98 Jetta cold start & stall issues

My new to me Jetta does not like cold weather starting. It *will* start but takes a lot of cranking to get there. I have prior diesel background to know it was most likely the glow plugs, so I did a search on here and performed the Glow Plug testing procedure 2.0

Plugs were .5 .5 .5 .9 from passenger side to driver side of motor.

I tested the glow plug harness and got 12V @ all 4 connections.

So now I'm lost, what could be causing my hard start issue?

Also I got a check engine light after finishing all of my testing and reconnecting the glow plug harness, and its still there after 2 start ups. I'm guessing it threw a code because the harness was unhooked? Will it go away or will I need to get it cleared? Will it require a certain scan tool, generic scan tool, or can I just unhook the battery?

Also for S&G's I decided to slowly bring the rpm's up after it had been running for a while. When the car got to 3500rpm's it began to sputter, smoke, run rough and died within seconds. It did start back with A LOT of cranking, but it was white smoking while trying to crank? Any idea's as to what caused this? The car ran great driving down the road shifting at 3500 the other day?

Thank you in advance!

Since the car is new to you, a good start would be to replace fuel and air filters. Also, there is a clear tube from the filter to the injection pump, in which you should be able to see fuel flowing to the pump.

What is the car's mileage? Still on original injectors? When was the timing belt last replaced? Do you have access to VCDS (Vag-com)?

Also, is this only when the engine is cold. Or does it always happen with cold weather regardless of hot or cold engine?

More info would help. Also, check out the hard starting section of the faq.

...one more thing...

When I bought my 98 Jetta TDI the battery worked well for cranking until the weather got real cold. Then, it didn't quite have the power reserve to crank the engine with enough vigor to reliably start the engine. If your battery looks old you may need a new one. Lots posts on different batteries that work well with the TDI engines. I bought an Autozone Duralast 49-DL and it has worked very well even in sub-zero temps.

xubio said:

Since the car is new to you, a good start would be to replace fuel and air filters. Also, there is a clear tube from the filter to the injection pump, in which you should be able to see fuel flowing to the pump.

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I will check for that clear tube tomorrow. Unsure of mileage on filters previous owner said the fuel filter was still good till spring, but he gave me a fuel & oil filter when I bought the car. The air filter has some dirt on it, but is far from clogged. The car made a 700+ mile trip home from NY to TN without issue running 70-80mph

schultp said:

What is the car's mileage? Still on original injectors? When was the timing belt last replaced? Do you have access to VCDS (Vag-com)?

Also, is this only when the engine is cold. Or does it always happen with cold weather regardless of hot or cold engine?

More info would help. Also, check out the hard starting section of the faq.

Click to expand...

Car's mileage is 203,000 and the previous owner had Frank install some Bosio Sprint 520 tips last year. Timing belt was replaced 2 months ago, and no I don't have access to VAG-COM yet. Cannot locate anybody close to me that has it unfortunately, as the injectors need the IQ's lowered because of the bigger tips.

This is only when the car is cold...runs rough for a few seconds then clears up. Once warm has no trouble restarting.

schultp said:

...one more thing...

When I bought my 98 Jetta TDI the battery worked well for cranking until the weather got real cold. Then, it didn't quite have the power reserve to crank the engine with enough vigor to reliably start the engine. If your battery looks old you may need a new one. Lots posts on different batteries that work well with the TDI engines. I bought an Autozone Duralast 49-DL and it has worked very well even in sub-zero temps.

Click to expand...

Battery is fine...been replaced within the last year motor spins over fine just doesn't want to fire like a glow plug not working?

How long should the glow plug light stay on? When I roll the key over its off within 5 seconds?

If your GP's check Ok and you get 12V at the four points on the harness, maybe try disconnecting the temp sensor to get the maximum glow-time (default) from the ECU. You don't need a whole lot of glow-time in 35-40 degree temps. Think you may have something else going on though like timing or fueling or worse, compression. Start with the small stuff like ~$5 worth of vacumn tubing and replace them all including the one in the ECU.

Mcgink said:

If your GP's check Ok and you get 12V at the four points on the harness, maybe try disconnecting the temp sensor to get the maximum glow-time (default) from the ECU. You don't need a whole lot of glow-time in 35-40 degree temps. Think you may have something else going on though like timing or fueling or worse, compression. Start with the small stuff like ~$5 worth of vacumn tubing and replace them all including the one in the ECU.

Click to expand...

Can you tell me where the temp sensor is located? The Glow Plug instructions were off a newer model car.

The car will be going to a shop in Nashville as soon as I can get insurance on it, and time to do it as no one is willing to help me on another local forum. I have a friend who says he's going to buy the VAG COM but said it might be a couple of weeks before he gets his. Previous owner claimed to have replaced all of the vaccum lines recently before I bought the car...which ones are most important and where are they located?

Got Smoke? said:

Can you tell me where the temp sensor is located? The Glow Plug instructions were off a newer model car.

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How close are you to Versailles, Ky? Member Paramedick is a TOP NOTCH GURU on the VW diesels! Send him a PM.

Tony

TonyJetta said:

How close are you to Versailles, Ky? Member Paramedick is a TOP NOTCH GURU on the VW diesels! Send him a PM.

Tony

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I'm not....Lexington, KY is about 3.5-4 hours away from me.

I have a shop in Nashville (45 minutes away) called German Performance Options(I think that's it, everybody calls it GPO). I have spoke with them and they have VAG COM, but getting down there on a week day is a bit of a problem or me. I will make it eventually though since nobody else had VAG COM around me.

Thanks for the picure, I will see if I can locate it now.

I unhooked the coolant temp switch and got a long glow plug light like you would expect to get, and the car fires right up. Is that coolant temp sensor a dealer only item?

Got Smoke? said:

Is that coolant temp sensor a dealer only item?

Click to expand...

Nope...
idparts.com
worldimpex.com
www.1stvwparts.com (auburn Wa. VW dealer) good service & good pricing!

Tony

Tony: I was going to suggest that too!

Also, you can cycle the GP's by turning the key on till GP light goes off, turn key off and LISTEN for the relay click signifyng relay off..., then turn key back on and cycle GP's again(once/twice/three times depending temps. as needed)

CTS(coolant temperature sensor), can be tired and clogged!