akylekoz
akylekoz SuperDork
6/23/21 5:37 a.m.

akylekoz
akylekoz SuperDork
6/23/21 5:38 a.m.

akylekoz
akylekoz SuperDork
6/23/21 5:50 a.m.

Plugs on the left are drivers side, plugs on the right are passenger side.  The owner complained of a lack of power and miss.

2013 GT500 5.8 Supercharged.  Currently has about 8400 miles on it.

Overdrive pulley on the crank, under on the charger, Cold Air Intake, throttle body, NGK GT6 plugs, dual boost a pumps, longtube headers, full exhaust was installed with a few hundred miles on the car.  I have witnessed 21psi of boost, should be around 850 to 900 whores.

My research on this car tells me that plugs need to get changed every 3-5k, these have 6-7k on them.

Why is one band lean and one rich?

Which bank is correct?

Will a miss-firing plug or bad coil cause the whole bank to pull or add fuel?

It now has new plugs, coils, belts once they show up.  

My plan is to read the oxygen sensors out put and fuel trims once I get it back together.

alfadriver
alfadriver MegaDork
6/23/21 6:04 a.m.

One side is richer than the other, and the easy source of that is the headers relocated the O2 sensor in a place it gets a bad reading on one side or the other.  For this "error", the fuel trims probably are not reflecting reality, or they would be making the correction better.

Which bank is correct?  Probably neither- this is exactly why parts should get strong EO's before going out on the market.  But the plugs on the right are at least closer to what they should be.

In terms of the "dual boost pumps"- what does that mean?  Are they sequential or do they feed each bank independently?  

akylekoz
akylekoz SuperDork
6/23/21 6:23 a.m.

In reply to alfadriver :

The pumps are sequential, the Boost a pump is a voltage overdrive to get a little more out of the pumps.  1000HP requires bigger pumps and injectors, 850 to 900 just needs a little insurance for those cold days under full boost and traction, this almost never happens.

The headers came with the sensor bungs welded in the wrong position, they fit the floor.  I welded new ones in slightly forward and towards the inside to clear the floor.  

So you are leaning towards an oxygen sensor issue, location or function?

akylekoz
akylekoz SuperDork
6/23/21 6:27 a.m.

This car used to have catalytic converters until they blew out and wadded up, they are hollow now.

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) SuperDork
6/23/21 7:02 a.m.

Agreed on a bank issue, left plugs def are rich and right look closer. Assuming you get a primary O2 per bank so likely a sensor issue, or some air getting in causing that bank to show lean. 

akylekoz
akylekoz SuperDork
6/23/21 8:04 a.m.

All incoming air gets mixed and forced fed, there could be a leak between the MAF and throttle body but would not explain the bank to bank difference.   

I'm still waiting on a new supercharger belt, once that comes in I'll check the sensor function.

bigbrainonbrad
bigbrainonbrad Reader
6/23/21 8:19 a.m.
akylekoz said:

Plugs on the left are drivers side, plugs on the right are passenger side.  The owner complained of a lack of power and miss.

2013 GT500 5.8 Supercharged.  Currently has about 8400 miles on it.

Overdrive pulley on the crank, under on the charger, Cold Air Intake, throttle body, NGK GT6 plugs, dual boost a pumps, longtube headers, full exhaust was installed with a few hundred miles on the car.  I have witnessed 21psi of boost, should be around 850 to 900 whores.

My research on this car tells me that plugs need to get changed every 3-5k, these have 6-7k on them.

Why is one band lean and one rich?

Which bank is correct?

Will a miss-firing plug or bad coil cause the whole bank to pull or add fuel?

It now has new plugs, coils, belts once they show up.  

My plan is to read the oxygen sensors out put and fuel trims once I get it back together.

Not to be childish, but I'll be childish. Your power estimates made me giggle.

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) SuperDork
6/23/21 8:29 a.m.
akylekoz said:

All incoming air gets mixed and forced fed, there could be a leak between the MAF and throttle body but would not explain the bank to bank difference.   

I'm still waiting on a new supercharger belt, once that comes in I'll check the sensor function.

If it has a primary O2 on each bank, it's very likely the ECU is doing bank specific fuel trims. Even if things are OK going in, it doesn't assume things coming out are and will move fueling around accordingly. One example is if you have a header that has a slight leak at one port and drawing in air, it will show lean on that bank. This false-lean will cause the system to react and add fuel, leading to a scenario like you have above.

akylekoz
akylekoz SuperDork
7/9/21 5:24 a.m.

Welp I didn't drive this beast before fixing it so my test drive was somewhat inconclusive.  I told the owner that it loses traction around 10-12 pounds of boost in first thru third gear and sound great, he says that sounds about right on cold tires.  Back when I first put this car together I saw 21 lbs of boost in second gear, then had to pull my cheeks back on my face.

It had a code for a bad O2 sensor, I put two new ones in.  Idle was a bit rough when I first fired it up but after a test drive smoothed right out, probably just relearning the new sensors.

Checking the sensor function from a cold start it appears the one that went bad is a little slow to heat.  It initially showed fluctuating voltage then went flat for about 15-20 seconds after that both sided had similar readings.  We are calling it fixed.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
7/10/21 5:52 p.m.
Paul_VR6 (Forum Supporter) said:

Agreed on a bank issue, left plugs def are rich and right look closer. Assuming you get a primary O2 per bank so likely a sensor issue, or some air getting in causing that bank to show lean. 

I agree, especially when "longtubes" is mentioned.  Probably a header leak causing that bank to read falsely lean, so the computer cranks up the fuel.

 

Would love to see scan data with fuel trims at various points.

FatMongo
FatMongo Reader
7/10/21 9:02 p.m.

What brand headers?

akylekoz
akylekoz SuperDork
7/10/21 9:08 p.m.

In reply to FatMongo :

American Racing.

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