Is my exhaust system too restrictive for my 6.0L? :TECH ONLY:
10-28-2008, 08:48 AM
#31
I consider it toast because it takes awhile for it to start switching... Also it does not switch at the same frequency as the other side. Also when it finally starts switching it does not go up to the same maximum voltage as the other O2 sensor... I saw the exact same problem on my truck... It might look minor, but it cause my trims to be off quite a bit...
Also if it is not working propperly you will be overly rich since you tuned with the NB02 sensors.... Being overly rich can mask alot of problems... I would suggest switching them from side to side and see if the problem follows.... If the problem does not follow look for a bad ground or missing ground attachement... If it does follow buy a new o2 sensor....
I fought tuning problems for like 6 months and after replacing basically every mod on my truck, it turned out to be a bad o2 sensor....
Also if it is not working propperly you will be overly rich since you tuned with the NB02 sensors.... Being overly rich can mask alot of problems... I would suggest switching them from side to side and see if the problem follows.... If the problem does not follow look for a bad ground or missing ground attachement... If it does follow buy a new o2 sensor....
I fought tuning problems for like 6 months and after replacing basically every mod on my truck, it turned out to be a bad o2 sensor....
What indication do you see that it's "toast"? It's still switching however I see it's reading 150mv less than the one on the odd cyl bank. Could this possibly be an indication of a bad ground instead? Maybe I should try switching them side to side. The 02's were fine before the 6L swap I'm almost positive of it. Also on about 5 separate occasions since the swap, after startup I've been having what I would consider a soft miss like the truck isn't hitting on all 8 cylinders. A hard miss I would consider ignition related where it causes the engine to jerk, this definatly seems fuel related where it doesn't jerk but the engine just isn't quite firing like it should. I've checked all the injector connections and coil pack connections so I don't think that's it. Also mind you, when this occurs I AM NOT setting a cyl misfire DTC. Usually a mile or so of driving clears this up. It's similar to starting a twin cylinder engine when it's cold and it'll only hit on one cylinder until warmed up. At any rate, can someone tell me every point on the engine harness where the grounds connect? I should clean them and reattach them before I store the truck for the winter. I wonder if a bad ground is causing the bad 02 readings. Also the wideband is stuck up the tailpipe AFTER both pipes merge. Meaning if I had bad fueling on one side, I wouldn't know it since the reading is a combination of both pipes merging. Hmmm interesting point. Let's say on bank 1 I have a 13.1:1 AFR and on bank 2 I have a 12.1:1 AFR. Would this cause the CURVE of my graph to fall off like it is or just make my HP numbers higher? I'm not concerned about numbers at this point. Just confused when the curve drops off so dramatically. I hope this post makes sense.
10-28-2008, 09:06 AM
#32
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b2 sensor does look lazy, but at wot non of your trims are involved with fueling, nor are the 02's being used....
You loss some of your manifold pressure as rpm increases. Engine off you have 99kpa, engine at WOT and 3000 rpm you have 98kpa, Engine at 6000rpm you are at 92ish kpa. I would think that if the exhaust is too restrictive, the manifold pressure would not change.... My bet is on the intake problem....
You loss some of your manifold pressure as rpm increases. Engine off you have 99kpa, engine at WOT and 3000 rpm you have 98kpa, Engine at 6000rpm you are at 92ish kpa. I would think that if the exhaust is too restrictive, the manifold pressure would not change.... My bet is on the intake problem....
10-28-2008, 10:06 AM
#33
b2 sensor does look lazy, but at wot non of your trims are involved with fueling, nor are the 02's being used....
You loss some of your manifold pressure as rpm increases. Engine off you have 99kpa, engine at WOT and 3000 rpm you have 98kpa, Engine at 6000rpm you are at 92ish kpa. I would think that if the exhaust is too restrictive, the manifold pressure would not change.... My bet is on the intake problem....
You loss some of your manifold pressure as rpm increases. Engine off you have 99kpa, engine at WOT and 3000 rpm you have 98kpa, Engine at 6000rpm you are at 92ish kpa. I would think that if the exhaust is too restrictive, the manifold pressure would not change.... My bet is on the intake problem....
10-28-2008, 10:08 AM
#34
I consider it toast because it takes awhile for it to start switching... Also it does not switch at the same frequency as the other side. Also when it finally starts switching it does not go up to the same maximum voltage as the other O2 sensor... I saw the exact same problem on my truck... It might look minor, but it cause my trims to be off quite a bit...
Also if it is not working propperly you will be overly rich since you tuned with the NB02 sensors.... Being overly rich can mask alot of problems... I would suggest switching them from side to side and see if the problem follows.... If the problem does not follow look for a bad ground or missing ground attachement... If it does follow buy a new o2 sensor....
I fought tuning problems for like 6 months and after replacing basically every mod on my truck, it turned out to be a bad o2 sensor....
Also if it is not working propperly you will be overly rich since you tuned with the NB02 sensors.... Being overly rich can mask alot of problems... I would suggest switching them from side to side and see if the problem follows.... If the problem does not follow look for a bad ground or missing ground attachement... If it does follow buy a new o2 sensor....
I fought tuning problems for like 6 months and after replacing basically every mod on my truck, it turned out to be a bad o2 sensor....
Can you tell me where all the grounding points are on the wiring harness??? I am going to try to tinker with it this afternoon and would like to do everything at once.
10-28-2008, 10:20 AM
#35
Man I have no clue on the grounding points, I know there are several on the back of the heads... I would start with switching the O2 sensors from side to side... Also, in EFI Live you can display the stored Fuel Trim Cell values, do you know how to display those in HPTuners? If so could you post up a screen shot for each bank?
10-28-2008, 10:57 AM
#36
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[QUOTE=Wilde Racing;4035116]b2 sensor does look lazy, but at wot non of your trims are involved with fueling, nor are the 02's being used....
QUOTE]
But if youve been setting up a VE off of a bad sensor it would have effects. Also any positive trims are dumped on top of the commanded at WOT, IIRC
QUOTE]
But if youve been setting up a VE off of a bad sensor it would have effects. Also any positive trims are dumped on top of the commanded at WOT, IIRC
10-28-2008, 01:24 PM
#38
I think the power falling off has nothing to do with the tune. AFR is AFR - matter how you get it (right or wrong) in the end if the AFR is on it's on. We can have this discussion another time about part throttle tuning with bad 02's and improper grounds, etc but I'm still not convinced the falling off power is in the tune. I've confirmed the TB was opening all the way, no air intake tube and the exhaust sounds like it's well up to the task. Unless a 4.8L intake manifold is different which I'm told it's not, it has to be in the cam timing or valve events, right?
10-28-2008, 01:33 PM
#39
Ok, no more tune talk, sorry if I whored up your thread just trying to help...
Edit: I was wrong, grams/cyl should peak at peak TQ, then slowly drop down... Not Manifold pressure.... Yours keep climbing...
Edit: I was wrong, grams/cyl should peak at peak TQ, then slowly drop down... Not Manifold pressure.... Yours keep climbing...
Last edited by BlackGMC; 10-28-2008 at 03:08 PM.
