940 ECU's

[clocks2003]

Hi Folks,
Info needed please!
I have an N reg 940 turbo estatewith cruise control, with what I suspect is a failing ECU.
(Every so often the engine cuts out and the rev counter goes to zero, but I don't think it is the crank shaft sensor as I have A) changed it for one I know works and B) bypassed the connector socket. When the engine dies, if I switch the ignition off for a minute it then starts again perfectly happily. I am also getting occasional hiccups without the motor dying.)
I have a spare ECU for a more recent 940 but that car did not have cruise control.
Both the boxes are Bosh ones, and the numbers on the boxes are: 0 277 400 148, 3517369 P04 810 (and a 7 on the lid) (spare one, working from newer car) and 0 227 400 218, 9135590 P03 810 (and a V on the lid) (older car, but with air-con).
So what I need to know is:
A) Does it seem likely to you that it is the ECU?
B) If I put the newer one in will it work at all with the engine of will it have the wrong programming? and
C) If it does work at all will I still have air-con?

Many thanks in hope!
Andrew

[FullEnglish]

I've never really heard of a 7/900 ECU going bad, but it's not impossible.

Apparently turbo cars don't have an ignition amplifier, they have a power stage instead (never had a turbo myself). Have you checked that?

[clocks2003]

I wouldn't know how to!
Also, would it cause the rev counter to read zero even when the engine is being pushed round by the road wheels at 70 mph after the engine has died?
Andrew

[bob12]

Maybe have u tried the ignition amplifier.

The EKZ ecu ... 148 is for a '97 B230FT/GT. The ... 218 is not listed for a 700/900 engine up to 1997.

[Dirty Rooster]

Originally Posted by clocks2003

... but I don't think it is the crank shaft sensor as I have A) changed it for one I know works and B) bypassed the connector socket.

Bypassed : what does that mean & how do you do it?
So you have two working CPSensors and the problem is the same with either fitted?
How's the car after resetting the ECU by disconnecting the batter for some time? : if exectly the same the ECU sounds less likely to be the problem.

[Dirty Rooster]

Originally Posted by clocks2003

Also, would it cause the rev counter to read zero even when the engine is being pushed round by the road wheels at 70 mph after the engine has died?
Andrew

Try another CPSensor from the scrapyard ASAP : easy test, just in case... because that symptom is exactly a failing CPSensor, but you know that.
If it isn't - its bizarre.

[TonyS9]

The replace-scary-boxes approach rarely works as a diagnostic method. I second the comment that these boxes are reliable, as is the fact there are several modules.

BTW my turbo has an seperate ignition amp near the battery, its a coil driver basically. The lh2.4 is the fuel computer and the ezk is the ignition computer. The ignition computer varies with EGR which was removed around 96.

I'd be thinking about wiring up some extra led or buzzers to sound when power to the pump is stopped. You need to find out why the engine is stoppping, perhaps the fuel pump is intermittent, or there is a lose connection to the coil, anything really to narrow down the search.

It is difficult and if you are just guessing you are probably better paying for a proper diag (rather than a repair).

[Dirty Rooster]

Originally Posted by TonyS9

You need to find out why the engine is stoppping, perhaps the fuel pump is intermittent, or there is a lose connection to the coil, anything really to narrow down the search.

But if its a (only) fuel issue the revs will still show correctly as the car slows without power.
The indicated revs drop to zero when the engine is turning in gear as the car is moving... if I've read the O.P. right.

[clocks2003]

Sorry - it is a 219 not a 218 Bob. As you say, the ...148 does come from a '97 car. Where would I find the ignition amplifier?
Bypassed - I soldered a length of wire to each core of the cable going to the connector socket from the loom and then soldered the other end of each wire to the relevant core of the cable coming from the sensor.
I disconnected the battery for 1/2-hr today so we will see, but I don't expect it to make any difference as I did that a week or so back and the problem persisted. This probably means it is not the ecu.
It does sound like the sensor, but I am certain that the one from my old car (the one I am breaking) was working properly. It would be too much of a co-incidence for it to suddenly start to go at exactly the same time I put it into this car...

[bob12]

Originally Posted by clocks2003

Sorry - it is a 219 not a 218 Bob. As you say, the ...148 does come from a '97 car. Where would I find the ignition amplifier?
...

Thought as much . The Bosch EZ116K (pretty much standard for the last of the versions of LH2.4.x) ..... 219 is for a B230FT manual 1994/96.

That's an interesting question about the location of the ignition amplifier (a small little thin metal looking thing about, by memory, 3x2 inches in size with a loom connector), is usually to be found tucked away on the front'ish of the n/side inner wing level with the headlights (say about a foot or so in) and behind the air filter box, or whatever might be obscuring it, very much depending on model.

I agree that the ecu's vary rarely fail .. except early LH2.4.2's on the first of the 740's of the 1990 era. It's always a good start to disconnect the battery and see what happens. How about getting the codes read?

Have just read the rest of what u said .. my bet is it's something u have done whilst tinkering!!