17 gt pp missfire

[Platinum S550]

After all I have herd about dealerships I'm just going to do it myself. Just orderd a new intake of ebay for $90 with 10 miles on it. I will do it myself in my garadge so I know its done right and not take weaks. Plus if it work and goes smooth might do the 18 manifold later on

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[Platinum S550]

No still missing at low rpm stock. Not enough to throw a code but live data says 1 through 4 misfires. Runs fine under load. Hope this works its on the way.

 

[Kong76]

I found the same problem with mine. Cyl 6/8 test misfire. Not enough to throw any codes but like you feel slight quick instances of hesitation. Usually at light to medium throttle. Completely stock with 30k.

 

[ugstang17]

After all I have herd about dealerships I'm just going to do it myself. Just orderd a new intake of ebay for $90 with 10 miles on it. I will do it myself in my garadge so I know its done right and not take weaks. Plus if it work and goes smooth might do the 18 manifold later on

Before swapping the manifold did you note the vacuum at idle? There should be at least 15" of vacuum after warmup (stock cams and no cheesy fake ghost cam idle) You have a vacuum gauge on your dash in the gauges screen. Further LTFT's would indicate a potential vacuum leak by trying to over correct for the lean condition at idle and then clear up when you accelerated. This would also be seen in the AFR bank 1,2 data which you can observe using SCT's livelink II free download. Lund datalogs are saved as a .csv file so you can look at them as an excel spreadsheet or even through sct's free download called Livelink II. If you did not perform a step or sweep datalog there may not have been enough 411 to discern an issue.

Don't fail to factor in proper seating of fuel injector O-rings. If the rail is not seated properly the O-rings cannot seat, or they may allow air past below a certain vacuum level but seat as the intake plenum pressure gets closer to static (0.00 on your gauge).

As for what you "hear" about dealers, be more discerning than to simply take forum gossip and generalities about dealership experiences for gospel. If I were to believe everything on the internet, I would never leave my house, I would never buy a single thing because everything is a POS, and the world would have ended in 2012 based on the conspiracy of the Mayan Calendar. There are good tech centers and not so good tech centers. There are tech centers that are experts in certain areas because of the staff they have on hand. No tech (not even the average Joe) wants a return problem. There is no benefit in it. While the ignorance of the masses may think differently because they have never worked in a Field service or customer service or skilled trades maintenance repair position the fact is that satisfaction of one's job in these fields of work is based upon a first time resolve. Nothing worse than having to do exploratory work on an intermittent problem or hearing those dreaded words. "It's still doing it".

Best of luck to you.

 

[stangman638]

If it's not throwing a code how do you do you have misfires?

 

[Platinum S550]

Ya im almost positive it's the intake runner on one side. I could reach back there and activate the valves on the driver's side. Passenger nothing stuck. Look at the back of the intake you will see what activates them.

 

[Platinum S550]

I hooked up my buddys $2500 scan tool and drove it around. Said misfires 1-4.

 

[Platinum S550]

Lund said fuel trim is within 5% nothing that would show a misfire. But it's def missing my vac gauge says 20 if I go slow rpm will loose a little vac. looking at stft1 saying - 3 to -5 when it's cold warmed up it goes to 2 ltft1 is 4 at idle warm and cold?

 

[ugstang17]

If I understand the logging with Lund (just tuning my first car with them using Ngage) I would guess that would be similar to 1.04 on an SCT datalogger. 1.00 is no change on an SCT datalog. Not much there. Your indication that the intake runner damper is stuck on the passenger side (BANK 1) is def not a good thing. Since the car was running fine and now how this issue, I would agree with your findings on the mechanical issue you have come across more so than anything else. I keep forgetting about those stupid things because I have been running PD setups since my 2005. Good find.

 

[usgiorgi]

If I understand the logging with Lund (just tuning my first car with them using Ngage) I would guess that would be similar to 1.04 on an SCT datalogger. 1.00 is no change on an SCT datalog. Not much there. Your indication that the intake runner damper is stuck on the passenger side (BANK 1) is def not a good thing. Since the car was running fine and now how this issue, I would agree with your findings on the mechanical issue you have come across more so than anything else. I keep forgetting about those stupid things because I have been running PD setups since my 2005. Good find.

My intake manifold was replaced under warranty on my 2016 GT since I had P0300 and P0308 codes. I had stuttering at very light throttle around 2200rpm. They found the runner control valves were stuck because the manifold was cracked.

 

[Platinum S550]

Before swapping the manifold did you note the vacuum at idle? There should be at least 15" of vacuum after warmup (stock cams and no cheesy fake ghost cam idle) You have a vacuum gauge on your dash in the gauges screen. Further LTFT's would indicate a potential vacuum leak by trying to over correct for the lean condition at idle and then clear up when you accelerated. This would also be seen in the AFR bank 1,2 data which you can observe using SCT's livelink II free download. Lund datalogs are saved as a .csv file so you can look at them as an excel spreadsheet or even through sct's free download called Livelink II. If you did not perform a step or sweep datalog there may not have been enough 411 to discern an issue.

Don't fail to factor in proper seating of fuel injector O-rings. If the rail is not seated properly the O-rings cannot seat, or they may allow air past below a certain vacuum level but seat as the intake plenum pressure gets closer to static (0.00 on your gauge).

As for what you "hear" about dealers, be more discerning than to simply take forum gossip and generalities about dealership experiences for gospel. If I were to believe everything on the internet, I would never leave my house, I would never buy a single thing because everything is a POS, and the world would have ended in 2012 based on the conspiracy of the Mayan Calendar. There are good tech centers and not so good tech centers. There are tech centers that are experts in certain areas because of the staff they have on hand. No tech (not even the average Joe) wants a return problem. There is no benefit in it. While the ignorance of the masses may think differently because they have never worked in a Field service or customer service or skilled trades maintenance repair position the fact is that satisfaction of one's job in these fields of work is based upon a first time resolve. Nothing worse than having to do exploratory work on an intermittent problem or hearing those dreaded words. "It's still doing it".

Best of luck to you.

Thanks for the info

 

[ugstang17]

Hey! No problem. Your on the right track IMHO. Post up the results after you get the intake swapped out.

 

[Platinum S550]

Well it turns out it was the passenger imrc rod that activates them, snapped right where it connected behind the sensor. Car runs great again with the new intake. I guess people lock them out but I wanted to keep them.

 

[Platinum S550]

Hope this helps some people, my car wasen't even throwing any codes.

 

[ugstang17]

nice job.

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