The dreaded 'MISS'

[Ralphski]

Aye up.

I have a MY11 VE Series II Calais (LLT 3.6)
VIN 6G1EX5EV9BL543119
Engine LLT
179000kms on clock

It's developed a pesky missfire... Not always noticeable but most noticeable when under load (going up a hill) & sometimes when coming to a stop it'll shudder, almost stall then recover...
So, sparkplugs & coils replaced less than 10,000kms ago, no change.
No error codes

So, what's next team?

 

[greenacc]

Did you fit cheap ebay coils?
Check the throttle body, air filter, MAF and all their harness plugs are clean.

 

[J_D 2.0]

Are you sure it’s a misfire? I thought I had a misfire in my SV6 a while ago but it’s actually the transmission on the way out.

If it is a misfire have you checked your air filter and the air intake tract for leaks? Have you cleaned the MAF sensor lately?

 

[Ralphski]

Did you fit cheap ebay coils?
Check the throttle body, air filter, MAF and all their harness plugs are clean.

No, no cheap ebay coils. However the miss was there before the coils were replaced. It hasn't gotten worse with them in.
I'll dig into your suggestion, cheers.

 

[Ralphski]

Are you sure it’s a misfire? I thought I had a misfire in my SV6 a while ago but it’s actually the transmission on the way out.

If it is a misfire have you checked your air filter and the air intake tract for leaks? Have you cleaned the MAF sensor lately?

I've never cleaned the MAF during my ownership, no leaks I can hear. Cheers, I'll give the MAF a clean
Also got new O2 sensors on the way

 

[J_D 2.0]

I've never cleaned the MAF during my ownership, no leaks I can hear. Cheers, I'll give the MAF a clean
Also got new O2 sensors on the way

Make sure you use contact cleaner or the proper MAF cleaner to spray it down. Anything else will probably damage it.

 

[Immortality]

Are these things direct injection( I can never remember the exact Alloytec model variations)?

 

[Dirty WH]

Are these things direct injection( I can never remember the exact Alloytec model variations)?

Yes, the LLT’s are direct injection.

 

[Ralphski]

Are these things direct injection( I can never remember the exact Alloytec model variations)?

Yup, certainly is

 

[Immortality]

You could try an upper cylinder cleaner. The problem with direct injection is nothing cleans the intake valve. with port injection the intake valve always gets washed with the incoming fuel, direct injection doesn't so over time oil can build up on the intake valves. Well known problem with direct injection unfortunately.