Wanted: ECU for 16v

[mat_fenwick]

prm - You seem to know a lot about it

Worth checking the 3 wires are reaching the ECU, pins 23 and 25, from the connections on the plug/socket by the battery tray.
CAS Plug connections. With central casing locating pin uppermost and left and right lugs underneath, pin allocation, left to right - black, yellow/cream and then screen.
Screen joined to Pin 23 @ ECU.

The car will fail to run if the ECU is not seeing a constant AC voltage generated from this unit to operate the fuel pump relay, and believe, also to activate and ECU injector driver.
The static resistance on this unit - black and yellow wires, should be in the region of 525?.
Remove the distributor cap and CAS connection plug/socket, set test meter to AC voltage, connect between black and yellow/cream wires. Crank the engine, output from the CAS should be about 4 volts AC. Remove the plugs and crank again, voltage should between 4-8 volts AC.

Nah, I reckon he's just guessing...

Best of luck Matt!

[prm]

No problem Matt, pleased to help, just fire away.

I’m sure with the heads on the forum we can get the bugger running, so don’t despair. Been there, read the book!!

Going back some time, this identical problem racked my brains, or what’s left of them. Then started to dive into the depths of the 16v Motronic system.

………………………

Mat F.

If it doesn’t run, I will go back to my knitting - Cable stitch!!!

Regards

[akarso]

The static resistance on this unit - black and yellow wires, should be in the region of 525?.

I've measured 365? on mine, does it mean it's broken?

[prm]

At 365? resistance it’s certainly not broken. Where did you check the resistance from? ECU or the engine bay plug/socket??

The main consideration would be the cranking AC output voltage to trigger the ECU.
I’m not sure if this static resistance would vary between different manufactures? Also, if they fluctuate over time?

Any reference numbers or manufactures name on your unit?

Usually they just fail – dead. Or, the SS casing gets damaged and then fail.

You might like to plug the hole adjacent to the CAS socket.
There’re very handy for dropping small nuts and bolts down. I used a trimmed battery + terminal shipping cap.
The opening possibly acts as a vent for the clutch?…. Computer PRM sensor/signal?

The current 16v failed due to cable tie off-cuts dropped through this hole
and me missing a gear on the limiter, last time I looked the rev counter was around 8500-9000.
The flywheel acted as a fan, picked up the tie off-cuts and rammed them into the side of the CAS outer body.

Regards

[akarso]

At 365? resistance it’s certainly not broken. Where did you check the resistance from? ECU or the engine bay plug/socket??

The sensor is lying on my desk right now

Any reference numbers or manufactures name on your unit?

I assume it’s bosch, but I am not sure. It is very similar to this one:
http://moto.allegro.pl/item997588521_cz ... 2_1td.html

numbers: 3195 and 144303 are stamped on the unit

Usually they just fail – dead. Or, the SS casing gets damaged and then fail.

I would be glad if it was just dead, at least I would be finally able to explain what’s wrong with my car. I cannot track down the failure. HT leads checked, fitted new, plugs new, ingnition amp checked (tried with another one, no luck), distributor cap new, fuel pressure correct, connections between injectors and ECU checked, ok, fuel pump new, ignition and fuel pump relays seem to be ok, also.

Right now the car just doesn’t start anymore, i.e. it starts and runs for a second, then gradually loses spark on cylinders and goes dead. If I’m trying hard it is possible to start it after about 10 – 20 trials, and it works on two cylinders.

It seems that the condition was worsening with time, and begun with engine loosing power after right turns.

I suspect either ECU, or some loose cables. The latter issue I am afraid I won’t be able to fix, so the car will have to be scrapped, or sold for parts. Pity, since I’ve already bought another freshly overhauled engine. But I’m really tired with all this

[prm]

From your link it would???? Appear the wrong type?? Unless it cross references with Bosch Part No. 0. 261. 210. 043. 3 wire control.
If you can obtain a CAS to match the Bosch number, certainly worth a try before you consider scrapping the car.

The 16v Motronic systems are old hat, but they can certainly cause some head scratching moments.

If the car recently ran on all 4 cylinders we’re half way there ….. Hopefully, as you mentioned initially misfiring on turns.

Two areas I would definitely check..
AFM and Ignition module cable connections.
Remove the rubber boots from both multi pin plugs and inspect the wire connections.
Several terminal connections can be very brittle, especially on the ignition module where it receives a fair amount of engine heat.
Close up any female plug connections that appear slightly wider, and fit adjacent cable ties on both supply looms to stop them flapping around.

You can’t rule out any possible mechanical problems as I’m totally green in respect of a 16v engine tied into an auto box.
Backing off the throttle on turns appears to have been a problem, you might also need to remove the top cover on the AFM to inspect the tracking, reset the TPS and adjust the throttle body stop screw.

Has the car got Air-con?
The car appears to sound fine on your video. What’s happened?

Regards

[akarso]

From your link it would???? Appear the wrong type?? Unless it cross references with Bosch Part No. 0. 261. 210. 043. 3 wire control.

This is the one I have fitted, only very small differences in shape. 3 wire it is, for sure.

Two areas I would definitely check..
AFM and Ignition module cable connections.
Remove the rubber boots from both multi pin plugs and inspect the wire connections.
Several terminal connections can be very brittle, especially on the ignition module where it receives a fair amount of engine heat.
Close up any female plug connections that appear slightly wider, and fit adjacent cable ties on both supply looms to stop them flapping around.

Been there, done that... multi plug seems to be in perfect condition (I cannot say that about rest of the wiring, but to rule it out for sure, I’d have to swap all of the wiring loom).

This engine works with AFM disconnected, just switches into some kind of “bronco mode”, so I doubt it’s AFM, flap works just fine, and as I said, disconnecting AFM causes change in engine behavior, but this change seems to be apart from my problem.

You can’t rule out any possible mechanical problems as I’m totally green in respect of a 16v engine tied into an auto box.
Backing off the throttle on turns appears to have been a problem, you might also need to remove the top cover on the AFM to inspect the tracking, reset the TPS and adjust the throttle body stop screw.

TPS also seems to work fine, if disconnected causes just high rpm on idle, but that’s not connected to spark missing on two cylinders.

Has the car got Air-con?
The car appears to sound fine on your video. What’s happened?

Donor car had it, but radiator was damaged, so now I’ve got just the wiring and switches. Adds to the mess, I think

Soon afer I took the video problems began, at first they were not so much disturbing, sometimes after the right turn car just seemed to loose power for a few seconds, I thought it might have something to do with fuel pump, so I fitted new one, but it went even worse. And one day I couldn’t get car moving any further than first traffic lights. Next day I took it to the mechanic, and it stood there for 3 weeks, different diagnoses but nothing was fixed, car just seem to live the life of its own – worked (almost) perfectly for a few weeks, then my wife had to leave it downtown, because it went dead at the traffic lights. After few trials I was able to get it back, and then went for a ride to check. Began to loose power and trying not to stall an engine rear ended in some audi 80… Now it sits in my brother-in-law’s garage, front section requires little pulling out, left lamp and indicator light broken, and it refuses to start.

I’m really a bit desperate about this, I’m buying another car soon, but I have to do something with BX anyway…

[prm]

Running through some additional possibilities.

If the air-con solenoid on the throttle quadrant arm is still active? Disconnect it completely, mechanically and electrically and reset the throttle stop screw.
Don’t throw the solenoid and AC switches away. I might need them.
You’ve definitely got a maze of spare wiring.

As mentioned, unsure if? or how? -- the auto box maybe connected to any of the ECU circuits.
Stupid question I know , firing order correct and fuel OK??

Connect a meter across the pump relay main contacts to check for continuity and fuel pump supply terminal to chassis for voltage, note any possible changes during cranking. Repeat the same operation with the main ECU relay.
Can you detect the fuel pump is running by holding the fuel line supply hose?
Any splits on the rubber hose from the fuel rail regulator to inlet manifold?

You can possibly?? rule out an injector problem, unless, 2 are blocked or restricted, as all four injectors fire at the same time. But, it might be worth removing them to check.
Connect a 9 volt torch battery, PP9, to the injector terminals and gently apply compressed air at about 30 psi to the nozzle tip. Clears the filter screens on the fuel supply side. Slowly increase the pressure if any appear to be jammed. Careful not to eject the screen with too higher pressure.

As you appear to have changed or substituted most components on the ignition side. Can you identify the particular plugs/cylinders not working?

Best of luck. Keep trying.

Regards

[akarso]

Remove the distributor cap and CAS connection plug/socket, set test meter to AC voltage, connect between black and yellow/cream wires. Crank the engine, output from the CAS should be about 4 volts AC. Remove the plugs and crank again, voltage should between 4-8 volts AC.

I tried this (but with distributor cap fitted, I was in a hurry a bit) but can't get the reading, maybe some 0.4 volts. I'll try again this week, but is removing of distributor cap required?

Almost every week I discover some strange things in this car, it seems that CAS is from 1.6, but since flywheel is bigger on 1.9, someone assembled a pile of spacers on the CAS unit, glued them with silicone, added tube spacer to the mounting screw and fitted it this way... moreover, screw in the gearbox casing is in bad shape, resulting in wobbly CAS (I fixed this one with a bit of tinware).

I guess I'm having bad luck with the car...

[prm]

At least you’ve determined an AC voltage generated from your “Heinz 57” CAS.
Any other components substituted? It does sound you’ve got a mixture of parts and wiring.
Would have thought you need the correct unit. Normally a very tight fit into the engine block socket, preset for the correct height above the flywheel.

Any voltage increase with the plugs removed? Gives a guide for injector start and idle pulse duration.

Not sure if your 0.4V reading was from a digital meter? Analog meter readings on a single point AC generator will oscillate, but have a quicker response time than digital. Several makes can be slow to register, or, only indicate a stabilised voltage. Oscilloscope gives a far more accurate reading.

Removing the distributor cap is just a safety angle from me, after leaning over one car, with my hair looking like Don King. They certainly give out a fair old whack.
Never been the same since..

An approx outline on the Motronic system that may help, and guide to an area worth checking.
No spark, no fuel …. Main ECU power and ignition `On` supplies. Main ECU relay fault. I’ve never known a faulty unit. Internal diode fitted to this relay.
Then electronics can be broken down into 3 areas.
Components that register a signal. CAS, AFM
Components that measure a reading. ATS, CTS
Components that respond to a signal. Injectors, IMC valve.

Running through some further possibilities if the ECU is ok.
No spark, no fuel …. CAS fault…. ECU is not receiving a signal the engine is rotating.
No spark or misfire..... Coil pack and ignition module. Module and coil can breakdown hot, or misfire at approx 1100 rpm and above.
Poor erratic idle and acceleration..... AFM tracking ATS, CTS and AFM mixture setting.
Then you’ve got the mechanical side TPS, throttle stop screw, distributor - leads, plugs and inlet tract. Fuel pump and pressure regulator. Plus all the electrical circuits and multi-pin plugs and sockets. Sounds a bl**dy maze, take one section at a time.

Just had one thought, its not going to boil down to a faulty or intermittent ignition key switch ON, supply fault? Try a direct connection from the battery to the supply side of the main ECU relay coil, would temporarily bypass the complete ignition key system and also link the supply to the coil pack and pump relay. But meter test the circuit first.
Still, it wouldn’t explain running on two cylinders,

Regards