Volvo 940 stalling problems

[Stevecym]

Hello. I came on here some months back. I have a 95 940 base model that stalls like 20 minutes after start up. I have changed too many things that i care to discuss. I want to ask readers several questions:

The car stalls like clock work.

1. How long does "safe mode" last?

2. Is there any way to get the car to remain in "safe" mode?

3. When the car stalls, it lugs as if the alternator is overloaded. So at one point i hooked another car up to the battery via cables. When it went to stall, it lugged and took off again. Could this be happening as it is leaving safe mode and could something be starting that is overloading or shorting the system intermittantly?

I really just need to get this car running for now. It is not a daily driver. I have no time to spend trying to analyze this. I put the engine in a couple years back and it ran great then this happen. I have changed rear fuel pump, filter, alternator, cleaned tb, disconnect and ran without iac.

My main question is : what happens at 20 minutes and what can i do to by pass that or keep car in safe mode.

Thank you.

[Laird Scooby]

Try a new Coolant Temperature Sensor, it between #2 and #3 inlet tract on the head. Don't use anything like PTFE tape on the threads to ensure it seals, it's not necessary and will cause running problems.

You also don't mention whether you've changed the fuel filter or if you've tried running it without the fuel cap fitted to see if it goes longer than 20 minutes.

[TonyS9]

Please state the type of engine, do you mean a 2 or 2.3L Injection non-Turbo or is it a classic with an actual turbo.

I have no idea what you mean by "safe mode" or "lugging". Is lugging just nearly stalling? Do you have a Lambda light lighting up, are the rpms unusually high.

Its not possible to do diagnosis from the symptoms only.

If you want to find out what is wrong with it you need to do diagnosis, rather than randomly changing parts. This is why you are frustrated. If you don't know and don't want to learn then take it to someone who can.

If you want to learn then tell us what has been "checked" so far. not just the list of parts.

Things to check

Fuel pressure, try clamping the return line and also check for fuel smell at the input to the regulator.
Look for Air leaks
Check the voltage of AMM at idle
Check the adjustment of the throttle closed position and switch.
Have you cleaned the throttle body? A dirty throttle body can cause stalling.
Measure the voltage at the battery during idle.
When you hooked up another car did you run the engine in both cars?
Why do you think the alternator is overloaded. Normally the alternator will expire when it is overloaded, the engine should have plenty of power to run it. It is easily checked with a volt meter, these cost about £5.

Generally if the ECU isn't happy there is no way to force normal running, that is its job.

[Laird Scooby]

Originally Posted by TonyS9

I have no idea what you mean by "safe mode" or "lugging". Is lugging just nearly stalling? Do you have a Lambda light lighting up, are the rpms unusually high.

Its not possible to do diagnosis from the symptoms only.

As far as i've always known it Tony, "lugging" is an American term to describe labouring when an engine is working unnecessarily hard because the driver can't be bothered to drop down a gear.

As for safe-mode, i suspect he's referring to Limp Mode which suggests LH2.4 and should have bourght the Engine Management Light (aka Lambda light) on in the instrument cluster.

I have to confess to throwing out a suggestion based on roughly what i could interpret (rightly or wrongly) of what he said to try a new CTS as that is a common cause of similar problems - if i've understood what he's said correctly of course!

As you rightly point out, diagnosis, diagnosis, diagnosis!

[irishcarfan]

Some other things to check:

Blocked exhaust could be an issue.

Fuel filter or fuel line clogged.

Crank position sensors can give problems when hot.

Check your earth/ground connections.

Rust, debris in the fuel tank. When you changed the fuel pump, was there any rust on the pump?

re your question of what happens at 20 minutes, the engine/cooling system has reached a particular operating system. Or the perhaps the fuel / exhaust system has reached its capacity to operate if not flowing freely.

[Forrest]

I have only ever had two problems that caused the car to stall when moving/hot. One was a very specific vacuum leak which caused a stall when coming off the throttle suddenly. The car would restart straight away. The other, which has already been suggested, was a faulty crank position sensor. The car sometimes needed to cool down a bit before restarting.

The key symptom of the latter was the revs seeming to stick and then drop to zero just before all the dash lights came on. If you’re seeing anything like this then it’s definitely worth trying a new sensor. Replacing one is a ten minute job but has to be done pretty much by feel as access is tricky. Be careful not to break the bracket or drop the screw into the bell housing. That would turn the ten minute job into a major project.

I have had many other weird running problems but they have all manifested themselves when (preventing) starting from cold.

[Stevecym]

Originally Posted by TonyS9

Please state the type of engine, do you mean a 2 or 2.3L Injection non-Turbo or is it a classic with an actual turbo.

I have no idea what you mean by "safe mode" or "lugging". Is lugging just nearly stalling? Do you have a Lambda light lighting up, are the rpms unusually high.

Its not possible to do diagnosis from the symptoms only.

If you want to find out what is wrong with it you need to do diagnosis, rather than randomly changing parts. This is why you are frustrated. If you don't know and don't want to learn then take it to someone who can.

If you want to learn then tell us what has been "checked" so far. not just the list of parts.

Things to check

Fuel pressure, try clamping the return line and also check for fuel smell at the input to the regulator.
Look for Air leaks
Check the voltage of AMM at idle
Check the adjustment of the throttle closed position and switch.
Have you cleaned the throttle body? A dirty throttle body can cause stalling.
Measure the voltage at the battery during idle.
When you hooked up another car did you run the engine in both cars?
Why do you think the alternator is overloaded. Normally the alternator will expire when it is overloaded, the engine should have plenty of power to run it. It is easily checked with a volt meter, these cost about £5.

Generally if the ECU isn't happy there is no way to force normal running, that is its job.

Yes, that is what i mean by lugging. The engine is under so much load it is about to stall. Sometimes it will stall. People learning how to drive stick lug them all the time.

I reread these. I have tried some of this but i did wonder if cat is clogged. It makes sense.

Thank all of you on board. I am going to start with exhaust.

[GingerMagic]

I'm thinking Crank sensor too - or the wiring that feeds it, as it seems to be a problem when the engine is hot.
Metal expands - sensor is moved marginally out of it's reading range.

Does the car start again straight after it stalls or do you need to wait for a while for things to cool down?

Sadly I don't own the diagnostic equipment for the Volvo, yet, so I can't help you in that respect.