Engine: 70 T5: Cutting out when hot

[Luxobarge]

Originally Posted by Derry

Just had a look not the cheapest sensor Would crankshaft position sensor failure register any codes. Never had any codes so far.

Sometimes it will register a code, but often not - the reason is that if the CPS signal suddenly disappears, then the ECU simply thinks that the engine has stopped, i.e. been switched off, which it thinks is perfectly legitimate and so does not generate an error code. Live data would tell you if this has happened at the point of failure, but you need a good scanner for this.

[Derry]

Haven't tried it yet, but how about this resistance test, https://www.youtube.com/watch?v=RvuzZJqQDf4 is it a reliable method of testing the CPS. This guy is saying if resistance readout is between 2000 - 2500 ohms then it should be good, and then to do a ground test on the connection.

[aaronturbo]

not sure its the same issue however seems very similar,

on my c70 i had this exact issue, after the car had got hot after a run around 50miles start to run rough once sat in traffic, an miss, then be a nightmare to restart. the first time it happened i let the car cool off and it worked, the second time same thing,

when it happened again i disconnected battery cables for a few seconds low and behold it restarted. so if it dose it again try this.

so again it happened i got an etm light, only briefly then car again run like sh*t battery cable off for a few secs restarted fine.

Over that weekend took etm off, this is a bit of a pain. clean up with carb and contact cleaner. if you have a yellow sticker on the etm you have a newer model the white stickers are older and prone to fault but can be upgraded with the new sensor.

I also went over all earths and battery connections and cleaned them all, with contact cleaner and a brush.

This has not happened again since, has been around 5 months now.

The car did not throw a code apart from the etm light once however this did not return again or store a code, on a decent handheld or vida.

hope this helps.
Aaron.

[Derry]

Originally Posted by aaronturbo

Over that weekend took etm off, this is a bit of a pain. clean up with carb and contact cleaner. if you have a yellow sticker on the etm you have a newer model the white stickers are older and prone to fault but can be upgraded with the new sensor.

Thanks Aaron, correct me if I am wrong but I don't think my 1996 850 non-turbo has a ETM.

[aaronturbo]

hi,

no problem,

no etm as you have a cable throttle, but you do have a tps (throttle position sensor) and this would have very similar symptoms,
As well as your idle control valve, again similar symptoms, the throttle body is actually nice and easy to get to on the 850.

I think its worth a shot as you can do it at home for a can of cleaner and a few hours.

Aaron.

[Derry]

I tried the car today and issue still persists. What I also have now, possibly related is when stationery, moving auto selector from N to R, i hear a loud thud coming from where gearbox is, shaking the car. Reverses ok. then (while stationary) from R to N then D i get very slight thud not very noticeable. Off brake peddle, car stars moving forward (in slight gradient) a few meters...and engine stalls, all dash lights come on, with lamda flashing for a while then going out, other lights stay on, since ignition in on position II.

Again no codes, starts fine and drives ok, R 'thud' also gone!

One thing I have noticed is when its about to stall, I see the arrow coming on/off in the dash as if 3 or L is selected / or limp mode I guess.

I will replace the Crankshaft Sensor tomorrow and test.

£4.93 from ecp! nearly 95% discount

[Shinsplintz 101]

Have you cleaned or replaced the ICV? ( assuming its pee ME7 car)

This is often the cause of rough running at idle, and very easy to fix. Clean the throttle body whilst you're at it.

I've always found the sensors on these cars to be fairly bullet proof - but go OEM if you do have to change any as aftermarket ones can make matters worse, not better.

Good luck.

[Derry]

Originally Posted by Shinsplintz 101

Have you cleaned or replaced the ICV? ( assuming its pee ME7 car)

This is often the cause of rough running at idle, and very easy to fix. Clean the throttle body whilst you're at it.

I've always found the sensors on these cars to be fairly bullet proof - but go OEM if you do have to change any as aftermarket ones can make matters worse, not better.

Good luck.

I have cleaned the ICV and also the throttle body, they were spot less from the amount of time I have cleaned them in the past. I'll try the sensor tomorrow when I get it just to see if there is any difference, mean time for the auto box i'll follow the fluid checks mentioned in Haynes. I did renew the ATF and also the PNP switch (just to get the reverse light working) couple of years ago and was ok after that.

[Derry]

The auto test was ok, just need to top up the ATF as it is a little above the COLD MIN mark (cold as I hadn’t driven the car, just idling), the colour looks ok to me and no burning smell.

I then did the exact test journey, same time/weather/temp and not a hint of any issues/codes!

[Luxobarge]

Best way to check the auto fluid is to take it for a decent drive to get the fluid hot, then check it against the "hot" mark with the engine ticking over - a more accurate level will be indicated. I've always seen the "cold" mark as a way to get enough fluid in the box so you can drive it safely, then do the hot test for a final reading.

Glad you seem to be making progress!