dreaded 2.2 lumpy idle ?

Matt

hi all, newbie here but have read a fair bit and think the site is great so thought i would join to hopefully find the remedy for my car.
The problem is that i have a lumpy idle and flat spot at low revs and hesitation or misfire when coming down through the gears. The car is a 2003 with 88000, full service history to 77500. Once the car picks up, say 30 and above it drives faultless and smooth and pulls well, when idling it kind of chugs and the headlights grow brighter then dim in succession. From the threads i have read to cure this i have :

changed coil packs, not once but twice
changed the egr and then blanked off
swapped out cts
fitted new plugs
swapped out crank shaft sensor
changed fuel filter
checked compression, all perfect
checked fuel pressure, spot on
meticuously cleaned the throttle body
cleaned and checked all breathers.
changed maf sensor
Yet the problem still persists and am at the end of my tether here and sick of wasting money where it is not required
I had this hooked up to a machine and came back with p0300, multiple miss fire but the emissions light was the only one that came on. the guy stated that he was 100% sure it was either maf or egr ( this was after an hour of live data capture and head scratching ) but since changing them i`m still no further forward. Please can someone help me on this. Just to add it has never stalled yet , just bloody lumpy and chugging.

Ellbubb

Hi peanut,
Welcome to z22se, Have you had any trouble with the cat or have you check to see if the pre-cat has broken off and is blocking the exhaust ?, i'm still learning the engine myself but there are more experienced members here who should be along to help as well.

Matt

i had heard of maybe a blocked cat so a mechanic i use normally for servicing etc loosened the down pipe bolts so the cat was almost off and it still ran the same. as for the precat....no idea. it doesnt blow or anything if thats what you mean.

Ellbubb

viewtopic.php?f=3&t=19992&p=1178758&hilit=pre+cat#p1178758

pre-cat in the pic. Its just before the cat and can cause issues when blocked or become loose.

MikeS

front lambda sensor also

i seen z22se with a faulty front lambda and has lilke a misfire at low revs and lumpy idle but no fault was pending or live

so you need to monitor front lambda volts and how it pulses

Dan

I had a very similar problem with mine not long ago, turned out to be the lambda sensor. Like mike says monitor the reading from the front lambda and it should pulse up and down from about 50mv to 850mv (averaging around 450-500).
The best thing to do if you can get your hands on a diagnostics tool, is take it for a drive and data log the readings from all the engine sensors. Then you will be able to spot the problem a lot easier.

If you can't borrow a diagnostics tool I would recommend something like this one below. It'll save you fortune in time and un-necessary parts.

http://www.ebay.co.uk/itm/OP-COM-OPCOM- ... 648wt_1110

Good Luck :thumbup:

Matt

i`ll look into that cheers. been reading also about the chain and that it might have jumped a tooth !!!! but would it still run a1 away from idle ?? just trying to eliminate any other possibilities. the car is running quite rich lately and fuel usage has gone through the roof....

astra22bertoneauto

peanut said:
i`ll look into that cheers. been reading also about the chain and that it might have jumped a tooth !!!! but would it still run a1 away from idle ?? just trying to eliminate any other possibilities. the car is running quite rich lately and fuel usage has gone through the roof....

If your chain had jumped a tooth you would know about it! But you've said compression test is ok. what were your figures?

If fuel use has increased then the lambda controls this so if its playing up......

Matt

im sure it was 180 somethings ?!? across all 4 cylinders. even had fuel press. tested and that was spot on. I mean really...would a knackered lambda cause idle misfire and hesitation, even from first turn of key in the morning ?

astra22bertoneauto

yes its possible. I would look at 2 things before going any further; 1. check lambda readings & 2. check to see if your precat has not broken up & fallen down blocking the lambda/cat.

Removing the precat is a good cheap mod anyway. this has been known to break up and fall down inside the downpipe blocking the lambda/cat.

Dan

try disconnecting the lamda sensor see if it makes a difference. the connectors are on top of the gearbox if you look down behind the battery, the front lambda usually has a blue plastic part on the plug and the rear sensor has a red part on the plug.
The ecu should estimate the readings based on reading from the other sensors. you will probably get a EML light when after the engine warms up, but it will disappear after a few starts with it reconnected.

the front sensor
http://i.ebayimg.com/15/!BSzEh-!!2k~$(K ... w~~_35.JPG

the rear sensor
http://i.ebayimg.com/22/!BQqPMCgBGk~$(K ... Q~~_35.JPG

Dan

Did you find the cause of your problem mate?

martint10

had the same problem with mine. Idle was a bit lumpy and the mpg was way down. Changed the front O2 and its all sorted now.

Adrian_Marshall

Got the the same prob with my 2.2 sri vec , going to change both front and rear o2 sensors at the week end , wish me luck , this is going on for the last 2 years now and got to sort it ,!!!!!!!!!!!!!!!