Helping somebody else...LTFT negative, but O2s are flatlining from actual lean mix...
#1
Helping somebody else...LTFT negative, but O2s are flatlining from actual lean mix...
Hey, I am helping somebody out on here that is having a rather peculiar problem that I think is related to a bad tune. I have been thinking about this all day, and can't quite seem to figure out where they could have gone wrong. I wish I could look at the whole tune, but he is running Edit, and I have HPTuners...sucks...but anyways, here is the deal:
The car started running like crap on the drive home after the tune, the LTFTs are reading like -5 to -12, or something like that, which means it is pulling fuel, however the O2s are reading an actual lean mixture. He is getting a lean stumble. The Stoich sounds stock (14.737, which is actually leaner than my stock of 14.6 something), but I have a 98, and he has a 02.
He is running Flowtech longtubes, heads, cam, dual fuel-pumps (sometimes 66 psi of pressure), 28 lb injectors (new), new O2s. His VE table looks reasonable compared to mine. His IFR looks pretty close to stock though, but I thought the computer would compensate?? It sounds like the computer is actually causing most of the lean condition.
Other than the IFR table, (and maybe the MAF table which I haven't seen yet), I can't think of what could be wrong. He isn't getting a big swing in LTFTs and they seem to be going the wrong way.
The car started running like crap on the drive home after the tune, the LTFTs are reading like -5 to -12, or something like that, which means it is pulling fuel, however the O2s are reading an actual lean mixture. He is getting a lean stumble. The Stoich sounds stock (14.737, which is actually leaner than my stock of 14.6 something), but I have a 98, and he has a 02.
He is running Flowtech longtubes, heads, cam, dual fuel-pumps (sometimes 66 psi of pressure), 28 lb injectors (new), new O2s. His VE table looks reasonable compared to mine. His IFR looks pretty close to stock though, but I thought the computer would compensate?? It sounds like the computer is actually causing most of the lean condition.
Other than the IFR table, (and maybe the MAF table which I haven't seen yet), I can't think of what could be wrong. He isn't getting a big swing in LTFTs and they seem to be going the wrong way.
#2
TECH Junkie
iTrader: (36)
Here is a screen shot of what is going on.
Here is a copy of the edit file I am using also.
Edit File
I also have got Insufficient switching codes for both bank 1 and 2 and can't seem to figure it out. I have replaced the o2's several times to no avail. Thanks to all for the help.
Chad
TEA 5.7L Stg 2. Heads milled .030
FM11
Flowtech Headers/ORY
Ported TB
Stock MAF
Hooker Catback
SLP Lid
Walbro 255 Inline/Intank Fuel Pumps
02 28.8 Injectors
Here is a copy of the edit file I am using also.
Edit File
I also have got Insufficient switching codes for both bank 1 and 2 and can't seem to figure it out. I have replaced the o2's several times to no avail. Thanks to all for the help.
Chad
TEA 5.7L Stg 2. Heads milled .030
FM11
Flowtech Headers/ORY
Ported TB
Stock MAF
Hooker Catback
SLP Lid
Walbro 255 Inline/Intank Fuel Pumps
02 28.8 Injectors
#3
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Join Date: Apr 2003
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Here are a few options you can start off with. Try these out and see if the basics are working correctly. If they are then we can narrow it down to easier.
I would also tap into each wire on the O2 sensors using a Digital Volt Meter. Ensure that you are a getting a Heater Signal (+5v), A PCM Reference Signal (+5v), and a PCM Return Signal (This is what the O2 outputs back to the PCM it should be what you are seeing in EFILive,etc...) You can monitor this with a DVM as well.
Just for the heck of it I would also ensure that your headers have a good ground to the frame.
I would also tap into each wire on the O2 sensors using a Digital Volt Meter. Ensure that you are a getting a Heater Signal (+5v), A PCM Reference Signal (+5v), and a PCM Return Signal (This is what the O2 outputs back to the PCM it should be what you are seeing in EFILive,etc...) You can monitor this with a DVM as well.
Just for the heck of it I would also ensure that your headers have a good ground to the frame.
#4
TECH Junkie
iTrader: (36)
I follow checking the o2 sensors, but don't understand where the headers would be grounded at? I am wondering if it is the o2 extensions that I am using. They are 36" and I had to coil them up so they wouldn't touch anything.
Here is another screen shot that might be better.
Here is another screen shot that might be better.
Last edited by HC02SS; 07-13-2004 at 10:56 PM.
#7
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Likely not heating correctly, because they are not
in the correct place (long tubes, after 3 feet of
"radiator").
I believe the PCM shuts off heat power once warmup
is done. It may reapply power but would do this only
once it decides the O2s have "gone dark". If it has
to run power too much or running power still does
not suffice to get them lit, I think this is where you
get O2 heater codes. However I would like to find an
authoritative description of the basis of those codes,
this is just my shade-tree understanding.
in the correct place (long tubes, after 3 feet of
"radiator").
I believe the PCM shuts off heat power once warmup
is done. It may reapply power but would do this only
once it decides the O2s have "gone dark". If it has
to run power too much or running power still does
not suffice to get them lit, I think this is where you
get O2 heater codes. However I would like to find an
authoritative description of the basis of those codes,
this is just my shade-tree understanding.