00550 Loud Engine-Advanced Timing

MicroRacer

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Sep 16, 2005
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Reelsville, IN
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My daily driver 98 Jetta is in dire need of help. I keep throwing a 00550 code (immediately after resetting codes) and eventually 00575. I have checked the timing with a VagCom and it is advanced off the chart. The engine is very loud. It sounds as loud as my 84 Mercedes Benz TB. I have verified with my mechanic that the mechanical time is still set and that it hasn't jumped a tooth. I have given my mechanic a $200 dollar limit to try to find the problem, but if he's unable It's going to be up to me (which I think will be the end result). Below is the particulars to my car. I was hoping I could get suggestions on where to start to resolve my cars problem. I have read on here about the different problems with noise and the 00550 code, but I'm more than a little confused by all the different discussion. Nowhere have I read where a code 00550 (and never personally experienced this) could cause the timing to go off and nowhere have I read where the timing could cause a 00550. Since the timing is mechanically right, I suspect something with the injection pump, but what. The car doesn't smoke anymore or any less than usual. I appreciate any help I get before tearing into this problem.

I thought I would add that the car starts very easy (1st crank) as usual cold or hot.


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Timing Belt replaced - Approx 25000 miles ago - I took the car to mechanic and it is mechanically still in time, but VagCom shows advanced off the chart.

109 Relay - 11 months old

Fuel Filter - New

Air Filter - Less than 23,000 miles

Mileage - 182,000

Hoses - High quality silicone 3 years old.
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MicroRacer

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Reelsville, IN
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After more reading my guess is that I am having trouble with the N108 valve. This is the cold start valve, but my car starts like great. I'm trying to find it used, but no such luck. From what I have seen you can get a new one for $300, but i have found rebuilt pumps for $430.

Both are expensive options.
 

P2B

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Joined
Jan 11, 2006
Location
Toronto & Muskoka, Canada
TDI
2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
N108 is often incorrectly called a cold start valve, but it's actually the advance solenoid which controls timing by regulating fuel pressure - this document describes how it works and how to replace it.

In some cases a bad N108 can be temporarily "fixed" by running the N108 output test in VAG-COM for a couple of minutes - sometimes the timing will be back on the chart after the output test "exercises" N108. It won't be long before it throws the code again, but the test confirms N108 is the problem.

Simon
 

MicroRacer

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I'm off work today and my plan is to to this test, but also clean the connectors going to the valve and try to trace out the wiring. I plan to make sure there is no problem with the wiring before I purchase a N108 or IP Pump.
 

MicroRacer

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Reelsville, IN
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My decision is to decide whether I can fix this valve or whether I need a new N108 valve. I've never had one of these valves off so I know nothing about them.

I measured 15 olms across the valve coil (so not shorted or open). but it must be stuck open because it is way way advanced. I'm not sure what the coil should measure. Anyone know? I can adjust the timing to where the car runs right without throwing a 00550 code, but at that point it will not start anymore. I have took as much advance out of the timing so that it will just barely start when cold. At this point the timing is still way advanced.

I'm hoping to get some feed baxk about this valve. Is it possible to get this valve ($325) going again or am I going to have to bite the bullet? Suggestions?
 
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MicroRacer

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Sep 16, 2005
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Reelsville, IN
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After doing some more research I found that the coil on the Cold Start Valve should measure between 10 and 20 ohms. I have read were this valve can get plugged up so I am going to attempt to remove the valve and see if there is any way I can fix it.

I have read some horror stories about removing this valve and frankly I'm more than a little nervous to try. No guts no glory:)
 

smelly621

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Nov 13, 2008
Location
Sonoma County, CA
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2001 Golf, 2003 Tacoma
I would advise adjusting the injection pump to see if you can at least get timing in spec in vag-com. There are instructions in the how-to section of this site. If you can't get timing in spec through manipulation of the pump angle I would then ask your mechanic how he ensured the timing belt had not skipped a tooth. If he used the appropriate lock down tools or just visually checked. My jetta was behaving similarly and it turned out to be the timing belt jumped a tooth, but none were broken and the belt really didn't look that worn. I attribute the jump to improper installation of the old timing belt. If this is your problem make sure to get the belt changed by a qualified individual, one that will use the TDI specific lock down tools during install and vag-com to then further adjust timing to exactly where you want it.
 

honda_vtec2

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Jul 16, 2008
Location
Toronto
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2000 Golf ALH tdi, 1997 Jetta 1z tdi
smelly621 said:
I would advise adjusting the injection pump to see if you can at least get timing in spec in vag-com. There are instructions in the how-to section of this site. If you can't get timing in spec through manipulation of the pump angle I would then ask your mechanic how he ensured the timing belt had not skipped a tooth. If he used the appropriate lock down tools or just visually checked. My jetta was behaving similarly and it turned out to be the timing belt jumped a tooth, but none were broken and the belt really didn't look that worn. I attribute the jump to improper installation of the old timing belt. If this is your problem make sure to get the belt changed by a qualified individual, one that will use the TDI specific lock down tools during install and vag-com to then further adjust timing to exactly where you want it.
I agree with this post. Also what P2b said. Before removing the solenoid. I'd run a can of diesel purge on the pump and in VCDS, run the n108 output tests in a loop position for 10 min while purging. Then check and see if timing is still the same on the graph. Repeat the procedure until the purge is done.
 

Houpty GT

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Aug 31, 2008
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South Carolina
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Corrado TDI, 2000 Golf, 1996 B4 Variant
I wanted to add a few things to this thread for reference, since I found it helpful. I was having problems with a loud engine after installing a used pump. The timing set well initially but the engine sounded loud in the 2,000 RPM range. After driving 3 hours on the interstate, I noticed the car being loud at idle and I had a check engine light. The car also said it had tons of advance at idle. I think it said 70 degrees. I determined that the advance was sticking and jumping low to high and back.
The engine code I got was 65533 Unknown Error Code 17-10 Control Difference - Intermittent. If you search you won't find anything about what it means. I called Rosstech and they said this was not one of their codes and the tuner must have messed something up. They recommended calling the tuner and trying a different tune. When I contacted Malone Tuning, they told me they did not know what it meant. I put in a Rocket Chip tune and it gave me a legitimate engine code. The new code was 00550 Start of Injection Regulation 17-10 - Control Difference - Intermittent.
The Rocket Chip tune was also much quieter, smoother, and better behaved than the Malone tune in these conditions, but the advance was still sticking.

I did 4 things to fix the problem in a shotgun approach.
I replaced the fuel filter.
I replaced the case pressure relief valve. The old valve was stuck barely open and would not move.
I replaced the N108 with a known good cold start valve.
I remove the 2 covers for the advance mechanism and made sure I could move the plunger with heavy thumb pressure. I did file off a few burrs from the plunger also.

I hope this helps someone in the future.
 
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