ECU Error Code 41

[chandrab]

Last weekend my 91SE got a new water pump (a bear to change in the car!) and new Ignition Module & Coils (aftermarket using interchange list). Now I'm getting a Check Engine light (Error Code 41, Engine Speed Signal Missing)...but the engine seems to be running fine. I'm confused as I would think the engine would stumble with such an error.

I'm confused if the problem is the coils or the module or something else.

Questions:

1. Is the car safe to drive home from the garage with this error or will it die on me?

2. Whats the proper way to change the Ignition Module/Coil...I had great difficultly removing the entire module/coils/heatsink assembly (screws are in wheel well)....Is there a better/easier way to remove these parts?

Thanks,

Chandra

91SE

Edited October 19, 2007 by chandrab

[esp88]

Hi Chandra

According to the manual:

" The engine speed signal is a 5 volt digital input to the ECM (Connector J3C11) The signal is used by the ECM to set the alternating firing of the injectors "

And the manual suggest check the all cable connections between from ECM J3C11 and 5 pin DI connecotor B!

My guess is you are using aftermarket Ignition Module & Coils may caused your problem !

Good luck !

Y.Hotta

[Paula&Marcus]

Hi Chandra,

... been there done that ...

Your problem actually is the aftermarket ignition module which lacks the connector for the engine speed signal (

IIRC, there already is a thread about the very same problem here on the forum.

Cheers

Marcus

Last weekend my 91SE got a new water pump (a bear to change in the car!) and new Ignition Module & Coils (aftermarket using interchange list). Now I'm getting a Check Engine light (Error Code 41, Engine Speed Signal Missing)...but the engine seems to be running fine. I'm confused as I would think the engine would stumble with such an error.

I'm confused if the problem is the coils or the module or something else.

Questions:

1. Is the car safe to drive home from the garage with this error or will it die on me?

2. Whats the proper way to change the Ignition Module/Coil...I had great difficultly removing the entire module/coils/heatsink assembly (screws are in wheel well)....Is there a better/easier way to remove these parts?

Thanks,

Chandra

91SE

[chandrab]

I was afraid I would have to replace the ignition module.

What's the proper/fastest way of replacing this?

Must I remove the heat sink plate - it was difficult removing the 3 bolts on the wheel wheel.

Any shortcuts?????

Thanks,

Chandra

[Paula&Marcus]

Chandra,

Yes its the complete unit that you have to replace what sits under the coils.

Where is your old one ? Is it broken ?

Cheers

Marcus

I was afraid I would have to replace the ignition module.

What's the proper/fastest way of replacing this?

Must I remove the heat sink plate - it was difficult removing the 3 bolts on the wheel wheel.

Any shortcuts?????

Thanks,

Chandra

[chandrab]

Marcus...I still have my module, but was hoping I could remove the individual components from the front instead of the entire module + heatsink...the wheel wheel bolts were difficult to access/remove. The coils/module hook into the heatsink plate, which is then hooked into the side of the wheel well.

Any hints on removing this?

I assume the module is a Lotus only part?

I put in a new module because at 17+ years old I figured the car could use a new module thats all...is that wrong thinking?

What I am really surprised at is how well the motor runs without this signal!

Thanks,

Chandra

91SE

Edited October 20, 2007 by chandrab

[Paula&Marcus]

Chandra,

If I were you I would put back the old basis module and just use the coils from the new module. This way you have at least new coils ;o)

JFYI, the flywheel sensor signal is directly fed to the DIM (=direct ignition module, floating signal, earthless). Thats why your car runs. It just the connection between DIM and the ECU that is missing.

Cheers

Marcus

www.PUKesprit.de

Marcus...I still have my module, but was hoping I could remove the individual components from the front instead of the entire module + heatsink...the wheel wheel bolts were difficult to access/remove. The coils/module hook into the heatsink plate, which is then hooked into the side of the wheel well.

Any hints on removing this?

I assume the module is a Lotus only part?

I put in a new module because at 17+ years old I figured the car could use a new module thats all...is that wrong thinking?

What I am really surprised at is how well the motor runs without this signal!

Thanks,

Chandra

91SE

[juki75]

Hello!

Unscrew only 4 coil pack screws as you see at the picture!

Jukka

[islandbloke]

Coil packs are available from Lotus for around

[chandrab]

I ended up replacing the coils + ignition module this weekend....the job isn't very easy as unscrewing the 4 screws, as 1 of the screws is covered by a fat A/C compressor hose (at least 91SE)...so the entire backing place with the module/coil has to come off. Even with a lift and air tools it took me a long time! It really is a 2 man job.

Now with the old module + new coil packs, everything seems to be running great...smoother idle and no check engine.

The question I have is that if I had bought a genuine AC DELCO/GM ignition module - would I have had this problem?

-Chandra

91SE

Hello!

Unscrew only 4 coil pack screws as you see at the picture!

Jukka

Edited October 22, 2007 by chandrab

[Squelch]

The error code 41 will disable some functions...

Three choices:

1. Use the genuine Lotus ignition module, since it has the internal connection for the signal.

2. Use a Delco or after market ignition module and pop the unit apart and solder in a small jumper wire to bring the signal out to the connector

3. Read the code from the mem-cal, Tweek the MALF fault word 1 bit 7 and disable error 41, The engine will run fine.

The engine speed signal is used during setup up and tuning during development of the code, for some reason Lotus left it in. Other Delco equipped cars that use the same ECM don't use the speed signal.

[juki75]

I have replaced DI-unit (original lotus part) and flywheel sensor and still error 41. CEL is not always on.

I have to check the wirings next.

Jukka

[sanj]

I have replaced DI-unit (original lotus part) and flywheel sensor and still error 41. CEL is not always on.

Did you clear the error codes after you replaced the DI module? Even if the CEL is not on, the code will remain until cleared.

[juki75]

Did you clear the error codes after you replaced the DI module? Even if the CEL is not on, the code will remain until cleared.

I disconnected the battery and with the first start there was no CEL but after second and third start CEL was on.

[spiritoflight]

So, here it is about 15 years later than this post and I have the same error code 41. I know of nothing specific that may have happened to trigger the CEL. 

The major factor I have noticed, is that when I'm in traffic, like going thru a packed, slow, drive-thru fast food place and the water temp gets up to 90c to where the 3 front fans kick in, then turn off the engine, then restart it, the engine light sometimes goes off. Then, when I drive easy it stays off. But, when I get on it the light can come on again, I'm assuming because of air flow cooling. But, several times it allowed me to get all the way home with some spirited high boost use without turning the CEL on. It ran for over an hour the other day with the CEL off, after heating it up good. 

  But, that is an intermittent/inconsistent experience. But, getting it nice and warm/hot seems to be a mandatory factor, regardless, as the CEL never stays off if the temp just sits at 80c or less. 

  Also, during the CEL on time, the boost won't exceed ~. 5 bar. Once the CEL goes off, it can boost normally, to the top 1.x bar. 

  So, if you're still around juki75 did you get the issue fixed at some point? 

  - Mark (91SE) Wiens