Car shuts down while driving?
 

I hope someone here can help me.

Recently, when decelerating or braking (for a light, stop sign, or just to slow down to make a right turn, say), my 1990 300E just shuts down, and all the lights at the base of the dash display (oil; battery; wiper fluid; etc.) come on.

After this happened 3 separate times, I took it to the shop that normally services the car. They couldn't get the problem to demonstrate while they test drove it, but after looking under the hood recommended a full tune-up, guessing the problem might be caused by worn sparkplugs, etc.

Full tune-up was completed 2 days ago, and the car was running beautifully.

Then this morning, it cut off again when I slowed to make a right turn.

In each of the 4 instances, the car has started right back up again.

My regular mechanic is stumped. Anyone have any suggestions of what to look for next?

Thanks in advance.

Re: Car shuts down while driving?
 

The first thing I'd recommend it to find a new facility that knows how to troubleshoot problems. Six spark plugs will not go bad simultaneously and cause the engine to quit!!! It sounds like you have an intermittent open in the ignition circuit. Start out by wiggling the primary ignition wires and connectors and coil to distributor wire while the engine is running to see if it quits. Also check out the cap and rotor and secondary wiring. Remove all the primary connectors and carfully inspect the pins and receptacles for corrosion or damage. If all the wiring and connectors check out, the coil is suspect. Worse case is the EZL module.

Intermittent problems like this are tough to troubleshoot, but if it happened to your car it has probably happened to other similar models. Maybe someone who has experienced a similar problem can chime in with a hint.

Duke

check your fuel pump relay and pump wiring.

Thanks very much for responding to my question. I'll give your suggestions a try!

Your idle control valve is sticking closed, a very common problem on the CIS injection.

Clean it and check the condition of the associated hoses. If they are rock hard, replace them as they are leaking, making the problem worse by causing intermittant overlean mixture on coast, too.

Fuel pump relay or fuel pump will cause intermittant stalling at any speed or driving condition, not just on deceleration.

Peter

My experience with stalling on deceleration or when braking for a corner turned out to be a foiled fuel pump relay.

The stalling never occured at speed, only on decel or braking at low speed.

My 2 cents.

My 560SEL did something almost identical to what you're describing about 6 months ago. My mechanic replaced the over-voltage protector relay (OVP) and the fuel pump relay and I haven't had any problems since.

Peter's suggestion is good, but IMHO you should not eliminate the possibility of a fuel pump or relay problem.

Same syptoms on a 190E 2.3 lead to the fuel pump relay. I would:

Fuel system:

1. Check the idle control valve.

2. Check the fuel pump relay and filter.

3. Check the fuel pump.

Ignition system:

1. Cap/Rotor and related components.

Investigate one thing at a time until your diagnosis is accurate. After elimanting those things, then further work will be needed if not solved.

You might make sure the wire from the distributor to the ignition coil is firmly connected to the coil. My car died going down the road from this. I doubt this is your problem, but you might as well check the simple things first.