Electrical problem 940

[Ammorack]

Originally Posted by Laird Scooby

Good. Did you happen to notice if the rev counter was steady or bouncing around when it was running rough?

It was bouncing as usual. It’s only on cold start the tachometer goes to 1500rpm and then goes down to 650-750rpm and after 2sec it bounces and rough idle

[Laird Scooby]

Originally Posted by Ammorack

It was bouncing as usual. It’s only on cold start the tachometer goes to 1500rpm and then goes down to 650-750rpm and after 2sec it bounces and rough idle

What happens if you bring the revs up to 1500rpm using the throttle? Does the tacho remain steady?

[Ammorack]

Originally Posted by Laird Scooby

What happens if you bring the revs up to 1500rpm using the throttle? Does the tacho remain steady?

To 1500rpm the tachometer remains steady. It happens randomly if tachometer is steady or not on 1500rpm. Yesterday tachometer was fine. Could drive fine. Still hesitation if I floor the gas pedal.

So that test with 1500rpm with manually opening throttle. Yes. It remains steady.

[Laird Scooby]

Originally Posted by Ammorack

Still hesitation if I floor the gas pedal.

What do you mean "still" - you've never mentioned hesitation before?

Is it manual or auto? Seem to recall you said it was manual? If so, there should be an inspection plate on the fron end of the bellhousing below the rear end of the engine. If so, get the car on ramps, remove this plate and clean round the edge of the flywheel where the holes/gaps are for the CPS pick up to work on. It's a long shot but i'm wondering if a combination of oil, dirt etc is causing a small problem to how the CPS reads the flywheel timing holes. They are cloer to the gearbox than the ring gear on the flywheel so cleaning it isn't goign to be easy, might be easier to remove the starter motor for access.

Alternatively, remember those three small lengths of wire i mentioned for the TPS? Refit those but leave the red/white one out. Try that to see if the idle improves and if it now performs (mostly) as it should.

[Ammorack]

Originally Posted by Laird Scooby

What do you mean "still" - you've never mentioned hesitation before?

Is it manual or auto? Seem to recall you said it was manual? If so, there should be an inspection plate on the fron end of the bellhousing below the rear end of the engine. If so, get the car on ramps, remove this plate and clean round the edge of the flywheel where the holes/gaps are for the CPS pick up to work on. It's a long shot but i'm wondering if a combination of oil, dirt etc is causing a small problem to how the CPS reads the flywheel timing holes. They are cloer to the gearbox than the ring gear on the flywheel so cleaning it isn't goign to be easy, might be easier to remove the starter motor for access.

Alternatively, remember those three small lengths of wire i mentioned for the TPS? Refit those but leave the red/white one out. Try that to see if the idle improves and if it now performs (mostly) as it should.

Hesitation is there with rough idle.
It’s m47 gearbox

So for the CPS. Removing that bell housing. If it breaks. I’m cucked?
I’ll try and see how it goes. Can try to use compressed air sown the hole to CPS and see

[Laird Scooby]

Originally Posted by Ammorack

Hesitation is there with rough idle.
It’s m47 gearbox

So for the CPS. Removing that bell housing. If it breaks. I’m cucked?
I’ll try and see how it goes. Can try to use compressed air sown the hole to CPS and see

NO! Don't remove the bellhousing! Don't even touch the CPS either!

Forget that idea.

Instead, find the cable the CPS plugs into on the cars loom and check that carefully for any breaks/damage, you should know where to find this seeing as you renewed the CPS recently.

[TonyS9]

The dirt would have to be magnetic to mess with the CPS. If you can find the connector just check it for contunity, but there are 3 wires 1 is the shield ground, the other 2 are the coil which you want to check for resistance while you move the lead around.

[Ammorack]

Originally Posted by TonyS9

The dirt would have to be magnetic to mess with the CPS. If you can find the connector just check it for contunity, but there are 3 wires 1 is the shield ground, the other 2 are the coil which you want to check for resistance while you move the lead around.

Its 160ohm on CPS somewhere within range?

[Laird Scooby]

Originally Posted by TonyS9

The dirt would have to be magnetic to mess with the CPS.

Just like clutch dust in fact! Also by it's inherently near-identical nature, brake dust which can create umpteen kinds of havoc with an ABS system is if loads up on a reluctor ring or sensor tip. The CPS should be new in this case so you really needed to explain that better Tony. Ammo has measured the resistance of the sensor, not the loom which is what will need doing to make sure there are no breaks in it.

Anyway, thanks for volunteering to take over!

Ammo - i'll leave you in Tonys capable hands................ good luck!

[Ammorack]

Originally Posted by TonyS9

The dirt would have to be magnetic to mess with the CPS. If you can find the connector just check it for contunity, but there are 3 wires 1 is the shield ground, the other 2 are the coil which you want to check for resistance while you move the lead around.

I didn’t quite understand what you meant there with moving around the lead while measuring those 2 wires that goes to the coil. Moving around the loom and check resistance on coil leads. Or Measuring ohm on coil while I wiggle that loom that connects to CPS? Sorry. I misunderstood this

3,78kohm on coil leads
3,74kohm on CPS loom

3,97kohm from negative coil lead to Black and red wire on CPS loom.

5,9ohm from positive coil leads to black and red wire on CPS loom