Lambda causing my lumpy idle!?

8th May 2012, 23:07

Car had erratic idling so removed lambda and been fine for a week. Installed a new ntk sensor and the car is idling crap again. All i have is 421, decat supersprint and bmc cda. Why when the lambda is connected is it idling poorly?

Vts with one lambda before cat.

9th May 2012, 15:03

12th May 2012, 13:17

nobody experienced this?

Tested the new lambda and it is working perfectly so lambda is all good.

15th May 2012, 22:49

Might be the idel control valve mate. On back of throttle take it of and clean it up or test it should sort it out

16th May 2012, 10:29

it could be your idle control valve or map sensor or it could be your coil pack

16th May 2012, 11:42

If you clean the icv without putting a dab of oil on the plunger when refitting it can be a it sticky which slows down its response to rpm fluctuations.

When I oiled mine the lumpiness disappeared.

16th May 2012, 12:21

Im gonna give that a go my idle can be a little lumpy at times, I just put it down to the map/cam combo

16th May 2012, 12:50

Three Saxo's and a 106 and the idle has had a mind of its own on all of them, can't be arsed to look at it anymore.

Mine revs a little high when cold but settles after a few minutes of driving.

16th May 2012, 18:15

yeah, crazy.

Nothing else can be wrong though can it? I ran the car for a week without the lambda and it idled perfectly. It is only when a perfectly working lambda is connected the car will start idling crap again.

It can only be the straight through exhaust causing this which means a re-map is in order.

16th May 2012, 18:29

If you can then borrow a mates ecu & try it on your car & see if theres a difference mate.

16th May 2012, 18:40

possibly.

Are you suggesting the ecu might be knackered?

16th May 2012, 18:42

Quote:

Originally Posted by Psycho18

possibly.

Are you suggesting the ecu might be knackered?

It won't be your ECU , if they fail it wont run at all or cut out 24/7.

16th May 2012, 18:45

i had this! changed temp sensors and sorted

16th May 2012, 19:04

Quote:

Originally Posted by Psycho18

possibly.

Are you suggesting the ecu might be knackered?

Not completely knackered or it wouldn`t run at all but possibly faulty somewhere.

7th June 2012, 23:02

So i can just run any old ecu from a mk1 vts yes? If i can get hold of one i'll try otherwise just going to live with it. Not too bad with new lambda in.

29th March 2016, 16:39

Sorry for raising this thread from the depths of time but this is exactly my issue with my 16v vtr. Can anyone else shed any light? I will change both temp sensors first however

29th March 2016, 17:30

Just an idea.... Your second lambda on the straight through... Is it sleeved or have you just left it as it was? And gandi699 - what mods have you got on the car? Have you tried cleaning icv, changing spark plugs, changing fuel filter?

29th March 2016, 21:54

It's got a 421, cat and cat back exhaust. It's a single plug 16v so no second lambda for cat monitoring. Fuel filter is new, icv cleaned along with throttle body, new oil, new filter, new plugs, cleaned and oiled the enclosed air filter.
If I Unplug the lambda it idles lovely it only does it with lamdba plugged it, it'll idle nice for a while then drop into lumpyness when warming up and hot. switch off and on again when warm and its ok for a moment then goes lumpy. Had various lambdas in it and all were decent brand like Bosch - known good ones cause to do this weird issue, shagged ones just make the car cut out when warm.
I've yet to change any sensors on this engine other than the map sensor for a known good one. Could be coolant temp sensor or air temp maybe? That said my 8v didn't idle too well in this car either.....
Both have absolutely stunk of fuel when idling like mega rich but I'm running the right fpr for a vts - 3 bar and was on the 8v too. Guess I shouldn't compare the two as the old 8v was a hybrid rallye/vtr thing and this 16v is standard as they come

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29th March 2016, 23:03

These engines don't really like idling smoothly at lambda-1. They like idling leaner than that less still. The lambda sensor has it fluctuate above and below lambda 1 and this makes the idle fluctuate.

You can improve them slightly by advancing the exhaust cam just a couple of mm on the bolt slots on the pulley. Undo the three bolts, put a spanner on the centre bolt (it's either 16mm (5/8") or 21mm (13/16") and turn it clockwise a couple of mm.

Advancing the exhaust cam moves the valves away from the pistons so there's no issues with bending valves.

You can also retard the intake cam but you'll lose midrange torque.

30th March 2016, 13:05

Quote:

Originally Posted by Chipwizards

These engines don't really like idling smoothly at lambda-1. They like idling leaner than that less still. The lambda sensor has it fluctuate above and below lambda 1 and this makes the idle fluctuate.

You can improve them slightly by advancing the exhaust cam just a couple of mm on the bolt slots on the pulley. Undo the three bolts, put a spanner on the centre bolt (it's either 16mm (5/8") or 21mm (13/16") and turn it clockwise a couple of mm.

Advancing the exhaust cam moves the valves away from the pistons so there's no issues with bending valves.

You can also retard the intake cam but you'll lose midrange torque.

Reckon thats worth a shot then adjusting the timing? I find it astounding that they would have done this from new like that, it is quite bad enough to make you think something is very wrong.
My idle speed cold or hot is 1000rpm, it doesnt go any lower than this ever so its not so much bouncing around on the tacho but you feel the lumpyness in the cabin and the exhaust note changes. Very hard to describe probably need a video doing of it

30th March 2016, 17:43

Possibly just sleeve the lambda and plug back in?

30th March 2016, 20:20

Very similar symptoms for me too! I've tried the usual cleaning ICV, coolant temp sensor, obviously normal service stuff. Disconnected TPS and MAP with it running, no change. Haven't tried disconnecting lambda yet.

Hopefully you can find a solution, the lumpy feeling inside drives me insane sitting at lights haha

30th March 2016, 22:21

Quote:

Originally Posted by Shadowslayerzz

Possibly just sleeve the lambda and plug back in?

Same as leaving it unplugged effectively - . It it's not monitoring the exhaust gas then it's doing nothing anyway

30th March 2016, 22:22

Quote:

Originally Posted by johnmclaren

Very similar symptoms for me too! I've tried the usual cleaning ICV, coolant temp sensor, obviously normal service stuff. Disconnected TPS and MAP with it running, no change. Haven't tried disconnecting lambda yet.

Hopefully you can find a solution, the lumpy feeling inside drives me insane sitting at lights haha

Is yours 16v too?

30th March 2016, 22:25

Quote:

Originally Posted by Gandi699

My idle speed cold or hot is 1000rpm, it doesnt go any lower than this ever

Are you sure it's stock and not had cams and a remap (cams requiring a faster idle)

It shouldn't idle at 1000 rpm.

30th March 2016, 22:31

Cams are totally bog standard oem jobbies, ecu is unknown but for the money I paid for a loom and unlocked ecu combo I would highly doubt it. That or I had a massive bargain! But yeah pretty much 1000rpm all the time, I'd have wagered 7/800 when warm but no. However as I say, if I get it warm then switch off it idles well for 10 seconds or so still high rpm at 1000 but idles quite sweetly then drop backs into chuggy lumpy idle. It's one of those annoying niggles as it seems you can change nearly every sensor but not get anywhere same as on the previous 8v engine. Being a mk1 I don't even get any fault codes or a management light

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30th March 2016, 23:31

Quote:

Originally Posted by Gandi699

Is yours 16v too?

Yeah it's just a fully stock 03 VTS

30th March 2016, 23:32

So obviously the later 3 plug cars still do it eh. Weird

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30th March 2016, 23:42

Only thing different really is I have a normal idle speed once hot.

Don't get any fault codes either! May have to whip the belt covers off and look to see if the pulleys have moved?

31st March 2016, 20:43

I've never once seen an engine management light on mine and I've had it running light shit when deliberately pulling sensors out of the equation. Don't even know why it's there on a mk1!

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2nd April 2016, 01:29

Only ignition coil failure, Mixture adjustment and ECU memory failure put the light on.

Everything else just logs codes and some faults also cause 'Emergency Mode' (limp)

2nd April 2016, 01:55

I could really do with a reader that works with this generation of Saxo, my current one works on the rest of my cars but not the mk1s unfortunately. I'll have to source one
I've got a spare air temp sensor I'll bosh in this weekend and maybe try the timing adjustment weather and time dependant. maybe a new CTS