Running very rich at idle, lean on throttle
03-14-2012 | 03:55 PM
#16
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From: San Jose, CA
If the car was truly that lean, when you drove it - it would be backfiring through the intake, probably bucking, and generally be unpleasant to drive...
Note, that an extremely rich condition will show up as lean on a WBO2. (this is due to misfiring, which leaves un-burnt O2 in the exhaust) Your smog reading also indicates an extremely rich condition!
So lets start by focusing on things that will cause it to be way to rich:
First, have you verified fuel pressure? I know you have a 3bar regulator on, but I've ran into a few 3bar regulators which were ~10psi too high.
Second, verify the AFM:
http://www.clarks-garage.com/shop-manual/elect-22.htm
Additionally, with the car running, test the AFM output voltage to the DME - it should be on the lower-end of its 5volt range. If it seems reasonable, and goes up with throttle input, then double-check it at the DME plug. (also, you are using a 951 AFM correct? The 944S/S2 AFM looks very similar)
Next, check the MAP sensor is outputting the correct voltage. With the key-on, but engine off, measure the voltage on the green wire. It should be around 1.5 volts. Then, start the car. With the engine at idle, measure the green wire again. It should be around 0.7 volts.
Also, what vacuum is the engine pulling at idle?
A coolant temp sensor (or wiring) will also cause the car to run quite a bit richer.
If this stuff checks out, then the first thing I suggest doing is to put back in the 2.5bar FPR, and switch to FQS position #2. This combined should reduce fueling quite a bit. Obviously this isn't what I suggest permanently, rather to immediately get the car in a more normal AFR range. Then see if your WBO2 is telling us something more sensible.
Another thing, can you pull a spark-plug and send me a picture of it.
Note, that an extremely rich condition will show up as lean on a WBO2. (this is due to misfiring, which leaves un-burnt O2 in the exhaust) Your smog reading also indicates an extremely rich condition!
So lets start by focusing on things that will cause it to be way to rich:
First, have you verified fuel pressure? I know you have a 3bar regulator on, but I've ran into a few 3bar regulators which were ~10psi too high.
Second, verify the AFM:
http://www.clarks-garage.com/shop-manual/elect-22.htm
Additionally, with the car running, test the AFM output voltage to the DME - it should be on the lower-end of its 5volt range. If it seems reasonable, and goes up with throttle input, then double-check it at the DME plug. (also, you are using a 951 AFM correct? The 944S/S2 AFM looks very similar)
Next, check the MAP sensor is outputting the correct voltage. With the key-on, but engine off, measure the voltage on the green wire. It should be around 1.5 volts. Then, start the car. With the engine at idle, measure the green wire again. It should be around 0.7 volts.
Also, what vacuum is the engine pulling at idle?
A coolant temp sensor (or wiring) will also cause the car to run quite a bit richer.
If this stuff checks out, then the first thing I suggest doing is to put back in the 2.5bar FPR, and switch to FQS position #2. This combined should reduce fueling quite a bit. Obviously this isn't what I suggest permanently, rather to immediately get the car in a more normal AFR range. Then see if your WBO2 is telling us something more sensible.
Another thing, can you pull a spark-plug and send me a picture of it.
I am sure it's the 951 afm. Checked the MAP sensor voltage with key on and engine running, good.
Vacuum at idle is -.46 bar or -350 mmHg.
My coolant temp sensor is new and the wiring was in good condition when I installed it.
I switched the the FQS to position 2 (-3% fuel) and the afr hovers a little above 14, woohoo! This is still using the 3 bar FPR.
Slight throttle application shows a more consistent afr reading. It's only with little blips does the reading go way rich and then way lean.
I think I may be getting closer...
03-15-2012 | 09:42 PM
#18
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I also changed out the FPR to the 2.5 bar version with the FQS at position 2. The idle starts at around normal (14.7) then dwindles down to around 13:1.
I'm having trouble tracking down a gauge for my fuel rail, but, I'll get one soon.
03-15-2012 | 10:55 PM
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Ok, so more updates. So I tested the AFM voltage and it is very consistent according to the clark's garage. The wiper arm shows a steady reading.
I also changed out the FPR to the 2.5 bar version with the FQS at position 2. The idle starts at around normal (14.7) then dwindles down to around 13:1.
I'm having trouble tracking down a gauge for my fuel rail, but, I'll get one soon.
I also changed out the FPR to the 2.5 bar version with the FQS at position 2. The idle starts at around normal (14.7) then dwindles down to around 13:1.
I'm having trouble tracking down a gauge for my fuel rail, but, I'll get one soon.
http://www.clarks-garage.com/shop-manual/fuel-18.htm
Testing the AFM, it is best to do a reality-check with it in the car running. This way you can watch the voltage to see if the AFM is sticking or is abnormally high.
03-16-2012 | 12:18 AM
#20
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I noticed when I started the car, the AFM wiper arm was jiggling back and forth quite a lot. I gave it a little throttle and then it stopped.
Also, my idle has gone up to 1400 even with the ICV disconnected and the idle screw all the way in.
Maybe I need to check for vacuum leaks again.
Also, my idle has gone up to 1400 even with the ICV disconnected and the idle screw all the way in.
Maybe I need to check for vacuum leaks again.
03-23-2012 | 04:49 PM
#23
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So, I've double checked vacuum leaks, none found. However, it looks like my TPS has taken a dump. I disassembled the TPS and found the brushes were totally messed up.
That's probably the cause of my 1500 idle, and then 2500 idle. Sheesh...
One thing down, another comes up. I've angered the Stuttgarian Gods again...
That's probably the cause of my 1500 idle, and then 2500 idle. Sheesh...
One thing down, another comes up. I've angered the Stuttgarian Gods again...
03-28-2012 | 06:23 PM
#24
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Ok, so, here are the changes I made:
Changed TPS, for a known good working one.
This made the idle return to normal (950 +-50).
Triple-checked vacuum leaks, none.
At this point, I maintained around 14:1 until it got warm, then it dropped to 13:1.
So I charged up the battery again, it was pulling low voltage from sitting. Then, I switched the FQS switch back to the "0" position. Fired her up, sure enough consistently between 14.3-14.7:1.
I find it funny that it ran more lean when I effectively took fuel away from the mix.
Changed TPS, for a known good working one.
This made the idle return to normal (950 +-50).
Triple-checked vacuum leaks, none.
At this point, I maintained around 14:1 until it got warm, then it dropped to 13:1.
So I charged up the battery again, it was pulling low voltage from sitting. Then, I switched the FQS switch back to the "0" position. Fired her up, sure enough consistently between 14.3-14.7:1.
I find it funny that it ran more lean when I effectively took fuel away from the mix.
04-04-2012 | 08:00 PM
#25
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Ok, another update, failed smog AGAIN.
Pulled the plugs... They look pretty good.
Smog Report...
I did realize that my wiring harness was missing the "California Coding Plug". It's a plug with a red wire. I found one at that yard, but, the above test was without it.
On the possibility I had a weak spark, I tested the coil and it checks out too.
Any thoughts on how much this coding plug could affect my smog situation? At this point, there is no reason why it should be failing, but still is.
Pulled the plugs... They look pretty good.
Smog Report...
I did realize that my wiring harness was missing the "California Coding Plug". It's a plug with a red wire. I found one at that yard, but, the above test was without it.
On the possibility I had a weak spark, I tested the coil and it checks out too.
Any thoughts on how much this coding plug could affect my smog situation? At this point, there is no reason why it should be failing, but still is.
04-04-2012 | 08:45 PM
#26
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You are still way too rich...
Considering how much you have already gone through this, we could do one of two options:
1 - I can reburn your chip, and set it up for a significantly leaner fuel scaling.
2 - You can swap back in the 2.5bar FPR, which will reduce fueling by ~10%.
Not exactly the solution I would like to see, because the car shouldn't be this rich - it is indicative of another problem somewhere. But, I think we've been chasing this problem long enough already.
The coding plug no longer works quite the same, rather I re-tasked it - the coding plug is now how you select between pump gasoline and race gasoline maps. In factory form the coding plug wouldn't have helped your situation much.
Considering how much you have already gone through this, we could do one of two options:
1 - I can reburn your chip, and set it up for a significantly leaner fuel scaling.
2 - You can swap back in the 2.5bar FPR, which will reduce fueling by ~10%.
Not exactly the solution I would like to see, because the car shouldn't be this rich - it is indicative of another problem somewhere. But, I think we've been chasing this problem long enough already.
The coding plug no longer works quite the same, rather I re-tasked it - the coding plug is now how you select between pump gasoline and race gasoline maps. In factory form the coding plug wouldn't have helped your situation much.
04-04-2012 | 08:57 PM
#27
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EDIT: I put in my other aftermarket chip, for the stupidity of checking. The idle goes back to 850, it's not horribly rough at idle (as in chair massage) and then my AFR's seem to level out at 14.2. Smooth as silk now. I may even try passing smog with this chip. Just for the sake of science, I noticed the difference in AFR's between FQS positions. Position 0 put me at around 12, then position 2 put me up to over 14.
Looks like my chip needs a re-flash.
Well, I REALLY appreciate your assistance here.
I used the 2.5 Bar FPR for this test. Is it possible my chip was burned with some goofy mapping?
Also, if I was running really rich, wouldn't my plugs looks all black?
Looks like my chip needs a re-flash.
Well, I REALLY appreciate your assistance here.
I used the 2.5 Bar FPR for this test. Is it possible my chip was burned with some goofy mapping?
Also, if I was running really rich, wouldn't my plugs looks all black?
Last edited by doabarrelroll; 04-04-2012 at 11:08 PM. Reason: updates
04-04-2012 | 11:26 PM
#28
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How long did you warm-up the exhaust before the test? In a turbo car - the turbo takes a lot of heat, and it can take quite a while to get the cat really hot.
I suppose it is possible the chip was burned with the wrong mapping - I'll send you another just make sure.
I suppose it is possible the chip was burned with the wrong mapping - I'll send you another just make sure.
04-04-2012 | 11:30 PM
#29
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I went for a 20 minute drive before the test, so I figured it was pretty good and warm by that point.
Since I got the chip second hand, I'm pretty sure it was burned to a "custom" setup or something. I say this because all I changed was the chip and there was a HUGE change. I trust your setup and I think someone messed with mine at some point in its lifetime.
Since I got the chip second hand, I'm pretty sure it was burned to a "custom" setup or something. I say this because all I changed was the chip and there was a HUGE change. I trust your setup and I think someone messed with mine at some point in its lifetime.