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Discussion Starter #1
Hi all, just have a question if someone with diesel knowledge can maybe assist, golf 4 TDI ahf engine, engine recently replaced, running good just downpiped it yesterday sounds good! Now today I was driving a bit hard, engine was warm I heard a pop almost like a backfire and saw a black cloud of smoke not too big. Then the turbo was working intermittently like from 2000 it worked cut out worked again at 2300 then cut out and the higher the revs the less the turbo worked, I opened up the hood to find the intercooler connection behind the headlight was not connected, car always drove fine before downpipe when driving hard, I reconnected the intercooler and took it for a spin, seems better now but it's not hot so I'm scared to drive till it's hot again, I will be driving like a chior boy from now on, probably a good thing! Anyway I just want to find out should that intercooler pipe disconnect itself due to vaccume? Doesn't make sense which makes me think it was always disconnected since the new engine in which case the turbo wasn't getting sufficiently cooled air? Also can a turbo overheat and be fine again when it cools?

Any advice is appreciated!
 

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Driving like a choir boy from now on huh? ;) Exhaust gas enters the turbocharger, making the turbine spin and help push (compress) more (fresh) combustion air into the engine. It sounds like you may have experienced excessive pressure on the intake side, making the hose pop. Downpipe eliminated restrictions from stock exhaust, increasing flow for the exhaust... I have no experience with downpipe installs, so I cannot comment on specific effects on the turbo - and possible/needed adjustments.
The problem may have also been helped by turbo sticking vanes, sticking/malfunctioning actuator etc…
ECU probably sensed overboost, getting the engine into limp mode to prevent (further) damage to the turbo. When you restart the car, the limp mode is reset until triggered again… Not sure if you are able to check any codes, but I encourage you to do so. You may want to check proper functioning of turbo, including the actuator (maybe re-adjusting it). Here are some links for you… I would be worried about turbo damage - now or in the future. Was the hard pipe (connected to intercooler) damaged by the power steering pump pulley?


https://idpartsblog.com/2014/08/11/vnt-1517-actuator-calibration/
 

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Discussion Starter #3
Hey man thanks for the input! It wasn't exactly limp mode, limp mode as I've experienced it before cut the turbo off completely, this was like the turbo half working when it wants to and cutting off at different times during acceleration. But there may be more forms of limp mode then I am aware of? Because my limp mode previously didnt go away till errors were cleared. I did scan for errors and nothing came up, and no damage besides a little surface scratches on intake pipe. I guess I will try service my old turbo to prepare for the worst and see if it happens again. But I doubt it will happen if I just drive like a respectable human :p
 

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I'm told VW do a repair kit for the VNT but they aren't easy to fit. When I find the post on another forum I will post the part number.
 

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Well check the connectors. Typically the one at the anti shutter valve goes first. The solution is a product called a doggie collar. There are also more connectors on the inter cooler. The common problem on all the joints wear. Either the nubs on the hose, the o rings or the clip connector. These joints only need a little gap to leak. The more leak the more of a black smoke show.

Sent from my SM-G900T using Tapatalk
 

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Discussion Starter #7
Anti shudder valve connector seems fine and car runs perfectly after reconnecting the intercooler to it, I'm thinking there was just too much pressure in the system I was hitting like 4500 revs possibly, turbo was working very hard will look into doggie collars but I'm thinking just drive chilled for a while then do a front mounted IC with stronger clips? Would this likely solve the issue? And thanks for all the replies everyone, this forum is amazing!
 

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Auto or manual? I have an auto and when getting on it hard shifts at 4200.
Try shifting earlier and see if the IC connectors stay completely attached. Wouldn't be a bad idea to monitor boost with a gauge. Torque pro with a BAFX bluetooth adapter is most cost effective. If IC Connectors are still getting loose the aftermarket connector are $50 each. It may sound steep but if you only replace the seals for $50 to $60 and it doesn't work your buying the connectors too.
 

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Discussion Starter #10
It's a manual, just did it again had a look and there's oil residual where it clamps down so removed it cleaned the oil off and re fastened it as well I could, we will see if it happens again, also used some zip ties to keep the hose to the left so if it does pop off the hose doesn't hit the ps pump, as a side note there doesn't seem to be any o-rings or spaces for any. Do you guys think a decent fmic would fix this?
 

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I don't know where I got this but I thought you had a pd engine like the North American BEW. The connectors are much less reliable than previous clamp systems. If you are getting oil out of the joints there is a leak. MonI toeing the boost is still a good idea. If your turbo is overboosting I can't see a new intercooler system fixing that. Get the car to work as designed.

If the joints leak, get them sealed. No need to throw money at it until you figure out what the problem is.
 

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Discussion Starter #12
Nah it's the ve, and not much oil like just a little residue, my previous engine ran away so it's most likely from that since I don't think the garage cleaned the pipes properly, they did send the ic for cleaning though. Wouldn't overboost put it into limp mode?
 

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Nah it's the ve, and not much oil like just a little residue, my previous engine ran away so it's most likely from that since I don't think the garage cleaned the pipes properly, they did send the ic for cleaning though. Wouldn't overboost put it into limp mode?
What kind of time frame was the engine replaced? It seems as the shop had a responsibility to get everything back together and running properly before they handed it back. It would only make sense to look for boost or vacuum leaks and turbo operation while doing the engine swap.
 

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Discussion Starter #14
What kind of time frame was the engine replaced? It seems as the shop had a responsibility to get everything back together and running properly before they handed it back. It would only make sense to look for boost or vacuum leaks and turbo operation while doing the engine swap.
Was replaced last year September, but they did a really shite job, the metal cover by gearbox was bent, some cable holders etc were not in properly, like not lined up properly and held in with one bolt, the piping was on incorrect causing my Aircon fan to take some damage, didn't top up fluids properly also put the wrong coolant in, I also had to request my old injectors because they were slyly put to the side and not returned with the rest of my now spare parts, my one wheel nut was also missing they swore they didn't have it so basically I don't have any faith in them anymore, they just put it in started it up and said here you go, I don't even want to take it back to them to complain because the owner is a nice guy but his mechanics are dodge to say the least, I'm just done with them really. Rather doing everything myself from now on atleast then I know exactly what has been done, but I will look on the bright side atleast they changed the timing belt right, will look up how to check for boost or vacuum leaks thanks again for the input!
 

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Discussion Starter #18
Just thought I'd give an update, haven't had any issues since cleaning off the oil between the joints, have been pushing it from time to time with no pipes popping off thankfully. Thanks for the input all. Must also add that downpipe with straight exhaust (no tuning yet) I can feel a difference in power output on higher revs, normally the car would feel sluggish throughout the rev band but now it feels like it just keeps giving.
 

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Thanks for the update. It sounds like you're enjoying your handy downpipe work - nice job!...

Maybe we'll get a chance to see it in-person one of these days - though it is far away. Cheers!
 
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