Rough starting when hot.

[artiedtke]

As the title suggests, recently with the hot (ish) weather I am experiencing a very rough start issue, but only when the engine is hot.

Timing is absolutely spot on.

It's been doing it ever since I had my belts changed 24 months ago, albeit not as bad. I did the IP timing myself and it's been checked recently and is bang on spec.

When you turn the key is sounds like the starter cuts out for a split second every now and then causing a very erratic start.

When it starts it runs fine, and also if you let the engine cool for 20 mins or so it also starts smoothly (well as smooth as can be for a diesel).

Any ideas ?

[outnumbered]

Check the plug to the fuel pump
its the one thats a bugger to get to .
take it off and give it a clean.
mike

[klunk]

Approx 4 connectors, 4 torx screws, lift out the top relay mount, Disconnect top I/C pipe and lift out the cooling fan assy and it isnt quite a bugger to get too!

[skyship007]

Originally Posted by artiedtke

As the title suggests, recently with the hot (ish) weather I am experiencing a very rough start issue, but only when the engine is hot.

Timing is absolutely spot on.

It's been doing it ever since I had my belts changed 24 months ago, albeit not as bad. I did the IP timing myself and it's been checked recently and is bang on spec.

When you turn the key is sounds like the starter cuts out for a split second every now and then causing a very erratic start.

When it starts it runs fine, and also if you let the engine cool for 20 mins or so it also starts smoothly (well as smooth as can be for a diesel).

Any ideas ?

First of all, what exactly was changed on the cam belt ??

Have you checked for stored codes ??

It would also be good to know which items involved with the ECU, wiring or sensors are disturbed during the cam belt and aux belt change.

If it's not cam belt related, I would take a look at the connections from keys to relay, solenoid and starter. Then look at the starter motor mounting bolts etc.
If the water pump was not changed, it can cause trouble when hot by dragging on the cam belt. The same can happen with systems on the aux belt making it tough to turn over when hot, although that belt tends to slip more.
Lots of other possibilities, but without some codes it's guess work.

Wild guess but I would put a dodgy relay or solenoid top of the list, but the fact it started after the belts were changed does confuse things.

[artiedtke]

Originally Posted by skyship007

First of all, what exactly was changed on the cam belt ??

Have you checked for stored codes ??

It would also be good to know which items involved with the ECU, wiring or sensors are disturbed during the cam belt and aux belt change.

If it's not cam belt related, I would take a look at the connections from keys to relay, solenoid and starter. Then look at the starter motor mounting bolts etc.
If the water pump was not changed, it can cause trouble when hot by dragging on the cam belt. The same can happen with systems on the aux belt making it tough to turn over when hot, although that belt tends to slip more.
Lots of other possibilities, but without some codes it's guess work.

Wild guess but I would put a dodgy relay or solenoid top of the list, but the fact it started after the belts were changed does confuse things.

First of all, what exactly was changed on the cam belt ?? Everything. Tensioners, both belts.

Have you checked for stored codes ?? Yes. No codes stored.

It would also be good to know which items involved with the ECU, wiring or sensors are disturbed during the cam belt and aux belt change. None as far as im aware ?

If it's not cam belt related, I would take a look at the connections from keys to relay, solenoid and starter. Then look at the starter motor mounting bolts etc.
If the water pump was not changed, it can cause trouble when hot by dragging on the cam belt. The same can happen with systems on the aux belt making it tough to turn over when hot, although that belt tends to slip more.
Lots of other possibilities, but without some codes it's guess work.

Waterpump was changed with cambelt.

Wild guess but I would put a dodgy relay or solenoid top of the list, but the fact it started after the belts were changed does confuse things.

If it was a dodgy connection then I would have seriously expected it to play up whilst the engine was running, not just upon starting.

Everything else about the car seems fine, power, economy etc.

It is exactly the same symptom as you would get if the IP timing was out, the difference here is according to VOL-FCR the timing is bang on, unless im getting a false reading ?

I reckon (altough VOL-FCR says im ok) that im too advanced. When the car is cold and in the colder weather it is now much much more eager to start than it used to be. Timing too advanced on a hot engine would give "hard starting" issues also.

What sensor does VOL-FCR take it's timing reading from and is there a possibility that the reading it's giving me is erroneous ?

[skyship007]

OK, I thought you could hear the starter motor cutting out, was the timing disturbed changing the cam belt ??

If the wrong locking tool was used, then even one tooth out will cause starting trouble, although it seems odd if it then runs correctly. If the timing is off it should sound wrong (Rattles) it either cold or hot idle.

Does this engine smoke after a cold start or at hot idle and is the idle RPM spot on?

Not sure how good this FCR is, because this site gives a warning about checking with current Volvo software about timing, although I presume that is just for the limiting figures:

http://www.ilexa.co.uk/diagnostic-to...ick-guide.html

If that test was done correctly and no fault codes show, then the only other reason the actual timing might be off, is some muppet has done a dodgy map change, so the FCR/ECU are looking at a cooked number in a critical file address, about the same result as fitting the wrong cam position sensor.

Some less common fuel pump supply issues do cause hot start failures, BUT the idle RPM would probably be in error, or there would be some smoke visible if you walk around the back. The ones I'm thinking of only occur if there was a previous incident with petrol use (Or long term use of cheap and nasty fuel additives). That will trash seals in the HP pump and injectors that then cause internal leaks when hot.

[klunk]

I would do the pump timing with a DTI, Just done mine and it hardly cranks when starting stone cold or stinking hot!

[martin_r_smith]

First of all what klunk said. Secondly ignore skyship. Thirdly, the starting maps in the ecu are selected according to temperature. There are 8 different maps and the ecu pics one on the information it has from the sensors, namely the coolant temperature sensor. I had all the symptoms you had and just changing the sensor sorted it, obviously I'm not going too guarantee it will fix it but it's where I would start. I've tweaked the starting maps on mine as I run a good bit of advance and as you stated this does not help hot starts.

Oh and just for skyship, remaps and decats rule can't beat a bit of Nox in the morning!

[skyship007]

Originally Posted by martin_r_smith

First of all what klunk said. Secondly ignore skyship. Thirdly, the starting maps in the ecu are selected according to temperature. There are 8 different maps and the ecu pics one on the information it has from the sensors, namely the coolant temperature sensor. I had all the symptoms you had and just changing the sensor sorted it, obviously I'm not going too guarantee it will fix it but it's where I would start. I've tweaked the starting maps on mine as I run a good bit of advance and as you stated this does not help hot starts.

Oh and just for skyship, remaps and decats rule can't beat a bit of Nox in the morning!

Martins ECU map fiddling and exhaust mods in action (Not sure how you finish up with less than 200 hp from all the mods listed):

[martin_r_smith]

The OP's 'MAP' has not been fiddled and neither had mine at the time when hot starting was an issue.

That pic is quite funny thank you for finding it for us. Producing that much black smoke is a personal hate of mine and just shows a complete lack of understanding when properly tuning a diesel. My car doesn't smoke, however it did when it was factory spec... Interesting huh.