Hi,

 

Let's see if anyone can answer this before the workshop owner calls me tomorrow morning!

 

Leaving for a rehearsal earlier tonight shifted up to 4th on a cold engine leaving the village speed limits, forgetting about the upcoming slope. Just when I was reaching to retrograde because I felt the engine struggle I got the dreaded beep (thinking it was just the silly outside temp warning) and felt all power drain.

 

The glowplug signal came on, steadily.

 

Put myself on the shoulder, cut the engine, waited a few seconds and then switched her on again. Glowplug signal remained on, steadily.

 

I had to reverse down-slope to turn back the way I came because the engine started to buck when I approached 20krpm, as if a hard rev-limiter had engaged. Or I maybe only had 2 live cylinders, who knows.

 

That's not the symptom I had the 2 times I blew an injector, where I could still rev the engine gently and reach 90kph on flat stretches of straight road.

 

I just see that I had both the exhaust and the glowplug warning lights on the 1st time; I didn't note which lights were on for the 2nd but if I were to guess it was not *only* the glowplug warning light.

 

Am I right that a glowplug failure on a cold engine is indeed something that will affect the engine running seriously and could maybe lead to flooding or other un-niceties if you try to overfeed an engine that can't manage to burn all that fuel?

 

Car has about 171k km on the odo and those plugs haven't been changed in the 71k that I've owned her, to my knowledge at least.

 

If so I might not be in it for an arm and a half this time (though I wouldn't put it above VAG to sell the glowplugs only as part of an entire engine rebuild ...)?

 

 

From the track record on this forum with the 1.6 engine, it is probably an injector, that said, it could be a number of things but glow plugs is not one of them, not unless a tip has snapped off and caused major damage

 

The glow plugs stay on post starting to help combustion and emissions but I doubt you would notice if one or more suddenly stopped working.

 

Looks like whatever the problem, the car knows about it and you are in limp mode

Given the kind of limp mode I was in it'd probably be 2 injectors... it really didn't feel like running on 3 legs this time. I had a faint hope that it was the last one I changed, thinking that was last fall, but no ... it was fall '23 already.

 

Anyway, would the engine even start from cold without a sufficient number of glowplugs working? I did have a number of start failures the past couple of weeks, where the first attempt on a cold engine did absolutely nothing, not even a relay click (battery is from summer 2023 too, though I do really drive very little these days).

 

I've also been running without the thermo/acoustic/whatever cover on the engine since last monday evening (meaning just 1 <10km return trip). I'd been smelling a faint fuel smell inside and on checking with the same mechanic who replaced my fuel return hose assembly just after he replaced that last blown injector we did find a bit of diesel around the feet of injectors 1 and 2. The hoses and connectors looked clean so he thinks that was just fuel that had been hosed against and absorbed by the foam cover, and only driven out now by the alternating cold and wet cycles.

Without that cover the engine must take longer to reach normal working temperature.

 

With less noise absorption I would probably have had to hear the "major damage" being caused by a broken glowplug tip, no? All I heard was the soft, low "not really purring anymore" sound from an engine not turning fast enough for the work asked from it.

FWIW, the manual says that a blinking glowplug warning light coming on while the engine is running indicates some other problem. But then it also doesn't say that failing plugs will activate limp mode. But again, what if more than 1 really fail and the corresponding cylinders can't burn the injected fuel quickly/well enough? The manual does confirm my assumption that that is the result of worn glowplugs (by warning for sooting up of the exhaust system, damage to the cat etc).

I think getting the codes from the car will probably reveal all!

I have no doubt. I also have no doubt that I'll be woken by a call from the workshop tomorrow morning that will also reveal all, including how much it's going to cost me...

 

I realise I didn't mention it: I just made it to my regular workshop before closing time and still caught the owner who also gave me a ride home. I probably wouldn't have been able to make it up my "mountain" and if it's really the plugs I probably wouldn't have been able to start on a completely cold engine tomorrow morning so the car is exactly where she needs to be to get the attention she needs as soon as they can give it.

 

My last injector repair was handled in less than 24h because we have the national VAG distribution hub in the same neighbouring town I was going to. They're probably not open on Saturdays though.

Edited 31 January, 20251 yr by RJVB

Dont forget that the glow plug warning light is also used as a master indicator that there is a major fault code stored. So the glow plug light can come on when the glow plugs are OK.

On earlier Mk 1 cars  such as my son's Audi, the light came on for a failed breaklight bulb!

 

The 1.6TDI 105 CR has a history. If one injector fails, the others fail soon after. I chose to change all mine after one failed and one had poor test readings.

After changing all four the car seemed a little sluggish initially but now, 2000+ miles later, The performance is the best ever. Perhaps the ECU adapts to the new injectors?

47 minutes ago, pikpilot said:

Dont forget that the glow plug warning light is also used as a master indicator that there is a major fault code stored.

 

The manual does say something like that, but claims it will blink in that case. In my case the thing remains on.

 

But sure, wouldn't it be fun if my attempt to accelerate in 4th gear had stuck the EGR valve in the wrong position and I'm in for a 2nd replacement of the thing...

 

Talking about histories and track records: how many replaced injectors have been known to fail? Is there any indication that the underlying "bug" has been identified and corrected?

I have 2 re-conditioned injectors that I know of, one done by the workshop combining the replacement mechanical part with the electronic component from the blown one that tested OK, the other one bought as such. The maintenance records show now indication of injector replacements before I got the car so I have to assume I still have 2 original ones.

 

If replacing these things prophylactically is a guarantee against future failures then the cost is justified. If the replacements can fail just as happily I don't really see the point in anything other than having them tested at an appropriate interval.

1 hour ago, RJVB said:

Talking about histories and track records: how many replaced injectors have been known to fail? Is there any indication that the underlying "bug" has been identified and corrected?

 

It is hard to quantify that but I know that when I see a failed injector post on this forum it will be a 1.6 and not a 2.0, I have no idea why, essentially it is still a very similar injector.

 

No idea what years are worse for it and whether the probem has improved or not. What is a sensible idea maybe is if you have one fail, replace the full set, especially if it has reasonable mileage on it. I do appreciate most people don't want to buy 4 injectors when they only need 1

As I said, it would make sense if you know that it'll prevent future nuisances that could even be dangerous. First one I blew was on the left lane of a very busy Italian freeway - losing power there isn't reassuring at all (esp. when you don't understand what just happened, your partner starts to scream and no one thought it'd be a good idea to activate the warning flashers as part of limp mode.

 

But if those replacements can fail just as happily without much possibility to predict when you're just throwing money to replace 3 "perfectly good" injectors with 3 similarly good ones.

 

You'd expect that all diesel injectors should be "very similar" because they all play the same role. But from what the mechanic in Italy told me is that they see a lot of the problem, my mechanic here of the time confirmed that (and that the 2.0 engine was affected too) and I think both claimed that both the mechanical and the electronics parts are known to fail. The latter one shouldn't  (except as the exception that confirms the rule), not in a properly maintained vehicle where the engine never overheats etc). For the mechanical part you would indeed expect wear over time, but I'd say there's more than enough evidence that such mechanisms can last a lifetime.

 

Hmmm, I filled her up with regular supermarket diesel after 2 tanks of Total Premium (for cleansing purposes!), but that was on the 13th. I made 5 of those short return trips since and I had only about 50km of range left on the reserve so it doesn't seem very likely that I put in gasoline by mistake 🤣

6 hours ago, pikpilot said:

After changing all four the car seemed a little sluggish initially but now, 2000+ miles later, The performance is the best ever. Perhaps the ECU adapts to the new injectors?

Apparently they're not simple unscrew-and-replace devices but you need to tell the computer it has new injectors or something like that. I suppose that was done?

1 hour ago, RJVB said:

Apparently they're not simple unscrew-and-replace devices but you need to tell the computer it has new injectors or something like that. I suppose that was done?

Yes, that was the done. The new injectors are supplied with an individual code on the top. These codes were entered into the ECU.

I don't know if the ECU "learns" beyond the on-the-fly adjustments  that are always made to the injection but if it does it could also be that it had to "unlearn" the compensation it used to have to make for the old injectors. That seems more logical.

Did you notice anything at in the instantaneous or average fuel consumption readings? I suppose those are directly related to how much fuel each injection consumes though we have to guess whether that's a theoretical/ballistic estimate or an actual measurement coming back from the injectors.

15 hours ago, RJVB said:

Did you notice anything at in the instantaneous or average fuel consumption readings?

 

Not yet as I am enjoying the new found power!

I keep a log of fuel connsumption so I will check after a few more fill ups. I can't say about instantaneous as currently I am taking short trips, often not reaching full coolant temperature until near the end. I will report back soon.

Interesting. I recall I did notice a loss of power when the 1st injector failed, but not with the second (maybe it was the electronics part the 2nd time, which could also explain why the failure was detected at once after turning on the ignition unlike the 1st time).

 

The feeling sluggish at first sensation may just have been you trying to look for continued signs of trouble, and the better performance related to colder temperatures and thus air that's richer in oxygen? I know that was a definite effect on my (air-cooled) MC and I think it must exist for all types of IC engines.

 

FWIW, I use spritmonitor to log my fuel consumption, expenses etc. (also gives me the nice gadget in my sig).

Well, inevitably I was just wishfully thinking and you guys were right. This time it's injector #3 - for a while I feared it was the one I'd changed in Italy in 2016 but that was #4.

 

Except that this time part of a screw or bolt holding the thing in place broke off during removal and fell into the engine. The way it was presented it was (of course...) an unhappy accident, not an error on their part, but now they'll have to find the time to disassemble the upper part of the engine to go fishing for a loose aluminium (?!) bit inside an aluminium case.

 

I didn't dare to ask what the chances are of a successful repair though he seemed confident enough, just not willing to make an estimate about the number of hours this would take. I suppose I have to hope that he'd have preferred admitting small chances of success rather than wasting hours that he could also spend to make other clients happy.

 

He was also certain that it couldn't have falling into the combustion chamber (where it should be a whole lot easier to find). And that I don't understand. The injector injects into the combustion chamber, just like a plug fires (or glows) into that compartment. Is there a sort of double wall, and what else is inside that space into which the broken bit could have fallen? Apparently not the crank case because there were no plans to put the vehicle on a lift - but maybe they plan to lift the engine out?! (He did talk about a berceau but from what google tells me that's probably the engine cradle of another car they had on a lift that he was working on when I walked in.)