Open Loop all the time with no WB?
05-08-2007, 05:07 PM
#1
Open Loop all the time with no WB? My 98 seems to have an 02 sensor problem or something. When in closed loop it goes south, the fuel trims are -11 and above. I dont have a wideband in the car so I will not be able to monitor the AFR. I plan to tune the VE table in SD first and then dial in the MAF so if the MAF fails the VE should stand good. Whats your opinions on this?
05-08-2007, 06:32 PM
#3
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The normal failure for an O2 sensor is low output (indicating lean)
so you would expect sensor issues to manifest as positive trims.
A gross fail would peg the trims one way or the other, seeing a
"sane" number indicates to me a different sort of error in the
system.
If you monitor closed loop O2 voltage in steady running and it
switches fairly rapidly, you can discount O2 sensors as the root
of mis-trimming (it is working well enough for the loop to center
itself).
Both narrowbands and wideband oxygen sensors can be fooled
by excess air but this would again jack it lean (+ trims). Point
being if you have -something- that fools a narrowband O2 then
a wideband is not necesarily a reliable "tiebreaker".
so you would expect sensor issues to manifest as positive trims.
A gross fail would peg the trims one way or the other, seeing a
"sane" number indicates to me a different sort of error in the
system.
If you monitor closed loop O2 voltage in steady running and it
switches fairly rapidly, you can discount O2 sensors as the root
of mis-trimming (it is working well enough for the loop to center
itself).
Both narrowbands and wideband oxygen sensors can be fooled
by excess air but this would again jack it lean (+ trims). Point
being if you have -something- that fools a narrowband O2 then
a wideband is not necesarily a reliable "tiebreaker".
05-08-2007, 08:04 PM
#4
Originally Posted by jimmyblue
The normal failure for an O2 sensor is low output (indicating lean)
so you would expect sensor issues to manifest as positive trims.
A gross fail would peg the trims one way or the other, seeing a
"sane" number indicates to me a different sort of error in the
system.
If you monitor closed loop O2 voltage in steady running and it
switches fairly rapidly, you can discount O2 sensors as the root
of mis-trimming (it is working well enough for the loop to center
itself).
Both narrowbands and wideband oxygen sensors can be fooled
by excess air but this would again jack it lean (+ trims). Point
being if you have -something- that fools a narrowband O2 then
a wideband is not necesarily a reliable "tiebreaker".
so you would expect sensor issues to manifest as positive trims.
A gross fail would peg the trims one way or the other, seeing a
"sane" number indicates to me a different sort of error in the
system.
If you monitor closed loop O2 voltage in steady running and it
switches fairly rapidly, you can discount O2 sensors as the root
of mis-trimming (it is working well enough for the loop to center
itself).
Both narrowbands and wideband oxygen sensors can be fooled
by excess air but this would again jack it lean (+ trims). Point
being if you have -something- that fools a narrowband O2 then
a wideband is not necesarily a reliable "tiebreaker".
05-08-2007, 11:55 PM
#5
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Originally Posted by 99ChargedFRC
What else could it be? MAF?
P.S. The plastic bag on the air filter actually happened to me so I thought I'd mention it.
05-09-2007, 07:33 AM
#6
Originally Posted by 99ChargedFRC
My 98 seems to have an 02 sensor problem or something. When in closed loop it goes south, the fuel trims are -11 and above. I dont have a wideband in the car so I will not be able to monitor the AFR. I plan to tune the VE table in SD first and then dial in the MAF so if the MAF fails the VE should stand good. Whats your opinions on this?
If your trims are "-11 and above", I'm assuming you mean between -11 and 0... So what's the problem here? They will lock in at ZERO at WOT like they should.
I'm not sure what the title of the thread has to do with this post either.
I guess I'm saying that I don't understand what the problem is?
05-09-2007, 07:57 AM
#7
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To answer the question in the title of the thread....
Even once you get it tuned, running open loop full time with out a way to monitor things is just asking for trouble. I run open loop full time and I don't go anywhere without my laptop or my WBO2. There have been times where IAT's and ETC's shot up, and so did my AFR. Until traffic got moving again, the bi-directional controls were a quick fix. Had I not had my laptop or my WB, I may have been ok. But, I'm glad I did.
Even once you get it tuned, running open loop full time with out a way to monitor things is just asking for trouble. I run open loop full time and I don't go anywhere without my laptop or my WBO2. There have been times where IAT's and ETC's shot up, and so did my AFR. Until traffic got moving again, the bi-directional controls were a quick fix. Had I not had my laptop or my WB, I may have been ok. But, I'm glad I did.
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05-09-2007, 08:38 AM
#8
Originally Posted by Frost
If your trims are "-11 and above", I'm assuming you mean between -11 and 0... So what's the problem here? They will lock in at ZERO at WOT like they should.
I'm not sure what the title of the thread has to do with this post either.
I guess I'm saying that I don't understand what the problem is?
I'm not sure what the title of the thread has to do with this post either.
I guess I'm saying that I don't understand what the problem is?
That post has everything to do with the title. I want to know if I can run open loop all the time without a wideband because I seem to have some problem going to closed loop. If I cant find the problem I will run open loop all the time. The car has always been fine in closed loop and now all the sudden its having this problem.
The problem is when I go to closed loop the car surges and bucks and has -11 and worse fuel trims.
05-09-2007, 09:32 AM
#9
Originally Posted by 99ChargedFRC
I should have said that a different way... it is never higher, closer to 0, than -11.
That post has everything to do with the title. I want to know if I can run open loop all the time without a wideband because I seem to have some problem going to closed loop. If I cant find the problem I will run open loop all the time. The car has always been fine in closed loop and now all the sudden its having this problem.
The problem is when I go to closed loop the car surges and bucks and has -11 and worse fuel trims.
That post has everything to do with the title. I want to know if I can run open loop all the time without a wideband because I seem to have some problem going to closed loop. If I cant find the problem I will run open loop all the time. The car has always been fine in closed loop and now all the sudden its having this problem.
The problem is when I go to closed loop the car surges and bucks and has -11 and worse fuel trims.
Well a tune doesn't "go bad", and something has definitely changed to cause this problem. How long since you have swapped out O2s? Running OL without a wideband doesn't sound like the best or even a good solution if everything used to work fine.
05-09-2007, 09:36 AM
#10
Originally Posted by Frost
Well a tune doesn't "go bad", and something has definitely changed to cause this problem. How long since you have swapped out O2s? Running OL without a wideband doesn't sound like the best or even a good solution if everything used to work fine.
05-09-2007, 09:44 AM
#11
I'm having some overheating issues with mine; they are at the end of each of my tubular manifold, and they make my closed loop AFR go nuts until I let it cool for a few mins...
Twin turbo vette?? spend the 250 to have your own wideband, it's not even pennies in that bucket. You will thank yourself for doing it.
Twin turbo vette?? spend the 250 to have your own wideband, it's not even pennies in that bucket. You will thank yourself for doing it.
05-09-2007, 10:26 AM
#12
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Maybe you should look at the cylinder mode misfires
when it commences to bucking (if that is not already
dummied out) and see if it's just a drool problem or
something.
Any chance this might have a manifold referenced
fuel pressure reg and lost its line, or something like
that, which would enrich low load, low MAP unusually?
when it commences to bucking (if that is not already
dummied out) and see if it's just a drool problem or
something.
Any chance this might have a manifold referenced
fuel pressure reg and lost its line, or something like
that, which would enrich low load, low MAP unusually?
05-09-2007, 12:45 PM
#13
Originally Posted by jimmyblue
Maybe you should look at the cylinder mode misfires
when it commences to bucking (if that is not already
dummied out) and see if it's just a drool problem or
something.
Any chance this might have a manifold referenced
fuel pressure reg and lost its line, or something like
that, which would enrich low load, low MAP unusually?
when it commences to bucking (if that is not already
dummied out) and see if it's just a drool problem or
something.
Any chance this might have a manifold referenced
fuel pressure reg and lost its line, or something like
that, which would enrich low load, low MAP unusually?
05-09-2007, 02:17 PM
#14
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Correct me if I'm wrong here....but, wouldn't a vacuum referenced *anything* have to go AFTER the throttle body, which is the bottle neck restricting airflow???