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rage385
12-20-2014, 08:49 AM
Hello,

Is it possible to run a HFC with stage 1 tune? Will I see a check engine light?

I am currently running a test pipe on an APR stage II tune, but would like to go back to a stage 1 with a HFC.

Thanks!

mpsmith
12-20-2014, 08:55 AM
It's just a tune. You can run your cat with stage 2, why would you drop down?

Seerlah
12-20-2014, 08:56 AM
What is an APR stage 2? K04?

Tanzimur
12-20-2014, 10:17 AM
he probably means the apr 1+ 18psi of boost vs the stage 1 15psi...

Cybersombosis
12-20-2014, 01:31 PM
A stage 2 tune from APR is the exact same tune as a stage 1 tune with the secondary O2 sensor coded out. So running your high flow cat with the stage 2 tune is what I would do so I wouldn't get a cel.

Doug

rage385
12-22-2014, 05:55 AM
Thanks guys.

To be honest, I want to go back to a cat for two reasons.

1. Emission reasons.
2. troubleshooting a potential bad tune.

Regarding line item 2; I am the second or third 1.8T APR stage II that my mechanic has seen where the car seems under powered. I am not saying the tune is bad right now, but going back to a cat was something I had intended on doing anyway, so why not see what happens.

fed0ra
12-22-2014, 07:26 AM
Thanks guys.

To be honest, I want to go back to a cat for two reasons.

1. Emission reasons.
2. troubleshooting a potential bad tune.

Regarding line item 2; I am the second or third 1.8T APR stage II that my mechanic has seen where the car seems under powered. I am not saying the tune is bad right now, but going back to a cat was something I had intended on doing anyway, so why not see what happens.

If anything adding a cat to a catless system will only serve to make the car even more underpowered. You probably won't notice it, but I don't get how adding in a cat will help with that issue.

Mad Cow
12-22-2014, 08:17 AM
If anything adding a cat to a catless system will only serve to make the car even more underpowered. You probably won't notice it, but I don't get how adding in a cat will help with that issue.

034 proved that a test pipe has very minimal gains over a HFC with a k03, you wouldn't notice the loss in power.

rage385: Why go back to stage 1? Are you trying to stay with APR or something?

fed0ra
12-22-2014, 08:22 AM
034 proved that a test pipe has very minimal gains over a HFC with a k03, you wouldn't notice the loss in power.

rage385: Why go back to stage 1? Are you trying to stay with APR or something?

Yea, I know, I said he wouldn't notice it, my point was simply that it won't increase power over a test pipe.

rage385
12-22-2014, 10:48 AM
I wanted to stick with APR because downgrading the ECU could be done for free. I am not overly concerned about the power loss between a test pipe or a HFC. I wanted to do this because I am wondering if the stage II tune from APR is bad. Like I said, I wanted to go back to a Cat anyway, so its not like Ill be throwing money away.

Mad Cow
12-22-2014, 10:53 AM
Oh ok, you should be fine with a HFC in that case. Maybe you'll need to run a small O2 sensor spacer.

viceprp
12-22-2014, 03:09 PM
I ran 034 hfc and got a CEL after 2 years. They tested the cat and it passed will the cel on..

What's wrong with the car that you suspect the tune?

alexvanlewen
12-22-2014, 11:12 PM
I run an 034 HFC with APR Stage II and it works well, had it on stage I with no problems, no spacers

viceprp
12-23-2014, 04:33 AM
$300 HFC < $300 towards fixing actual problem.

rage385
12-23-2014, 04:57 AM
I ran 034 hfc and got a CEL after 2 years. They tested the cat and it passed will the cel on..

What's wrong with the car that you suspect the tune?

vice,

As I mentioned before, my mechanic drove the car and it felt under powered to him. He is also not the only person to say that too. I have never driven another 1.8T, so I cannot judge for myself. As far as fixing the actual problem; we performed leak test and compression test. All numbers look normal. He even inspected the turbo.

viceprp
12-23-2014, 06:14 AM
Find someone with a stage 1 tune around you, swap ECU quick and take it for a spin. Or buy one to resell. I wouldn't mess with the tp/hfc. That doesnt help your situation at all besides blowing away money.

I would buy a boost gauge before a hfc. Also, are you sure you're not just in limp mode?

rage385
12-26-2014, 07:30 PM
That is an excellent idea. I'll find someone with a P box stage 1 and give it a try.

I am running a podi boost gauge and I am getting 18 psi of boost.

Car feels dead off the line.

UCFQuattroguy
12-28-2014, 08:25 AM
Something I noticed with APR and a test pipe: The PID boost control tables aren't up to the task of your now quicker spooling K03. Not enough for limp or CEL, but just enough spike over requested to see a pretty harsh N75 adjustment. Harsh enough for my MAF values to actually *drop* between 3200-3600rpm.

Given that APR won't give this tune the time of day to "refresh" it...the only solution is to plumb a MBC in parallel to the N75 and set it to wherever your logs start to look happy again. Mine ended up being around 18.5psi. Left alone, I would get a peak of 19.0 before the ECU told the N75 to make the correction to 17. My MAF plots now show a much better rise with no indication of a flat-spot or drop as seen previously. I've validated actual performance increase by plotting an acceleration curve via ECUxPlot. Larger area under the curve and a flat torque curve from 3,000-4,5000rpm FTW!