EST and CAS fault

[rololux]

Last week the engine check light came on, accompanied by misfire, when accelerating hard in third. I continued driving (gently). Next time I started, the light was off. Over the weekend I eventually got Elanscan working on the MAC (Whoopie!!) and discovered EST monitor errors and CAS fault stored. I did a full scan on the way to work today - car was running fine with no indications of problems, but I was not pushing it too hard today. I'm not that familiar with Elanscan data - can someone have a look and let me know what I can learn from this?

Thanks,

Roland

[Steve A]

I eventually got Elanscan working on the MAC

Sorry to go slighty off subject (ok alot) but I take it you were running windows to do this

[rololux]

I have parallels running XP on a Macbook with Snow Leopard. It works very well actually - the only problem I had was figuring out how to install the Elanscan interface driver and figuring out which port was being used by the USB serial port (took me ages to find device manager!!)

But Elanscan works perfectly with this setup.

[Steve A]

Thanks for that rololux

[saska]

Last week the engine check light came on, accompanied by misfire, when accelerating hard in third. I continued driving (gently). Next time I started, the light was off. Over the weekend I eventually got Elanscan working on the MAC (Whoopie!!) and discovered EST monitor errors and CAS fault stored. I did a full scan on the way to work today - car was running fine with no indications of problems, but I was not pushing it too hard today. I'm not that familiar with Elanscan data - can someone have a look and let me know what I can learn from this?

This scan looks quite normal to me with the exception of the stored EST and CAS faults.
The EST faults may be due to CAS faults since if the ECU doesn't receive a CAS signal it can't calculate EST so may log a fault.
Before I started replacing bits I'd check the electrical connections to the CAS. Then retest with ElanScan and try to provoke the fault (accelerate hard in third).
If you still have a problem then I'd replace the Hall Effect Sensor in the CAS. Available from Aftersales. Instructions for fitting new type HES are HERE
If you still have a problem then get back to us.
BTW well done with Parallels and the USB Com port

[rololux]

Been too busy recently to investigate further, but today I did another scan and managed to catch the fault. It started misfiring about 90 sec into the run, and shortly afterwards the engine check light came on again.

I cannot really interpret anything from this scan - the only thing that seemed to happen at the same time as the fault occurred is that the coolant temp suddenly dips. Do you think this is related, or just a coincidental error - or maybe it is as a result of the CAS fault??

Before I embark on a repair, I'd appreciate an expert opinion.

BTW, I did re-seat the CAS connector before going out - it was very clean and showed no corrosion.

Thanks,

Roland

[GeoffSmith]

I take it that you experienced it when you changed from 3rd to 4th at about 75mph Roland.

[GeoffSmith]

The apparent coolant temperature drop may be related to e.g. a poor earth / connection but more importantly the dips are coincident with the "Input flags | CAS" flag going low between 87.5s & 97.8s and again at 103s & 118.5s ; I presume this means that the ECU has detected a fault (probably loss of CAS signal) and reverts to hope and pray mode.

There are probably two scenarios:

a) The coolant temperature dip occurred as a result a poor connection going open circuit as a result of vibration due to misfire as a result of an intermittent problem with the CAS.

b) There is a poor connection somewhere in the loom / earthing that results in erroneous CAS signals.

As the cost of replacing the CAS is relatively low and is a known and recurrent problem, I would change the CAS and see if the problem continues. If it does then it's a case of checking all the earth connections and following the signal line back to the ECU. In case you haven't already found it, there is information about earthing and wiring in the Wiki.

[Brit-Car-Nut]

I believe Geoff meant the HALL Sensor in the CAS is a low cost item. Get one from the current Lotus Aftersale (March 2011) for £15.00 + VAT. Search "March 2011" on the forum and you should find the details.

[GeoffSmith]

Correct John.

[wayne]

Had the same problem a couple of times recently Code 41 & 42 then limped home. luckily I was only about 1 mile from home.
I let the car cool down for a while and restarted fine no light and ran smooth. It turned out to be one of the pins in the new style HES plug not locking in position properly.
Had the same thing again tonight. Quick wiggle of the wires and all was fine.

Going to remove the plug and crimp / solder/ heat shrink the connections.
If you have changed the HES to a new style one it may be worth checking the connections on the plug. Give the wires a good tug and make sure they do not pull out of plug.

[rololux]

I take it that you experienced it when you changed from 3rd to 4th at about 75mph Roland.

I'm intrigued - is this not the normal speed at which to change up??

But thanks for your comments - it seems to me that an earthing / connection problem is most likely to blame. In the scan the lack of temperature sensor data is so coincident with the loss of CAS data that I cannot see this could be related to a vibration issue - it must be the same root cause, or maybe as a result of the ECU response.

I had a good poke around the earthing points (as described on Wiki), and it looks really solid. I cannot find any connection problem, but intermittent electrical faults are notoriously difficult to isolate - much professional experience here, although not on cars. One other factor is that the problem does seem to occur more frequently when the car is hot - yesterday the drive to work in the morning was flawless (i.e. no faults - no assessment of my driving intended!), but after the car had sat in the sun all day, leaving work it started misfiring even before I hit the open road. This would be consistent with a dry joint.

Not sure how to proceed. Will probably change the HES anyway, as as you say it is cheap and easy. But how to isolate an intermittent earthing issue???

Roland

[rololux]

Just realised I never closed this one out. I replaced the HES and fault has not returned (yet!!) so I am hopeful that it is now sorted.

Many thanks for all your guidance.

Roland