Can anyone in North East help me diagnose an ETM or boost leak?

[britten_mark]

I've had my 1999 T5 auto a few years now and one problem which has persisted since the day it was bought is cold weather starting, which results in the exhaust stinking of fuel and "shunting" for the first 30 seconds or so if left idling on the drive. Dropping the car into gear puts the engine in load and lessens the symptoms ie. no bunny hopping down the road

Summer's are a delight, but right on cue (October and cool damp nights) it's started doing the same again.

I've never had any warning lights or codes. My father in law's ETM went screwy and the symptoms were way different (racing idle) whereas these symptoms come and go with the ambient conditions. I've never been confident that spending £300 on an ETM would cure things so haven't done it, there always seems to be something else to do.

I tried and failed and making a smoke machine to check for the boost leaks that someone suggested. Can anyone regionally help me out? It's the only issue with the whole car.

[jamesy12345]

I've had my 1999 T5 auto a few years now and one problem which has persisted since the day it was bought is cold weather starting, which results in the exhaust stinking of fuel and "shunting" for the first 30 seconds or so if left idling on the drive. Dropping the car into gear puts the engine in load and lessens the symptoms ie. no bunny hopping down the road

Summer's are a delight, but right on cue (October and cool damp nights) it's started doing the same again.

I've never had any warning lights or codes. My father in law's ETM went screwy and the symptoms were way different (racing idle) whereas these symptoms come and go with the ambient conditions. I've never been confident that spending £300 on an ETM would cure things so haven't done it, there always seems to be something else to do.

I tried and failed and making a smoke machine to check for the boost leaks that someone suggested. Can anyone regionally help me out? It's the only issue with the whole car.

There is an ex-volvo guy in Southwick, garage is named Scotts bank motors he might be able to help diagnose correctly

Or failing that there is a Volvo main dealer near A19/A1231 junction (Mill Volvo)

//edit

could it be something on HT side of ignition? Coil/ leads/plugs? Just from your description it sounds like fuel not being burnt when cold. A boost leak wouldn't be noticeable at idle, an air leak is more likely to cause a high idle than an unsteady one

//edit edit

but anyway here is a diagnostic flow chart for the ETM...

http://xemodex.com/us/pdf/ETM%20Flow%20Chart%2099-00-new-final.pdf

[britten_mark]

Great flowchart, I'll try that in the office car park at lunchtime and tomorrow morning when it always happens.

Sorry should have said "vacuum" rather than boost.

It's all temperature dependant, cool moist mornings are the trigger. And it usually has to be left overnight, although occasionally it will happen later in the day if the car has stood long enough to cool right down

[LeeT5]

So it's a cold start issue!!

Your car, like all modern day cars without a manual choke, relies on the opening and closing of the injectors to control the amount of fuel. More fuel on cold starts would be the same as 'pulling the choke' on an old car to adjust the Fuel/Air ratio and make the mixture rich for cold starts. This controlling of the injectors fuel delivery, is crucial when the engine is cold.
The opening and closing of the injectors, known as 'switching', is controlled by the ECM (Engine Control Module). However, in order for the ECU to correctly 'switch' the injector solenoids at the right time and, more importantly, for the right length of time, or 'dwell', it needs to know the Temperature of the engine.
This information comes from the coolant temperature sensor and is normally stepped in 10 degree increments, ie, 0, 10, 20, 30 degrees and so on.
If your CTS is telling the ECU lies then this will explain why the car is lumpy, over fuelling and running rough when cold and not when warmed up because the ECM can only control the switching based on the info it receives from sensors on the engine.
If the CTS is open circuit for example, then it normally tells the ECU -40*C. Therefore the ECU will assume it's freezing cold and will switch the injectors for a longer time in the 'open' position, therefore allowing more fuel in for cold running.

First thing I would do is replace the CTS on top of the Thermostat housing. They are not expensive and easy to change. if that don't work, then your gonna need diagnostics and live readings to see what's going on.

:)

[britten_mark]

Thanks for the pointer and cheap "try".

On Wednesday's lunch break I followed a couple of lines on that flowchart; no codes, took out the relevant fuse and relay a few times (not blown) and the ETM clicked and whirred. Took the relay out and reinstalled and the ETM did the same (which would indicate to me that it works but the flowchart said replace the relay, still haven't worked that one out? :confused:). Next step was a couple of voltage tests but thought I'd leave that to the weekend when I could get my tester.

Funny thing these past 2 mornings it hasn't chugged despite the weather conditions being perfect for it. Not counting chickens yet, but could something have "reset" itself or had corroded contacts?

[LeeT5]

Thanks for the pointer and cheap "try".

On Wednesday's lunch break I followed a couple of lines on that flowchart; no codes, took out the relevant fuse and relay a few times (not blown) and the ETM clicked and whirred. Took the relay out and reinstalled and the ETM did the same (which would indicate to me that it works but the flowchart said replace the relay, still haven't worked that one out? :confused:). Next step was a couple of voltage tests but thought I'd leave that to the weekend when I could get my tester.

Funny thing these past 2 mornings it hasn't chugged despite the weather conditions being perfect for it. Not counting chickens yet, but could something have "reset" itself or had corroded contacts?

If you pulled the fuse to the ETM, then you'll have reset it - making it 're learn' your cars values etc. The same thing would happen if you disconnected the battery for long enough.

[jamesy12345]

Thanks for the pointer and cheap "try".

On Wednesday's lunch break I followed a couple of lines on that flowchart; no codes, took out the relevant fuse and relay a few times (not blown) and the ETM clicked and whirred. Took the relay out and reinstalled and the ETM did the same (which would indicate to me that it works but the flowchart said replace the relay, still haven't worked that one out? :confused:). Next step was a couple of voltage tests but thought I'd leave that to the weekend when I could get my tester.

Funny thing these past 2 mornings it hasn't chugged despite the weather conditions being perfect for it. Not counting chickens yet, but could something have "reset" itself or had corroded contacts?


That flowchart looks good for confirming whether the ETM needs replacing but for anything else I personally would be suspicious of it. Sounds like you have confirmed the ETM is OK though so that is a plus

Not sure which route you followed on the flowchart but I guess it led you to 'Replace Engine Management Relay'

It seems to say the following test can be used to confirm whether that same relay is OK, if you are not sure

Connect one lead to the fuse#2 and the other lead to the battery negative (-) post. Is the voltage equal to the battery voltage?


If you pulled the fuse to the ETM, then you'll have reset it - making it 're learn' your cars values etc. The same thing would happen if you disconnected the battery for long enough.

For an ECU to 'learn' anything it must have default values (similar to limp mode where some sensor values are ignored)

so it will reset, go to factory presets, then learn the new ranges from the sensors as you say

If the OPs coolant sensor is buggered (or in fact any other sensor) then the problem will reappear after some hours of use.

Some info here on the CTS, including resistance values at different temperatures. It would be worth checking this out with a multimeter or getting codes read prior to changing any sensor

http://www.matthewsvolvosite.com/forums/viewtopic.php?t=52203

[LeeT5]

For an ECU to 'learn' anything it must have default values (similar to limp mode where some sensor values are ignored)

so it will reset, go to factory presets, then learn the new ranges from the sensors as you say

If the OPs coolant sensor is buggered (or in fact any other sensor) then the problem will reappear after some hours of use.



Absolutely!!