Cold engine chug/clunk noise at low rpm?

[ApproachMedium]

So my engine when started up makes some kind of noise, almost like it did when my injector harness failed on the #1. It does this once the engine runs for a minute and idles down. If i tap the gas gently it stops making the noise. It sounds like its coming from the bottom end of the motor. I first noticed this months ago after the injector harness was repaired and had it running up on my lift. I figured it was from the fuel and it being so cold out. Now it seems to do it when the engine is cold. Once it warms up it goes away but then the engine idle vibration is felt in the cabin more pronounced than id think. This is less when its warmer out, much worse when colder. Im thinking that part is the dogbone mount.

Could the mount be causing the noise i am hearing? Injectors? the number 1 injector was replaced. I do also need a timing belt replacement, i have 126k and no history on the car so its possible its worn a bit? Just trying not to blow this car up.

 

[super1]

So my engine when started up makes some kind of noise, almost like it did when my injector harness failed on the #1. It does this once the engine runs for a minute and idles down. If i tap the gas gently it stops making the noise. It sounds like its coming from the bottom end of the motor. I first noticed this months ago after the injector harness was repaired and had it running up on my lift. I figured it was from the fuel and it being so cold out. Now it seems to do it when the engine is cold. Once it warms up it goes away but then the engine idle vibration is felt in the cabin more pronounced than id think. This is less when its warmer out, much worse when colder. Im thinking that part is the dogbone mount.

Could the mount be causing the noise i am hearing? Injectors? the number 1 injector was replaced. I do also need a timing belt replacement, i have 126k and no history on the car so its possible its worn a bit? Just trying not to blow this car up.

Have you scanned for codes via VCDS or OBD eleven?
Check Engine Light on?
DMF bad?

 

[ApproachMedium]

Of course. I have VCDS. I have a EGR Low flow code and i have a DPF its cracked yer screwed code. No other codes or problems coming up and i check every few weeks since the light will cycle on and off between regens. These codes have been present since i got the car basically. This problem only happened after the car sat dead in my garage for a month when the injector pigtail wire broke, which was in nov. Its been back on the road since christmas.

 

[super1]

When it’s making the noise & if you rev it up some does the noise get faster while you rev it up?

 

[ApproachMedium]

If i gently tap the gas, it goes away completely.

 

[TdiG]

I’m having the same issue. Acts like a bad injector is how I’d explain it too. Had the egr/dpf replaced a few months ago through dealer and it was doing it before and still after. No check engine lights and the only codes were related to the dpf/egr issues. Told the dealer but of course they didn’t experience it so did nothing. It does it almost every startup now. Maybe something with the regen? Anybody got any other thoughts on this?

 

[ApproachMedium]

Well, I took my car apart yesterday to do the timing belt. I found the large upper idler pully to be NFG. I also found my accessory belt tensioner pully to sound like one of those spinny toys full of sand you give an infant. Im not sure if these are related but ill see if theres a diff after im done.

 

[ApproachMedium]

I’m having the same issue. Acts like a bad injector is how I’d explain it too. Had the egr/dpf replaced a few months ago through dealer and it was doing it before and still after. No check engine lights and the only codes were related to the dpf/egr issues. Told the dealer but of course they didn’t experience it so did nothing. It does it almost every startup now. Maybe something with the regen? Anybody got any other thoughts on this?

Funny you and i have the same issue. My DPF is cracked. My EGR is def gummed up. I havent replaced or cleaned either yet. No other codes. It def sounds like the bad injector/lack of fuel sound almost.

 

[ApproachMedium]

Okay so i had the flashing glow plug light again. The egr valve was stuck. Removes both valves on intake side of engine. Clogged full of crap. Cleaned as well as i could. The original post problem is now gone. Engine starts runs idles great. Vcds testing of all solinoids verifies they open close correctly, including exhaust flap.

New problem. The car surges when crusing on the highway. Cruise control is impossible. It will go away on its own and come back at random. Hitting the accel a decent way makes it stop. Stopping the car and restarting the engine makes it go away for the rest of the drive. My dpf has had a code (cracked) and the egr has had the low flow code just as long. I am wondering if its finally time to replace both items. It of course has to happen to me during the time that all of my other vehicles are down.

When i ran the codes yesterday after it first had the surging problem i had misfire codes on all 4 cyl as well as the p0300 for random multiple cylinder misfire. If i drive the car like i stole it, it runs fine.

 

[ApproachMedium]

Changed DPF. Engine runs great now. Everything drives perfect but when it idles cold after startup the original clacking/clunking is still there. Gently tapping the gas makes it go away. It will still do it after i shut the car off from driving for a while and restart but goes away quick.

Im thinking its an injector on its way out but i know nothing on diesel injectors. Checking the balances in vcds shows injector 1 and 4 (1 was replaced by my mechanic) in negative, and 2 and 3 +2 ish postive. Money is extremely tight right now or id go pull them and replace but throwing parts isnt an option unless i can determine thats the exact problem.