanks for the replies so far- keep them coming if there are any more suggestions. I can say that the pins on the FV are clean, tight and not corroded. I am confident it's not a connection problem there.

If the relay is fine and the spades are ok, where is my next port of call? I will be back at the car tomorrow to try a few more things, gone home for the day now- 7.40pm here now.

Thanks again,

Stephen

[dmc6960]

You should still check for 12v on the connection going into the FV. If you have 12v, either the FV, LAMBDA computer, or the modulated GND between the two are bad. If there is no 12v then there is some sort of connection problem upstream. Figure out which one it is and work from there.

[Bitsyncmaster]

With the wrong lambda relay you get 12 volts at the FV or the lambda ECU but not both with the engine running. Your test should confirm you have both 12 volt powers to the FV and the ECU with the engine running.

[Jimmycxc]

I had a similar problem. Car would start and drive ok for about 1 minute. As soon as the engine was warm, it would bog down and almost stall on me. Dave T. was gracious enough to come to my house and check it out for me. Turned out that the relay just went bad. I ordered a new one, replaced it and ran like brand new again.

[stevie67cars]

Ok,

I checked the ground on pin 5 of the lamda ECU and ran a new ground- no difference.

I then revisited the Lamda relay in the fuse compartment and replaced it with the one out of my other car (which looks ancient and original) and resut- the FV was buzzing and the car was taking revs fine. Drove it down the road and it feels a whole lot better with less of the bogged down issues I was having.
I guess the Bosch relay was an incorrect replacment after all. (thank you to all who suggested this)

On the downside, the car is now hunting pretty bad on idle from around 600- 1400rpm. If I disconnect the now functioning Frequence Valve, the idle settles.

The car also smells a bit rich. Would somebody have adjusted the CO on the metering head to compensate for the non functioning FV? It definately has been worked at before as it has been plugged with a bit of sealer.
Do you think that it could be too rich and need adjustment or have I another problem?

Thanks again in advance.

Stephen

[Bitsyncmaster]

You still use that same adjustment even if your running open loop (no working lambda). So yes, most likly the mixture setting will need adjustment with the lambda working.

[David T]

It's probably set a bit too rich because the frequency valve was not running. You can also have dirty injectors and vacuum leaks messing up your idle.
David Teitelbaum




You still use that same adjustment even if your running open loop (no working lambda). So yes, most likly the mixture setting will need adjustment with the lambda working.