My fuel trim readings

[newbie78]

Used the new torque app and I get

Long Term B1 10.9 (idle) 15.6 driving about 40-50mph
Long Term B2 10.2 (idle) 13.3 driving about 40-50mph

My rpms at idle RPM fluctuate 606-646 all different numbers.

I don't have any check engine lights but I still have the pinging noise (i think) between 1500-2000 rpms only under load.

I don't know much about fuel trims but from quick reading you want the numbers to be close to 0 as possible. And anything above 10 + or - when you add the long term and short term numbers is a sign of a problem.

My short term numbers are -.08 to 1.6 fluctuates. With idling fuel trim numbers I'm already out of spec.

In my research I have a lean fuel mixture so the ECM is adding more fuel.


Am i right I have an issue? The engine misses when Idling as you can tell by the fluctuating rpms 606-646.

From what I'm reading a lean fuel mixture can be caused by about 20 different things. Like I said no check engine lights either.

 

[afpj]

With torque app you should check to see what your O2 sensors are doing. When they start going bad fuel trims can be off, and you might see the O2 sensor voltages misbehaving. You won't get a code until the sensor craps out completely. Cleaning your MAF would also be a cheap easy start.

 

[newbie78]

With torque app you should check to see what your O2 sensors are doing. When they start going bad fuel trims can be off, and you might see the O2 sensor voltages misbehaving. You won't get a code until the sensor craps out completely. Cleaning your MAF would also be a cheap easy start.

I cleaned my MAF last summer trying to diagnose some codes I had like p0300 and another one I forgot. Found the fuel pressure regulator was bad replaced that with a Delphi unit and all those codes went away.

I'm going to take a drive now and check the 02s.

---------- Post added at 07:08 PM ---------- Previous post was at 05:39 PM ----------

I checked the O2s on the live graphing and the bank1 and bank2 sensor 1 were looking fine up and down from .1 to .9 . The sensor 2's were pretty steady around .4 at idle. I thought all 02s are supposed to go up and down steady throughout the voltage range?

I also have a couple fails under the "test results" in the torque app.

TID $04 CID:$20 high sensor voltage for switch time calculation

And about 3 others of these fails. I have no idea what this means.

 

[afpj]

The precat sensors should have rapid oscillation ( rapid sine wave). The post cats are a slow sinusoidal iirc. Sorry can't help with that error code. Checked your plugs lately?

 

[newbie78]

The precat sensors should have rapid oscillation ( rapid sine wave). The post cats are a slow sinusoidal iirc. Sorry can't help with that error code. Checked your plugs lately?

I think on these trucks 3 of the sensors are upstream and 1 after the cat.

I checked the sensors again the bank 1 sensor 2 seems to be acting funny I could be wrong. The sine wave is kinda all over the place and not up and down like sensor 1. Sometimes it will stay almost flat at .2 and .3 then it will wake up and go up to .7 never up to .9 Stayed flat on .2 and .3 for like 15 seconds that I watched it while idling. So is it a possibility that 02 is bad?

 

[SunlitComet]

two pre cat and two post cats. if you do not have any vacuum leaks and your injectors and ignition system check out the switching error would likely results from failing 02 sensors. your rear waveform should be steady without much of any change indicating properly working cats. the post sensors should not be on the bottom of the scale really.

 

[newbie78]

two pre cat and two post cats. if you do not have any vacuum leaks and your injectors and ignition system check out the switching error would likely results from failing 02 sensors. your rear waveform should be steady without much of any change indicating properly working cats. the post sensors should not be on the bottom of the scale really.

I'm going to just replace all 4 when I get the money. $105 for all 4 at RockAuto for Densos or I can get the Delphis for $135 total. The truck has 190k on it and if the 02s are original I bet they are fouled with exhaust contaminants.

 

[SunlitComet]

delco or delphis only. no denso stuff.

 

[newbie78]

delco or delphis only. no denso stuff.

What's wrong with Denso? I read that AC copied their design on the 02 sensors.


Also now I'm thinking my evap charcoal canister might be bad causing these high fuel trims. I put a new fuel filter on today and it runs better but now did not change the fuel trims.

Now I notice loud pops coming from the gas tank area. It did it twice while I was idling and was pretty loud. Sounds like a can popping.

So maybe there is a problem with my Evap canister or purge valve?

p.s. I also noticed some fuel vapors coming out of the gas tank when I took the cap off. I took the cap off to help relieve the pressure before changing the fuel filter. Does that mean fuel vapors are blocking up in the tank? Shouldn't all those vapors be heading into the evap canister?

 

[SunlitComet]

yes they should accumulate into the canister. make sure lines are routed properly.