Only getting 160 miles on 25gal tank
- Thread starter pcharm129
- Start date
- Aug 15, 2012
- 191
I took these coming back from CT. Just snapped one every few seconds. Most are on cruise. 2 or 3 may not be. Couldn't record video sl i figured back to back shots were the next best thing... Thought these may help the thread get a better picture of what's going on. I have no idea how to interpret these...
gmcman
Member
- Dec 12, 2011
- 4,656
On the last pic, your o2 1x1V graph is about what it should look like at cruise with a steady pedal, but still not where it should be.
On the other previous pics, did you take the screenshot after the screen was opened or was it opened the whole time? Reason I ask is when the screen is opened, it takes a fee seconds for the graph to fill in from right to left. If it was left open the whole time, then the upstream o2 sensor is either toast, or you are just getting u metered airflow or unregulated fuel entering the engine and it would appear to be unregulated fuel along with a bad o2 sensor.
So was the screen you have posted opened the whole time, or did you take the screenshot right after it was opened.
On the other previous pics, did you take the screenshot after the screen was opened or was it opened the whole time? Reason I ask is when the screen is opened, it takes a fee seconds for the graph to fill in from right to left. If it was left open the whole time, then the upstream o2 sensor is either toast, or you are just getting u metered airflow or unregulated fuel entering the engine and it would appear to be unregulated fuel along with a bad o2 sensor.
So was the screen you have posted opened the whole time, or did you take the screenshot right after it was opened.
Tiggerr
Member
That upstream O2 looks wonky to me. That as obviously not gonna cause the kill in mileage totally but still looks wrong compared to mine.
That last pic looks better though.
That last pic looks better though.
BlazingTrails
Member
- Apr 27, 2014
- 19,409
Longest tech thread in the History of forums award.
Sib
Member
- Sep 6, 2014
- 3,446
Dont be. Im just reading along hoping that you will find a resolution before you throw the towel in and get rid of the vehicle. I commend you for the diligence.pcharm129 said:
gmcman
Member
- Dec 12, 2011
- 4,656
I took your screenshot and paired it with mine which are in the blue. When the upstream O2 sensor detects more oxygen it will richen the mix, and vice versa. This wave continues up and down but in small increments. Your SHFT or short term fuel trim tends to mirror the upstream O2 sensor as it's changing the mixture and the O2 sensor is picking it up, the downstream should be more steady as the cat is burning off the excess fuel or unburned hydrocarbons.
Your upstream is all over the place and the downstream tends to follow it. It seems like the PCM just can't learn a normal rhythm and keep things in check based on all the operating conditions..or it's doing what it can to at least try to keep the fuel mix in check.
When I changed my fuel pressure regulator, I noticed an immediate improvement, small but noticeable and my MPG's increased about 2 MPG. That doesn't mean yours is bad, and it's about a $100 gamble. Without driving it, or hearing it run, getting my hands dirty on it, it looks like a fuel injector issue, carbon deposits, or maybe even a bad O2 sensor.
The long green line at the bottom of the earlier graphs would seem to indicate that's right after the graphs started plotting, that's why I asked if they were just pulled up. Best thing to do is when the graph is opened, wait for the green line or the first reading from the flatline at the bottom, to reach the far left side.
Your upstream is all over the place and the downstream tends to follow it. It seems like the PCM just can't learn a normal rhythm and keep things in check based on all the operating conditions..or it's doing what it can to at least try to keep the fuel mix in check.
When I changed my fuel pressure regulator, I noticed an immediate improvement, small but noticeable and my MPG's increased about 2 MPG. That doesn't mean yours is bad, and it's about a $100 gamble. Without driving it, or hearing it run, getting my hands dirty on it, it looks like a fuel injector issue, carbon deposits, or maybe even a bad O2 sensor.
The long green line at the bottom of the earlier graphs would seem to indicate that's right after the graphs started plotting, that's why I asked if they were just pulled up. Best thing to do is when the graph is opened, wait for the green line or the first reading from the flatline at the bottom, to reach the far left side.
Attachments
- Aug 15, 2012
- 191
Thanks. Im really trying. But i definitely have started looking for a replacement... If i find something acceptable before i solve this issue, she's definitely gone. Problem is, i put so much $ and work into her, i'll never get enough for her to feel content...smh. If i can find another EXT, younger, less mileage, loaded, and maybe with a V8, i can swop everything i put on her, THEN get rid of her. Thats my thoughts. Cause i have a lifetime guarantee on many of the parts... Man...even my Alternator cost me $450...DAlastDON said:
Gerbil21
Member
- May 28, 2014
- 839
Didn't fully read the whole thread and I'm not sure if this was gone over already but all I can say is,
The 44k won't hurt anything, I have used it in my 05 voy and it seemed to have helped, that was a while ago but it didn't hurt anything. Its only $20 on amazon or you can get redline fuel cleaner for $15 on amazon aswell, I have definitely not heard anything bad about redline.
Also doing seafoam through the vacuum line is more dangerous that any known brand pour in fuel cleaner.
And make sure you only use top-tier fuel GM had a tsb put out for their injectors on our trucks and it says they will get clogged pretty quickly with cheap fuel so make sure you don't use the cheap brands. Also make sure you check the furthest in the back exhaust manifold bolts, they are know to break and can cause air to leak in the exhaust causing wrong readings on the o2 and mess with fuel trims.
Also I plan on running some acdelco x66p directly through the fuel rail and see if that helps, if there's any big difference I'll post it
The 44k won't hurt anything, I have used it in my 05 voy and it seemed to have helped, that was a while ago but it didn't hurt anything. Its only $20 on amazon or you can get redline fuel cleaner for $15 on amazon aswell, I have definitely not heard anything bad about redline.
Also doing seafoam through the vacuum line is more dangerous that any known brand pour in fuel cleaner.
And make sure you only use top-tier fuel GM had a tsb put out for their injectors on our trucks and it says they will get clogged pretty quickly with cheap fuel so make sure you don't use the cheap brands. Also make sure you check the furthest in the back exhaust manifold bolts, they are know to break and can cause air to leak in the exhaust causing wrong readings on the o2 and mess with fuel trims.
Also I plan on running some acdelco x66p directly through the fuel rail and see if that helps, if there's any big difference I'll post it
- Aug 15, 2012
- 191
Sorry for the long delay. This is one of my busy months. Im booked all month working like a slave. I got a chance to check the tailpipe. All clear...gmcman said:
I also just replaced the FPR and added an 11oz can of 44K to about 3/4 tank of gas. So, stay tuned sports fans! I'll let you know the results soon...
gmcman
Member
- Dec 12, 2011
- 4,656
Can you take a pic of the resonator, that doesn't look at all like the stock tailpipe. The resonator is the last component of the exhaust.
There's a chance this could be the root cause of your problems. Still hard to tell but it looks like a choke point for your exhaust.
There's a chance this could be the root cause of your problems. Still hard to tell but it looks like a choke point for your exhaust.
Tiggerr
Member
gmcman
Member
- Dec 12, 2011
- 4,656
Sure doesn't.Tiggerr said:
What exhaust is on there now, can you get under and post some pics? Is the entire assembly welded or clamped somewhere? If clamped maybe you can remove the rear portion, I know the factory muffler is pretty quiet to drive without a tailpipe or resonator, quiet enough to not attract any attention.
DocBrown
Member
- Dec 8, 2011
- 501
Yes, that's very strange.
I haven't followed this thread for a while, but in looking at the OP's profile photo something else came to mind. The custom grill shell. I have one on my Sierra. Guess what? Strange O2 sensor behavior. Occasional codes related to MAF and upstream O2. I ended up removing the grill due to trans heat issues while towing down south last week. Magically all my O2 issues went away too. Short story, air flow is critical to getting proper readings on the sensors. Coupled with that small resonator outlet...
I haven't followed this thread for a while, but in looking at the OP's profile photo something else came to mind. The custom grill shell. I have one on my Sierra. Guess what? Strange O2 sensor behavior. Occasional codes related to MAF and upstream O2. I ended up removing the grill due to trans heat issues while towing down south last week. Magically all my O2 issues went away too. Short story, air flow is critical to getting proper readings on the sensors. Coupled with that small resonator outlet...
- Aug 15, 2012
- 191
Exactly!Sparky said:
Its welded...gmcman said:
Nope. Its the stock pipe. There's no restriction. It just looks like a piece of rod got caught in there....gmcman said:
Its the same diameter of the stock pipe. And no bends... Generic tip. But all that was done long before i had this issue. Years before... And no change thus far. Actually back to the whole 160 per tank thing. Tank just hitting E so this will be my first fill up...gmcman said:
Point taken DocBrown. I've been meaning to run a hose from vent to intake. Giess i better make that happen now. No O2 codes tho. Actually no codes at all. Thats part of the problem...
gmcman
Member
- Dec 12, 2011
- 4,656
I cant draw anything on the pic right now but what I'm looking at is the smaller opening at the other end of the tip at the weld. Is it me or does that opening look about half of what the opening should be? Or is that about a 4 or 5" diameter tip thus making the opening in question correct for the application.
Point I'm making is if you have a restricted opening in the exhaust you will have increased backpressure.
Point I'm making is if you have a restricted opening in the exhaust you will have increased backpressure.
