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Working on an 89 non charge cooled for a friend. its got a code 41 crank sensor signal missing. Cleared the code several times it returns immediatley. Have tried a new sensor Di module coilpacks etc... Tested the wiring from sensor to Di Module it's fine, from module to ECU it's fine. Checked the pins at ECU for damage there good. tested A/C voltage at ECU harnes while cranking it's good. Used ECU out of a Quad 4 with prom switched over, same story code 41. The testing sequence always leads back to an ECU being faulty. Grounds at the bellhousing and intake manifold are good. Any ideas???

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Cant rid a friends car of code 41 tried most everything i can think of any ideas? keeps resetting on start up . new sensor, wiring checked, ecu tried, grounds checked, pins connections checked, AHHH!!

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Topics merged, no need to duplicate your query.

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If it looks and sounds like a faulty ECU then that's your first port of call. Do you know of a spare you can swap it out with?

  • CODE 41 Engine Speed Signal Circuit
This Code will be set if the following conditions are met:
  • The ECM does not receive signal pulses from the Direct Ignition (DI) module for more than 8 engine revolutions during cranking.

OR

  • The ECM does not receive signal pulses from the Direct Ignition (DI) module for more than 4 successive engine revolutions while the engine is running.

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Engine runs fine, but you still have a code 41?

It's the incorrect ignition module, not a genuine Lotus part.

The genuine Lotus part is actually a part used during factory tuning of the engine, it has an additional output signal that is helpful during the code development.

This part was not intended to be used on a production run.

In a normal development cycle, after the code is all worked out and the engine tuned, the engineers would disable the flag in the code for code 41 then the production cars are built the "standard" ignition module that does not have the signal output would be used.

So, you have an after market ignition module. Here are your two choices:

1. get a genuine ignition module (limited availability)

2. disable the flag for 41 in the code

The is the same reason that may versions of the early code have the "engineering bypass" flag set, it skips some of the checksums at power on. The programming engineers never "cleaned up" after themselves. Things are much better on the 1995 S4s code, but it still has the flag for 41 enabled.

Steve

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Hi, Steve: You write "2. disable the flag for 41 in the code", but how ?

I have an Eprom programmer, I have the MemCal program and I have an hex editor. But, I can't identify the

offset to change the malfunction code 41 on-to-off. Can you help us, please?

Thanks, Feijucho.

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Working on an 89 non charge cooled

Is this a US car, in which case didn't they have BOSCH FI??

If it is BOSCH, are the codes still relevant??

All other FI cars were charge cooled??

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Hi Feijucho,

The starting address is $8000, where the first two bytes are the EPROM ID.

Important the following is applicable for an EPROM with ID 09EB, there are more versions for a Turbo SE Esprit with an AC Delco system, I don't know if it is applicable for the other versions. (One more thing I'm pretty (almost 100 %) sure but have not tested it) (except for the offset).

If you want to disable (mask) Error 41 bit 7 (where b7 is th MSB and b0 is the LSB) must be made 0 (0 = disable Error, 1 = enable Error) at address 8D1F which is Error word 1 Mask. The EPROMchecksum should also be changed located at addresses 8006 / 8007.

Freek

Edited by fjmuurling

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I do not know why you would want to disable the error checking of the engine speed signal; without this signal the ecu doesn't know the rpm.

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Hi Feijucho,

When you click on my Profile there is an option send PM (Private Mail) for sending me an email.

Sailobob makes a good point, if there is something wrong with the engine speed signal changes are that the ECU doesn't get the correct RPM infomation. There are quite a lot of lines of code involved with the error 41, the disabling of the error is not that difficult but what goes on after that is more complicated.

Freek

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Freek, your email-box must be plein, I can't send you a PM. Or,please, write me to a my private mail (wanadoo),

or brush your box.

Thanks, Feijucho.

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Why not keep the discussion here? That way others may benefit from your findings or offer their own insight into your problem.

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Rank, Ineed send a file to Freek, don't be conspicous.

Freek, if you agree, I send you my Eprom file, I can't understant something about it!

Thanks, Feijucho.

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Hi Feijucho,

if your EPROM is an original S4S code than it has an different ID than an SE EPROM (mine is an 09EB). I only have some knowledge about the 09EB which i'm disassembling. Once this is completed I will probably start with the other ones. For starters let me know the ID number of your EPROM.

BTW the first two bytes of the code are the EPROM Id.

Freek

Edited by fjmuurling

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My ID is: 27 8A, the first two bytes (0 and 1). But I think - I'm sure- that the distribution code ist the same for all versions of the ours ECU with the Eproms 27C256.

Regards, Feijucho.

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0x278A is the high torque S4S code (aka chip #3).

Edited by sailorbob

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I can't be 100% sure, my lovely is a SE model year 1991, and the Eprom code isn't from my car (It is the Eprom placed in the actual MemCal,

running perfect condition): the provider say me this info.

Feijucho.

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