22 replies to this topic

[Mr Apex]

My stage 2 SC has recently started running even richer than its Courtenay map intended. I have a wide band AFR and it seems to be showing some odd behaviour with the fuelling:

AFR 13.2 in cruise at constant 70mph. Used to sit at 14.7

AFR 11.0 at WOT

AFR 14.7 at idle

About 50% of the time, AFR drops to max lean 22.0 indicated on the overrun. The rest of the time it goes rich - around 13.2.

 

It looks as though one of the sensors is throwing a wobbly, but the EML is not lit, so the ECU seems to think that all is OK. I'm guessing Lambda or MAP. Any ideas before I throw money at new bits?

[siztenboots]

thermostat stuck open , or water temp sensor wiring fault

[vocky]

the mixture lambda sensor would be worth replacing, it's the one nearest the exhaust manifold.

 

Coolant temp sensor can play up, they are quite cheap from the dealer (£20 ish)

[Nev]

My best bet is the second lambda sensor too, as it's output directly controls fueling. Do make sure you get an propper one (not some copy)

[CHILL Gone DUTCH]

have you tried just driving it a bit longer, if you last used the car in the summer and first time you have used it recently it might just be a cae that the fuel trims need to catch up a bit 

[smiley]

I"m with Nev on the postcat sensor.

[Ormes]

How about an issue with the wideband 02/lambda sensor its self...?

[Mr Apex]

Fuel consumption indicates that the Wide Band is not telling porkies! Nev, I can't remember if we removed the post cat lambda when we re-packed the zorst? If so, we might have disturbed something? I've just been on a quick drive and this time mixture seemed fine most of the time, but jumped to 12.2 AFR at idle. Where does the coolant temp sensor sit? It is probably one of the few things that I haven't yet replaced, so I might as well do that now before it dies...

[Ormes]

May sound mad but remove the lambda, untwist/untangle the wires, clean up the electrical connections and try again. I had my car back from a new exhaust and remap and threw errors (P402 from memory) relating to the emmission control system... did as I suggested above (4 years ago), and haven't seen the fault since.

[FLD]

Try an opcom and look at the live data. Might be useful to pin it down.

[slindborg]

Secondary lambda does or should do, nothing for fuelling. Primary is well worth a look on opcom etc, or slap a multimeter on it and watch

[Nev]

Fuel consumption indicates that the Wide Band is not telling porkies! Nev, I can't remember if we removed the post cat lambda when we re-packed the zorst? If so, we might have disturbed something? I've just been on a quick drive and this time mixture seemed fine most of the time, but jumped to 12.2 AFR at idle. Where does the coolant temp sensor sit? It is probably one of the few things that I haven't yet replaced, so I might as well do that now before it dies...

 

God knows, I really can't remember if we took the lambda sensor out.... sorry.

 

On the Z20LET the first lambda is narrow band and used for idle/low rev control, and the second (post cat lamda) is wider band for closed loop mixture. Not sure if your setup is the same though...

 

[siztenboots]

 

Fuel consumption indicates that the Wide Band is not telling porkies! Nev, I can't remember if we removed the post cat lambda when we re-packed the zorst? If so, we might have disturbed something? I've just been on a quick drive and this time mixture seemed fine most of the time, but jumped to 12.2 AFR at idle. Where does the coolant temp sensor sit? It is probably one of the few things that I haven't yet replaced, so I might as well do that now before it dies...

 

God knows, I really can't remember if we took the lambda sensor out.... sorry.

 

On the Z20LET the first lambda is narrow band and used for idle/low rev control, and the second (post cat lamda) is wider band for closed loop mixture. Not sure if your setup is the same though...

 

 

 

both lambdas are same , different wire length. first lambda does everything , second measures cat efficiency only.

[Nev]

 

 

Fuel consumption indicates that the Wide Band is not telling porkies! Nev, I can't remember if we removed the post cat lambda when we re-packed the zorst? If so, we might have disturbed something? I've just been on a quick drive and this time mixture seemed fine most of the time, but jumped to 12.2 AFR at idle. Where does the coolant temp sensor sit? It is probably one of the few things that I haven't yet replaced, so I might as well do that now before it dies...

 

God knows, I really can't remember if we took the lambda sensor out.... sorry.

 

On the Z20LET the first lambda is narrow band and used for idle/low rev control, and the second (post cat lamda) is wider band for closed loop mixture. Not sure if your setup is the same though...

 

 

 

both lambdas are same , different wire length. first lambda does everything , second measures cat efficiency only.

 

 

On the Z20LET the lambdas have different part numbers and I seem to remember different bandwidths too...

 

Position1 (front): Part # 9193148

Position2 (rear): Part # 9201421  

As I remember (and maybe my brain cells are fading!) the front one was something like +/- 0.5 lambda and the rear one was more like +/- 1.5 lambda.

Edited by Nev, 28 March 2017 - 11:53 AM.

[chickendippers]

1st and 2nd lambda are definitely different on a Z20LET

[siztenboots]

z20let , both lambda are 4 wire , zirconia type narrowband, only the wire length differs and hence part number.

 

meanwhile , on the 2.2 supercharged running CS software and what sounds like an wideband sensor ... or maybe just a wideband gauge

[siztenboots]

is the wideband gauge an LC1 by chance?

[chickendippers]

Can you not just map it out in the Dutch software?

[CHILL Gone DUTCH]

Dutch software If your running V 2 you need both oem narrow band lambda with seperate wideband ( 3 bungs) In pro you use oem primary narrow band and you can disable 2 nd lambda and install the wideband in the same bung You can also use the wideband for live fueling Or use it the same as V2

Edited by CHILL Gone DUTCH, 28 March 2017 - 12:44 PM.

[CHILL Gone DUTCH]

Can you not just map it out in the Dutch software?

You would have to buy the Dutch software and have ecu flashed with it