Pulsing acceleration on light throttle...
07 September 2005, 05:13 PM
#31
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Originally Posted by PhilA
plugs under steering column, just stick your head up:
set of black and set of green.
set of black and set of green.
07 September 2005, 10:27 PM
#33
Ecu Specialist
On a MY99-00 car to check that it is merely fueling oscillation caused by closed loop control just unplug the lambda sesnor, leave it in the exhaust though. You will find all stops and the car drives fine, I always map these ecu's like this as I remove the sensor and fit my wideband, I then map the whole lot for correct open loop fueling which minimises the effect when the lambda is brought back into service, bigger injectors make the effect worse as does higher fuel pressure.
bob
bob
09 September 2005, 07:03 PM
#34
Originally Posted by Scott.T
It's the Lambda sensor getting up to temperature. The ECU gets a little confused until the Lambda is warm.
To prove this drive with the Lambda disconnected and it will be nice and smooth, due to the ECU using the base fuel map rather then using the input from the Lambda to achieve shoich (14.7AFR).
You can drive for quite a while without the CEL coming on. Infact when I disconnected mine it didn't come on at all......
To prove this drive with the Lambda disconnected and it will be nice and smooth, due to the ECU using the base fuel map rather then using the input from the Lambda to achieve shoich (14.7AFR).
You can drive for quite a while without the CEL coming on. Infact when I disconnected mine it didn't come on at all......
If it's really getting on your tit's then leave it unplugged until MOT time, then plug it in again for the MOT.
I find that optimax exagerates the problem. Esso SUL is alot smoother when the engine/lambda is cold.
09 November 2005, 07:41 AM
#35
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I too have this problem.
MY02 STI Type UK, TEK 3, APS FMIC, 3" exhaust inc sports cat, 650cc injectors, 20G Turbo, Sx reg.
When on very very light throttle and showing -15 to -20 vacuum on the boost gauge the car pulses like mad, and the SECS display LAMBDA jumps up and down like a yo-yo.
Very annoying, and the problem is much worse when going down a decline.
No difference is engine is cold or hot.
Car has done 60k, and has just had a new MAF fitted (for peace of mind).
Can this problem be irradicated by fine tuning the map ?
MY02 STI Type UK, TEK 3, APS FMIC, 3" exhaust inc sports cat, 650cc injectors, 20G Turbo, Sx reg.
When on very very light throttle and showing -15 to -20 vacuum on the boost gauge the car pulses like mad, and the SECS display LAMBDA jumps up and down like a yo-yo.
Very annoying, and the problem is much worse when going down a decline.
No difference is engine is cold or hot.
Car has done 60k, and has just had a new MAF fitted (for peace of mind).
Can this problem be irradicated by fine tuning the map ?
09 November 2005, 11:02 AM
#36
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My my94 wrx used to do it until i fitted a de-cat which already came with its own lambda which i have used in place of the original.
Out of interest what effect will it have on the car if you leave it unplugged?
Out of interest what effect will it have on the car if you leave it unplugged?
12 November 2005, 08:27 PM
#37
Originally Posted by rolyatescort
My my94 wrx used to do it until i fitted a de-cat which already came with its own lambda which i have used in place of the original.
Out of interest what effect will it have on the car if you leave it unplugged?
Out of interest what effect will it have on the car if you leave it unplugged?
It should run fine and probably won't light the CEL, but it won't get you through an MOT until you plug the Lambd back in again.
17 November 2005, 08:14 PM
#40
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My '98 did this on the motorway and it used to drive me nuts. It disappeared after I had an Apexi PFC and AVCR fitted so presumably it's an ecu or boost controller problem.
Last edited by RaymondH; 17 November 2005 at 08:18 PM.
18 November 2005, 05:35 PM
#41
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My understanding of it is:...............
When the engine is cold, it is the Lambda sensor constantly telling the ECU to richen/weaken the fuel map, as the Lambda needs to upto temp for it to work properley. As Bob said, the Lambda only really controls this on closed-loop operation such as light throttle applications, say round town driving.
When the car warms its better cos the Lambda sensor is upto temp, and is doing its job effeciently. perfectly normal, although somewhat annoying at times
Its an emissions/economy thing thats why it constantly adjusts.
When the engine is cold, it is the Lambda sensor constantly telling the ECU to richen/weaken the fuel map, as the Lambda needs to upto temp for it to work properley. As Bob said, the Lambda only really controls this on closed-loop operation such as light throttle applications, say round town driving.
When the car warms its better cos the Lambda sensor is upto temp, and is doing its job effeciently. perfectly normal, although somewhat annoying at times
Its an emissions/economy thing thats why it constantly adjusts.
18 November 2005, 06:17 PM
#43
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Originally Posted by AVI-8
Do any of you guys who's car does this have a boost guage, and if so is the boost pressure fluctuating when this happens?
agree it's a bit un-nerving, keep expecting a big bang!
does seem like a few guys on this thread need to stop spunking money trying to sort a problem that seems unfixable!
the 'pulsing' was there when i bought the car and it's still there now, had a few minor mods and a remap and there's been no difference.
another 'scooby characteristic'
19 November 2005, 07:59 AM
#44
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Originally Posted by chrispurvis100
So it wouldn't cause any damage running the engine with the lamda disconnected?
21 November 2005, 08:28 AM
#45
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Hi everyone, I,ve only had this same problem since fitting a universal Lambda Sensor, and was told by a subaru mechanic that alot of universal Lambda Sensors dont switch fast enough for the ECU, he recommends fitting a genuine part.
Mine is a 3 Wire Titainia Bosch Sensor Mounted in the manifold which i'm told £175 +VAT from Subaru where as the 4 Wire Zirconia sensor mounted in the down pipe are cheaper approx £95
Mine is a 3 Wire Titainia Bosch Sensor Mounted in the manifold which i'm told £175 +VAT from Subaru where as the 4 Wire Zirconia sensor mounted in the down pipe are cheaper approx £95
Last edited by WRX-SHEFFIELD; 21 November 2005 at 08:35 AM.
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