Exhaust, Otr, Dyno and some noise :-(

[St3k]

Good morning.

I have VF SS 08/2013 commodore.
I have done Full cat back, Hi Flow Cats and 1-3/4 exhaust headers. (all x-force brand).
Check engine light been turned off by changing computer settings (computer been told car has hi flow cats so o2 sensors doesn't go crazy anymore).
After this - car is running much smoother, helped bring fuel consumption back to normal. (17l/100 all in peak hour traffic).

But i start noticing some taping/knocking noise (very hard to hear) which starts about 2700-3000 rpm and mainly on 3rd gear. i only can hear it when radio is off
and windows is fully up. I took car back to shop. They checked car for a leaks by using hose on exhaust headers and tidying up bolts. they sad one of spark plugs was loose, but no exhaust leaks at all.
1. Question is: this noise is normal or not.
and what else I can investigate.
2. Should I do OTR and dyno tune? some people saying i must do it, some says nope. And if yes which shop you will recommend. (Sydney, NSW).

Thank you.

 

[monstar]

Good morning.

I have VF SS 08/2013 commodore.
I have done Full cat back, Hi Flow Cats and 1-3/4 exhaust headers. (all x-force brand).
Check engine light been turned off by changing computer settings (computer been told car has hi flow cats so o2 sensors doesn't go crazy anymore).
After this - car is running much smoother, helped bring fuel consumption back to normal. (17l/100 all in peak hour traffic).

But i start noticing some taping/knocking noise (very hard to hear) which starts about 2700-3000 rpm and mainly on 3rd gear. i only can hear it when radio is off
and windows is fully up. I took car back to shop. They checked car for a leaks by using hose on exhaust headers and tidying up bolts. they sad one of spark plugs was loose, but no exhaust leaks at all.
1. Question is: this noise is normal or not.
and what else I can investigate.
2. Should I do OTR and dyno tune? some people saying i must do it, some says nope. And if yes which shop you will recommend. (Sydney, NSW).

Thank you.

I think it is slight knock in Open Loop under peak load, evidence that changing induction and exhaust pressures mean recalibration.
In Sydney Oztrack and AutoWerks are great for this sort of tune.

 

[St3k]

I think it is slight knock in Open Loop under peak load, evidence that changing induction and exhaust pressures mean recalibration.
In Sydney Oztrack and AutoWerks are great for this sort of tune.

is this just recalibration or its dyno?

 

[monstar]

is this just recalibration or its dyno?

You definitely don't need a dyno to tune your car, unless you are actually racing, or have a custom setup, or a specific tuning target based on comprehensive logging.
Having said that, people do tend to spend large on custom dyno tuning unopened engine and pretty much off-the-shelf bolt-ons that 99% everyone else with a GenIV V8 has.
So unless you have a specific target (not kW dreams but tuning target) the effective gains of custom dyno tuning vs flashing a proven tune and a few tweaks is mainly for the dyno printout.
Both these firms offer a range of tuning as a service from mild mannered better driving to well proven safe tunes as that work (as above) to wild custom tune at the limit for racing.

 

[St3k]

You definitely don't need a dyno to tune your car, unless you are actually racing, or have a custom setup, or a specific tuning target based on comprehensive logging.
Having said that, people do tend to spend large on custom dyno tuning unopened engine and pretty much off-the-shelf bolt-ons that 99% everyone else with a GenIV V8 has.
So unless you have a specific target (not kW dreams but tuning target) the effective gains of custom dyno tuning vs flashing a proven tune and a few tweaks is mainly for the dyno printout.
Both these firms offer a range of tuning as a service from mild mannered better driving to well proven safe tunes as that work (as above) to wild custom tune at the limit for racing.

thank you for your response. just to clarify - what is Open Loop process? and how recalibration will help? ( I'm just confusing little bit coz , some adjustments been made on car's computer to take engine light off and adjust o2 sensors?) is this another adjustment? and how long i can drive with this issue without causing any damage?
and any thoughts about Sams performance?
(exhaust shop guys recommended this place)
thank you.

 

[monstar]

thank you for your response. just to clarify - what is Open Loop process? and how recalibration will help? ( I'm just confusing little bit coz , some adjustments been made on car's computer to take engine light off and adjust o2 sensors?) is this another adjustment? and how long i can drive with this issue without causing any damage?
and any thoughts about Sams performance?
(exhaust shop guys recommended this place)
thank you.

Open loop basically when the ECU switches out of typical fuel injection feedback loop - trimming the fuel based on feedback from the O2 sensors - into more complex modes of operation like cold startup, high speed air calcs (rpm), power enrichment. ECU monitors conditions and commands from 500 rpm to 3000 rpm to switch into Open Loop.
See those idiots who say you don't need a tune and the computer will adjust, are talking about fuel trims under typical conditions - Closed Loop. Yes there is some scope (+/-20%-30% trims) to get fuelling right in Closed Loop but when the ECU switches to Open Loop the calibrated values are preset, and are definitely incorrect for the change in induction and exhaust pressures.
Tuning the Malfunction Indicator Light off for a Diagnostic Trouble Code relating to improper value reported from rear Heated O2 Sensor does not affect the tune, unfortunately, no.
If you drive like a granny (as it appears most people are fine with by just turning off the MIL for the DTC caused by the HO2S value), then probably fine. But the engine is way out of optimal tune, potentially destructive and drives worse.
Sams Performance is a pillar of the Sydney tuning scene but a bit aloof, LS1 (GenIII era) tuning tools and method, bit expensive I thought last time I looked seven years ago.
As I said earlier all will do the job, not as if one is magically going to whip up something extraordinary out of the known combo. If they did then that's a worry

 

[bruiSSer]

AutoWerks did the full exhaust,OTR and dyno tune on my 6L vf. Overall I was happy with the work performed,the outcome and the price. Haven't had any issues since this was done about one and a half years ago. I would definitely go back there

 

[St3k]

AutoWerks did the full exhaust,OTR and dyno tune on my 6L vf. Overall I was happy with the work performed,the outcome and the price. Haven't had any issues since this was done about one and a half years ago. I would definitely go back there

thank you for your reply

 

[St3k]

Open loop basically when the ECU switches out of typical fuel injection feedback loop - trimming the fuel based on feedback from the O2 sensors - into more complex modes of operation like cold startup, high speed air calcs (rpm), power enrichment. ECU monitors conditions and commands from 500 rpm to 3000 rpm to switch into Open Loop.
See those idiots who say you don't need a tune and the computer will adjust, are talking about fuel trims under typical conditions - Closed Loop. Yes there is some scope (+/-20%-30% trims) to get fuelling right in Closed Loop but when the ECU switches to Open Loop the calibrated values are preset, and are definitely incorrect for the change in induction and exhaust pressures.
Tuning the Malfunction Indicator Light off for a Diagnostic Trouble Code relating to improper value reported from rear Heated O2 Sensor does not affect the tune, unfortunately, no.
If you drive like a granny (as it appears most people are fine with by just turning off the MIL for the DTC caused by the HO2S value), then probably fine. But the engine is way out of optimal tune, potentially destructive and drives worse.
Sams Performance is a pillar of the Sydney tuning scene but a bit aloof, LS1 (GenIII era) tuning tools and method, bit expensive I thought last time I looked seven years ago.
As I said earlier all will do the job, not as if one is magically going to whip up something extraordinary out of the known combo. If they did then that's a worry

thank you very much for your reply, may I ask you another silly question - should i add OTR? im not chasing a kw, but I think OTR together with 2.5 inch full exhaust gives better air flow and helps keep engine cool.

thank you.

 

[monstar]

thank you very much for your reply, may I ask you another silly question - should i add OTR? im not chasing a kw, but I think OTR together with 2.5 inch full exhaust gives better air flow and helps keep engine cool.

If you are not getting a tune then no need to do CAI in any form (including OTR) unless you want the noise. If getting a tune then yeah tune to CAI and headers.