Still having problems after replacing cats

[bacon_pancakez]

Hi

I have a series 1 2010 ve sv6 sedan and am still having prooblems after replacing cats.

A little history. About 1.5 yrs ago the car went into limp mode and the mechanic replaced the spark plugs and coils.

Went into limp mode couple more times over the next 1.5 yrs so put some engine cleaning stuff through the engine and fuel tank which seemed to resolve the issue.

Just recently the car was shuddering and misfiring. Mechanic replaced cats (checked after they were out and def stuffed) and while the car does drive a lot better, as soon as I put the foot down a bit or go up a hill it starts shuddering and misifirng again. Mechanic said it was shutting down cylinders but when you really put the boot down, it activates the cylinders again for a short period. Was told it might just be the car getting used to the new cats but I'm not sure on that.

Any ideas?

Cheers

 

[the_boozer]

getting used to the new cats is a bs story. Does it do it every time? Find a real mechanic that doesn't just change parts.

 

[krusing]

As above ^^^^^
Your mechanic is taking you for a ride in your car, at your expense !

"might just be the car getting used to the new cats"
I think that statement needs some kitty litter !

Is the MIL on ?
If so, do you know what DTC's its activated ?
There has to be more to the fault/s than he is letting on.

Find another mechanic that knows his stuff.

 

[bacon_pancakez]

The check engine light comes on when you start the car and flashes/dings on the display when it misfires when putting foot down.

I think it was displaying the P0420 code before replacing the cats (haven't checked again after picking it up though)

It was once showing inconsistencies when I had the 02 sensors tested, could they cause this?

I'll try another mechanic and see what they say.

 

[krusing]

The check engine light comes on when you start the car and flashes/dings on the display when it misfires when putting foot down.

I think it was displaying the P0420 code before replacing the cats (haven't checked again after picking it up though)

It was once showing inconsistencies when I had the 02 sensors tested, could they cause this?

I'll try another mechanic and see what they say.

Ask the next mechanic for his advice first,
Maybe let him have a look at the car,
and he hopefully will provide a reasonable explanation.

But be aware of the Parts Cannon, they are always primed and ready to fire.

PO420 quite possible is/was just a O2 sensor fault. " Catalyst Efficiency Below Threshold (Bank 1)"
or worst scenario,
Timing chains.
As I had a very similar issue, I replaced the o2 sensor and fixed the fault.

However, a P0420 can indicate a number of issues, including a Intake/Vac & exhaust leak.

 

[bacon_pancakez]

So I went to another mechanic and they are saying it's possible injector problem or ECM. Cat code has gone and now getting codes p0301, p0303, p0305, cylinder misfire.

This was their report:

- inspected fuses for odd bank injectors and coils - OK
- inspected ground points on head and block - OK
- inspected for vacuum leaks - OK
- check evap solenoid operation - OK
- inspected plugs and coils for damage and bad connections - OK
- Applied heat to ECM to check for possible bad contact while flexing housing - OK
- watching data slight misfire occured on cylinders 1 and 5

Possible bad injectors or contamination down bank one fuel system, would require manifold and injector seal kit to be removed to inspect, could try top end / injector cleaner before dismantling.
Also can not fully rule out ECM - May have intermitant bad cicuit drivers

They have quoted me $1500 to inspect injectors. $900 in parts and the rest in labour.

What would cost $900? Only things that might need replacing as far as I understand (they said to just inspect it) would be the manifold gasket, spacer and injector o-rings..?

 

[Ginger Beer]

Cleaning and flow testing the injectors would be a few hundred I assume if the shops sends them off site to do

Then cleaning the fuel lines, new fuel filter

I picked up contaminated fuel once, my fuel system was full of crud, tank came out, new fuel pump, filter, lines needed cleaning, and injectors came out for cleaning and flow testing

Now that was a PITA

 

[losh1971]

What cats did he fit. If he fitted different ones to factory you can have problems.

 

[bacon_pancakez]

It just says Holden SIDI 3.6 Cat on the invoice. No other info.

 

[lout]

see this post

https://forums.justcommodores.com.au/threads/ve-ss-throwing-codes-and-missfire.300849/page-2#post-3376517