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240 n/a b23e k jet good/acceptable afr values

1

12david34

New member
Joined
Sep 1, 2012
Location
Slovak Rep.
hi there
starting this thread, becasue few month ago i did a wrong thing...
started to play with k jet,(increasing/lowering pressures on warm up regulator and adjusted mixture on fuel distributor) without any monitoring device. since then my car ran really rich and i lost lots of power..and now i need help.
in order to fix this faulty step of mine, i bought a wideband.
and it works great and now i actually can see what is going on etc.

in the mean time i was able to readjust the wur back to +/- original setting, and now the car runs much better, but its still not right, and need some more fine tuning.
now since i have this wideband i would like to know what is your opinion on the values the gauge shows me. so tell me how much did i fu(ked my k jet?

here are the values:
1 cold idle- 15,5-16:1
2 warm idle- 16,5-17,1:1
3 cruising/keeping up with traffic- 15,2-16:1
4 load/wot- when i floor it,afr drops down to high 10 or mid 11:1,engine hesitates a bit, but within 2-3 seconds it starts to climb up and then it shows from low 13s to low 14s.

(all values are +/- becasue the numbers are changing guicky)
honestly, i have no idea if thats OK to run that lean on idle or cruise..
thx for your input, if possible please post your values too, so i can compare them.
 
What tool/gauge did you buy?

How did you take your reading to set your air flow meter adjust at idle and where did you take your sample?

For now, 14.7:1 being the theoretical ideal, you're not running that lean if I'm understanding your data

Also, I have to ask, why would/did you want to fool with the control pressure on your CPU? More so, how did you change it (literally) Did you open it up?

There is no simple way to get it back to specs (depending on what you did), you really needed to take measurements before you changed anything in order to put it back where it was before you started -
taking control pressure readings with a manometer or at least a fuel pressure gauge plumbed in the system when cold

If your wide band tool/gauge is what I think it is, it will be of little to no help with resetting your CPU, unless someone here knows something about a CPU that I don't - the CPU's operation is a function of temperature, not air/fuel information provided by the O2 sensor

What were you trying to solve/cure/or improve by tampering with the CPU?
 
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Jimmy E. James said:
What tool/gauge did you buy?

How did you take your reading to set your air flow meter adjust at idle and where did you take your sample?

For now, 14.7:1 being the theoretical ideal, you're not running that lean if I'm understanding your data

Also, I have to ask, why would/did you want to fool with the control pressure on your CPU? More so, how did you change it (literally) Did you open it up?

There is no simple way to get it back to specs (depending on what you did), you really needed to take measurements before you changed anything in order to put it back where it was before you started -
taking control pressure readings with a manometer or at least a fuel pressure gauge plumbed in the system when cold

If your wide band tool/gauge is what I think it is, it will be of little to no help with resetting your CPU, unless someone here knows something about a CPU that I don't - the CPU's operation is a function of temperature, not air/fuel information provided by the O2 sensor

What were you trying to solve/cure/or improve by tampering with the CPU?
Click to expand...

thx for your input.
i bought a innovate motorsport wideband. a bung(for a bosch sensor/sender unit) was welded just few centimeters after the header Y collector.

the reason why i ,,played?? with the Warm Up Regulator/ Control Pressure Regulator was that i started to have problem to start the car up during colder autumn and winter months.. and yes the WUR was also dissasembled for visual check.

i do have a 0-6 BAR fuel gauge installed in a fuel circuit.

CPR/WUR has a huge effect on A/F ratio.
 
12david34 said:
thx for your input.
i bought a innovate motorsport wideband. a bung(for a bosch sensor/sender unit) was welded just few centimeters after the header Y collector.

the reason why i ,,played?? with the Warm Up Regulator/ Control Pressure Regulator was that i started to have problem to start the car up during colder autumn and winter months.. and yes the WUR was also dissasembled for visual check.

i do have a 0-6 BAR fuel gauge installed in a fuel circuit.

CPR/WUR has a huge effect on A/F ratio.
Click to expand...

Sure it does - but it's factory calibrated for the system and designed to do it's thing over a very specific band primarily during open loop operation

You asked about air/fuel ratios - you don't have to/need to/should not tamper with the CPR in order to fine tune those - and Bosch made the COLD determination for you with the CPR's calibration - to get the bi-metallic element and all components back where they were from the factory is going to be next to impossible unless you took measurements as you disassembled the unit

How did you arrive at the conclusion that the cold start issues were CPR related? What "adjustments" did you make to the CPR?

Initially, I understood your concern to be that your engine was running too lean at operating temp (and now am I correct to think that you feel the CPR "adjustments" are responsible for this?)

Put everything aside, is the engine running satisfactorily now? How does is measure in front of the cat and at the tailpipe?
 
Last edited:
Jimmy E. James said:
Sure it does - but it's factory calibrated for the system and designed to do it's thing over a very specific band primarily during open loop operation

You asked about air/fuel ratios - you don't have to/need to/should not tamper with the CPU in order to fine tune those - and Bosch made the COLD determination for you with the CPU's calibration - to get the bi-metallic element and all components back where they were from the factory is going to be next to impossible unless you took measurements as you disassembled the unit

How did you arrive at the conclusion that the cold start issues were CPU related? What "adjustments" did you make to the CPU?

Initially, I understood your concern to be that your engine was running too lean at operating temp (and now am I correct to think that you feel the CPU "adjustments" are responsible for this?)

Put everything aside, is the engine running satisfactorily now? How does is measure in front of the cat and at the tailpipe?
Click to expand...

some informations(from greenbook/internet forums) led to to believe that maybe adjusting the WUR will fix my problems, and it actually did, car started well since then, but at that time i didnt had the wideband, so i had no idea that im running rich.. i found out just now, two weeks back when i finally bought a wideband.

when i adjusted the WUR, i hammered the round pin downwards a bit, like 0,5mm.

my car has no cat.
 
12david34 said:
some informations(from greenbook/internet forums) led to to believe that maybe adjusting the WUR will fix my problems, and it actually did, car started well since then, but at that time i didnt had the wideband, so i had no idea that im running rich.. i found out just now, two weeks back when i finally bought a wideband.

when i adjusted the WUR, i hammered the round pin downwards a bit, like 0,5mm.

my car has no cat.
Click to expand...

Well, you either fixed the problem or covered it up

Either way, if the car runs well now I wouldn't worry about it - those readings you shared from your wide band aren't theoretically perfect, but they're not that far off the mark

If I were in exactly your situation I'd look at the tail pipe (4 gas) for real peace of mind over what the electronics are telling me from a wide band gauge - they are only a helpful tool, not the final word

Have you tried fattening it up at the airflow meter just a touch to see if you can bring that O2 number down a little?
 
Find the Greenbook that covers testing K-Jet fuel pressure, and search here for the DIY K-Jet pressure tester. The pressures need to be within the correct ranges & times for K-Jet to work well.

Assuming you have a Lambda / Oxygen sensor and control box, it should automatically adjust the mixture to around 14.7 AFR once warmed up and either idling or steady speed. The control box swings the mixture up and down around 14.7 -- it won't be steady if the control system is working.

During warmup and acceleration, the control box is open loop and simply sets the frequency valve rate to give a fixed mixture. You can check this using the greenbook instructions and a dwell meter on the test connector.

Once you've verified pressures, you can adjust the open loop idle mixture by disconnecting the O2 sensor (when warmed up first) and adjusting the K-Jet air plate screw until you see ~14.3 on your wideband. This should be close to the 1.0% CO setting. (Be careful that the disconnected wire from the O2 sensor doesn't short to ground or it can damage the sensor.)

Your AFR numbers for idle/warmup/cruise are lean. I'd expect the control box to bring them closer to 14.7 if pressures aren't too far off. Have you calibrated your wideband O2 sensor?
 
bobxyz said:
Find the Greenbook that covers testing K-Jet fuel pressure, and search here for the DIY K-Jet pressure tester. The pressures need to be within the correct ranges & times for K-Jet to work well.

Assuming you have a Lambda / Oxygen sensor and control box, it should automatically adjust the mixture to around 14.7 AFR once warmed up and either idling or steady speed. The control box swings the mixture up and down around 14.7 -- it won't be steady if the control system is working.

During warmup and acceleration, the control box is open loop and simply sets the frequency valve rate to give a fixed mixture. You can check this using the greenbook instructions and a dwell meter on the test connector.

Once you've verified pressures, you can adjust the open loop idle mixture by disconnecting the O2 sensor (when warmed up first) and adjusting the K-Jet air plate screw until you see ~14.3 on your wideband. This should be close to the 1.0% CO setting. (Be careful that the disconnected wire from the O2 sensor doesn't short to ground or it can damage the sensor.)

Your AFR numbers for idle/warmup/cruise are lean. I'd expect the control box to bring them closer to 14.7 if pressures aren't too far off. Have you calibrated your wideband O2 sensor?
Click to expand...
Excellent post, excellent clear and concise instructions, but if I'm understanding him correctly he's running lean open and closed loop. If the CPR tampering is really out of whack he's stuck with whatever it is until that's straightened out (cold)
I suggested just tweaking the air flow meter as well (warmed up) while observing his wide band to see if he could fatten things up a little there but he'll still have his lean cold condition

Which is why I've asked so many questions; he's reporting almost identical readings cold idle and cruising - only significant change is during and immediately after wide open throttle - doesn't make a lot of sense what he's describing (look at #1 and #3) unless he really did screw up that CPR
12david34 said:
here are the values:
1 cold idle- 15,5-16:1
2 warm idle- 16,5-17,1:1
3 cruising/keeping up with traffic- 15,2-16:1
4 load/wot- when i floor it,afr drops down to high 10 or mid 11:1,engine hesitates a bit, but within 2-3 seconds it starts to climb up and then it shows from low 13s to low 14s.
Click to expand...
 
bobxyz said:
Find the Greenbook that covers testing K-Jet fuel pressure, and search here for the DIY K-Jet pressure tester. The pressures need to be within the correct ranges & times for K-Jet to work well.

Assuming you have a Lambda / Oxygen sensor and control box, it should automatically adjust the mixture to around 14.7 AFR once warmed up and either idling or steady speed. The control box swings the mixture up and down around 14.7 -- it won't be steady if the control system is working.

During warmup and acceleration, the control box is open loop and simply sets the frequency valve rate to give a fixed mixture. You can check this using the greenbook instructions and a dwell meter on the test connector.

Once you've verified pressures, you can adjust the open loop idle mixture by disconnecting the O2 sensor (when warmed up first) and adjusting the K-Jet air plate screw until you see ~14.3 on your wideband. This should be close to the 1.0% CO setting. (Be careful that the disconnected wire from the O2 sensor doesn't short to ground or it can damage the sensor.)

Your AFR numbers for idle/warmup/cruise are lean. I'd expect the control box to bring them closer to 14.7 if pressures aren't too far off. Have you calibrated your wideband O2 sensor?
Click to expand...
i do have those greenbooks, once again, my car is not lambda equipped from factory, its a pure dirty k jet, with no factory lambda or catalytic converter. also there si no control box.
yes the wideband sensor was calibrated prior the installation.
 
so finally i have some more things to add.
been playing with the system a bit more. i was lucky enought to find my original old WUR/CPR which was originally on a car back in 2014 but shortly after it failed, so i had to replace it with another old but working unit.
so i compared those two units and with a vernier caliper i measured how deep is the pin pushed down. based on the measurements of the original failed WUR/CPR, i managed to set the pin on the newer unit into the same position(+/-0,2mm) which drastically affected the AFRs.
then i played with mixture adjusted screw and later i adjusted the idle, and went for a ride..
unbelievable,but i got high 14s to low 15s AFR at idle and cruise and at wot AFR dropped to low 12 but within seconds(or more like as the RPMs went past 3500) gauge showed mid to high 13s( which is still on the rich side, but its said its good for performance).
i was very happy with it, but my good feeling lasted only 24 hours or so, next day i again went for a ride and for a change the car ran rich (low 14s at idle, high 13s to low 14s at cruise and wot was at mid 11s to high 12s, sometimes low 13s. i could feel the car lost some power again.

7 hours after, i went for a ride again, and it changed again. this time back to good AFRs.
since then i started to check the fuel pressure gauge immadietly after cold start and then when the car is fully warmed up. seems like the cold pressure is set just fine, as at 20C-25C is shows 2-2,1BAR( which according to greenbook is in specs) but something is wrong with the warm pressure as one time it shows 3,5 BAR(which is in specs), but sometimes it shows 3 or even 2,8BAR.. which is way out of specs...
 
12david34 said:
so finally i have some more things to add.
been playing with the system a bit more. i was lucky enought to find my original old WUR/CPR which was originally on a car back in 2014 but shortly after it failed, so i had to replace it with another old but working unit.
so i compared those two units and with a vernier caliper i measured how deep is the pin pushed down. based on the measurements of the original failed WUR/CPR, i managed to set the pin on the newer unit into the same position(+/-0,2mm) which drastically affected the AFRs.
then i played with mixture adjusted screw and later i adjusted the idle, and went for a ride..
unbelievable,but i got high 14s to low 15s AFR at idle and cruise and at wot AFR dropped to low 12 but within seconds(or more like as the RPMs went past 3500) gauge showed mid to high 13s( which is still on the rich side, but its said its good for performance).
i was very happy with it, but my good feeling lasted only 24 hours or so, next day i again went for a ride and for a change the car ran rich (low 14s at idle, high 13s to low 14s at cruise and wot was at mid 11s to high 12s, sometimes low 13s. i could feel the car lost some power again.

7 hours after, i went for a ride again, and it changed again. this time back to good AFRs.
since then i started to check the fuel pressure gauge immadietly after cold start and then when the car is fully warmed up. seems like the cold pressure is set just fine, as at 20C-25C is shows 2-2,1BAR( which according to greenbook is in specs) but something is wrong with the warm pressure as one time it shows 3,5 BAR(which is in specs), but sometimes it shows 3 or even 2,8BAR.. which is way out of specs...
Click to expand...
Is this a fresh engine build you are concerned about protecting or a typical high miler?

You are worrying over something that is a waste of time (especially if your car is running good now)

Fluctuations will also show (and are perfectly normal) on a high mileage car (engine)

I rebuilt 100s of carburetors over the years with excellent results and customer satisfaction - made a lot of cars pass the smog test as well - point is, very few cars, after they have significant age on them would run at "spec" - even if I could get everything to be stable at "spec" - mainly idle RPMs (fast idle, curb idle etc) the car(s) would run like ****, shaky idle quality, lean idle misses I could feel, rolling..........it's a function of wear, and at some point it's basically a +- 10 to 15% or so on "specs" to give good driveabilty

Early fuel injected cars work the same way - you're shooting for a laboratory ideal that was established on a new car and it ain't going to translate into the reality of the real world

Those wide band gauges are a tool - an assist - to give you an idea of the general health of your system - some being better than others

But, the readings are averaged electronically on all of them

Either way, if I am understanding what you are writing, there's nothing "wrong" with your numbers

If you REALLY want to know what the fuel delivery system is doing you need to put it on a loaded mode dyno and see what the 4-gas says - will be extremely meaningful as you have no cat ad no O2

It's not an OBII system with instantaneous corrections

Run a tank through it with some CRC G2P and then see what your numbers "say"

Stop stressing over something you can't do anything about except adjust the best possible (normal baseline tune up adjustments) and forget it - and enjoy your car
 
Jimmy E. James said:
Is this a fresh engine build you are concerned about protecting or a typical high miler?

You are worrying over something that is a waste of time (especially if your car is running good now)

Fluctuations will also show (and are perfectly normal) on a high mileage car (engine)

I rebuilt 100s of carburetors over the years with excellent results and customer satisfaction - made a lot of cars pass the smog test as well - point is, very few cars, after they have significant age on them would run at "spec" - even if I could get everything to be stable at "spec" - mainly idle RPMs (fast idle, curb idle etc) the car(s) would run like ****, shaky idle quality, lean idle misses I could feel, rolling..........it's a function of wear, and at some point it's basically a +- 10 to 15% or so on "specs" to give good driveabilty

Early fuel injected cars work the same way - you're shooting for a laboratory ideal that was established on a new car and it ain't going to translate into the reality of the real world

Those wide band gauges are a tool - an assist - to give you an idea of the general health of your system - some being better than others

But, the readings are averaged electronically on all of them

Either way, if I am understanding what you are writing, there's nothing "wrong" with your numbers

If you REALLY want to know what the fuel delivery system is doing you need to put it on a loaded mode dyno and see what the 4-gas says - will be extremely meaningful as you have no cat ad no O2

It's not an OBII system with instantaneous corrections

Run a tank through it with some CRC G2P and then see what your numbers "say"

Stop stressing over something you can't do anything about except adjust the best possible (normal baseline tune up adjustments) and forget it - and enjoy your car
Click to expand...

this particular engine is a lowish mileage engine. i got it from a guy, who has it stored as a spare engine in his garage for 10+ years, that was back in the 2014, i have it stored two more years in the garage, and finally in summer 2016, the short block got rebuilt(inspected and turned out to be all in specs, the bores were slightly honed, it got new crankshaft bearings, rod bearings, and piston were cleaned and got new rings)...
im going to monitor the AFRs each day to see what is the total outcome... but it still needs a bit of tuning., maybe the WUR is failing again.
 
The WRU is a very simple device. If the heater resistance is stable, meaning that the external electrical connections are good, there is not much to go wrong with it other than cleaning trash out of it.

Using a wide band O2 sensor to tune a non-Lamda K-jet seems like a waste of time.
 
TestPoint said:
The WRU is a very simple device. If the heater resistance is stable, meaning that the external electrical connections are good, there is not much to go wrong with it other than cleaning trash out of it.

Using a wide band O2 sensor to tune a non-Lamda K-jet seems like a waste of time.
Click to expand...

yes i know the WUR is a simple thing. but sometimes the moisture gets is and then it tends to fail, or the intake port gets full of debries from fuel system. or the heater unit fails..
why do you think using wideband for those purposes is a waste of time?
 
12david34 said:
yes i know the WUR is a simple thing. but sometimes the moisture gets is and then it tends to fail, or the intake port gets full of debries from fuel system. or the heater unit fails..
why do you think using wideband for those purposes is a waste of time?
Click to expand...

He's right and as for the why?

It's just an average value - same as a digital scope - by the time you "see" an event it's already history (even on the good ones)

As for warm up regulators going bad? - STOP reading crap on the internet - it's the closest thing to a bullet proof part in the fuel system
 
TestPoint said:
The WRU is a very simple device. If the heater resistance is stable, meaning that the external electrical connections are good, there is not much to go wrong with it other than cleaning trash out of it.

Using a wide band O2 sensor to tune a non-Lamda K-jet seems like a waste of time.
Click to expand...

You Sir are correct - only to assist with basic tune numbers (maybe)
+1
 
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