Diagnose Lean Conditions

[vr4]

[quote=""Duck Vader""]Average shop charges $100 to diagnose. If over the life of the tool I use it 3x it would pay for itself.

That said.

It sounds like I have air coming from the vacuum on the top center of the intake.

Put in the new maf sensor as well.

Problem is I went to reconnect the battery and the negative cable bolt broke/stripped. Ordered a new one off Amazon for tomorrow delivery. Hope it's the right one.[/quote]

Side terminals? Any parts store will have the bolts. They're a few bucks.

[quote=""Duck Vader""]I think it's the pcv valve line and where it connects to the intake. That's where it kind of sounds like it's leaking/whistling.

Any ideas on how to check without smoke?[/quote]

That's not a common leak point. If the intake isn't broken, the hose isn't split, the fitting is tight, probably not a leak. Plastic intakes are loud. My mom's Maxima sounds like it has a leak. No leaks. Checked it multiple times.

[Duck Vader]

[quote=""vr4""]Side terminals? Any parts store will have the bolts. They're a few bucks.



That's not a common leak point. If the intake isn't broken, the hose isn't split, the fitting is tight, probably not a leak. Plastic intakes are loud. My mom's Maxima sounds like it has a leak. No leaks. Checked it multiple times.[/quote]

Yes side. Truck is blocking the jeep. Wife is at work. Don't feel like walking to the parts store. Lol

Hose doesn't look split from what I can see. Unless it's on the under side. Probably just loud then being plastic. Was going to spray it with something to see if it changes rpms but without being able to start it, that's a no go for now.

[Duck Vader]

These are the ones I got.

https://www.amazon.com/dp/B000CO7DIQ/re ... KFbHRFMXM9

Should be here tomorrow.

Then I'll drive the truck a couple hundred miles (1 week) and do another log and hope for the best.

[mjannusch]

I'd hope you tried O2 sensors first.

[Duck Vader]

Going to be honest with you. Completely spaced out on those. Lol. Very well might be factory ones still in there at 157k. I'll order a set and replace them.

[mjannusch]

Log 'em, see what they are doing.

[Duck Vader]

On the last log I did - 5 min of steady state driving

O2S11 read - Min 45.oo mV, Max 825.00 mV, Value 755.0 mV
O2S21 read - Min 45.oo mV, Max 835.00 mV, Value 755.0 mV

Still learning - so is that good numbers?

[Duck Vader]

These are the numbers from my log the other day.

[mjannusch]

You need to look at the graphs. I'd probably warm the vehicle up, disconnect the battery for a minute, hook battery back up, and then start the car and log O2S11 and O2S21. You are looking for "laggy" graphs where the sensor doesn't change quickly if you give it some throttle, or doesn't drop down to 0mv after you let off the gas and let RPMs drop from a higher RPM.

I'd think the max O2 readings would be higher than 835mv, but I don't know your vehicle well - so not sure on that.

When O2 sensors go bad, they typically read leaner than they normally would, which makes fuel trims rise (ECU thinks the engine is running lean, when it isn't) and your gas mileage goes down. If that's the situation you are looking at, I'd probably replace the O2 sensors and see what the fuel trims do after that.

[Duck Vader]

I'm going to replace them anyway. Read gm recommends replacing at 100k. Not sure if previous owner did it so I'm going to. Using gm oem sensors.

[Duck Vader]

Huge improvement with the new MAF sensor. Mac of 7.8 and 9.3 for longft1 and longft2. Down from 17. Might still swap O2 and see if I can get it even lower.

[vr4]

[quote=""Duck Vader""]Huge improvement with the new MAF sensor. Mac of 7.8 and 9.3 for longft1 and longft2. Down from 17. Might still swap O2 and see if I can get it even lower.[/quote]

That's about expected with e10 fuel and your airflow mods.