E36 328 intermittant limp home mode

[neil_bolton]

Morning all,

Been having a few issues recently, starting with what I thought was a sensor issue, which flags up as a Coolant level low warning: upon checking the coolant is fine.

However, on the motorway the other day, I felt a thump, a little like the diff engaging, and the car lost power, and eventually I crawled over to the hard shoulder, and it would not rev, yet was idling happily.

Upon restarting her, she ran fine for the rest of the weekend, and I thought that perhaps as it was raining rather hard, that some water had got into something and the ECU spazzed out.

However this weekend, the car stalled on me, a fault of mine for not pulling away correctly, however the car didn't like starting, and when it did, I had no power. I crawled along for a bit but she really wasn't happy.

A restart, and some revving seemed to do the trick, and away we went, making a mental note that perhaps stalling was a bad idea.

However the girlfriend was driving the car over the weekend and she had the same two things happen, to which she repeated what I did to get it going again.

However she did say that additional symptoms of the rev counter dropping, and the mpg indicator varying whilst maintaining a steady throttle on the motorway - which doesn't seem particularly great?

I'm thinking perhaps another sensor is possibly on its way out, or the coolant sensor is now completely fubared, causing the ECU to do all sorts of damage limitation things?

Can anyone advise?

[eliot]

Perhaps we should have a sticky for people who have access to diags. I'm Milton Keynes and could read your codes for you.

[neil_bolton]

eliot said:

Perhaps we should have a sticky for people who have access to diags. I'm Milton Keynes and could read your codes for you.

Thanks for the offer however its a bit of a drive

I've read that I can do a trick when starting up the car with the accelerator to get a read out of the fault codes, so I'm going to do that later and see if it works and work from that.

Failing that I'll pop over to ForzaWest's place in Chepstow for a diag and see.

[TheEnd]

First off, the coolant level sensor is unrelated, it only feeds info the the On Board Comp, and the ECU doesn't take any action.

I have a feeling it'll be something like the crank position sensor, but the diagnostics check out would be the best way to check.

[neil_bolton]

Bumping this again as I've replaced the cam sensor, and no avail!

I posted this on the E36forums...

"I have recently started experiencing on the motorway the car 'thumping' into limp home mode, and on bumpy roads occasionally dropping all revs and then picking up again. A restart always cures this. Keeping the Vanos engaged stops the problem occuring it seems - +4000 rpm usually.

A faulty cam sensor was diagnosed by a friend, and so I replaced this today.

However, upon doing this and test driving the car, I now have a lack of low down torque until the car hits the Vanos range, and then it takes off.

I've since reset the ECU, and it still has not cured the issue, and I was wondering why a new cam sensor would do this - perhaps something else is at fault?

Hopefully someone may have seen this, and could help me! I'm going to head over to ForzaWest on Tuesday to pull the diag codes, but until then - help!

Anyone any ideas?

Edited by neil_bolton on Saturday 23 May 21:01

[phelix]

neil_bolton said:

Keeping the Vanos engaged stops the problem occuring it seems - +4000 rpm usually.

How do you do this - keep the VANOS engaged?

neil_bolton said:

A faulty cam sensor was diagnosed by a friend, and so I replaced this today.

How was the diagnosis arrived at and what's the brand of the new cam sensor bought (dealer sourced or ??)

[neil_bolton]

phelix said:

neil_bolton said:

Keeping the Vanos engaged stops the problem occuring it seems - +4000 rpm usually.

How do you do this - keep the VANOS engaged?

neil_bolton said:

A faulty cam sensor was diagnosed by a friend, and so I replaced this today.

How was the diagnosis arrived at and what's the brand of the new cam sensor bought (dealer sourced or ??)

I've been around to ForzaWest (thanks Stuart ) and we've identified that the old cam sensor was indeed flagging error codes.

However, my nice spangly new cam sensor is also buggered (A GSF pattern part no less). It throws failure errors at startup, and we've run a multimteter over the sensor pins, and between 1 and 2 we've identified a short, which indicates it's hosed.

Annoyingly this mean whipping it out and putting another new one in...and then seeing what happens.

It seems that the sensor causes the car to go into a default backup ECU mode to protect the car as it can't work out what angle the camshaft is at, and so therefore this is the reason for the lack of torque.

Revving to the Vanos range means you then get the rush of power as this runs correctly.

I'll report back later

[Shropshiremike]

Good follow-up Neil - most people never bother to reply with what the cause/resolution was!

[phelix]

neil_bolton said:

However, my nice spangly new cam sensor is also buggered (A GSF pattern part no less). It throws failure errors at startup, and we've run a multimteter over the sensor pins, and between 1 and 2 we've identified a short, which indicates it's hosed.

Have heard of this before using non-BMW cam sensors - people have had problems with pattern parts.

[neil_bolton]

phelix said:

neil_bolton said:

However, my nice spangly new cam sensor is also buggered (A GSF pattern part no less). It throws failure errors at startup, and we've run a multimteter over the sensor pins, and between 1 and 2 we've identified a short, which indicates it's hosed.

Have heard of this before using non-BMW cam sensors - people have had problems with pattern parts.

Just to let everyone know, I brought a Cam Sensor from BMW today, and swapped over the sensors.

I now have a much smoother, much more torquey BMW