My 92 Jetta started having a new problem last night. It was about -15C outside and it would start and run for 2 seconds and then stall. If I keep the revs up for about 30 seconds then it will idle but it idles rough and is running very rich. I say it is running rich because I can smell fuel as it is idleing. I drove it home and once it was warmed up it seems to idle and run fine. It will also restart with no problems when warm. Where can I start to troubleshoot this?
When is the last time you checked the plugs and wires? And how strong is your coil? As you state that it runs fine when warm, that suggests away from the cold-start system and more towards a weak spark problem.
Assuming this is a 4-cyl, gasoline engine.
If it happens to be a diesel, go immediately to your glow-plugs and check those. They are easy to reach and to check.
lol And to agree with pfjw .............. It does help when you get more info like if it is gas or diesel, 8 valve or
16 valve, USA model or CA-spec model or elsewhere. ;-)
I will ASSuME that it is an 8V gas engine in the USA and that you have tuned it recently....RIGHT? I would suspect ground wiring to the intake manifold or coolant pipe on the rear of the cylinder head, or the flap in the air flow box is sticking or the fuel pressure regulator has ruptured. Also some possibilities are the Coolant Temperature Sensor, Oxygen Sensor or wiring.
Anything is possible, but if the thing purportedly runs properly when warm, then the coolant temp is out-of-circuit and the Oxygen sensor is limited. Generally as well, when the coolant sensor fails it will run very rich when warm or lean when cool...
Could be a loose wire or ground as you suggest, but I would start with the spark. And on general principle, I would run a can of Techron through it in a fresh tank of gas in case any injectors are fouled.
WIthall, these cars are pretty simple-minded (which does not mean "simple"). Ignition/spark, fuel, sensor(s). Given the timing of this defect (on starting), I would discount sensors until the first two are proven OK.
Sorry guys, it is a 1.8L 8v gas engine. I am in Canada, I don't know if the car will be any different or not, its probably the same as the USA version.
It seems to be intermittent because it started and ran fine yesterday. Today may be a different story as it is -30C right now but if it acts up I may just take it into a shop because I don't want to be outside in this cold trying to troubleshoot it.
What is a can of Techron? Is it just fuel injector cleaner? I've got
3/4 of a tank of gas but I'll t> dave AKA vwdoc1 wrote:
SeaFoam is also very good and sold at some auto parts stores and some Home Improvement stores (Menards). BG 44K makes some very good cleaners too that are recommended by others. I can't seem to find them locally though. :-(
If the engine has the 3 wire 02 sensor and the wires are fused to each other it might cause a rich condition possibly within minutes of starting the engine. I have seen this happen after the wiring touched the exhaust manifold and fused together. And the engine seemed to run better when warm too but could not pass the emissions test.
Of course it is nice to only have 1 problem, but there may be more problems that need correction. ;-) Whenever I check a car for a problem I try to go down a checklist, but still need to test almost everything and assume nothing. I have even seen an oil pump cause an engine running problem! 8^o
YES check the easy & simple stuff first like the quality of the spark!
IIRC, he didn't say how he knew it was rich other than saying it smelt of gas when cold.
I mentioned the vac leaks, etc because sometimes a 'rich report' is actually way lean. Without enough gas in the intake charge, all the gas doesn't burn, which gives more gas smell in the exhaust (at cold anyway) than a rich condition would unless it's VERY rich.
Pulling the plugs is a good idea tho', since a read of their condition can tell a lot.
Yes that is true. When mine had a vacuum leak to the pressure regulator it was nearly flooding the engine. When i pulled a plug it was wet and also smelled a lot of gas.
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