GP Glow plugs cycle too short

2002 Golf Manual transmission. I've searched everything I can think of and haven't read anything that describes this issue, hence the post. Read the GP 101 sticky.



With ECT plugged in I get about a 0.5 second until GP light turns off. Will have to crank engine at least 30 seconds with ambient air temp in 60's first thing with stone cold engine. When I unplug ECT, get approximately 15 second of GP light and engine fires almost instantly.



So, replaced ECT with VW OEM from IDParts. Same symptoms.



So, I think, "Probability is small, but new ECT could be bad." Replace with REIN. Same thing.


BTW, I pulled the harness and get battery voltage at each leg when I cycle key with GP light on. All GP's test at about 1.0-1.2 Ohms.


Does this point to a bad timer/relay? Bad wiring?


Besides the computer getting faulty information about engine temp, is there a problem driving it like this?

Above about 40-45*F the half second GP light out is about perfectly normal. If you are actually needing pre-glow in 60*F ambient temp you have some other issues (low compression, very late/retarded injection timing, slow cranking speed, etc, etc) and that extending the glow time is just masking the real issue(s).

I'm assuming ECT is the coolant temperature sensor, correct?

It's possible your glow plug relay has failed. That's not too common on '02s, but they do fail.

And I agree with jettawreck that even if the glow plugs aren't cycling your car should start easily this time of year. I don't even cycle the plugs until it's below 50 in the morning.

Yep, your glow plug cycle is not too short for that temperature. Your engine is just having a hard time starting. A few years ago, I had a similar issue. Checked for bad battery, fuel line leaks, etc. Turned out to be an aging starter motor. It would only noticeably take a long time to start in the morning making it seem like it should be something else. A remanufactured starter fixed the issue. Good luck.

Agreed... forcing the glow plugs on by pulling the temp sensor is very likely just masking something else... even here in the great white north glow plugs aren't needed until there's at least a foot of snow on the ground.

Even with cut pistons and very low compression, starting does not take but 5 seconds of cranking when below 30f

check your injection pump timing, and camshaft timing
IP can cause tough starting and still not set codes for timing faults, camshaft timing can cause VERY hard starting and will never set any codes under any circumstances on an ALH

Geomorph said:

Yep, your glow plug cycle is not too short for that temperature. Your engine is just having a hard time starting. A few years ago, I had a similar issue. Checked for bad battery, fuel line leaks, etc. Turned out to be an aging starter motor. It would only noticeably take a long time to start in the morning making it seem like it should be something else. A remanufactured starter fixed the issue. Good luck.

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x2. Happened to me. I thought glow plugs were bad, checked contacts, replaced plugs, ran injector cleaner, etc. Ended up being a slow starter. Once it started grinding/whirring it was obvious, but it had slowed down so gradually I hadn't noticed. New starter cranked so fast (and it wasn't a bad connection, etc) it turned the engine right over.

You have something else happening, it isn't the glow system. Forcing a longer preglow period is just masking the problem.

I would check the ECU values for the temp sensors when cold, they all three should be nearly the same.

Thanks everyone. I'll run down all these suggestions and get back to you with what I discovered. Thanks for your valuable advice.

There is an issue that as to be addressed. I suspect that the timing is off to the point fuel will only ignite with some heat on the combustion chamber.

If it was compression, it would not happen in all cylinders, would start but misfire, unless you have low compression, linearly, on all cylinders ...

agree

k_pt said:

There is an issue that as to be addressed. I suspect that the timing is off to the point fuel will only ignite with some heat on the combustion chamber.

If it was compression, it would not happen in all cylinders, would start but misfire, unless you have low compression, linearly, on all cylinders ...

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My thoughts as well. There is something other than the ETS / GP duty cycle.

A little history would help.

Just get the car? Just start acting like this? Gotten worse since the last eclipse?

Thanks for the suggestion to look at IP timing. Way off - Basic settings, group 000, field 2 showing 000. Adjusted IP static so field 2 showing 65-72 Following this suggestion. Will report tomorrow if better startup upon cold. Will leave ECT plugged in for test tomorrow so I should get an appropriately controlled GP time. Thanks everyone. BTW, for other folks, had poor acceleration and a significant miss under heavy acceleration when cold.

had poor acceleration and a significant miss under heavy acceleration when cold.

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Not to be a Kibitzer, but you really shouldn't do "heavy load" when that motor is cold. Wait at least until the dummy gauge moves past the three little fat hash marks. I have it on good authority that's how you need to treat the ALH.
FWIW, I noticed my '03 glow light went out a lot faster after I recently replaced the coolant temp sensor.

One more thought: if I assume whomever did the TB last set the IP timing correctly, does that point to a belt that has stretched and that I should be worried? According to service history I got on this vehicle, the TB was done about 75k ago.

STDOUBT said:

Not to be a Kibitzer, but you really shouldn't do "heavy load" when that motor is cold. Wait at least until the dummy gauge moves past the three little fat hash marks. I have it on good authority that's how you need to treat the ALH.
FWIW, I noticed my '03 glow light went out a lot faster after I recently replaced the coolant temp sensor.

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eh
being nice to them when they're cold is how you wet stack the intake manifold
hop in, start it and go as soon as the lifters stop ticking, stock they do not have enough power to hurt themselves

GasNoMore said:

One more thought: if I assume whomever did the TB last set the IP timing correctly, does that point to a belt that has stretched and that I should be worried? According to service history I got on this vehicle, the TB was done about 75k ago.

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1) never assume anything with unknown TB service
2) I've never had a TB "stretch" to any degree during its service life
3) How long ago was 75k miles? I put rather low miles on annually between the two TDIs, so consider my service interval 75-80k miles max. Perhaps it's about time to schedule a service. I will probably be changing the 2003's TB this spring.

Suggested in post #2 the timing was probably retarded.

being nice to them when they're cold is how you wet stack the intake manifold

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I'm not talking about babying the car in general -- just not putting really high revs on it right after cold startup.

I got that info from DBW's break-in thread.
http://forums.tdiclub.com/showthread.php?t=252501
...and the owner's manual as well.

jettawreck said:

1) never assume anything with unknown TB service
2) I've never had a TB "stretch" to any degree during its service life

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x2.

Changed that TB. Who change the TB could also haven't tight the tensioner as it should or tight any bolt correctly, don't trust the rest of the job.

Just to close the loop, I now have 2 days of stone cold starts. I'm marking this WO as closed. Car fires in under 0.5 seconds. Used to take 20-30 seconds of cranking while ECT sensor plugged in or ~20 seconds of GP light with ECT unplugged. For those who don't know what "basic settings, block 000" is referring to. I used VCDS to monitor these settings as reported via the OBD2 port. Most valuable tool I own when it comes to maintaining a TDI!!

Excellent!
So what was the fix, engine time?

BobnOH said:

Excellent!
So what was the fix, engine time?

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Injection pump timing was significantly retarded. Too early to report definitively, but seat-of-the-pants fuel economy seems improved and no doubt engine is smoother and more responsive.

Yea, you got it. Timing is critical at start condition, sounds like yours was clear outside the range. Don't know if that zero read you got was a default or it was just way retarded. I could see an experienced mechanic, too lazydumb to read, thinking that's where it belongs. Could have even looked at directions for a PD.

I doub't it

BobnOH said:

Yea, you got it. Timing is critical at start condition, sounds like yours was clear outside the range. Don't know if that zero read you got was a default or it was just way retarded. I could see an experienced mechanic, too lazydumb to read, thinking that's where it belongs. Could have even looked at directions for a PD.

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More likely the person that did the timing belt didn't even use VCDS ..I'd wager that the T/B job was done by the "Mark & Pray" technique .