clk 430 hesitation issues when accelerating

[maani]

Hi All,

I am getting a bit lost on ideas now, and would appreciate any help.
I find the car hesitates when I put my foot down, there is a long pause then the car slowly starts picking up speed.

I changed the MAF for original bosh part, and spark plugs were changes in Nov 2010. I also checked the live data on a star and all coil packs are in range and no issues were seen with any sensors. Also there are NO error codes stored. The emission tests at local MOT station showed no issues either.

I have also cleaned the throttle body and idle seems to be ok, with a very slight fluctuation ever minute or so.

Also when accelerating I do not feel the inrush of AIR like before, and not sure what values the AIR mass filter should show on the live data output.

Has anyone had similar issues or can anyone comment on anything I have missed out or can try?

Thanks
maani

 

[BlackC55]

Blocked cats?

 

[maani]

thanks BlackC55, would the emission test not show this?
Is there a way to test if i have blocked cats?

I have also put BG44k fuel cleaner additive.

 

[BlackC55]

If the cats are blocked they get very very hot and often glow red.

The value on a star for the air mass at idle is about 16 but no more for your engine.

 

[maani]

great I will recheck the air mass at idle.
Sorry but is will this glow be visible anywhere as I am not sure how to check this?

 

[BlackC55]

You will see the glow as it is quite obvious. Check when its dark outside.

 

[BlackC55]

Might be worth checking fuel pressure too. You need a proper guage to do this that will fit your fuel rail. 4 bar is right from memory

 

[maani]

Thanks a lot for the great advise as always, I now have some further things to check

 

[maani]

Hi Olly,
quick update, I took the connections to the air mass sensor off and drove the car. it felt exactly the same, also idle was no different :-(

I am now wondering if the air mass sensor is toasted as it is a new OEM bosh part.
On star the value was coming in as 12 on idle. Also I had a look under the car and could not see anything glowing red after I did a 5 min drive, so I hope this means the cats are ok....

Is there any other things I can do to check if I got faulty air mass sensor, i did not by it from ebay ;-) ?

When disconnected I started the car and also checked the voltage on the output from the top 2 connectors going in the the air mass sensor and I was seeing around 8volts, is this ok?

Thanks