98 S70 NA manual stalling when first moved

[flexiheep]

I’m a new member but a long time listener learning about my 98 S70 NA with a manual. It’s a fun car and currently has 294k miles. I’ve searched many many times about stalling problems but I haven’t found my exact situation yet.

About 1.5-2 years ago the car started stalling when you started driving. If you let it sit and idle for 1.5-2 min it drives 100% fine. If you start it and start driving it will die about 15-30 seconds into driving. It always starts immediately after but will die 2 more times and restart and then be just fine. When it dies it acts like you turned off the ignition but the dash and everything else seems normal.

The problem is 100% repeatable, any time you don’t wait it dies while the car is moving.

Things I’ve noted:
No check engine lights or codes.
The gas gauge turns off/falls to zero about 1/2 the time while driving but not in sync with the dying.
I’ve checked for vacuum leaks and replaced most all vacuum lines.
You have to let the engine stop before you restart it, it won’t restart if you leave it in gear and drag the engine.

It feels like the computer is commanding the engine shutdown. I just have no clue why the car has to be moving for the stalling to happen or what logic would cause that.

Thanks for any help or suggestions.

Dale

[abscate]

This is going to be a tough one.

Here are a couple of weak things on a high mileage, high age p80 Volvo

Fuel pump relay, test by swapping or by jumping with a wire. I’ll find a thread to which to link.


Ignition switch, electrical part. This is a $60 part that sits on the left side of the steering column thst wesrs out at 150k or so

Ignition coil and wiring

Distributor cap, rotors plug wires..age and brand?

Wiring fault? Tough to find. How’s your electrical fu?

This symptom points there a bit…

The gas gauge turns off/falls to zero about 1/2 the time while driving but not in sync with the dying.

[flexiheep]

This is going to be a tough one.

Here are a couple of weak things on a high mileage, high age p80 Volvo

I cleaned and redid the PCV system as it was so gunked up it was going through a quart of oil every 300 miles or so. Had to put a heater core in it too. I did a fuel filter, oil change, plugs/wires/cap/rotor when I bought it at 255k miles.

Fuel pump relay, test by swapping or by jumping with a wire. I’ll find a thread to which to link.

I haven’t tried the relay yet. I’ll be honest I’ve kinda been hoping the problem would get worse and then be easier to find. Hasn’t worked out very well yet.

Ignition switch, electrical part. This is a $60 part that sits on the left side of the steering column thst wesrs out at 150k or so

I’ve thought about the ignition switch, I’ve read they do very odd things in other posts. I don’t like firing the parts cannon at projects but I might call the switch preventative maintenance at some point.

Ignition coil and wiring

I would expect this to get worse over the last two years. I’ve had coils die or act erratically but not like this.

Distributor cap, rotors plug wires..age and brand?

4 years and 40k ago. I can’t remember the brand off hand but I try to stay with stock plugs on fuel injected cars as they can be sensitive to plugs and sensors.

Wiring fault? Tough to find. How’s your electrical fu?

It can be what it needs to be. I’ve fixed plenty of electrical problems and even pulled and modified a fuel injection wiring harness from a Dodge Durango to put the engine in my Jeep Grand Wagoneer.

This symptom points there a bit…

It’s an on or off thing. Never reads low or high, just turns off and goes to empty. Then later turns on again.

The gas gauge turns off/falls to zero about 1/2 the time while driving but not in sync with the dying.

Last thing I can remember at the moment is I did pull the MAF connector to try to see if it had an effect. No change in how it dies.


I’ll be honest, I believe the computer is shutting the engine down on purpose, I just don’t know why. Some logic seems to say to kill the engine in the first 1.5-2 min if the car is moving (any speed, even first gear in the driveway) It will idle all day if the car stays stationary.

[Vova585]

I would say ECU is acting up. Possible logic that in those 2 minutes the ecu is able to "warm" up and all is back to normal. Any difference in the winter time? For example if the weather is 20F and car was outside it will take it 4 min to idle to work without issues?

[flexiheep]

I would say ECU is acting up. Possible logic that in those 2 minutes the ecu is able to "warm" up and all is back to normal. Any difference in the winter time? For example if the weather is 20F and car was outside it will take it 4 min to idle to work without issues?

It might take a little more time in winter than summer but not much. Maybe 30 second change at most. My daughter drives the car and just listens to the radio while she waits but hasn’t had to go past a half song in her “counting”. Car has to completely cool to create the problem again. So first thing in morning, you have to wait, stop at a store for 20 min, just get in and drive normal. I would estimate about 2 hours to cool off enough that the stalling is a problem again.

[scot850]

The guys beat me to a response and have covered all the suggestions I would as a starting (no pun intended) point to get a baseline.

Things I would add as additional suggestions and info gathering:

1) When was the distributor cap and rotor last replaced. I would remove the cap and check for corrosion on the contacts and a worn rotor.
while in there also look for oil leaking in from the camshaft seal into the distributor body. Check the distributor cap for cracks. When I had really worn cap/rotor on one Volvo I bought it was reluctant to start and drive in wet weather or when really cold or damp. Once it was warm it would run normally.
2) When was the ECT (coolant temp sensor) last replaced? Check the connections at the connector at the back of the steering pump as well as the wires into the connector are not corroded. There are figures you can also check for resistance values relative to ambient temperature to see if the ECT is in tolerance. If this is bad, or reading incorrectly it helps the car when cold by enriching the fuel until the engine has warmed up. If it is not correct the car will stall when cold as it acts like a choke in an older car.
3) How old are your spark plugs and leads? What brands have you got fitted and when were the plug gaps last checked?

Good Luck!

Neil.