P0171 after VMP GEN2R install

[abmobil]

Still chasing bugs. I’ve had the Gen2r for about 3 weeks.

Yesterday the CEL came on. P0171. Bank 1 too lean. Can’t find any vacuum leaks. It just came back from the installer who corrected a leak and VMP confirmed the logs were good.

Since the install it has a hot start stumble at idle. Not every time but about 50% of the time. If anyone has any ideas please share.

The car also had code U0415 but I think that is related to the dyno pulls from Monday.
Starting to really wish I left the car stock.

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[YukonRally]

Did the installer do any of the tuning, or just VMP? I only ask because I had multiple issues with my VMP tune that they never corrected. I was in a similar situation and regretting the install. I ended up contacting Lund and they got me all squared away and I'm loving it now.

 

[SheepDog]

Still chasing bugs. I’ve had the Gen2r for about 3 weeks.

Yesterday the CEL came on. P0171. Bank 1 too lean. Can’t find any vacuum leaks. It just came back from the installer who corrected a leak and VMP confirmed the logs were good.

Since the install it has a hot start stumble at idle. Not every time but about 50% of the time. If anyone has any ideas please share.

The car also had code U0415 but I think that is related to the dyno pulls from Monday.
Starting to really wish I left the car stock.

What are your fuel trims (STFT, and LTFT) when the engine is warmed up and Idling? Any other codes? How does it run other wise? How are you checking for Vacuum leaks?

Lean codes on only one bank are almost always vacuum leak related. Second would be fuel delivery issues, 3rd probably a bad B1S1 O2 sensor.

 

[abmobil]

Did the installer do any of the tuning, or just VMP? I only ask because I had multiple issues with my VMP tune that they never corrected. I was in a similar situation and regretting the install. I ended up contacting Lund and they got me all squared away and I'm loving it now.

Only VMP has done tuning so far. I was also getting a slight dead pedal after boost when going back to cruising speeds.
They sent a tune revision after I did a good amount of logging. Drivability is great now.

Still struggling with the idle issues.

 

[abmobil]

What are your fuel trims (STFT, and LTFT) when the engine is warmed up and Idling? Any other codes? How does it run other wise? How are you checking for Vacuum leaks?

Lean codes on only one bank are almost always vacuum leak related. Second would be fuel delivery issues, 3rd probably a bad B1S1 O2 sensor.

I’ll have to check the trims. Im new to data logging but I can probably figure this out in the logs I’ve already recorded.

I sprayed carb cleaner all over the place and couldn’t detect a leak. I can’t hear one either. Hopefully will have it on a smoke machine this week.

It’s runs great when driven though. Made 602 WHP last week.

 

[YukonRally]

Only VMP has done tuning so far. I was also getting a slight dead pedal after boost when going back to cruising speeds.
They sent a tune revision after I did a good amount of logging. Drivability is great now.

Still struggling with the idle issues.

I was having the exact same dead pedal issue. 5 revisions and they never fixed it. It would magically start working again as soon as I dipped below 2500. My idle was off also, would almost die shortly after startup. I'm glad they got you sorted, but I had to give up and try another tuner. The car was essentially undrivable.

 

[SheepDog]

I’ll have to check the trims. Im new to data logging but I can probably figure this out in the logs I’ve already recorded.

I sprayed carb cleaner all over the place and couldn’t detect a leak. I can’t hear one either. Hopefully will have it on a smoke machine this week.

It’s runs great when driven though. Made 602 WHP last week.

Really you just need to view live data while the engine is warmed up and running. A small vacuum leak may not even be noticeable in your logs. You can get a cheap OBD2 scan tool that will show live data. What are your AFR's (represented in Lambda) during your logs?

 

[abmobil]

Really you just need to view live data while the engine is warmed up and running. A small vacuum leak may not even be noticeable in your logs. You can get a cheap OBD2 scan tool that will show live data. What are your AFR's (represented in Lambda) during your logs?

This is from 2 min of idle at operating temp and a slow rev to 7,000 rpm after the idle time.

Bank 1 - values
Minimum - 0.97
Max- 1.04

Bank 2 -
Minimum - 0.98
Max - 1.38

The next day after these logs they sent me a new tune to fix my dead Pedal issue. I have put maybe 80 miles on the car since. Not only is the dead pedal gone but overall it just seems much better. Idle and all.

I am under the impression that this tune adjustment wasn’t meant to fix anything with the idle but so far it’s better.

I was supposed to use the diesel techs smoke machine at my job today. His machine wasn’t working well so that’s on hold. I’m in the process of moving. Once I finish I’ll find a shop for the smoke test and log again with the updated tune if there isn’t a leak or after I repair it.

 

[SheepDog]

Could be the tune I guess. Look for a leak around your throttle body. When you clear the code, does it come back instantly or after a few drive cycles or?​

 

[abmobil]

Could be the tune I guess. Look for a leak around your throttle body. When you clear the code, does it come back instantly or after a few drive cycles or?​

As you know when you upload the new tune it Deletes any codes before progressing or at least that’s how it’s it’s been with my
SCT X4. So yeah the 80+ Miles and no engine light yet.


The tuner did say in Most cases the leak is around the CAI, but mine seemed tight in all areas. I have considered just pulling it out all together reinstalling.
What did to think of my values from the log?

 

[SheepDog]

As you know when you upload the new tune it Deletes any codes before progressing or at least that’s how it’s it’s been with my
SCT X4. So yeah the 80+ Miles and no engine light yet.


The tuner did say in Most cases the leak is around the CAI, but mine seemed tight in all areas. I have considered just pulling it out all together reinstalling.
What did to think of my values from the log?

Reving the engine during the log disturbed the values. Also, every time you reflash it resets the fuel trims. Lambda values are not helpful in determining a small leak because the PCM will add or remove fuel to achieve ideal stoichiometric ratio. 1.0 lambda is 14.7:1 for gasoline. you need to see if the PCM is adding or subtracting fuel, which is why you need to view live data fuel trims. If the code didnt immediately reset, at least you know its not a broken wire or damaged O2 sensor.

 

[SheepDog]

Check the seal where your MAF is bolted on, the O-ring where your throttle body mounts to the blower, any tubes that are after the MAF

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