Fault codes 41,42 and 54

[DavieBow]

Hi Guys ,
my car is running really lumpy on idle , i have recently fitted an Everest chip and after the first real good blast out the lumpyness started .
i have done a fault code reading and got errors 41 , 42 and 54 .

as far as i undertsand :-
41 - Engine speed sensor so possible CAS fault ??
42 - electronic spark timing circuit so again linked back to CAS fault ??
54 - CO potentiometer circuit - possibly needs adjusting to run better with new Everest Chip ???

can anyyone shed any light on this please , is it likely that i do need to replace the CAS or a slight adjustment to the CO potentiometer will fix it .

i've done a scan ...with one of Geoff's adsl cables but cant get it to upload onto here , can someone let me know how i do that so you guys can take a look at it and advise please ,
thanks
Dave

[dapinky]

i've done a scan ...with one of Geoff's adsl cables but cant get it to upload onto here , can someone let me know how i do that so you guys can take a look at it and advise please ,
thanks
Dave

This is a bit of a 'first' for me..... a question about fault codes and elanscan that I can answer - but only because the bit I know has nowt to do with either fault codes or scans.....

The forum doesn't allow certain 'file extensions' to be uploaded, so you will need to compress the elanscan file to a .zip file - it can then be added to the thread

[Steve A]

If you've just recently fitted the chip maybe it's not quite seated properly ? they are quite tight

[DavieBow]

here you go , i could only get it to upload as a pdf

1st scan engine running Sheet1.pdf

[rip]

CAS often throws back strange errors elsewhere.
I have an old scan of an Elan which was suffering from a CAS fault... I don't have the error code numbers but..

EST Monitor Error: On
Cas fault: On
CO pot circuit: On

This was not my Elan but I believe the CAS was the only thing at fault.
It looks very similar to what it sounds like yours is like.


It is unlikely your CAS needs replacing. It is usually the hall effect sensor causing the issue & I believe this can sometimes be repaired. I have never needed to look at mine but you may find a write-up in the wiki.

Jeff020907.zip

[DavieBow]

i'm pretty sure its seated properly ,but i will double check, i'd read about someone having issues with it not being fitted properly before i installed it , so made sure it was in right.
The car was running fine for a couple of days with normal tootling around , it was only after i went on a bit of a spirited drive that i had the issues

[rip]

I can't open your .ecu file.
I opened it in notepad to look at the raw data & it seems to be in a different format to mine.
Hopefully you can download the one I posted & compare it with what your own.

[DavieBow]

I'm taking the engine out on Friday for a complete overhaul at which point i will be replacing every sensor where possible with new , i just don't know whether to just replace the whole CAS or whether i should just replace the hall sensor within the original CAS unit , theres a £250 difference in price between the 2 options , although i'm not approaching it with a penny pinching attitude , i don't see the point in spending £270 if i only have to spend £20 .

[Brit-Car-Nut]

You will need to rename the .ecu file just call it a .xxx file so you can upload it to the forum

[DavieBow]

mine's a pdf file , you should be able to open it with a pdf reader , oddly yours unzipped as a .ecu file and my computer scratched its head at that too

[Brit-Car-Nut]

That won't help. To graph and analyze the file it needs to be imported into something like Excel. As a PDF, the file is changed. Just save it as yyy.xxx or zip it and whoever wants to look at it will change the extension as needed. The file will need to be converted to be useful.

[DavieBow]

ok , thanks
like this ??

1st scan engine running.xls

[Brit-Car-Nut]

NO. It is NOT an .XLS file, it is an .ECU file. Unfortunately, the BBS program will not allow a file with the extension of ECU to be uploaded. so you need to "cheat" and name it something else. Use a zip program and zip the results and then post that file.

EDIT:
Having looked at the file, you converted it to .XLS, so that will help with the graphing/charting, but the .ecu format lets someone else (more knowledgeable than me) that can understand the results open it up in the ElanScan program for further study.

[rip]

No wonder I couldn't open it. I thought you just renamed it.
I renamed yours to .ecu & tried to open it with Elanscan but it didn't like it.
I tried using Excel to examine data but did not find it very useful. Elanscan displays it much better.

Elanscan does not really install. It runs as an executable. The program installation process adds registry entries to identify file extensions & tell Windows where to find the programs to open them.

[DavieBow]

Ahh , i didn't realise you could open it in elanscan , I have a lot to learn about it obviously

[John_W]

Davie,
I've just seen this thread. I spent many happy weeks last year tracing the origins of codes 41,42 & 54 that appeared on my car, and finally solved it very cheaply. Before you start replacing sensors, consider checking everything I mention below and you might get a cheap fix too. If the engine is already out of the car, I apologise for not having seen this earlier.

On my way to a Lotus day on 1st May last year my engine hiccupped twice. Strange, I thought, and checked Elanscan which showed a code 42, 54 and CAS code error. I read up on the sources of the errors which seemed to point to EST signal problems and much expense. However, it was a very minor hiccup and extremely intermittent, so I wasn't convinced by the fault code chart. I had a good look around the area of the CAS (as one thing the fault chart says is to check the wiring) and one of the HES leads came out of the plug when I wiggled the wire (years ago I had replaced the HES for the new type which means fitting fiddly new connectors). Aha!, I thought, I must have pulled it while working in that area a few weeks previously, and re-crimped the lead into the minute connector on the HES replacement plug. That got rid of the problem until July when I was on french and german motorways and the misfire and the same error codes re-appearred at high boost. By keeping acceleration moderate, I could drive round the misfire and the car behaved fine. By experimenting over hundreds of miles of auto route, I discovered that the misfire and error codes only appeared when boost went over 0.7 bar (I have an Everest chip fitted). So if I still had the original chip (which would never get boost to 0.7 bar), I would never have seen any misfire or errors.

Investigation when I got home showed that my static timing had shifted to 30 deg btdc (it was OK in May). I reset it and the car behaved OK for a while. Then on the way to the LEC Buxton weekend in Sep'16 the misfire and error codes re-appearred when boost went over 0.7bar. Again, so long as I drove to keep the boost low, everything was fine. When I got home, I traced the fault to the plug gaps being too wide. I simply re-gapped them to 31 thou and at same time tightened the clips on all the plug caps. The misfire under high boost was immediately completely cured and I have had no error codes or misfire since.

My explanation is that, at moderate boost, you can get away with your ignition settings being pretty far out or components a bit ropey, however at the higher boost allowed by the Everest chip, you had better ensure that everything is properly set up. Damaged or incorrectly adjusted components or connections are more likely to show their faults when pushed to the edge of their envelope at higher boost (e.g. incorrect plug gaps, poor wiring connections or cracked plugs).

You say that your problems appeared after fitting the Everest chip. That fits with my theory that problems with poor components will manifest themselves at higher stress levels (like the greater boost given by the Everest chip), however faults may remain hidden at lower boost levels. I have seen incorrect plug gaps cause misfires at high boost on other cars, and corrected them. So you might ask why it took me four months to check the plug gaps on my own car. I think that it was because of the error codes. I did not think that incorrect plug gaps could be capable of causing error codes 41, 42 and 54. However, my investigations over four months have led me to believe that they can.

On a related matter, you say that you have a lumpy idle after fitting the Everest chip? Did you re-trim the CO pot after fitting the Everest? This is a known phenomenon. As your car is an SE, it may have had the older 9929 PROM chip in it (unless it's been replaced), whereas Lotus upgraded the SE chip to 9930 PROM to satisfy new emissions test requirements (there was a Service Bulletin issued - 1995/24). As the SE Mountain chips are based on the more modern PROM id, cars which had the older 9929 chip fitted will need their CO pot adjusted to suit the newer 9930 specifications.

John

[John_W]

edited above post to give the Service Bulletin number.