P38A Height sensor adjustments

cornishboater · May 30, 2022

I had to swap out my EAS valve block due to a leaking exhaust valve and I thought I would try and fix the constant (and very consistent height) lean to the RH issue (2 3/4" on std height) I have tested the right rear sensor which I had thought was the issue but it has tested absolutely fine. I have adjusted the sensor height to 12 bits higher than the LH but it has only gained me an inch, how far can I go to equal the LH?

Datatek · May 30, 2022

cornishboater said:
I had to swap out my EAS valve block due to a leaking exhaust valve and I thought I would try and fix the constant (and very consistent height) lean to the RH issue (2 3/4" on std height) I have tested the right rear sensor which I had thought was the issue but it has tested absolutely fine. I have adjusted the sensor height to 12 bits higher than the LH but it has only gained me an inch, how far can I go to equal the LH?

How did you test the sensor? Normally I would not expect to see a difference in bit count of more than 5 across the axle so something is not right. Go too far and the EAS will throw a wobbly reverting to defaults. You cannot adjust just one corner because weight transfer will affect the other 3 corners.

cornishboater · May 30, 2022

Ta for the reply, I tested with a multi meter as per the info posted a while back and it passed the criteria. I am getting differing opinions on the difference, some exactly what you are saying and some saying to just adjust until the height is reached. So far the adjustment made to the right rear hasn’t affected the other corners and with the 12 bit adjustment I have lifted by 1 1/2 now that things have settled down.
I have had this lean for pretty well most of the time I have owned the car (12 years) I thought it was time to see about lifting it as it has now been mentioned by the MoT tester.
Difficult to figure which way to go really, obviously the sensor is signalling because it responds to data changes without kicking off!

Datatek · May 30, 2022

cornishboater said:
Ta for the reply, I tested with a multi meter as per the info posted a while back and it passed the criteria. I am getting differing opinions on the difference, some exactly what you are saying and some saying to just adjust until the height is reached. So far the adjustment made to the right rear hasn’t affected the other corners and with the 12 bit adjustment I have lifted by 1 1/2 now that things have settled down.
I have had this lean for pretty well most of the time I have owned the car (12 years) I thought it was time to see about lifting it as it has now been mentioned by the MoT tester.
Difficult to figure which way to go really, obviously the sensor is signalling because it responds to data changes without kicking off!

As I said, go too far and the EAS will throw a wobbly and change all settings to defaults. Either the sensor is faulty, is loose or misplaced on the chassis or maybe the actuator arm is bent or the joints are worn. Something is certainly wrong to have such a difference across the axle.
Is that corner low on all height settings?

cornishboater · May 30, 2022

Hi Keith,
On wade it was 3”, std 2 3/4, motorway 1 1/4 and access it is the same as the others.

cornishboater · May 30, 2022

My next step I think is to swap sides, the arms are in good nick and not bent, I have run the resistance test as per a couple of posts on LZ and the readings were as smooth as silk. As mentioned it has been consistently wrong for a long time. I have done all of the electrical tests including the white connector in the LH kick panel (cut and soldered) I agree that it is not normal to have this difference but by changing the bit count it has adjusted so I assume the sensor is sending info albeit rather high….

Datatek · May 30, 2022

cornishboater said:
Hi Keith,
On wade it was 3”, std 2 3/4, motorway 1 1/4 and access it is the same as the others.

That really sounds like a duff sensor, there are 2 concentric resistance tracks in the sensor that act in opposition, one rising and the other falling, this is to reduce the sensitivity. I'm guessing, but if one track has failed, I reckon that would give you the result you have.
Swapping side to side is a good idea, be interesting to see what happens.

cornishboater · May 30, 2022

Everything I touch on her is an interesting journey Keith
I think the hard bit will be getting the nuts undone, I have soaked them in plus gas but the uppermost ones are pretty well mullered! The bolts look to have rivet style heads so I guess that’s going to be a drill out job…..
Gotta drill the bolts from the back bumper too, the heads sheared off, oh the joy!

cornishboater · Jun 2, 2022

Datatek said:
That really sounds like a duff sensor, there are 2 concentric resistance tracks in the sensor that act in opposition, one rising and the other falling, this is to reduce the sensitivity. I'm guessing, but if one track has failed, I reckon that would give you the result you have.
Swapping side to side is a good idea, be interesting to see what happens.

I think you were right Keith, the 12 bit change has not just lifted the saggy right hand rear but now the left hand is reaching for the sky. It is actually now 2 1/2 inches higher than the standard height setting! Pity because it was bang on before along with both front measurements. The front ones fortunately have stayed the same. Will fit my new “Chinese” one tomorrow, can’t be any worse than what I have now!

P38A Height sensor adjustments

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