SEMI OT: VW cold start issue..........

[Dave M]

My sister's 92 vw jetta (1.8 gas) has pretty serious cold start problem. We're talking -20 celcius. It goes like this:

When its cold out, it won't start .

OK, enough kidding, it turns over like a deamon, smells like its flooding, but won't start. If its plugged in (block heater) over night, it'll start first turn of the key and idle fine. When I HAD to start it in the cold, it cranked and cranked, then finally (with the help of the gas pedal) sputtered to life, but spewed unburned fuel and stunk up the street (gas).

In the last four months, I've replaced: Plugs, wires, distributor, coil and I believe (i have to confirm) the coolant temp sensor. I'm thinking its another sensor (engine temp??), but don't know these well enough to diagnose.

Does anyone have a clue as to whats going on?

Any help would be much appreciated,

Dave M

[whiskychaser]

My sister's 92 vw jetta (1.8 gas) has pretty serious cold start problem. We're talking -20 celcius. It goes like this:

When its cold out, it won't start .

OK, enough kidding, it turns over like a deamon, smells like its flooding, but won't start. If its plugged in (block heater) over night, it'll start first turn of the key and idle fine. When I HAD to start it in the cold, it cranked and cranked, then finally (with the help of the gas pedal) sputtered to life, but spewed unburned fuel and stunk up the street (gas).

In the last four months, I've replaced: Plugs, wires, distributor, coil and I believe (i have to confirm) the coolant temp sensor. I'm thinking its another sensor (engine temp??), but don't know these well enough to diagnose.

Does anyone have a clue as to whats going on?

Any help would be much appreciated,

Dave M

Had a similar problem with my partner's Rover but only 2 or 3 times in four years. It got fuel, the strobe flashed and if you pulled a plug you got that to flash too. We had a Honda with the same engine so I used to warm plugs in that and swap them over. After the Honda went I just put the plugs on the gas ring like my dad used to do I replaced the parts you did including the dizzie cap and rotor arm but that didnt help. Close inspection of the low tension side revealed no faults. It was cold but certainly not -20. I put it down to dampness-only happened if she parked the car facing the wind

[RallyD]

pretty sure it is digifant and not CIS.
does it have a MAF or a fuel distributor with steel braided lines?
I have limited experience with the CIS and might be able to help if the car is so equipped

[RallyD]

on those cars the coolant temp sensor plays a huge part in fuel metering. Possibly when the temp is so cold and not plugged in, the sensor is out of range and gives you an incredibly rich mixture.

[Dave M]

on those cars the coolant temp sensor plays a huge part in fuel metering. Possibly when the temp is so cold and not plugged in, the sensor is out of range and gives you an incredibly rich mixture.

Thank you both, gentlemen.

Its digifant. My old Scirroco was CIS and never had these issues.

Regarding the coolant temp sens, if I unplugged it at start-up, would it send a tropical weather report or default to a cold report/rich mixture ?? May try it tomorrow am.

Thanks again,

Dave M

[RallyD]

it would probably do the opposite. resistance and temperature have an inverse relationship. Unplugging the sensor would give infinite resistance.
i'm sure the ecu can work around an unplugged sensor, just won't run well.
I'm not sure of the resistance but you should test the sensor with a meter and see if it is within spec.

if it smells flooded just hold the pedal to the floor, it'll let in the most air and trip the WOT switch killing the injectors.

my old car. it was a restoration project that I actually broke even on when I sold it.

[Dave M]

it would probably do the opposite. resistance and temperature have an inverse relationship. Unplugging the sensor would give infinite resistance.
i'm sure the ecu can work around an unplugged sensor, just won't run well.
I'm not sure of the resistance but you should test the sensor with a meter and see if it is within spec.

if it smells flooded just hold the pedal to the floor, it'll let in the most air and trip the WOT switch killing the injectors.

Tried pulling the cts to no avail. Same result as you predicted As well, the only way I've got it to go was by tromping the gas pedal to the floor. Even with that, it took a while. Plugs were likely soaked.

I'm sure I replaced the sensor, but I'll test it and post the results. Thanks again for the help. Oh, and lovely cab

Dave M