3.0T Engine Code Qurstion

[MSq5]

3.0T Engine Code Question

I have a '17 Q5 with our 3.0 supercharged engine. Its 034 Stage 2+ tuned and 100,000 miles. It now has lost compression on two cylinders. Scope shows cylinder wall scoring. Likely ring land failure. Not the fault of 034, as most miles were on EPL and its my heavy right foot.

I am trying to source a low mileage donor engine to swap my pulleys and use my existing ECU. 034 says it can work that way.

This is a CTU engine code, specifically CTUC. My research says that is correct for the Q5 272 hp variant, its original OEM tune. Of course its been upgraded with all the things needed, Merc HX, 3.25 pulley ratio, RedStar shielded test pipes, downstream bottle cats, high flow intake and such.

I'm having trouble finding a CTUC code engine with low miles. I have found a low miles CTUD engine from a '16 SQ5. Given that I plan to carry over my existing ECU, will this swap work?

Is there anything different about the CTUD engine other than the ECU tune? Is there anything else I might need to know, or is this not going to work? There id sn old thread here cimparing the various CTU variants, including the "C" and "D" versions, including cimparison of part numbers of every engine part. The "C" and "D" seem to be identical except for the different ECU (272 hp vwrsus 354 hp).

Has anyone put a CTUD code 3.0 in their CTUC code Q5?
Thanks, guys

[Smac770]

CTUA = C7.0 A6/A7
CTUB = B8.5 S4/S5 & D4.0 A8
CTUC = B8.5 Q5
CTUD = B8.5 SQ5

They're all the same engine, CTU. The driveplate will depend on the transmission. The exhaust manifolds for the 272hp applications (A4 CMUA, Q5 CTUC) are different from the 300+hp applications. But you can just move yours over; same for the drive plate.

[MSq5]

CTUA = C7.0 A6/A7
CTUB = B8.5 S4/S5 & D4.0 A8
CTUC = B8.5 Q5
CTUD = B8.5 SQ5

They're all the same engine, CTU. The driveplate will depend on the transmission. The exhaust manifolds for the 272hp applications (A4 CMUA, Q5 CTUC) are different from the 300+hp applications. But you can just move yours over; same for the drive plate.

Thanks! It was your analysis of part numbers in the old thread I found so helpful. I wonder what the exhaust manifold difference actually is. You did point out the part number difference. Same question about the drive plate. Is there any difference in the ZF8 between the two? Bolt pattern? I'm already self tuned with HP Tuner software and also have the 034 ZF8 tune.

Easy to swap out. Just curious.

[Smac770]

The drive plate will depend on the transmission. It's whatever it is as documented in the parts catalog. Looks like all CTUC and CTUD are the same drive plate, guess they were only paired with the ZF8 in the Q5. Looks like CTU+ZF8 (Q5,SQ5) and CTU+DCT (S4,S5) use the same drive plate anyway, while CTU+6MT (S4,S5) is a different plate (expected due to needle bearing). It's a more varied mess on the 2.0T. As for mounting, the 0BK is the 0BK, whatever engine it's bolted to.

No idea what's up with the exhaust manifolds, I'm sure something optimized for the different hp capabilities.

[silver_tt]

Sounds like LSPI. Were you using an oil with high Calcium detergency?

[MSq5]

The drive plate will depend on the transmission. It's whatever it is as documented in the parts catalog. Looks like all CTUC and CTUD are the same drive plate, guess they were only paired with the ZF8 in the Q5. Looks like CTU+ZF8 (Q5,SQ5) and CTU+DCT (S4,S5) use the same drive plate anyway, while CTU+6MT (S4,S5) is a different plate (expected due to needle bearing). It's a more varied mess on the 2.0T. As for mounting, the 0BK is the 0BK, whatever engine it's bolted to.

No idea what's up with the exhaust manifolds, I'm sure something optimized for the different hp capabilities.

Thank you. Looks like I just run my ECU with 035 Stage 2+ tune, move over the pulleys and roll. We can compare exhaust manifold at tge time.

Very much appreciated.

[MSq5]

Sounds like LSPI. Were you using an oil with high Calcium detergency?

I think it was a heavy right foot, 100,000 miles of aggressive driving, many hard launches and 1/4 mile Dragy runs, and as much as 21 psi boost, 7200 rpm shift points, coupled with piston design. Oil was Mobil 1 FS 0w40 religiously changed at 5,000 miles with Mann filter.

The dual pulley tune caused a driver side cat failure at about 80,000 miles. I installed test pipes, but it may not be coincidence that the two scored cylinders turned out to be on the side with the earlier cat failure.

There has been no measurable oil consumption between changes, no coolant in the oil, minimal fuel contamination. It just started oil fouling of plugs on cylinders 5 and 6. Compression was low on those cylinders - zero on 6, 70 on 5. Scope revealed cylinder wall scoring. All other cylinders are fine with compression in the 180-185 range. We have not broken down the engine to examine those pistons.

[silver_tt]

I see, thanks. I was also wondering if you possibly burned exhaust valves which I have seen several times on the 3.0T but if the cylinder walls are scored it sounds like like the rings bit the dust.

[MSq5]

Update: I have found a CTUC code donor engine with 67,000 miles. It is being shipped as I speak. The seller, a salvage yard with a good reputation, does not realize it is the same engine as in the SQ5 but for ecu tuning. They charge more, a lot more, for the Sq5 CTUD with 100,000 miles, thinking it is different/better. They have had few inquiries about the CTUC because there are much fewer Q5s with the 3.0T engine. Its been in inventory a long time and was not moving.

I think I got lucky at $3150 - $3600 crated and shipped. We shall see.

[NikolaZ]

You got really lucky, now make sure to open up the engine and check the piston rings. It will be a good idea to check the chains, or at least change the upper tensioners while the engine is down.

[MSq5]

You got really lucky, now make sure to open up the engine and check the piston rings. It will be a good idea to check the chains, or at least change the upper tensioners while the engine is down.

I just replaced the chains and tensioners on the original engine. I could move them over while its out. We will see what the replacement looks like. No real way to inspect ring lands without major disassembly. I will bore scope the cylinders for evidence of scoring, and verify static and leak down compression, though.