Upstream vs Downstream O2 Sensors

[Dmascari1984]

That looked to me like an inexpensive gauge, one not dampened with oil. The pressure looked normal. If the fuel pressure was really bouncing around that much one would think the idle would have been terrible. I'd like to see what the scan tool sees for FP.

It was a fuel gauge kit from oriely. And the idle is terrible. On the gauge video i was resting my hand in the car and the vid is shaking. The scan tool has it going from about 40-45psi just not as erratic. Not sure where the pressure gauge is getting the reading from as the analog gauge was on the rail. I did fill up with E85 vs my regular mid grade and it seemed to help a bit.timing wasn’t soo crazy and fuel pressure seemed to stabilize a bit. Not trying to hijack the thread but I feel like no one has found a solution and this one was the closest I could find to my issue.



On a separate note. I found both my front wheel bearings were bad and got some yesterday from oriely because they are closed today and I’m leaving to florida from Houston tomorrow morning. Well the sold me the wrong ones soo now I have to do it after work tomorrow. [emoji19]


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[swathdiver]

It was a fuel gauge kit from oriely. And the idle is terrible. On the gauge video i was resting my hand in the car and the vid is shaking. The scan tool has it going from about 40-45psi just not as erratic. Not sure where the pressure gauge is getting the reading from as the analog gauge was on the rail. I did fill up with E85 vs my regular mid grade and it seemed to help a bit.timing wasn’t soo crazy and fuel pressure seemed to stabilize a bit. Not trying to hijack the thread but I feel like no one has found a solution and this one was the closest I could find to my issue.



On a separate note. I found both my front wheel bearings were bad and got some yesterday from oriely because they are closed today and I’m leaving to florida from Houston tomorrow morning. Well the sold me the wrong ones soo now I have to do it after work tomorrow. [emoji19]


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Ok, if the pump is delivering fuel that erratically, if it were mine, I'd replace the whole fuel pump assembly with GM OE or ACDelco.

What part of Florida are you heading to? My little brother lives in Houston.

 

[Dmascari1984]

Ok, if the pump is delivering fuel that erratically, if it were mine, I'd replace the whole fuel pump assembly with GM OE or ACDelco.

What part of Florida are you heading to? My little brother lives in Houston.

we are going to Pensacola beach. I stay on the west side of Houston.
I will probably do the fuel pump even though the wife says no [emoji48] hehe. It’s one of those things I have to figure out. I will definitely post back when it gets done weather it helps or not


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[swathdiver]

we are going to Pensacola beach. I stay on the west side of Houston.
I will probably do the fuel pump even though the wife says no [emoji48] hehe. It’s one of those things I have to figure out. I will definitely post back when it gets done weather it helps or not

Are you taking this one to Florida? If you get in a jam down here, there's a bunch of us Floridians sprinkled around the state who'll be happy to help out.

 

[Hi-psi]

Are you sure it's detonation and not timing being pulled?

100% sure. It's audible detonation.

Confirmed with data logs. This was a frame shot from a recent WOT blast.

I was sick all through the holidays and the weather hasn't been cooperating either around here. I have two new upstream sensors ready to install, just have to get to it. Looking good weather wise so far for this coming Saturday.

I'll update as more info post-install is available.

 

[Dannydean]

Have you noticed bubbles in the fuel after running e85. If you dont see any like you did when your running gas , then I'd say the air bubbles are from the heat of the engine causing vapor lock air bubbles.

 

[Dmascari1984]

Are you taking this one to Florida? If you get in a jam down here, there's a bunch of us Floridians sprinkled around the state who'll be happy to help out.

Yup. We will be there today. Leaving Biloxi in a few hrs. Gotta change the wife’s BMW X5D thermostat and pulleys when I get there also. The Tahoe is pretty reliable but it’s the small things. I’m curious as to what the OP trims look like at idle I can post mine as well. I’m not sure my scanner does knock retard etc so can’t compare that with him. Btw my ride only had 58k miles. I think I got a lemon lol.


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[Dmascari1984]

Have you noticed bubbles in the fuel after running e85. If you dont see any like you did when your running gas , then I'd say the air bubbles are from the heat of the engine causing vapor lock air bubbles.

I haven’t checked after the e85 as I’m on the road with the fam. It still stumbles but is greatly reduced. When purging the gas it felt slightly warm. I put almost a full tank of 93 in and it’s just like before. I also loaded the BBP tune in to see if that would change it but did not. I will check on it when I get home next week.


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[Dmascari1984]

100% sure. It's audible detonation.

Confirmed with data logs. This was a frame shot from a recent WOT blast.

I was sick all through the holidays and the weather hasn't been cooperating either around here. I have two new upstream sensors ready to install, just have to get to it. Looking good weather wise so far for this coming Saturday.

I'll update as more info post-install is available.

Hope you don’t put your issue. I know how annoying the little things are.

If you already have the sensors might as well put them in. Doesn’t the system go into open loop st full throttle runs? Wouldnt that take the sensors out of the equation... ?

 

[Hi-psi]

I’m curious as to what the OP trims look like at idle I can post mine as well. I’m not sure my scanner does knock retard etc so can’t compare that with him.

I'll try to do an idle log today after work and post a vid.