Die!

[mjb]

OK this is a weird one so I'm admitting defeat and opening the floor to suggestions.


When the car's hot, the coolant temperature gauge start to dance. The BSI is reporting (via PP2000) it's getting strange values from the engine ECU. The AC shuts off as a precaution when this happens. Pretty sure the CTS has gone south, BUTBUTBUT it started happening the same time as:

The engine will sometimes cut out. Previously thought it was when the engine was hot, but it did it barely lukewarm the other day. Throttle position is irrelevant. It hasn't happened while idling stationary. When it happens the rev counter still shows RPM, ruling out the CPS I previously thought it was (being close to the CTS and all...). I can usually get it going again within a couple of attempts at bump-starting it, the more viciously I dump clutch, the better, and when I come to a stop it seems the only way to get it going again is to crank it in gear, rocking the engine

The symptoms started a couple of months ago, and there was no work done on the car for some time before it started

Stinks of a knackered wire, loose connection, etc, but I'm at my wits end as to which one. PP2000 has decided it doesn't want to clear the codes off the engine ECU which include open circuit on all 6 injectors for some reason(!!!) as well as the mess you'd usually associate with me changing battery earlier in the year, so I can't see what this problem is actually causing on the ECU (if any)

Ideas?

[benczuk]

Don't know if it helps or not but the missus had a 206 which would intermittently refuse to start when hot. If you left if for (2+) hours woudl fire first time, tried replacing coil pack and all sorts with no joy. Finally borrowed and plugged in a diagnostic tool and it showed the temperature sensor reading fluctuating wildly between very very cold (minus hundreds!) and very very hot. Replaced this and problem solved.

[Doggy]

Sounds like you've got to eliminate the CTS - either change it or substitute a variable resitor & tweak it till PP2000 reports 80/90 deg.

[mjb]

I don't see how the CTS would cause the engine to stop, but I guess you're right - I'll get one ordered in the morning

[mjb]

Think I've found it... It's the green CTS, not the brown one I paid £20 for a few hours ago (and subsequently realised I don't have a deep 19mm socket to change it...)

Unplugging the green CTS causes the engine to cut out, and then fail to restart with an electronic ignition fault (which I forgot to mention has happened on one of the starting failures)

Unplugging the brown CTS just causes the cooling fans to spin at full speed

Unplugging green and brown together causes electronic ignition fault, full speed fans, and still a temperature on the dashboard. I guess that is done at least partly by the jobbie hidden behind the brown CTS, likely inaccessible without removing the thermostat housing

Anyhoo... The green CTS had a lot of corrosion on the connector so I've given it a bit of a clean and hope the car doesn't die horribly before I can replace it...

[Doggy]

That's the way to do it Matt - as post title - eliminate something.

(even if it's only the neighbour's cat)

[mjb]

Bah! It just failed it's MOT on account of being a 406 (handbrake)

[highlander]

Damn handbrake is a liability. Mine has had new shoes fitted this year, and the damn lever still needs to be all the way up (to the point where I think it'll snap if I pull it much harder) in order for the car to hold still on anything resembling an actual hill.

The Coupe is in the garage today getting some suspension stuff sorted out, and I've asked them to see if they can sort the handbrake as well. Not sodding likely.

[teamster1975]

Damn handbrake is a liability.

How they got the design off the drawing board is anyones guess!
The only time mine was any good was after replacing all the handbrake cables and readjusting the shoes (fairly new shoes/discs). Lasted a couple of months before needing readjustment. Total pants.

[DiscoPol]

Look on the bright side guys at least you have the option of just pulling the handle up a bit further, im dreading the C5's handbrake when it deteriorates as all i have is a silly little button and a read out on the display telling me its on or off, i dont even use the button as its all automatic and releases when you set off and applies when you stop the engine or on a hill to help with hill starts, all sounds lovely and it is at the moment but time will tell.

[jasper5]

I've had trouble with the green sensor before, I think the problem could well be the green sensor.

Regarding this handbrake thing, teamster, it's perfectly normal after new shoes and stuff have been replaced to need adjustment after a few weeks.....no matter what car it is or the design of the system.

In fact, whenever I replace shoes, handbrake shoes, or rear pads that work the handbrake I always tell the customer to ring me after a month or whenever the handbrake starts to come higher or less effecient so that I can readjust everything....I usually don't charge for readjustment as it's part of the job.

One idea that I use for certain cars to reduce the amount of adjusting that they need on the handbrake is to adjust the adjusting wheel then fit a "C" clip in the threads of the adjuster to stop the nut on the screw thread from backing off.

[mjb]

OK I've done a lot of work and got nowhere...

Replaced the crankshaft sensor, thermostat and all three CTS' yesterday. HOWTO coming soon Turns out my old thermostat was knackered and stuck open (well, not stuck, just virtually no resistance to opening). At least that's something positive - I'll get heating in winter *before* I pull in to the car park at work...

Just taken it for a drive from cold with the PP2000 and interestingly, the temperature gauge reads about 10 degrees over until the coolant hits about 70, at which point it goes haywire.

The engine ECU is reading the temperature correctly on its two values for it
The BSI is reporting strange values, or '--'
The instrument cluster's saying "I'm being sent crap here"

So it's obvious that the problem is south of the engine ecu, thankfully. The question is where... I guess the first step is to find out HOW the BSI gets the coolant temperature. Is it from the blue temperature sensor directly? Is it sent as an analogue/pwm voltage from the engine ecu? I don't know

Anyone got any resources (pin-outs for the MP7.0 and BSI, wiring diagrams, etc) which'll help? I'm kinda stuck here

[poddack]

is there any chance the connectors in the footwell can cause this?

[steve_earwig]

I have Sedre, what can I do? I seem to recall yours is an early D9 so the diagrams aren't so useful, off to find out what an MP7.0 is...

[steve_earwig]

Oh lordy, it looks like you'll need to know what's going on inside the ECU & BSI to know how they relate.

8008 : air conditioning engine coolant temperature thermistor > both wires straight to air con ecu.
1220 : engine coolant temperature sensor > 1 wire straight to engine ecu, other wire also but common with:
1240 : induction air temperature sensor
1312 : induction air pressure sensor
1360 : unit + gateway (whuh? Diagram shows 3 wires across a potentiometer and a picture of what looks like a choke - idle air bypass?)