New Exhaust = bogging?

[SwitchSkier]

I finally put on my Thermal 3" catback on today and have a problem. First, when I started driving, it will be fine, then if i give it to much gas, it will lose power and sound as if im really bogging then engine. It seems to be struggling and rocks back and forth, yet I am driving easily at 3k rpm. It sounds like this a lot at 2k rpm, and sort of goes away at higher rpms, but not really. When idling, it sounds fine. Then in neutral just giving it gas it sounds fine if I give it a little, gradually. But, when I tap the gas quickly, the car makes a few large, low, rumbles, then gets back to normal.
I only have intake, bov, and UICP on the car right now.
I dont know what's wrong.
I also litterally could not get the rear O2 sensor out of the stock exhaust, we even tried heating it with a torch, so I plugged it with a bolt and am running without one. I do not have a simulator yet. This shouldnt affect performance, but just thought I'd add that too.

 

[staticbrainwash]

Um, not having a rear o2 WILL effect performance. The ecu is not seeing part of the information it's used to seeing. Try making the simulator or weld in a bung and i bet it will be better. also make sure you don't have pre turbo exhaust leaks or boost leaks.

 

[Street_Killer]

Um, not having a rear o2 WILL effect performance. The ecu is not seeing part of the information it's used to seeing. Try making the simulator or weld in a bung and i bet it will be better. also make sure you don't have pre turbo exhaust leaks or boost leaks.

Since when? All the rear o2 does is make sure the cat is working properly.

 

[staticbrainwash]

But the ecu still reads it as vital info.

My car did the same thing you're describing when my o2 went out. Granted it was my only one, but i'd make sure you've got them both. And honestly, if you could just cap it and leave it, what would be the point of all the kits out there to sim it.

 

[Locke]

The rear o2's only purpose to provide information that, when compared to upstrem o2 readings, determines the presence and condition of the catalytic converter. I know you know this, Geoff.

edit: the point of the o2 simulator is to prevent a CEL.

 

[dsm-onster]

Hmmm, the question is will an o2 sensor malfunction (or absense) cause the ecu to operate on conservative fuel/timing maps and/or shut down the BCS.

Cut off the rear o2 sensor. Bad?

http://www.dsmtuners.com/forums/showpost.php?p=1803184&postcount=4

3 inch turbo back exhaust with no rear O2 sensor


To eliminate the rear o2 the right way:
Making your own rear o2 bypass/simulator

In the tradition of Uncle Bruce (Oldman): have you run a boost leak test? Sounds an aweful lot like you have a blown intercooler hose or leaky BOV gasket.

Edit: Locke beat me to it.

 

[SwitchSkier]

In the tradition of Uncle Bruce (Oldman): have you run a boost leak test? Sounds an aweful lot like you have a blown intercooler hose or leaky BOV gasket.

I can do that tomorrow. I was just confused because the car ran flawlessly, without any leaks, before I put on the exhaust.

 

[dsm-onster]

Is it possible that you 'got on it' to see how nice your new exhaust sounds/performs and the aftermarket intercooler pipe you installed has popped off? Nevertheless, you have a dsm. A boost leak tester should be in your glove box .

 

[SwitchSkier]

Is it possible that you 'got on it' to see how nice your new exhaust sounds/performs and the aftermarket intercooler pipe you installed has popped off? Nevertheless, you have a dsm. A boost leak tester should be in your glove box .

I checked the pipes and everything looks normal. I actually haven't been past 4k with the new exhaust. I drove it around again and noticed the bogging is always when im on the gas. And its asociated with some whistle-ish ticking on the engine. It just feels like I'm lugging the engine a lot, but its at all RPMs. I will do the boost leak tomorrow and see how it goes.

 

[staticbrainwash]

The rear o2's only purpose to provide information that, when compared to upstrem o2 readings, determines the presence and condition of the catalytic converter. I know you know this, Geoff.

edit: the point of the o2 simulator is to prevent a CEL.

Ugh, yeah, sorry. Long Long Long day. Part of which i spent arguing with AAA because one of their insured's drunk butts hit my baby Talon. And now they have to decide if she's toast or not.

Sorry all.

 

[SwitchSkier]

Well I did a boost leak test and everything is perfect. No leaks at all. Now the car idles bad and runs bad unless I press the gas in neutral very lightly. When there is any load is shakes/bogs. What do I do now?

 

[dsm-onster]

logging a run would be fabulous. If you can get a cheap logger setup going then it would really save you alot of headaches and money.

 

[SwitchSkier]

I didnt want to buy one yet. I am saving up for DSMLink. I just finished my rear o2 simulator. Once I make a holder for it I can put it up and see if it does anything. I know technically it shouldn't change, but thats the only thing that changed since I put on my exhaust.

 

[Boise Talon]

I had the a problem that sounds really similar on my 91 tsi. It would bogg down around 3000 to 3500 rpm, and it started doing it at high rpms also. To me it felt like the motor didnt' want to "go". I ripped into my motor about a week later replacing some other things (clutch, etc), and when i but it back together it was gone. Now I don't have the problem.

 

[SwitchSkier]

It was only at certain rpms at first, like it switched on, but now it's all the time. The idle goes up and down, and when I rev it in neutral, I hear this whistle-ish tick in the motor. I just put in my homemade o2 simulator, and now the check engine light is gone, but the problem is still the same.

 

[Zenja]

Check for exhaust leaks. Make sure all the gaskets and bolts are good and tight.

 

[SwitchSkier]

I checked and everything looks good. All exhaust bolts are good and tight. I don't know what else to try now. Do I really need to get a logger?

 

[dsm-onster]

Could a turbo-to-exhaust-mani gasket have cracked? or perhaps the exhaust-mani-to-head gasket? Do you have black smutty buildup on your head at the exhaust manifold or around the turbo inlet? This could cause the exhaust system to "injest" air (more oxygen) and throw off your o2 sensor reading significantly. This would also cause a sluggish spool.

Go over all of your sensor connections just to double check w/ a "jiggle". It's easy to do. Start at the maf go to the coolant temp sensor at the t-stat housing go straight back to the CAS connection at the firewall. Go down the line of each injector and the spark plug wires.

How old are your plug wires?

It's not likely there's a problem w/ your exhaust install that could cause this issue. You could have broke something in the engine bay during the install. Which I think would be difficult to do on a catback install, unless you took to beating your engine bay w/ an exhaust pipe.

Tunerstein logging can be affordable and is likely worth it even before getting dsmlink unless you plan on parking the car until you get link in the mail.

 

[diddy456]

How about the o2 housing? If it's stock, the catback 3 inch isn't going to help much, but make it bog because the air isn't flowing after the turbo a freely as it does when it hits the cat.

-Shane

Well I had this problem, but with a bigger turbo. I just read your mods and don't see an upgraded turbo so I don't know if this is your problem then.

 

[staticbrainwash]

What are you talking about? It's been proven that even for the first 36" or so that 2.5" is just fine. So having one section (o2 housing) instead of the whole thing would be even better.

Look at the sheer # of people running stock ported 2g o2 housings and 3" exhausts, then tell me that the o2 housing is a bottle neck for a smaller turbo.

 

[SwitchSkier]

I checked the gaskets, but they all looked fine to me, which doesn't rule it out though, I'm still kind of new to this 4g63 stuff. With the car started I couldn't hear any leaks, but it could just be me. It does maybe make sense that I could have cracked something pre-o2 sensor when I was messing with the cat/dp.
With the car started, at first it was okay, no bogging. But the idle was high, about 1200. Then I drove it down the street and it started again. The thing is that my turbo spools very early, just like normal.
All the connections were good. The plug wires are stock, and I dont know when/if they have been replaced. The car has 103k. I dont know about the plugs because I lost my plug wrench and need a new one. I have new plugs and wires in the mail though.
I might be taking it in, but well see.