My 1998 VW Jetta TDI (230,000 miles) recently developed cold starting problems. I replaced the glow plugs with no change in starting performance. The problem seemed to start when an oil change tech put 5w30 oil in last winter (which the operator manual says is ok in cold weather).I changed oil after 3500 miles and went back to Rotella diesel oil at my mehanic's suggestion. Could the thin oil have caused wear on the engine, or could something else be the problem? The car runs fine after it starts and doesn't use hardly any oil. I would appreciate any tips on solving this problem. [email protected]

You're in the TDI (diesel) solutions section so it uses glow plugs.
If it's a petrol engine 2.0L then it would be accessible above and below intake manifold using a swivel spark plug deep socket.

on that car, they had lots of problems with glow plugs and the wiring to the plugs, i would change them every 50,000 miles, there not expensive or hard to change,

glow plugs have absolutly nothing to do with the car not going over 20 mph. sorry, but you gotta keep on em. at a guess i would say it was due to them doing a t-belt and not setting the timing right somehow. but that's just a guess.... while I love my TDI, the service and parts at most VW dealers are at the bottom of the list

One wonders why.
The oxygen sensor is in the downpipe (exhaust) behind the engine undernearth the car.
From memory the glow plugs are below the injectors in the block.
I am sorry but the sensor escapes me.

this is a common problem for these cars glow plugs go bad like spark plugs however the smoke would lead to bad mass airflow meter. it is not telling ecu corrcet miss. disconnect mass airflow meter. when cold see if this makes it start better. it should would means you need new m.a.f. glow plug issue take a test light place clamp on positive of battery then pull off glow plug connectors place tip of test light on glow plug the bad one will have a dull light unlike the good one which will be brighter. will need new plugs and wire harness four **** connectors and wire striper and crimper will fix concern good luck

Have you checked all of your vacuum hoses for leaks? Any vacuum leak, even intake manifold or throttle body gasket, will cause an engine stall right after starting. Likewise with a fuel pressure problem. If you aren't getting voltage, maybe whatever switch starts your glow plug cycle(either turning ignition on or opening driver door, depending on model) is defective, or any of the wiring of the circuit. It's a cheaper guess.

well will it start using a little shot of starting fluid ? if so you might have a weak pump . try this and see . thanks Jerry

Ok , ok. Give me some more information and we'll solve this. We're talking about a jetta TDI 2000 with an ALH engine code I figure.
#1 Do you have an faults recorded in the ECM like a check engine.
#2 Are you using synthetic oil 5W40 preferably Castrol?
#3 How old is your fuel filter?

hi change the glow plugs and no its not normall there should be no air in the system it is either sucking air or it has not been bled properly last time system was worked on usually when changing the fiter check the whole system for signs of leaks if non found bled the system until you get rid of them yates210456

hi changing glow plugs is nothing to do with this code i would change the fuel filter and put a injector cleaner into the fuel tank as if this doesn,t cure the problem the only other thing that affects the pump is the timming belt has it slipped a tooth is there a marked drop in preformance if not these pumps are expensive very expensive best of luck yates210456