B230FD Problems :)

[Laird Scooby]

Originally Posted by Volvo940GL

Sorry if I ask dumb questions only dumb answer and good questions.

What should the readings be? And whether the ground is bad or not? From where does those two cables go from? From the ignition key and the other to the battery? How do I know if it’s a bad earth?

Bllue/red wire should go to coil +ve, red/white should go to coil -ve. Remove the coil mounting bolts, clean where the coil sits on the bodywork with sandpaper, wire brush or similar. Loosen the clamp on the coil body, clean the inside of the clamp and where it attaches to the coil body.

Refit the coil but don't tighten the bracket to body bolts yet, just fit them finger tight. Tighten the bolt on the coil clamp then tighten the two mounting bolts

Ensure the LT wires are on the correct terminals as above and that all connections are clean, bright and tight.

[Volvo940GL]

Originally Posted by Laird Scooby

Bllue/red wire should go to coil +ve, red/white should go to coil -ve. Remove the coil mounting bolts, clean where the coil sits on the bodywork with sandpaper, wire brush or similar. Loosen the clamp on the coil body, clean the inside of the clamp and where it attaches to the coil body.

Refit the coil but don't tighten the bracket to body bolts yet, just fit them finger tight. Tighten the bolt on the coil clamp then tighten the two mounting bolts

Ensure the LT wires are on the correct terminals as above and that all connections are clean, bright and tight.

I tried your solution. Cleaned mounting points, and coil, terminals, checked - and +
Still nothing. I gotta get my multimeter on these sensors

[Volvo940GL]

Originally Posted by Laird Scooby

Coolant sensor - ~2500 Ohms +/- 10% ish at 20C WRT earth - two pins in the body of the sensor, each has a sensor between it and the body of the sensor, under #2-3 inlet tracts on the head

CPS either works or doesn't, if you're getting a steady stream of sparks from the king lead during cranking, the CPS is working.

TPS is a microswitch, it's either 0 Ohms or open circuit when the throttle is in the idle position. Note that incorrect adjustment will alter whether it's open or closed.

Lambda should vary between about 0.1V to about 0.9V when hot and idling WRT 0V

MAF, i need to know the Bosch number (probably starts 0 280....) from your MAF as various different MAFs were fitted, the output pins were different and so were some voltages.

Rough rule of thumb is about 2V+/- 10% WRT 0V on a steady idle rising smoothly as the revs and therefore airflow increases.

It can be different depending exactly on which MAF you have though, as can the output pins!

My MAF starts with 0280212016

[Laird Scooby]

Originally Posted by Volvo940GL

I tried your solution. Cleaned mounting points, and coil, terminals, checked - and +
Still nothing. I gotta get my multimeter on these sensors

You checked the correct wires were going to the + and - terminals?

That's the correct MAF for your car, check the resistance between pins 2 and 3 on it, should be 2.5-4.0 Ohms. I'll double check the pins for checking the running voltage and let you know.

[Laird Scooby]

Does the engine misfire from cold? If so, the Lambda is ruled out, for cold running at least.

[Volvo940GL]

Originally Posted by Laird Scooby

Does the engine misfire from cold? If so, the Lambda is ruled out, for cold running at least.

It doesent misfire anymore, it runs better when it’s a cold start. When engine temperature rises it’s more rough idle and tachometer starts jumping, then all the lights in the dashboard is slightly lit, The Parkingbrake, brakefluid light, battery light is slightly lit, but is not actually an existing fault.

I checked correct cables for coil. I’ll check MAF now

[Laird Scooby]

Originally Posted by Volvo940GL

It doesent misfire anymore, it runs better when it’s a cold start. When engine temperature rises it’s more rough idle and tachometer starts jumping, then all the lights in the dashboard is slightly lit, The Parkingbrake, brakefluid light, battery light is slightly lit, but is not actually an existing fault.

I checked correct cables for coil. I’ll check MAF now

DON'T TOUCH THE MAF!!!!!!!

You have an alternator fault which will cause rough running!

[Volvo940GL]

Originally Posted by Laird Scooby

DON'T TOUCH THE MAF!!!!!!!

You have an alternator fault which will cause rough running!

Alternator fault you say. Hmm

Is the alternator itself faulty. Can it be fixed or do I need a new one?

[Laird Scooby]

Originally Posted by Volvo940GL

Alternator fault you say. Hmm

Is the alternator itself faulty. Can it be fixed or do I need a new one?

It can probably be fixed but you need to check the earth strap from alternator to engine first. That would cause the symptom you're getting, as would a duff rectifier inside the alternator.

That's without any other faults that may come to light when it's stripped down so there may be other faults causing the symptoms, not limited to but including a worn or incorrect drive belt, incorrect tension on the belt and several others.

I'm a few thousand miles away and can not see exactly what it's doing, however the fact the charge warning light and the others that are linked to it when the alternator isn't charging are on, even dimly points to an alternator fault so it's not charging. Could explain the flat battery!

Also if the engine management ECU doesn't see the correct charging voltage, it will throw everything out of kilter and cause among other things, rough running, misfires and umpteen other possible problems!

[Volvo940GL]

Originally Posted by Laird Scooby

It can probably be fixed but you need to check the earth strap from alternator to engine first. That would cause the symptom you're getting, as would a duff rectifier inside the alternator.

That's without any other faults that may come to light when it's stripped down so there may be other faults causing the symptoms, not limited to but including a worn or incorrect drive belt, incorrect tension on the belt and several others.

I'm a few thousand miles away and can not see exactly what it's doing, however the fact the charge warning light and the others that are linked to it when the alternator isn't charging are on, even dimly points to an alternator fault so it's not charging. Could explain the flat battery!

Also if the engine management ECU doesn't see the correct charging voltage, it will throw everything out of kilter and cause among other things, rough running, misfires and umpteen other possible problems!

This is getting more and more interesting
Yeah the lights is slightly dim.
The belt is new and I have always checked it. It’s right and tight. Not too tight. But cannot turn the alternator by hand. So I guess the belt is tight.

On higher rpm those lights in the dashboard fades slowly away. So it must be my alternator you say

I’ll check now
I haven a subwoofer aswell. That has gone into protection mode. Maybe because of loss of voltage. But hey. I’ll give this a try

Thanks