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Best options for a fresh(ish) motor?

socal87

Drag Race Newbie
I always told myself I'd run my car into the ground before I'd part ways with it, but I thought it would be a lot further down the road, so to speak.

2012 GTI, CBFA motor, 173k miles. APR Stage 2, Carbonio intake, SBC clutch. Intake manifold was replaced and intake valves cleaned about 17 months ago; timing chain tensioner failed and replaced some time in 2017.

I've been religious about oil changes and I always replace the filter. I do drive the absolute piss out of it, though, so I've ordered a BlackStone analysis to see if the oil shows anything.

I noticed the rattling/tapping a couple months ago; it only seems to occur under acceleration, and it's loudest under light acceleration. It doesn't make any noise during idle or overrun, only under load.

I also have a recurring random/multiple cylinder misfire code, as well as occasional "intake flap position sensor implausible". I've had a few very rough cold starts. I've changed the plugs and swapped the coil packs around to no avail. Bonus points if you know how to test a VW coil pack with a multimeter?

I'm considering seeing if the dealer will at least diagnose it, although I'm wondering if an enthusiast shop might be a little more honest and realistic. It's definitely a bad time to have to replace a car, for sure.
 

king1138

Ready to race!
When was your last carbon cleaning? Carbon building would explain all of your symptoms.
 

socal87

Drag Race Newbie
When was your last carbon cleaning? Carbon building would explain all of your symptoms.
I had the carbon scraped off when I had the intake manifold replaced in February '21.

You think carbon buildup would cause a knocking noise? Like maybe excessive valve lash?
 

GIACUser

Master Wallet Mechanic
Uh you may have a rod bearing going given the mileage and description. If that is the knock and it lets go the damage can grenade the motor.

Seems likely with that much mileage. Best not to drive it much or at all until you know what’s wrong.
 
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socal87

Drag Race Newbie
Uh you may have a rod bearing going given the mileage and description. If that is the knock and it lets go the damage can grenade the motor.

Seems likely with that much mileage. Best not to drive it much or at all until you know what’s wrong.
Pretty rare problem with these motors. Wouldn't rods knock constantly though? It only does it on acceleration, not idle or overrun.
 

GIACUser

Master Wallet Mechanic
Pretty rare problem with these motors. Wouldn't rods knock constantly though? It only does it on acceleration, not idle or overrun.

Probably not so rare on engines of this mileage.

Rod knock is a tapping that comes from within your engine that typically increases with speed or when the engine is under load.

These engines are robust but rod bearings do wear out on any motor. Once there is play the bearing will knock first and eventually give way, the rod breaks and bad things happen.

Typically it will keep on getting louder. Best to determine if this is your issue sooner rather than later.
 
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socal87

Drag Race Newbie
Probably not so rare on engines of this mileage.

Rod knock is a tapping that comes from within your engine that typically increases with speed or when the engine is under load.

These engines are robust but rod bearings do wear out on any motor. Once there is play the bearing will knock first and eventually give way, the rod breaks and bad things happen.

Typically it will keep on getting louder. Best to determine if this is your issue sooner rather than later.
For sure. What would be the best way to tell? Pull the oil pan and see if there's any play in the rod big ends?
 

GIACUser

Master Wallet Mechanic
For sure. What would be the best way to tell? Pull the oil pan and see if there's any play in the rod big ends?
Symptoms include knock but also low oil pressure, metal shavings in oil pan. If enough play guess you could tell by moving and if you removed cap and bottom of bearing you might see damage to crank
 

socal87

Drag Race Newbie
Symptoms include knock but also low oil pressure, metal shavings in oil pan. If enough play guess you could tell by moving and if you removed cap and bottom of bearing you might see damage to crank
I don't have a way of monitoring oil pressure unfortunately. I have a PolarFIS but there's no oil pressure transducer as far as I know.
 

Allchokedup

Autocross Champion
I don't have a way of monitoring oil pressure unfortunately. I have a PolarFIS but there's no oil pressure transducer as far as I know.
You can drain oil and see if it has a metallic sheen. I had a work truck they forgot to put oil in. After filling it up then draining again the oil glistened in the sun like metallic spray paint.

What about your turbo? Could be waste gate rattle but I assume you would have p0299(low boost I think)
 

GIACUser

Master Wallet Mechanic
I don't have a way of monitoring oil pressure unfortunately. I have a PolarFIS but there's no oil pressure transducer as far as I know.
Keep in mind we don't know for sure this is the problem. When it is bad enough you would get low oil pressure light. Easiest would be to pull oil pan and look for metal shavings.
 

socal87

Drag Race Newbie
You can drain oil and see if it has a metallic sheen. I had a work truck they forgot to put oil in. After filling it up then draining again the oil glistened in the sun like metallic spray paint.

What about your turbo? Could be waste gate rattle but I assume you would have p0299(low boost I think)
I just did an oil change, didn't notice anything abnormal, and nothing stuck to a magnet. Still, I have a sample on the way to Blackstone.

I think it's either bottom end or valve train because it taps in time with engine speed and gets louder as RPMs increase.

Keep in mind we don't know for sure this is the problem. When it is bad enough you would get low oil pressure light. Easiest would be to pull oil pan and look for metal shavings.

I should have thought of that before I changed the oil. Don't want to waste it...
 

GIACUser

Master Wallet Mechanic
I just did an oil change, didn't notice anything abnormal, and nothing stuck to a magnet. Still, I have a sample on the way to Blackstone.

I think it's either bottom end or valve train because it taps in time with engine speed and gets louder as RPMs increase.



I should have thought of that before I changed the oil. Don't want to waste it...
You can still pull the oil pan, the kind of metal that rod bearing is made of is non-ferrous usually so it wouldn't stick to a magnet. Now if it got really bad over a long time you could sustain crank damage and that would have iron in it. If you have had a rod bearing go you would see it in the pan and those pieces might not drain out.
 

socal87

Drag Race Newbie
You can still pull the oil pan, the kind of metal that rod bearing is made of is non-ferrous usually so it wouldn't stick to a magnet. Now if it got really bad over a long time you could sustain crank damage and that would have iron in it. If you have had a rod bearing go you would see it in the pan and those pieces might not drain out.
True, I forgot they're kind of bronze... copper, lead, aluminum

Taking the car to a shop on Monday to have it looked at. I'm praying it's top end valve train type stuff, if it's bottom end I'll either be junking the car or buying a motor. I really don't want this to be the end...I'm the original owner of the car. If there's any good thing about inflation, it's that I'm unlikely to find a decent beater for less than the cost of a rebuild...
 
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