hey guys!

 

Did a bit of work to my VRS at the weekend; new spark plugs, new coil packs, cleaned out throttle body, replaced oil/filter, dropped sump and cleaned inside it and the oil pick up pipe, and put some fuel injector treatment in with a full tank!...but still have a bad jolting and backfiring problem on start up/cold engine!

 

Tonight, my mate plugged in his diagnostic on the car, 3 faults came up...P1296 - which I have figured out to be possibly the stat, as i replaced the coolant temp sensor the other week. P0141 and P0036, which are O2 sensor faults, both being Bank 1 - sensor 2. It's causing my car to go into limp mode when i fire her up, wether it be first thing in the morning, or when th engine is warm (say i parked at the shops for 15 mins and start her up again).

 

Had the computer plugged in, and before i cleared the faults, the car was doing its usual starting problem/choking right away. (low revs and stalling after a few clunks and jolts). did that a couple of times, then cleared the faults, and hey presto! the car starts up with no problem whatsoever! even drove forward a bit and it didn't kangaroo and/or stall!

 

So I've figured the problem to be the O2 sensor..... now finally getting to the main part of this topic ( sorry for my life story :p ).... but which O2 sensor am I going to replace, before i change the wrong one...upstream sensor? or downstream sensor??

 

cheers guys!

Edited 4 March, 201412 yr by wally22

Bank 1 sensor 2 is the downstream sensor, after the cat. This shouldn't affect the running at all. In theory, the only reason it is there is to monitor the cat efficiency. I'm not on my PC at the moment so can't check them codes

Sent with Tapatalk

Thanks mate.

was just weird how the fault was cleared and she fired up perfectly with no idle issues. I was on nightshift last night and left the car alone after she was reset, and fired up no bother again half an hour ago. I can't see the stat causing this though?

Edited 4 March, 201412 yr by wally22

P1296 is the coolant temp sensor, wiring or thermostat. Did you fit a genuine CTS?

P0141 and P0036 are the downstream lambda sensor. Usually when you see both codes, it means the cable to the sensor has been 'scraped off'.

What is the temperature gauge doing?

I put in a genuine oem CTS on, that sorted out a problem where it would show a temp on the gauge, then the next min, all the way at the bottom! But now that i think the stat is involved, is because she never sits in 90?, usually sits around the 70 mark.

i bought a new lambda sensor and my mot is up today, so going to drop her off at my usual garage and see if they can get it on and also fit a new stat. I've had enough of tinkering around and replacing every single part it could be. I suppose she needed a bit of TLC though haha

Any cold running issues get aggravated when the SAI kicks in. So it may be a combination of things. I have just had to disconnect mine as it was getting really rough with the sai running.

Edited 4 March, 201412 yr by karlbar2k

I couldn't find or hear any problems with the SAI unit, as it never came up as a fault....or would it even register a fault code if it wasn't running right?

 

Car's at the garage anyway, probably for a few days as they had a fair number of cars waiting to be seen haha! Going to miss my baby :( even though it has been peeing me off the last wee while! Also I got a bus fot the first time in years today hahahaha!! I didn't miss it one bit I'll tell you that!!

Try unplugging the sai (from underneath is easier) and start the car. See how it runs.

I'll see what she's like when i get her back from the garage. Had a voicemail from the garage saying it needed a couple of bits done to pass the mot, so will find out tomorrow morning what she needs. Just hope it's not pricey!! :(

hmm I would be more suspicious of a faulty MAF or maybe a crank shaft sensor as i have seen both of these cause poor start up and running

 

Sometime the crank sensor maybe be in a better position to start car ok but then a restart and the car is back to normal poor running

 

just my 2 p worth 

I've tried starting it with the MAF unplugged, and made no difference.

 

And with the crank sensor... wouldn't a fault code come up if there was a problem? just a thought.

 

cheers

my baby passed her mot all she needed was bushes up front will be picking her up after a wee sleep (finished nightshift this morn haha!)

they fit the lambda sensor and the thermostat so shall post back if all problems are cured

I've tried starting it with the MAF unplugged, and made no difference.

 

And with the crank sensor... wouldn't a fault code come up if there was a problem? just a thought.

 

cheers

 

In theory yes a fault should appear but does not always.

 

Anyway hope you get it sorted.

 

Good news on Mot as well.

picked her up and one thing caught my attention within minutes, they didn't reallign the wheels, steering wheel is a bit off center :( booked it back in for another day! but everything else good