99 C2 Code P1531 Variocam Solenoid
05-21-2019, 11:02 AM
#61
Captain Obvious
Super User
Super User
I think the DME will come back from the re-builder and it will make no difference what so ever. The shop is rushing into conclusions without making 100% sure the problem is the DME. Chasing electrical problems is difficult if the person doing it is not systematic. When I did mine, took me several evenings to come to a 100% conclusion that the issue was with the transistor/driver in the DME. Doesn't matter how long it takes, the mechanic should be 100% confident that they know exactly what the issue is before ordering ANY parts. BUT for this the car owner has to understand that the mechanic's time will cost money to do all the investigative work.
Last edited by Imo000; 05-21-2019 at 02:34 PM.
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NachoJohnson (11-19-2020)
05-21-2019, 01:15 PM
#62
Rennlist Member
Funny you should ask. I just heard back from EDU doctors, and I am not at all surprised that they found no issue with the ECU. Here are their notes:
"The unit tested good, and it worked on our bench. Also tested the unit in a perfectly running car and found no problems. The problem might be located in the car.
"Check or replace CAM solenoid valve, Check grounds, Check wiring harness, Possible engine mechanical problem, timing chain issue or wiring harness issue.
We recommend these improvements to your vehicle setup:
Electric Connector Harness Cleaning Kit (more info)"
"The unit tested good, and it worked on our bench. Also tested the unit in a perfectly running car and found no problems. The problem might be located in the car.
"Check or replace CAM solenoid valve, Check grounds, Check wiring harness, Possible engine mechanical problem, timing chain issue or wiring harness issue.
We recommend these improvements to your vehicle setup:
Electric Connector Harness Cleaning Kit (more info)"
05-21-2019, 01:17 PM
#63
Rennlist Member
Yep - I'm $1500 in labor into this, and haven't gotten anywhere. So I agree with time spent, but how do we know the quality of the time spent is worth every penny? Hopefully I can talk to the shop again and not have to spend more money for faulty diagnosis...
05-29-2019, 06:50 PM
#64
Rennlist Member
Does anyone have any ideas? I just received my ECU back from ECU doctors and it tested good. They even put the DME in a vehicle (not just bench test) and it was good as well.
In looking at how Variocam works, I assume that below 1,300 RPM and above 5,920 RPM, the solenoid should be OFF, correct? In the range between 1300-5920, the solenoid would be ON, which would advance cam timing by 12.5 degrees (25 crank degrees) to better charge the intake. But outside of this range
What would cause the ECU to think that it needed to activate the solenoid, even at engine speeds where it should be off?
I've looked at the mk1 and mk2 service and workshop manuals, but I don't see where this is all explained or discussed
https://rennlist.com/forums/996-foru...-a-primer.html
In looking at how Variocam works, I assume that below 1,300 RPM and above 5,920 RPM, the solenoid should be OFF, correct? In the range between 1300-5920, the solenoid would be ON, which would advance cam timing by 12.5 degrees (25 crank degrees) to better charge the intake. But outside of this range
What would cause the ECU to think that it needed to activate the solenoid, even at engine speeds where it should be off?
I've looked at the mk1 and mk2 service and workshop manuals, but I don't see where this is all explained or discussed
https://rennlist.com/forums/996-foru...-a-primer.html
05-29-2019, 07:19 PM
#65
Rennlist Member
Does anyone have any ideas? I just received my ECU back from ECU doctors and it tested good. They even put the DME in a vehicle (not just bench test) and it was good as well.
In looking at how Variocam works, I assume that below 1,300 RPM and above 5,920 RPM, the solenoid should be OFF, correct? In the range between 1300-5920, the solenoid would be ON, which would advance cam timing by 12.5 degrees (25 crank degrees) to better charge the intake. But outside of this range
What would cause the ECU to think that it needed to activate the solenoid, even at engine speeds where it should be off?
I've looked at the mk1 and mk2 service and workshop manuals, but I don't see where this is all explained or discussed
https://rennlist.com/forums/996-foru...-a-primer.html
In looking at how Variocam works, I assume that below 1,300 RPM and above 5,920 RPM, the solenoid should be OFF, correct? In the range between 1300-5920, the solenoid would be ON, which would advance cam timing by 12.5 degrees (25 crank degrees) to better charge the intake. But outside of this range
What would cause the ECU to think that it needed to activate the solenoid, even at engine speeds where it should be off?
I've looked at the mk1 and mk2 service and workshop manuals, but I don't see where this is all explained or discussed
https://rennlist.com/forums/996-foru...-a-primer.html
Since it has already been established that bank 1 has 10.5v not activated, and bank 2 has 0.0v not activated, seems the logical thing to do is to swap the pins at the DME from bank 1 to bank 2 and visqa versa. If the 10.5v moves to bank 2, the DME is at fault, if it stays on bank 1 the bank 1 solenoid/wiring is at fault.
When to activate the vario-cam is strictly rpm related, except when oil temp is extremely high, then is delayed a couple hundred rpms.
Last edited by Porschetech3; 05-29-2019 at 07:37 PM.
06-04-2019, 12:16 PM
#66
Rennlist Member
The plot thickens. MPC is pretty insistent that the ECU is faulty, so they've asked to call ECU doctors to determine exactly what tests were done on my ECU to understand this better.
If I wanted to swap the pins at the DME myself from bank 1 to bank 2, is that easy to do? MPC said that for them to do it 'would cost more money, and don't be surprised if the results point to the DME.' Not sure how much is more money at this point.
As a reminder, MPC's findings:
- X59/1 pin 14 negative to chassis ground OFL
- DME pin 52 chassis ground OFL
- DME pin 52 to pin 2 on solenoid .3 ohm (ok)
- no short to ground in wire from DME to bank 1 cam solenoid
- DME is shorted internally causing bank 1 solenoid to be "always on" energized 10.5V
- with solenoid disconnected, vehicle runs noticeably better
- can jump solenoid, solenoid activates correctly
- engine mechanical timing confirmed within spec
If I wanted to swap the pins at the DME myself from bank 1 to bank 2, is that easy to do? MPC said that for them to do it 'would cost more money, and don't be surprised if the results point to the DME.' Not sure how much is more money at this point.
As a reminder, MPC's findings:
- X59/1 pin 14 negative to chassis ground OFL
- DME pin 52 chassis ground OFL
- DME pin 52 to pin 2 on solenoid .3 ohm (ok)
- no short to ground in wire from DME to bank 1 cam solenoid
- DME is shorted internally causing bank 1 solenoid to be "always on" energized 10.5V
- with solenoid disconnected, vehicle runs noticeably better
- can jump solenoid, solenoid activates correctly
- engine mechanical timing confirmed within spec
06-26-2019, 08:33 AM
#67
Rennlist Member
Since it has already been established that bank 1 has 10.5v not activated, and bank 2 has 0.0v not activated, seems the logical thing to do is to swap the pins at the DME from bank 1 to bank 2 and visqa versa. If the 10.5v moves to bank 2, the DME is at fault, if it stays on bank 1 the bank 1 solenoid/wiring is at fault.
They want $2600 to fix it. This is after the $1500 I already spent on the other work that led up to this. How did they not find this short a long time ago?
06-26-2019, 10:19 AM
#68
Rennlist Member
"They want $2600 to fix it. This is after the $1500 I already spent on the other work that led up to this. How did they not find this short a long time ago?"
Hmmm, and they were insiting that it was the DME/ECU ? How do they explain that position? Listen, everyone makes mistakes - but they should also own up to them. They should work with you on that $ number. It's not that big a job to replace the solenoid. I think a new solenoid is around $500 - but can be gotten cheaper as well. $2100 sounds like an awful lot for labor... Good luck
Hmmm, and they were insiting that it was the DME/ECU ? How do they explain that position? Listen, everyone makes mistakes - but they should also own up to them. They should work with you on that $ number. It's not that big a job to replace the solenoid. I think a new solenoid is around $500 - but can be gotten cheaper as well. $2100 sounds like an awful lot for labor... Good luck
06-26-2019, 02:16 PM
#69
Drifting
Variocam solenoid fault diagnosis
If you search on Renntech you'll find details of a simple functional test for the variocam solenoids..It is the click test performed with the engine off..
1. Listen for a 'click' when you use a 9v battery to apply voltage directly to the solenoid.
2. Or. rig simple MoM switch+small jumper leads+3A fuse to a 12v car battery and do the same.
In the case described in this thread a click/no click symptom would have produced the correct diagnosis for a trivial cost and at most 20 minutes of simple work..
Durametric can do the same thing..
These solenoids are probably the most expensive 12v switches in the world ! But the diagnosis is cheap and simple.
Just because the solenoids both click does not mean you won't get a solenoid malfunction code. Indeed, if the DME is faulty ,tht could be the cause. But at least the click test helps narrow down the possibilities.
There is a significant amount of labor/skill in replacing a solenoid if you are to avoid oil leaks afterwards. Patience, meticulous prep and the correct sealant help. Ahsai has a few posts showing some details.
Please check that the external wiring of the solenoid is not shorting before you buy a replacement.
Ask here for suggestions on the lowest price for a replacement solenoid. Someone may have a good used one.
Be very careful in the replacement process not to loose a spring.See Renntech for more.details.
Good Luck and I hope these comments help you.It is amazing how the engine 'sings' when both cams are in harmony:-).
1. Listen for a 'click' when you use a 9v battery to apply voltage directly to the solenoid.
2. Or. rig simple MoM switch+small jumper leads+3A fuse to a 12v car battery and do the same.
In the case described in this thread a click/no click symptom would have produced the correct diagnosis for a trivial cost and at most 20 minutes of simple work..
Durametric can do the same thing..
These solenoids are probably the most expensive 12v switches in the world ! But the diagnosis is cheap and simple.
Just because the solenoids both click does not mean you won't get a solenoid malfunction code. Indeed, if the DME is faulty ,tht could be the cause. But at least the click test helps narrow down the possibilities.
There is a significant amount of labor/skill in replacing a solenoid if you are to avoid oil leaks afterwards. Patience, meticulous prep and the correct sealant help. Ahsai has a few posts showing some details.
Please check that the external wiring of the solenoid is not shorting before you buy a replacement.
Ask here for suggestions on the lowest price for a replacement solenoid. Someone may have a good used one.
Be very careful in the replacement process not to loose a spring.See Renntech for more.details.
Good Luck and I hope these comments help you.It is amazing how the engine 'sings' when both cams are in harmony:-).
So I had them do this, and here’s what they found: “the culprit is an internal short in bank 1 cam solenoid”
They want $2600 to fix it. This is after the $1500 I already spent on the other work that led up to this. How did they not find this short a long time ago?
They want $2600 to fix it. This is after the $1500 I already spent on the other work that led up to this. How did they not find this short a long time ago?
06-26-2019, 04:12 PM
#70
Rennlist Member
"They want $2600 to fix it. This is after the $1500 I already spent on the other work that led up to this. How did they not find this short a long time ago?"
Hmmm, and they were insiting that it was the DME/ECU ? How do they explain that position? Listen, everyone makes mistakes - but they should also own up to them. They should work with you on that $ number. It's not that big a job to replace the solenoid. I think a new solenoid is around $500 - but can be gotten cheaper as well. $2100 sounds like an awful lot for labor... Good luck
Hmmm, and they were insiting that it was the DME/ECU ? How do they explain that position? Listen, everyone makes mistakes - but they should also own up to them. They should work with you on that $ number. It's not that big a job to replace the solenoid. I think a new solenoid is around $500 - but can be gotten cheaper as well. $2100 sounds like an awful lot for labor... Good luck
06-26-2019, 04:37 PM
#71
Captain Obvious
Super User
Super User
How many hours do they claim they need to swap out the solenoid? What happens if it doesn't fix the problem? Are they going to go back in and put the old one back and don't charge you for any of that work? I'll be perfectly honest, I lost confidence in this shop several posts ago. I don't know you haven't
06-26-2019, 08:17 PM
#72
Rennlist Member
How many hours do they claim they need to swap out the solenoid? What happens if it doesn't fix the problem? Are they going to go back in and put the old one back and don't charge you for any of that work? I'll be perfectly honest, I lost confidence in this shop several posts ago. I don't know you haven't
Where I’m at now is: I thought about doing the solenoid myself, at a cost of $700-$800 for parts. I cannot find the solenoid much cheaper than $500. There are other parts needed, such as o-rings, gaskets, spark plug tubes, fasteners, etc, maybe special tools. I’ve been without a car for 3 months, so doing it myself would cost me another week or two. I’ve paid them $1250 or so already, and they asked for another $1500, but I’m countering for $1150 more. So if I could do the job for $700-$800, another $300-$400 for them to do it is worth it. Unless they screw it up, lol. That said, I think they are competent - the engineer seems good. They claim to warranty their labor and parts for 3 years, so if it doesn’t fix the problem, can I put a warranty claim on it, lol? I think I just did that on my labor.
06-26-2019, 08:34 PM
#73
Instructor
Pelican has a good diy for this job. Doing the solenoid doesn't seem too bad. I just picked up a '99 throwing the same code, but this car has been diagnosed as having a bad actuator/tensioner which is a lot more work and more costly. My car has a bit of a rattle on startup and I'm told the actuator is bleeding down when the car is off, so the dme sees the cam timing off on startup very shortly until oil pressure builds back up.
06-27-2019, 12:33 PM
#74
Captain Obvious
Super User
Super User
Pelican has a good diy for this job. Doing the solenoid doesn't seem too bad. I just picked up a '99 throwing the same code, but this car has been diagnosed as having a bad actuator/tensioner which is a lot more work and more costly. My car has a bit of a rattle on startup and I'm told the actuator is bleeding down when the car is off, so the dme sees the cam timing off on startup very shortly until oil pressure builds back up.
06-27-2019, 12:40 PM
#75
Captain Obvious
Super User
Super User
Not sure how many hours, originally it was 7-9 hours. If it doesn’t fix the problem, that’s a good point. I don’t know, other than I would pay them after the work was done, not before, so I would have leverage at that point.
Where I’m at now is: I thought about doing the solenoid myself, at a cost of $700-$800 for parts. I cannot find the solenoid much cheaper than $500. There are other parts needed, such as o-rings, gaskets, spark plug tubes, fasteners, etc, maybe special tools. I’ve been without a car for 3 months, so doing it myself would cost me another week or two. I’ve paid them $1250 or so already, and they asked for another $1500, but I’m countering for $1150 more. So if I could do the job for $700-$800, another $300-$400 for them to do it is worth it. Unless they screw it up, lol. That said, I think they are competent - the engineer seems good. They claim to warranty their labor and parts for 3 years, so if it doesn’t fix the problem, can I put a warranty claim on it, lol? I think I just did that on my labor.
Where I’m at now is: I thought about doing the solenoid myself, at a cost of $700-$800 for parts. I cannot find the solenoid much cheaper than $500. There are other parts needed, such as o-rings, gaskets, spark plug tubes, fasteners, etc, maybe special tools. I’ve been without a car for 3 months, so doing it myself would cost me another week or two. I’ve paid them $1250 or so already, and they asked for another $1500, but I’m countering for $1150 more. So if I could do the job for $700-$800, another $300-$400 for them to do it is worth it. Unless they screw it up, lol. That said, I think they are competent - the engineer seems good. They claim to warranty their labor and parts for 3 years, so if it doesn’t fix the problem, can I put a warranty claim on it, lol? I think I just did that on my labor.