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Blown turbo? Maybe?

GTI's

Drag Racing Champion
Location
MD
It's as I described in post #22. It's the same sound as you get when you do a compression test with the plugs removed. It's as if there is no spark at all. At this point I feel like it has to be the CPS. There's nothing else that controls spark. Plus it died on a hill. In the cold. AND my tach was jumping around like crazy on first startup. All these are classic bad CPS symptoms.

And your scan tool can not look at the CPS while cranking to see if its working or not??
 

1131

Passed Driver's Ed
And your scan tool can not look at the CPS while cranking to see if its working or not??

I'm using the Torque app. I don't believe it can do that. Can VCDS do it? I may be able to borrow/rent a VCDS from someone. But by then the new CPS will have arrived. What measuring blocks should I be looking at and what does a normal reading look like?
 

GTI's

Drag Racing Champion
Location
MD
I'm using the Torque app. I don't believe it can do that. Can VCDS do it? I may be able to borrow/rent a VCDS from someone. But by then the new CPS will have arrived. What measuring blocks should I be looking at and what does a normal reading look like?

Yes Vcds can look at that sensor in multiple MB/AMV..............01 Engine --> 001.1 or 002.1 or 003.1 and at least 10 more locations

While cranking engine it will show the speed/ rpm the starter is turning the engine, somewhere in the 200 range and a running engine at the idle rpm or rpm the engine happens to be at.
 

1131

Passed Driver's Ed
Allllllllrighty then. So I managed to get ahold of a VCDS. I turned the key to the accessory position, fired up the software, opened the engine module, opened the measuring blocks and clicked "Go!" after groups 001, 002, and 003. All fields populated with zero values and showed green. Then I cranked the engine and got what you see below. Is this the smoking gun? Did I guess the diagnosis and get it right? Or am I more deeply effed than I realize? I have a sneaking feeling it's the latter. What else should I look at while in VCDS?

Looks like the new CPS isn't arriving until tomorrow late. Plus it's gonna be raining. So I won't be able to get to it before Tuesday. I've postponed cleaning my MAP and TB until I get this other situation worked out. I may have to pull the battery and top it up at home since I think the voltage has been drifting down while it's been sitting there in the freezing cold for the past four days. Might as well optimize my chances at a successful restart.
g28.jpg
 

vwengineer

Ready to race!
Location
Switzerland
Thanks. I did not know that. I have a backup N80. I'll throw it on if the new CPS doesn't fix it.
This was just an exemple that a vacuum leak could prevent the car from starting, if you didn't touch the N80 I don't see any reason of it to fail now
 

1131

Passed Driver's Ed
Vcds is on version 19.6.2 so download the newer free version here https://www.ross-tech.com/vcds/download/current.php unless you have got an illegitimate cable in which case don't and take what it scans with caution.

Have you done an Auto Scan saved it and tried to clear DTC.


So it turns out... if your battery voltage drops too low, VCDS starts to behave funny. I removed the battery and charged it at home. It still won't start the car, but according to VCDS my CPS (G28) is just fine?

cps ok.PNG


I'm going to swap it out on Sunday anyway because... what the heck else could prevent my car from starting? It's not the plugs. It's not the starter. It's not the battery. It's not the coilpacks. The engine appears to be fine. I can hear it turning over, and I confirmed this by manually turning it with a 19mm socket.

Once again I'll be relying on a Pelican guide for the swap:
https://www.pelicanparts.com/techar...Crankshaft_Positioning_Sensor_Replacement.htm
I don't know what exact vehicle Pelican dude is working on, but I'm guessing it's not a GTI. The oil filter is totally in the way. I've already tried jiggling the CPS connector to get it out of the bracket, all the while whispering under my breath pleasedontbreakpleasedontbreakpleasedontbreak. And. Of course. It's started to crack. Just the bracket though. So I've decided to stop messing with it until I can drain the oil and remove the filter. I'm waiting until Sunday because the rain is supposed to move on by then. So you guys have until then to correct my thinking and direct to me to something else I haven't considered.

I'm just about ready to throw in the towel. If I can't start the car by Sunday night, I'll bite the bullet and have it towed to a VW dealership and have them diagnose it. Kills me, but whatchagonnado.
 

1131

Passed Driver's Ed
Is it just me or has this forum been down more often that it's been up recently? I guess I should hurry up and update while I have this oppo then.

So it seems VCDS was right. There was nothing wrong with my CPS. Also, I apologize for using the acronym CPS. Apparently CKP is the preferred acronym on the internets so that there is no confusion with the CAMshaft position sensor.

There was about a quarter cup of oil that drained out of my charge pipe when I removed it. Oil, when it's in smoke form, goes wherever it wants I guess. The TB was remarkably clean. But I cleaned it some more anyway using CRC's TB and carb cleaner. The hardest part of this procedure was removing the TB hose. It's a 2-piece jobby. It's a band clamp that threads through a ring sleeve that's crimped onto the hose. It's ridiculously difficult to remove, even maximally loosened. I needed 3 pick tools. Also. Be super super careful about how much force you use to remove this hose. Your dipstick holder, IAT, and TB connector are all very fragile and right in the same vicinity. My TB connector was a casualty.

broken tb.jpg


Fortunately, it was just the connector, so i crazy glued it back together. But it broken again as I re-installed the radiator fans that I removed to make room. I have it duct taped together at this point.

With the charge pipe removed, there is enough room to remove the CKP without having to remove your oil filter. The 6mm hex bolt holding the bracket for both the CKP and knock sensor was seized. I hit it with some Liquid Wrench and let it sit overnight. I came back at it in the morning with a T40 t-handle wrench and it finally relented. The Pelican guide suggests that the CKP pops right out after removing the 5mm hex holding it in. It does not. I needed to grab it with channel locking pliers to get it out.

I was unable to clean the MAP sensor. One guess as to why. Yup. The two philips head screws were completely rusted. I hit it with some Liquid Wrench and let it sit overnight. No difference. With the charge pipe removed, I was able to Dremel a slot into the screw. I then proceeded to torque the heads of both screws completely off. Now, if I want to clean or replace my MAP sensor, I will have to drill these two screws out. Since I'm not sure what size screw this is, I decided to leave it be for now. It's unlikely that a bad MAP sensor would produce a no start condition. I was only cleaning it since I was in the area, and it was a good oppo.

So with TB cleaned and new CKP? Still no start.

So a thought occurred to me. I pulled the coilpack loom, the coilpacks, and the spark plugs. I then inverted the loom and reinstalled the coil packs onto the inverted loom. I installed the spark plugs onto the inverted coilpacks. That way, I could check for spark from within the cabin while trying to start the car. I did this test at night for maximum visibility. All four spark plugs are working. That means the entire ignition system is fine: battery, starter, loom, coil packs, and spark plugs.

I think I now need to investigate the fuel supply. Possible culprits are HPFP, LPFP, fuel pump relay, fuel filter, and injectors . It's not likely to be the injectors since it's unlikely that all four would fail simultaneously. It's not likely to be the fuel filter since I changed it back in the summer. I ordered a used HPFP which should arrive after Christmas. So I have some down time to think and to try stuff.

Here's a snapshot of my 103, 106, and 230 MBs. This is with the engine off because, like I said, the car will not start. Still, there seems to be a rather large discrepancy between requested and actual, no?

fuel.jpg



There are two things that bug me:

1. There have been NO DTCs concerning fuel supply issues. Are any of these parts that are likely to die suddenly while driving?

2. Isn't it peculiar that it happened immediately after my turbo swap attempt? I mean, suspecting the CKP seemed reasonable since it controls spark and the old one was indeed slightly covered with oil when I replaced it. But would a blown turbo cause a fuel pump to fail? That seems harder to believe.

Like I said. I'll have a few days to ponder things, so I'd appreciate any feedback I get on my dilemma. Provided, of course, that the forum doesn't go down again and you're able to read this at all.
 

zrickety

The Fixer
Location
Unknown
Car(s)
VW GTI
I may have missed it, but have you done a compression check? There could be something going on that's not electrical...
 

1131

Passed Driver's Ed
I may have missed it, but have you done a compression check? There could be something going on that's not electrical...

See post #1. I did one recently while diagnosing the blown turbo and it came back 190 in all four cylinders. I haven't done one since the turbo swap though so maybe I should. I am able to turn the engine manually using a 19mm socket so the engine is not seized.
 

vwengineer

Ready to race!
Location
Switzerland
Yeah the forum was down for. Some time.

Your fuel pressure seems OK, at least for the LPFP, it's normal to have such a big difference on the HPFP as long as then engine has not been run since it's a mechanical pump, it should move by cranking the engine I guess.

I would redo a compression test, everything is probably OK but as said, you probably ran the engine with low oil pressure for some time since the turbo leaking lots of it. I would also eventually remove the downpipe and inspect the catalytic converter as it might be clogged by the oil.
 

1131

Passed Driver's Ed
Yeah the forum was down for. Some time.

Your fuel pressure seems OK, at least for the LPFP, it's normal to have such a big difference on the HPFP as long as then engine has not been run since it's a mechanical pump, it should move by cranking the engine I guess.

I would redo a compression test, everything is probably OK but as said, you probably ran the engine with low oil pressure for some time since the turbo leaking lots of it. I would also eventually remove the downpipe and inspect the catalytic converter as it might be clogged by the oil.

Thanks. I might just go ahead and redo a compression test then. It's just a short walk and $40 rental from Autozone after all. It's just that I thought being able to turn the engine manually already demonstrates that it should at least be able to start. Similarly for the cat. Would a clogged cat prevent start? It may run like crap after starting, but it should start. That's what's got me scratching my head.

One odd other thing that I failed to mention is that when I pulled the plugs, they all smelled faintly of gasoline. That should never be the case. Any spark (even a weak one) would ignite any gasoline present. So I'm not sure what's going on with that either.

I thought about buying some starter fluid and squirting it into the port for the IAT after removing it. Just to see if it will start. I've been squeamish about that since I'm aware that it's not good for the engine. But just once for testing purposes should be ok I think. I might just do that while I'm at Autozone.
 

1131

Passed Driver's Ed
Well. On the bright side, I don't have to waste another week or so chasing down fuel supply issues. I appreciate the suggestion to redo the compression test. Unfortunately, it did not give me the result I was expecting. I get 110, 0, 0, 0. My engine appears to be destroyed.

I was so shocked by the result that I went back to cylinder one and tested it again. Same 110. There doesn't appear to be anything wrong with the gauge. Cylinders 2, 3, and 4 even sound different. Instead of the whirwhirwhir of the first cylinder, I hear more of a wheeeeeeeeeee.

Not sure how it happened. The engine was fine when I started the turbo swap. I filled the turbo with oil. There was the full 4.5L of oil in the system. I idled it for a full hour before the maiden voyage. No leaks. Even now. The dipstick says full.

I guess the turbo was blowing so much oil when it failed that it may have dried out an already old timing belt tensioner causing the chain to slip.

I think my next course of action will be:

1. Redo the compression test.
My online research indicates that I made several errors in conducting the test. I forgot to pull the fuse for the fuel pump. I forgot to put my foot down WOT. Technically, you're supposed to disable the power supply to the fuel injectors. I doubt that any of these things will significantly change the outcome. But I want to be complete. For the same reason, I suppose I ought to redo the test wet after dropping in a capful of oil into each cylinder. Somehow, I doubt this will make much of a difference for a cylinder reading zero.

2. Pull the timing cover and inspect the chain.

3. Potentially pull the head and inspect for damage.
I'm not even sure I can do this by myself.

4. Assess my options from there:
a) have someone rebuild it.
b) engine swap (with a used engine)
c) research the possibility of rebuilding it myself
(I'm thinking this is a bridge too far for my abilities)
d) sell it to a scrap yard.

I guess I'll be doing #1 and #2 on Christmas day. Happy holidays indeed.

I'm saddened. I really put a ton of time (and money) into salvaging the old girl.

smite.jpg
 
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vwengineer

Ready to race!
Location
Switzerland
That sucks definitely :( what's strange is that the engine first ran with the new turbo, it might be that the cam chain broke, remove the vacuum pump and have a look. I would say you are unlikely to bend valves on three cylinder simultaneously.

The cam chain broke on mine and nothing was harmed, although it can/should bend valves, it's not always the case.

Note that the ECU usually records a camshaft correlation error when you are out of timing.

Also pushing the accelerator pedal fully when starting does not cut fuel at least on my car
 

1131

Passed Driver's Ed
The only thing I had time for yesterday was redoing the compression test. I did not pull the DI power connector. I just pulled the 10A fuse for the HPFP. That's also what I did for the previous test. I stomped on the pedal and got these new values: 150, 0, 0, 0. So pulling the fuse did improve compression reading for cylinder one from 110 to 150. But zero still means zero. I also drizzled a capful of motor oil into each of cylinders 2-4. I didn't expect it to make a difference, and it didn't. It's not the rings. It's most likely the pistons.

The results are also consistent with what the spark plugs look like. There is a bit of char on the 1st plug. Plugs 2-4 are pristine (since they ARE brand new). I was a fool to ignore the fact that the plugs have a faint gasoline smell.

The results are also consistent with what I hear when I try to start the vehicle. I hear a whirwhirwhirTHUD whirwhirwhirTHUD. The thud is the one cylinder that is still firing.

The results are also consistent with what I felt immediately before the car died. The engine was shaking violently, as if valves were slamming into pistons.

That sucks definitely :( what's strange is that the engine first ran with the new turbo, it might be that the cam chain broke, remove the vacuum pump and have a look. I would say you are unlikely to bend valves on three cylinder simultaneously.

However unlikely it might be, that's what it appears to be. There is no other way to interpret a zero value on a compression test.

The cam chain broke on mine and nothing was harmed, although it can/should bend valves, it's not always the case.

I would say you got ridiculously lucky.

Note that the ECU usually records a camshaft correlation error when you are out of timing.

No DTCs of any kind. My computer is declaring "man, nothing is fucked here," while the goddamned plane has crashed into the mountain.

Also pushing the accelerator pedal fully when starting does not cut fuel at least on my car

We are talking about two different things. Pushing the accelerator ensures maximum air is available for the test. You cut fuel (by disconnecting the injector power cable or pulling the fuel pump fuse) to prevent it from spraying into the combustion chamber.

I'm googling videos on how to inspect for engine damage. I'll also be calling around for quotes on a rebuild. I know it would take me weeks if I want to try and do it myself.
 
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