Help with A/F ratio numbers with new turbo install. (2 Viewers)

[toddsmith1]

Brain trust,

I have installed a turbo and I am very happy with the results. Only running 5-6 pounds boost. Everything is stock. So the question I have is about the A/F ratio. In the attached link I have a short video of me driving on the highway showing my A/F gauge. It seems I am running lean at idle but its ok at speed and WOT??? I am also including a picture of the spark plug from #2 cylinder. It looks good to me. I pulled cylinder #1 and it was not quite as good(looked lean) but did not take a picture before I put it back in. I have about 15k miles on a complete top end rebuild that included a full injector cleaning. I have the feeling I am running lean on some cylinders but not others. May need to replace some injectors. No codes. I also pulled the plug on the o2 sensor and it did not make any noticeable difference. I tought it was odd that I did not get any codes when I unhooked the sensor. Should it throw a code?

The A/F gauge is all over the place, is that the way it is suppose to be? Would clogged/bad injectors cause it to very like that? Truck starts and runs great.

One last question, my turb is about 750 degrees. I have read that between 700 and 1000 is typical. Is that correct?

Cruiser

2 new items added to shared album

photos.app.goo.gl

Thanks in advance

 

[ChargedSHOTaco]

Brain trust,

I have installed a turbo and I am very happy with the results. Only running 5-6 pounds boost. Everything is stock. So the question I have is about the A/F ratio. In the attached link I have a short video of me driving on the highway showing my A/F gauge. It seems I am running lean at idle but its ok at speed and WOT??? I am also including a picture of the spark plug from #2 cylinder. It looks good to me. I pulled cylinder #1 and it was not quite as good(looked lean) but did not take a picture before I put it back in. I have about 15k miles on a complete top end rebuild that included a full injector cleaning. I have the feeling I am running lean on some cylinders but not others. May need to replace some injectors. No codes. I also pulled the plug on the o2 sensor and it did not make any noticeable difference. I tought it was odd that I did not get any codes when I unhooked the sensor. Should it throw a code?

The A/F gauge is all over the place, is that the way it is suppose to be? Would clogged/bad injectors cause it to very like that? Truck starts and runs great.

One last question, my turb is about 750 degrees. I have read that between 700 and 1000 is typical. Is that correct?

Cruiser

2 new items added to shared album

photos.app.goo.gl

Thanks in advance

View attachment 3500350

It would help to know what boost you are seeing at those AFRs. I honestly didn't think it ran lean at all, based on the video, but I don't know when the truck was in boost to definitively know.

 

[toddsmith1]

It would help to know what boost you are seeing at those AFRs. I honestly didn't think it ran lean at all, based on the video.

5-6 pounds of boost

 

[ChargedSHOTaco]

5-6 pounds of boost

There were instances where you stated that it you were "crusing at XX RPM" and the ARFs were in the 14's & 15's, if you were in boost during those times, and on the throttle, it would definitely be too lean.

While you were accelerating from 60-80MPH and the AFRs were dropping, the AFRs looked great.
If you are in boost, you would not want to see AFRs above 11.7 or so. IMO. Then as you accelerate and build boost, the AFRs should continue to drop from there.

 

[toddsmith1]

There were instances where you stated that it you were "crusing at XX RPM" and the ARFs were in the 14's & 15's, if you were in boost during those times, and on the throttle, it would definitely be too lean.

While you were accelerating from 60-80MPH and the AFRs were dropping, the AFRs looked great.
If you are in boost, you would not want to see AFRs above 11.7 or so. IMO. Then as you accelerate and build boost, the AFRs should continue to drop from there.

The 14s and 15s where not boosted. It drops to 11s underboost.

 

[scottryana]

Things look mostly fine, it is hard to tell in a video with just the AFR gauge and not the vacuum/boost gage and RPM, but for cruise and in vacuum those AFR's look fine, and then under boost those AFR's look fine. One thing I did notice is that your truck was still cold. The fueling when cold will be slightly different than when warm. Let it get to operating temps and check it again. But from what I saw I did not see anything alarming.

An yes the AFR gauge being all over the place is normal and what you want when you are using an O2 sensor to make decisions about fueling. You are using it just to monitor so you have to use your common sense to filter out some of the noise. You will always be lean on decel, anytime you shift you will see movement on the gauge, any slight pedal variation will likely decrease your AFR before the older and slower 1980's tech of the 80 series catches up to a modern O2 sensor.

 

[toddsmith1]

Things look mostly fine, it is hard to tell in a video with just the AFR gauge and not the vacuum/boost gage and RPM, but for cruise and in vacuum those AFR's look fine, and then under boost those AFR's look fine. One thing I did notice is that your truck was still cold. The fueling when cold will be slightly different than when warm. Let it get to operating temps and check it again. But from what I saw I did not see anything alarming.

An yes the AFR gauge being all over the place is normal and what you want when you are using an O2 sensor to make decisions about fueling. You are using it just to monitor so you have to use your common sense to filter out some of the noise. You will always be lean on decel, anytime you shift you will see movement on the gauge, any slight pedal variation will likely decrease your AFR before the older and slower 1980's tech of the 80 series catches up to a modern O2 sensor.

 

[toddsmith1]

Thanks for the replies. Feel better now. I went camping last weekend with a group of folks amd one builds high end hot rods for people and he said I was running way too lean. From what I have read in the forums siad that 14.71 was ideal at idle so I thought I was good.

Is the turbo at 750F good? I have had no issues with the truck over heating.

 

[scottryana]

You aren't going to hurt anything at idle. If you are lean under boost you will have detonation and that is when you have serious issues, at idle and cruise, because there is no WIDE band O2 and the old technology uses NARROW band O2 tech, the truck will kind of hunt between 14.2-15.2, the sensor only knows if you are between that range, if you are outside that range it doesn't know by how much etc.