Engine: 70 T5: Cutting out when hot

For some reason my 1998 v70 T5 cuts out when it is hot. The fault only seems to occur after the car has travelled at least 50 miles and then gets held up in slow moving/stationary traffic.

When it happens the revs dip to below the idle point and the engine gets lumpy - if left it soon dies. It is possible however to pump the throttle, little by little raising the revs above 4000 where the engine then stops missing. (Bit like getting a 2 stroke strimmer going) This doesn't make for easy driving in busy slow moving traffic!!

The last time this happened I managed to keep the engine running (at 4000 revs!) all the way out of town and once on open roads the problem wasn't apparent. When I got home I finally let the revs drop and it idled without a problem.

However, my wife has been relayed twice this week , once when having driven 300 miles the other 200 miles - and its clearly my fault!!!

The Mechanic from the breakdown service who attended the first incident said that it was the ignition module. This was replaced but........its still my fault..

I tried to recreate the fault for a mechanic by running the car at high revs but without success.

I've searched the site and the following seem to be the likely culprits:-

Fuel pump relay

Cam sensor

ETC

I'm going to change the Fuel pump relay as its the easiest and cheapest option - however I cannot understand why any of the three options should be so temperature dependent.

My wife is now refusing to use the car.

Any advise would be much appreciated. (On the car only please!)

[Jod T5]

Originally Posted by sc52

I'm going to change the Fuel pump relay as its the easiest and cheapest option - however I cannot understand why any of the three options should be so temperature dependent.

the fuel pump relay may when warm is more susepatable to the dry joints issue which cause its failure.....
have you checked out this thread... http://www.volvoforums.org.uk/showthread.php?t=20619
have you had any fault codes read...
the coolant temperature sensor is another favorite, as such it cannot detect that the engine is at its usual running temperature and applies more gas thinking it is fueling a cold car...
i would go for the codes asap,...
i bet she starts fine when cold, first thing....(the car that is, the wife seems to start anytime...)
and welcome to the forum...
cheers
jod

Originally Posted by jod t5

have you had any fault codes read...

When the problem occurred when I was driving, I went to the garage the following day but unfortunately there were no codes.

I'm taking the car in today to have the diagnostics run again to see if anything has been logged from the two recent incidents.

But I'm not expecting much

SC

[Chris_Rogers]

Guess here:

Assuming this is not a fly by wire electronic throttle version, if it is see the ETM threads.

The throttle body is dirty and so is the idle air valve there may also be a blocked crankcase ventilation system.

So my advice would be to clean the TB and IAV and have a look at the breather system, see the threads on this.

Does the temperature guage work properly?

I can't see it being the fuel pump relay if it will run at 4000 rpm!

[David Samuels]

I know this post is ancient. Any solution ever found? I've been chasing almost identical situation for nearly two years. Thanks!

Originally Posted by sc52

When the problem occurred when I was driving, I went to the garage the following day but unfortunately there were no codes.

I'm taking the car in today to have the diagnostics run again to see if anything has been logged from the two recent incidents.

But I'm not expecting much

SC

[Alpine]

coolant temperature sensor?

[Derry]

I am about to replace my (23 year old!) Coolant Temperature Sensor for a similar issue. I see there are many different brands and prices starting from £12.00.

Would this do?
https://www.ebay.co.uk/itm/Coolant-T...MAAOSwmfFfiAMv

[NewbieV70T5]

This sounds exactly like a crankshaft position sensor failure. I've had exactly the same across many Alfas and BMW's.

Even if its not reading a code, it could be losing the TDC reference when hot (typical) and cause an engine cut. You'll probably find when it's cooled down its working again.

I typically change them as a matter of course on older cars.

[NewbieV70T5]

And I did mean crankshaft sensor and not camshaft. The engine will typically run without a cam sensor (typically, the ECU will batch fire the injectors without a cam reference so you may hear the ticking of all injectors), but it won't without a crank sensor.

Get the crank sensor changed ASAP but ONLY use a Bosch original (all other none OEM ones are utter garbage).

[Derry]

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