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#31 northpole

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Posted 20 August 2020 - 02:02 PM

Aye, noticed the post. Did ask when it was in the garage 2 weeks ago for them to check all grounds and clean them up. So wondering now if they've not secured one properly or they've not bothered to do it. (Wouldn't surprise me.)

you can diy that it's not to much work... 




#32 DerPanzerWagen

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Posted 21 August 2020 - 07:47 AM

Righto, car now starts and communication is back on.

 

Either way:

  1. unplug MAF, car actually starts and runs better. In fact, you can get a good run in it once the ECU default setting kicks in! Only really complains once after about 3 journeys and flips the engine light. Only gives the MAF sensor code p0113 and not the p0420.
  2. plug MAF back in, car is fine for 1 journey. Then on the next journey, the car is harder to start, the engine plays up and it drags and it flips the engine light. Gives out only the p0420 code and not the MAF code. Stop the car to clear the code. Rinse and Repeat. 
  3. In fact, unplug any vacuum connection in the car and it will do the same thing. Triggers the default settings on the ECU and throws out the relevant fault codes but never the p0420. 
  4. Unlugging the lambdas only gives the lambda errors but car will run like utter rubbish. Lambda errors from the post-cat will give the error for the missing lambda first but not always the p0420 later.

So: fuel trims are fine during 1 & 3 but not during 2 & 4, (obviously). (Says to me that the p0420 is a weak error code that can be overwritten by higher priority circuits.)

 

No. 2: Fuel trims on bank 1 sensors 1 & 2 get stuck at just -2.5% at about 2400rpm. Car was in closed loop when it triggered the engine light. Light never comes on in open loop but you can feel it in the accelerator pedal when it's about to switch over. Throttle position is around 45%. 



#33 northpole

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Posted 21 August 2020 - 11:12 AM

So what did you do to sort it out other than testing? 



#34 DerPanzerWagen

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Posted 22 August 2020 - 11:39 PM

So what did you do to sort it out other than testing? 

 

Running things in test mode, getting the ECU to learn some manners while driving around with everything plugged in as it should be. So far, I've driven the car for 2 days without the engine light coming on. (A new record for the past 7 months!) Compression is back up to 10bar across all cylinders. Has allowed me to narrow down the slight misfire at idle too, (coil, spark or both). But can't fix that until Thursday. Hopefully then all good to go for the MOT.



#35 northpole

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Posted 23 August 2020 - 09:39 AM

Change the spark plugs first, than the plug cables, than the coil... it is going from cheap to more expensive... or be like someone who wants to make sure and buy the whole lot and do it all in one go...  but if you can't find a record of the plugs being replaced i would start with those... replace with NGK R platinum versions they work really well in the V6 engines and are slightly cheaper than their equivalent from Bosh... (stronger, wider and earlier spark, makes sure the fuel actually burns completely)



#36 DerPanzerWagen

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Posted 23 August 2020 - 01:15 PM

Change the spark plugs first, than the plug cables, than the coil... it is going from cheap to more expensive... or be like someone who wants to make sure and buy the whole lot and do it all in one go...  but if you can't find a record of the plugs being replaced i would start with those... replace with NGK R platinum versions they work really well in the V6 engines and are slightly cheaper than their equivalent from Bosh... (stronger, wider and earlier spark, makes sure the fuel actually burns completely)

 

I get the NGK R platinum plugs. Going to change all the iginition coils back to OEM and have some on order from VW. (I've been running cheap ones from ECP for the past year. I think the coils are creating a bit of a current draw on the battery as these aren't very good.)



#37 DerPanzerWagen

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Posted 31 August 2020 - 12:57 PM

Hola b*tches!

 

An update...

 

Internal head gasket failure. I predict it will only be cracks on the gasket between the cylinders and none around the oil or coolant ports. As there's no funny residue in the oil/coolant, the fully working cat, no external leaks and no increase in oil consumption. I will let you know if I'm right when the head comes off a week on Tuesday. So you can prove me wrong in the meantime.  :P

 

How? 

 

After fixing obvious bits around the engine and checking the fuel injectors, I did more cold compression tests I found these were all over the place and not repeatable. Then had a think last night and the only thing I could think of was that full compression in the cylinders (or rather a full vacuum) isn't being created due to internal cracks in the head gasket. All this is triggering an engine light under certain conditions but explain why at times, everything appears normal:

 

  1. lower speed=lower/worse compression values=engine light: Bad cold starts, misfires, gaps on gasket are larger, giving very little compression (vacuum).
  2. hard acceleration=too much variation in compression values=engine light: Some gaps are better than others, varying compression (vacuum) and perhaps over compensation. 

So therefore: Higher speed=higher/better compression values=no engine light: Engine heat closes gaps on the gasket, giving full compression (vacuum). 



#38 northpole

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Posted 01 September 2020 - 07:10 AM

Uhmmm that sounds plausible, but before you take the head off... check the head-bolts are tightened to manufacturers spec... it might not be tightened down enough causing some head-lift and therefore the weird readings... tighten them down to manufacturers spec and test the compression value after.. if those stay the same you probably have found the problem.. if not than you can go ahead and go for a new headgasket.

 

Mind you i have yet to see a head-gasket go on a VAG V-engine that didn't break the oil/water channel seals, but it cant be ruled out, so you are either lucky (less cleaning up to do) or it was a faulty gasket in the first place...  if you are going to do that yourself make sure you get the last version it is a little bit thicker and will account for the head-skimming that will have to be done also...  you can just use a wire brush drill attachment to clean the top of the  bottom block (and the head also to be honest, i have done it a few times but this was with heads that were water-level straight) ..... now when i do a head gasket on a VAG V-engine (vr5.vr6,v6, r32 or r36) i always get new headbolts unless they are fitted with ARP head-studs with nuts...so don't forget to put new ones on.. because if they have been reused a few times before they can cause head-lift. 



#39 DerPanzerWagen

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Posted 01 September 2020 - 09:41 AM

Uhmmm that sounds plausible, but before you take the head off... check the head-bolts are tightened to manufacturers spec... it might not be tightened down enough causing some head-lift and therefore the weird readings... tighten them down to manufacturers spec and test the compression value after.. if those stay the same you probably have found the problem.. if not than you can go ahead and go for a new headgasket.

 

Mind you i have yet to see a head-gasket go on a VAG V-engine that didn't break the oil/water channel seals, but it cant be ruled out, so you are either lucky (less cleaning up to do) or it was a faulty gasket in the first place...  if you are going to do that yourself make sure you get the last version it is a little bit thicker and will account for the head-skimming that will have to be done also...  you can just use a wire brush drill attachment to clean the top of the  bottom block (and the head also to be honest, i have done it a few times but this was with heads that were water-level straight) ..... now when i do a head gasket on a VAG V-engine (vr5.vr6,v6, r32 or r36) i always get new headbolts unless they are fitted with ARP head-studs with nuts...so don't forget to put new ones on.. because if they have been reused a few times before they can cause head-lift. 

 

I'm pretty confident about how the gasket has broken - I think I've caught it early enough to be able to lift it out in 1 piece. Been checking the levels before use and everything is the same each time. Leave it any longer though and i'm asking for further trouble where a crack may go through the channels. The head gasket was replaced along with the timing chains and guides before I owned it at around 30k. (There was an issue on some engines if I remember right. Those bolts haven't been touched since as far as I know.



#40 northpole

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Posted 01 September 2020 - 10:28 AM

I'm pretty confident about how the gasket has broken - I think I've caught it early enough to be able to lift it out in 1 piece. Been checking the levels before use and everything is the same each time. Leave it any longer though and i'm asking for further trouble where a crack may go through the channels. The head gasket was replaced along with the timing chains and guides before I owned it at around 30k. (There was an issue on some engines if I remember right. Those bolts haven't been touched since as far as I know.

Than change it to make sure... and yes they ised to burn out around the 3rd cylinder... that is why i said get the last type of headgasket, they are also a bit thicker not by much but a whole 2mm and that is quite a lot...

I forgot the part number for it but if i am correct it is the last one listed for your engine code on the oem parts catalogue and it has the highest number, it should also be listed as the replacement for the previous ones.

#41 DerPanzerWagen

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Posted 01 September 2020 - 04:03 PM

I forgot the part number for it but if i am correct it is the last one listed for your engine code on the oem parts catalogue and it has the highest number, it should also be listed as the replacement for the previous ones.

 

022103383F (as of 1st Jul 2020)?



#42 northpole

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Posted 01 September 2020 - 05:10 PM

Sorry mate I'm not home so o can't check my etka... so you might be able to double check it on 7zap

#43 DerPanzerWagen

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Posted 08 September 2020 - 07:32 PM

That's the one they've put on the job list. It's gone between cyl. 2 and 4 by the way.

 

So I was right in the end.  ;)


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#44 northpole

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Posted 08 September 2020 - 07:58 PM

Good you found the problem now you know how to sort it. Soon a good running engine

#45 DerPanzerWagen

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Posted 12 September 2020 - 06:50 PM

The engine is out of the bag. 

 

What I do know so far is that:

  1. Cylinder head has been sent off for pressure testing.
  2. No oil or coolant channels broken on the head gasket.
  3. Bank 1 (cyl. 1, 3 & 5) hasn't been badly effected - it's all looking fairly clean for the mileage but the valves are looking bit worn but will replace all.
  4. Bank 2 (cyl. 2, 4 & 6) are effected:
  • Head gasket - gone between cyl. 2 and 4.
  • Spark plugs 2, 4 & 6 look a bit grim for the very short amount of time these have been on for.
  • 12 Valves looking a bit worn with some showing a 2mm of bend on the stems - again, going to replace all of them, not an expensive thing.
  • 9 Piston rings to replace.
  • Possibly need to replace 3 pistons

 

Anyhow, won't be using the previous set of no hopers to fix my car. Business owner admitted that he's got an Audi A8 sat that he can't seem to fix despite putting a new engine in! :lol-lol: Past 6 months has been like watching a gig by the Pet Shop Boys: One doing the posing behind the laptop with VCDS and the other one singing about how they will change the EVAP stuff, replace all the lambda sensors, spark plugs, MAF, engine mounts, etc... And then proceed to look all pompous at the end of it all.

Attached File  psb.jpg   94.06KB   1 downloads

 

*because "my customer" doesn't scan.



#46 adam-

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Posted 13 September 2020 - 03:54 PM

If you need pistons, or any bare block bits for that matter, LMK.  I've got 2 dead blocks for abusing parts from.


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#47 DerPanzerWagen

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Posted 13 September 2020 - 07:15 PM

If you need pistons, or any bare block bits for that matter, LMK.  I've got 2 dead blocks for abusing parts from.

 

Ta for the offer - but due to some 'odd' errors in my VIN, they have to go to the special shed at VW, somewhere. As has my cylinder head.... 







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