Chevrolet Colorado & GMC Canyon Forum banner

1 - 20 of 23 Posts

·
Registered
Joined
·
48 Posts
Discussion Starter #1
Following some of the suggestions from people on the forum, I puchased an Ultragauge to help diagnose the mileage problem on my truck. If you my other posts you will find that, yes I do know how to use the search feature, and yes I have searched all the posts and yes I have tried EVERYTHING that has been recommended to diagnose my problem (I will post a list of everything I have done later) with the exception of a tune (cannot find anyone in Minnesota to do one) and replace my exhaust cam actuator solenoid (hopefully next week).

This tread is less about gas mileage, and more about the info I am getting from the Ultragauge. For example my LTFT it almost always between +9% and +10.5%. That seems a little high. I replaced the upstream O2 sensor, and it did not change.

For days any the LTFT is between +9% and +10.5% (except at idle and decelleration).

Also my engine temp in running between 178'F and 182'F, I know this is a little low, but I am not sure how low as I have never had a engine temp digital readout before.
 

·
Registered
Joined
·
48 Posts
Discussion Starter #2
Here are some of the thing I have done to the truck

New Tires (got rid of the mudders and got highway tires)
New Fuel pump and filter
New Sparkplugs (old ones looked great but replaced them anyway)
Clean TB
Clean MAF
Disconnect battery for ½ and reconnect
New Airfilter
New O2 Sensor
Added injector cleaner and Seafoam to gas (separate tanks)
Check E-brake (have never used it)
Check that brakes are not draging
Remove toolbox from truck bed (and everything else from truck)
Checked all fluids (and replaced most with synthetic)
Had transmission shop look at trans
Had dealership make sure all SW/FW was up to date( including fuel economy update)
Drive like a grandma (I got 19mpg out of ’97 blazer driving same route to work, I get 13.7 to 14mpg out of canyon)
I use curise
Check distance with GPS
Calculate mileage with calculator (Miles traveled/gallons added, I do factor in non-stock tire size +3%)
Over inflate tires
The fact alone that I got rid of the KM2 tires and went to Longtrails and it only changed my mileage by .2mpg says that something bigger is wrong
60% of my driving is with an empty truck on highway with cruise
I drive an ’07 Z71 3.5L with 265/75/16 and a 1” lift.
 

·
Registered
Joined
·
2,725 Posts
Sounds like its going to be the winter blend gas what are u looking at with the ug ?
 

·
Registered
Joined
·
76 Posts
Just thought I'd throw my two-cents worth at ya: My 2005 Crew Cab Canyon with 80K miles and 3.5 engine has always gotten no less than 17.5 MPG and as high as 22 MPG, depending on how much city vs highway driving I do. Keep in mind mine is all stock, right down to the wheels and tires.
 

·
Premium Member
Joined
·
365 Posts
It very well could be the gas. I've been getting better mpg's as of late. I was dipping as low as 15 mpg in the dead of winter, but that was with some 4x4 use.
 

·
Premium Member
Joined
·
3,849 Posts
Following some of the suggestions from people on the forum, I puchased an Ultragauge to help diagnose the mileage problem on my truck. If you my other posts you will find that, yes I do know how to use the search feature, and yes I have searched all the posts and yes I have tried EVERYTHING that has been recommended to diagnose my problem (I will post a list of everything I have done later) with the exception of a tune (cannot find anyone in Minnesota to do one) and replace my exhaust cam actuator solenoid (hopefully next week).

This tread is less about gas mileage, and more about the info I am getting from the Ultragauge. For example my LTFT it almost always between +9% and +10.5%. That seems a little high. I replaced the upstream O2 sensor, and it did not change.

For days any the LTFT is between +9% and +10.5% (except at idle and decelleration).

Also my engine temp in running between 178'F and 182'F, I know this is a little low, but I am not sure how low as I have never had a engine temp digital readout before.
OEM tune - LTFT of 7-10 is normal once warm and under load.
I would be concerned if LTFT goes above 10 consistantly (warm & under load)..

Engine temp seems normal under winter ambient temps, subcooling taking place due to the high delta T of 182 VS. ambient winter temp.... You might even see those temps dive lower when your at WOT for a sustained period.

Things to try that you have not done yet:

Inspect your ignition coil (internal spring) (IE: SuperSparks upgrade). Make sure all contact points on OEM springs are with in tolerances. For the short money, you should just swap the OEM springs out for the Spark tubes that Supermodulation sells.

Seafoam the top end of the engine, there is a how to write up on 355Nation.

You have thrown the kitchen sink at this one to diagnose, I agree to swap out the ECAS for S&Gs, short money $65ish from dealership for a vital engine component. Then that is also ruled out by process of elimination.
 

·
Registered
Joined
·
8,881 Posts
Ran this through the system instead of Wynns fuel flush. I averaged 2-3 mpg better in my Ford FiveHundred. My tech put in his 01 DTS and is averaging 5 mpg gains. I would have your dealer perform the flush on yours with it.
 

Attachments

·
Premium Member
2005 Chevrolet Colorado/ 2018 GMC Canyon
Joined
·
1,169 Posts
I see that used a injector cleaner and seafoam but, you might try running a fuel additive or cleaner. Like a octane booster to help the winter blend gas. Also, I run marvel mystery oil and put it in every tank of gas and it helps. Plus its pretty cheap.
 

·
Registered
Joined
·
48 Posts
Discussion Starter #9
Just thought I'd throw my two-cents worth at ya: My 2005 Crew Cab Canyon with 80K miles and 3.5 engine has always gotten no less than 17.5 MPG and as high as 22 MPG, depending on how much city vs highway driving I do. Keep in mind mine is all stock, right down to the wheels and tires.
Wayneman, thanks for letting me know I am not crazy.


Canyon08Z71, Thanks for the support, I will replace the ECAS this weekend. Even with the truck is warm and I am crusing down the highway, it is still not uncommon for me to see a LTFT of +10.5%.

What else should I be checking with the ultragauge to help diagnose?


Budman, I have kind of factored in the winter gas. I am keeping in touch with other friends locally who have the same truck to get a feel for how gas is affecting their mileage.


Matt Shadow, I don't think an octane booster will help the winter blend. I believe a higher octane will one retard ignition in situation of higher compression. I think these trucks and the compression they run at is esentionally tuned for 87 octane. I have run injector cleaner through, but it never hurts to run another can through.
 

·
Really Colorado Obsessed!
Joined
·
2,614 Posts
my LTFT is 7-10 and once in a blue moon I see 10.5-11 which is high but its never lasting. Im tuned so I attribute it to that :D yours is bang on average
 

·
Premium Member
Joined
·
5,710 Posts
Wayneman, thanks for letting me know I am not crazy.


Canyon08Z71, Thanks for the support, I will replace the ECAS this weekend. Even with the truck is warm and I am crusing down the highway, it is still not uncommon for me to see a LTFT of +10.5%.

What else should I be checking with the ultragauge to help diagnose?


Budman, I have kind of factored in the winter gas. I am keeping in touch with other friends locally who have the same truck to get a feel for how gas is affecting their mileage.


Matt Shadow, I don't think an octane booster will help the winter blend. I believe a higher octane will one retard ignition in situation of higher compression. I think these trucks and the compression they run at is esentionally tuned for 87 octane. I have run injector cleaner through, but it never hurts to run another can through.
I don't know if it will really help diagnose much, but check the engine load using UG too. It's interesting to see how quickly the load changes. When I was towing my jetski, just a normal cruise along the highway was relatively high (can't remember the numbers now, but it was significantly higher than empty). Also use the correction factor to calibrate for tire size.

I used GPS and cruise control. I drove down a straight section of road on cruise for several miles, made a change to UG, same thing back home. I did 3 or 4 tests until it was close. I'd set cruise so UG displayed a set speed, then compare against GPS. that might not be any different than the calculations you have performed, but it's worth a try.

As for the temperature, I don't know what temperature makes it run rich, but UG will show when it's running in closed loop.
 

·
Premium Member
Joined
·
3,849 Posts
Canyon08Z71, Thanks for the support, I will replace the ECAS this weekend. Even with the truck is warm and I am crusing down the highway, it is still not uncommon for me to see a LTFT of +10.5%.

What else should I be checking with the ultragauge to help diagnose?
Your welcome.

The LTFTs are well with in OEM spec, even up to 10.5%..
Do you have the OEM air cleaner assembly on the truck or an aftermarket intake?
Have you checked all the possible sources of vacuum leaks on the intake system?

What PIDs are available for you to monitor with Ultragauge?
 

·
Registered
Joined
·
48 Posts
Discussion Starter #13
Your welcome.

The LTFTs are well with in OEM spec, even up to 10.5%..
Do you have the OEM air cleaner assembly on the truck or an aftermarket intake?
Have you checked all the possible sources of vacuum leaks on the intake system?

What PIDs are available for you to monitor with Ultragauge?
I did hit a LTFT of +11.5% on the way home today.
Stock Intake
With the truck idling I have sprayed areas of potential vacuum leak ( hoses on back side of intake between intake and firewall) with brake clean, and ver notice any change in idle.

The ultra gauge said I had about 40 PID's, I am still getting a handle on what they all are. Trying to figure out how to get programmed AFR and actual AFR.

Is there some PID in particular I should be looking at?
 

·
Registered
Joined
·
48 Posts
Discussion Starter #14
Obviously everyone was correct, the spacer that I put in the MAF did not change the gas mileage.

Did not cost anything so it was worth a try.
 

·
maniac mechanic
Joined
·
5,779 Posts
My truck saw some LTFT's that high under the stock tune as the others have stated. I would start saving for a tune, I was able to squeeze a couple MPG's out of tuning mine and my truck feels so much more comfortable driving with the proper shift points and line pressure since GM did a horrible job on our transmission tuning.
 

·
Premium Member
Joined
·
3,849 Posts
I did hit a LTFT of +11.5% on the way home today.
Stock Intake
With the truck idling I have sprayed areas of potential vacuum leak ( hoses on back side of intake between intake and firewall) with brake clean, and ver notice any change in idle.

The ultra gauge said I had about 40 PID's, I am still getting a handle on what they all are. Trying to figure out how to get programmed AFR and actual AFR.

Is there some PID in particular I should be looking at?
Good that you covered the bases of leaks, that can negatively affect trims. I would not be too concerned with your current LTFT readings, your in the range I would expect.

Commanded AFR is nice to know. Set it up and see what it shows you. You should be seeing 14.7 most times (closed loop) and stray from that when you put the pedal to the floor board. Actual AFR is not available unless you install a wideband o2 sensor/controller to monitor actual AFR above/below 14.7:1.

Misfire or timing retard available with the gauge? I did not see it listed on their site.
Sad to say the gauge is limited in its diagnostic service to you IMO..

Obviously everyone was correct, the spacer that I put in the MAF did not change the gas mileage.

Did not cost anything so it was worth a try.
Seeing is believing sometimes. :thumbup:

My truck saw some LTFT's that high under the stock tune as the others have stated. I would start saving for a tune, I was able to squeeze a couple MPG's out of tuning mine and my truck feels so much more comfortable driving with the proper shift points and line pressure since GM did a horrible job on our transmission tuning.
I agree the OEM transmission tuning lacks, some years worst than others. My belief is that Grandpa (most 355 owners in my area) likes weak, sloppy, and premature shifting.. :lol:
 

·
Registered
Joined
·
48 Posts
Discussion Starter #17
I did notice today that my ultragauge is show about a 24% engine load when I am idling at a stop sign, and a 60% to 75% load when I am running down the highway with cruise at 70 mph and 2000 rpms. Is this normal?
 

·
Registered
Joined
·
48 Posts
Discussion Starter #18
Does anyone know how to get the ultragauge to show the AFR commanded ratio? I have looking to the ultra gauge manual, but the command does not seem to be one on of the options listed. I know the available options are different depending on what vechile the ultragauge is plugged into, but I got the impression that other people were able to the the commanded AFR from their ultragauge.
 

·
Premium Member
2005 Chevrolet Colorado/ 2018 GMC Canyon
Joined
·
1,169 Posts
When you go to select gauges on the ultragauge that is all it will read on that vehicle. So if it doesn't show up it doesn't read it.

Sent from HTC EVO 4G
 

·
Premium Member
Joined
·
5,710 Posts
I did notice today that my ultragauge is show about a 24% engine load when I am idling at a stop sign, and a 60% to 75% load when I am running down the highway with cruise at 70 mph and 2000 rpms. Is this normal?
I will set the engine load feature back on mine and try to remember to monitor it tomorrow when I head out.

*EDIT*
I set the engine load and fired it up. I put it in drive and let it sit and it was steady at 30.2.
 
1 - 20 of 23 Posts
Top