Backfire

Paul

Paul

Regular Member
Joined
Aug 28, 2013
Points
19
Location
Oxford
Model of Z
3 Sport 2.2i
Hi Guys

Just brought a Z3, 01 2.2i
It's just coming up to 90.000 has full service history, I've just had an oil service and changed the air filter and spark plugs using NGK BKR6EQUP. Since doing so the car has developed a backfire but mainly in the lower gears when letting off the accelerator. Apart from the this the car seems to running fine and not missing at all.
I've torqued according to info online, Could someone suggest what this should actually be? As I'm going to check again later or if there are any other thoughts?

Thanks
 
Hi Paul, and welcome!

When you say backfire, how loud are we talking? The 2.2i does tend to 'pop' and 'burble' a little when lifting off, and that's perfectly normal.

Obviously a loud backfire may be something else as the Badman says.

Cheers, Gary
 
Hi Guys, Thanks for coming back to me... I did check the coil packs and they all seemed fine...
Yeah, It's not a really loud backfire, It is more of a noticeable pop and only when lifting off in lower gears so perhaps this is normal then?
I guess I'll double check the plug torque and see then, But it seems to be running fine etc. Perhaps I'm just not used to it and it's as it should be :).
 
Hello Paul i've got a 2.2 2002 & i dont get any backfires, she does burble when foot of the gas
 
Could be a Cam Sensor. I had that on my 97 1.9, if I decellerated it would backfire and it felt as if the timing was going out of kilter.

Read the alarm codes and it came up as a Cam Sensor, since I've changed it, its been brilliant.
 
Thanks, I actually had both cam sensors changed with the oil service and it was fine since till the plugs were done, I'm going to check and re torque the plugs to 18-20 tomorrow. Fingers crossed it's that but will update tomorrow :D
 
The gaps on the new plugs will be different from the old ones (smaller), you probably just need to go for a decent run to allow the ECU to acclimatise to the change, I.e. timing adjustment. The pop is normally unburnt fuel igniting in the exhaust due to incomplete combustion ergo a timing issue. If it still does it after this then it can signify a cam or crank shaft sensor issue or an induction leak, but this will show up on a diagnostic and show up as a temporary loss of power.

I would just go for the long run, more fun ;) and see how it is after. The NGK plugs you have are really good and ensure a good burn, I have them in mine.

Hopefully it is the simple answer!
 
Hi Guys, I checked and reseated the spark plugs torque'd to 20... Took the car on a longish drive and all seems to be fine now :)
Thanks for the advice...
 
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