awful gas mileage after new turboback!!

[viperkd77]

Hey guys, i recently installed a new 3inch stainless steel turboback exhaust. Everything was initially tight and there is a bung for the rear 02 sensor. I reused the rear 02 in the new exhaust even though its worthless and there is no CEL. I used to get like 19mpg in town and like 24highway. Now im gettin like an average of 12mpg after this exhaust. Something is up and i cant figure it out. Ive tried a boost leak test, but the boost guage doesnt read that ne boost is building up and i cant hear ne leaks. I never touched my front 02 and i hope it didnt go bad coincidentally the same time i put this exhaust on. I think i could have minor exhaust leaks, but i dunno. I can hit full boost, but it seems boggy and slow. The car really jsut doesnt seem as fast as it should be and the exhaust (megan muffler) sounds worse everytime i drive the car except at wot. at lower rpms it sounds awful and choking like. Need help. not sure what to do. u can aim me at the username as well. ne help appreciate and i live in the pittsburgh area. thanks

 

[PieEyedPiper]

Do a boost leak test and let us know how it turns out

It always helps to knock off the easy stuff first before you get complicated.

 

[viperkd77]

hey, i tried a boost leak test and its not reading an psi on the boost guage. Im not sure what is up. The ic pipes all seem tight and i dont hear ne air coming out of the pipes, etc. The tester was tight on the turbo and seemed sealed. Im not sure what is going on...

 

[PieEyedPiper]

Odd indeed.
Sometimes if my motor is in JUST the wrong spot it wouln't build any pressure either. Put the car in first and roll it forwards about 6" or so (or just crank the engine for a split second). This should change the positioning of the valves/pistons etc enough to allow you to build pressure. At least that is what works for me when I can't build pressure.

Oldman is really the best for this kind of thing but I'll help as much as I can.
Also make sure your tester was built securely and it isn;t the tester itself that is leaking all the pressure.
After we cross these off the list we'll move onto different ideas

 

[viperkd77]

i fixed the tester, it must have not been on right or soemthing. I just messed with it. I built pressure up to about 10psi and let it run out. i didnt hear anything except where the bov was. I then plugged the bov recirc hole and did it again. I heard nothing. I really dont think there are ne boost leaks. I have made black smoke, etc. I have 12mpg as of my last tank. my vacuum at idle is about 15. my boost pressure is set at 14psi. ???

 

[abaum565]

I recently installed a turboback exhaust also...right after that i was getting horrible gas mileage, and it would stutter. I did the boost leak test and was negative. But i did end up changing the plugs and wires, and that was the problem. so i would check your plugs and wires and make sure that the plugs are gapped correctly (.28) on NGK BPR6ES. Hope that helps

 

[VtecvrsTurbo]

If you got a turbo back exhaust then it would be impossible not to have touched the front o2 sensor. If your o2 sensor (rear) is the only one you touched then thats gotta be your problem. There is no reason that a exhaust would give you worse gas millage. Its supposed to help it. I would look into your o2 sensor!

OH I forgot, mabye you love the sound of it so much you beat on it more!?

 

[viperkd77]

hey again, no boost leaks, did the test correctly. checked the plugs and wires. the plugs seem to be burnin actually a tiny bit lean based on the whiteness. 3 of the four plugs were a little loose actually. the wires seem fine. the plugs are all gapped at .030 and they are ngk bpr7es, not even 1.5k miles on them. I am thinklin the rear 02 is now dead since i have no cel from the exhaust. I have been told that having a cat actually will make the air really hot right after the cat (where the rear sensor is) and not having the cat, the air is actually colder there and the sensor cannot read it obviosuly if it si dead. remember we took a torch to it to get it off the old catback. maybe it is shot. Also, the front sensor was never touched bc it is on the 02 housing, not the downpipe. the exhaust mods on the car never got that far. I clueless for answers. Black smoke and soot in the muffler. But the plugs read clean mixture. some1 thats an expert please help

 

[redeclipse7782]

The only purpose of the rear o2 is to determine if the catalaytic converter is functioning properly, it has no effect on a/f ratio, this is all controlled by the front o2 sensor. My thoughts on this is your front o2 sensor is dead. They may have heated up the bolts holding the turbo onto the stock downpipe and damaged the o2 or perhaps damaged the wiring. Did someone maybe unplug the front o2 thinking it had to come off then forgot to plug it back in? Check to make sure its plugged in and check the wiring to make sure it is not damaged. You still may need to change your front o2 even if it appears fine physically, pick up a data logger or borrow someone's to see if the o2 is cycling. Also check for any exhaust leaks. Nothing is stuck in the exhaust pipes either right? You have normal amount of airflown come out of the exhaust?

 

[viperkd77]

hey, some1 helped me and it is possible that he used a torch to get the original dp of the 02 housing since he used a torch for other things aswell. I guess ill have to get under it and see if wiring is damaged or something. It is clearly plugged in though. I think the dealership (sin, but my friend works there (lincoln section, not mitsu) can help me out through a friend and scan it. I think they ahve a special scan tool, like a logger to view everything, not jsut cel's. Maybe ill ahve to have him do so. let me know. thanks... o, and lots of exhaust flow. pretty cold, not hot. i can drive ahrd, and stand behind it and itll be only awrm. on stock, it was hot after the same type of driving. i dunno. thanks

 

[PieEyedPiper]

Maybe I missed it but did you test your intake tract to 20psi? How long did it take to bleed off?
Also for those boost levels you should probably still be running bpr6es plugs gaped at 0.28 but it is interesting your current plugs show signs of a lean condition.
Ususally ina case like this one tends to think there is an ignition problem or too much fuel - the rich mixture hurting performance.
So far the signs say it's not the latter because your plugs are white, meaning lean, and if you had any boost leaks youd be running richer. Also I believe a bad 02 sensor would induce a rich condition as well but maybe I am wrong.

Did you get any improvements by tightening your plugs?
Regardless you should try adjusting your plug gap to 0.28 and use bpr6es's.

But we have to keep in mind that this all started after a dp install.

You're on the right track with the logger. Buy one (or borrow, but they're great to have) and post up a log for us.
Of particular intrest will be your timing and o2 values.

 

[gimpybrad]

I have the same problem and I was getting 23 mpg before the turboback and now i am getting about 17, My CEL is on and its coming back as P0170 which, upon researching usually means the front o2 sensor is bad, I am going to pick up a new one asap and let you know how it turns out.

 

[viperkd77]

my friend works at mitsu and said he can sneak it in today if he has time to scan it and look at whats goin on. Ill tell him to look at the 02 value and timing and see if we can decipher what the heck is wrong. Havent drivin it since tightening the plugs, but 3 out of 4 were a lil loose. yea, before the install, i was still gettin good mpg with the same plugs and obtaining the same coloration on the tips. ???? Hopefully its jsut a damaged front 02 from a torch and nothing more complicated, but ill post again after the scan.

 

[viperkd77]

hey, had it scanned today and for some reason, it only came up with incomplete drive cycles. I ahvent disconnected the battery recently or nething either. So i guess the tuning is jsut completely out of wack or soemthing bad happened, i dunno. I ahve a coolant leak somewhere but where the unfortunate a/t tranny is and near the turbo (passenger side of engine). Other than that, i dunno whats goin on. pleas ehelp

 

[PieEyedPiper]

Sorry what codes did it give you exactly?
And did you get a chance to view your o2 values and timing under WOT?

 

[viperkd77]

hey, it seems that the 02 values were bouncing around more than they should. -800 to + 800 millivolts. i dunno if thats alot or not. And i was told the timing was ok. According to this guy wh scanned a few things, it seemed the cpu was jsut out of whack and that its getting mixed signals from somewhere so i doesnt know what its doing with the fuel. I was told its gotta either be the 02 sensors or a messed up injector(s). let me know pelase

 

[PieEyedPiper]

Do your self a favor and go out and buy your own logger.
I enjoy the product avilable from www.pocketlogger.com

What you need to do is either 1 of 2 things right now.

1. Buy a logger. Do a WOT pull from 2k to redline while logging rpm, tps, o2, and timing.
2. Blindly throw a relatively expensive part at it, A new front 02 sensor.

or just carry on how things are now, though we can't really be sure if its dangerous to do so without a good log.

Let us know what you plan on doing.

 

[viperkd77]

I think im gettin dsmlink.. then maybe i can solve my problem???

 

[PieEyedPiper]

I think im gettin dsmlink.. then maybe i can solve my problem???

Heh, DSMlink is the ultimate mod for our cars so you'll get no complaints from me! Once you get that going though you're going to want to do some logs with it to find out if it is indeed your 02 sensor (I'm thinking it is, but we can't prove that yet).

Let us know whats up when you get this sorted out, its always nice to see threads with happy endings.

 

[95FlamingTalon]

I had the exact same problem of installing an exhaust and getting terrible mileage shortly after. There is a ground strap that connected the stock exhaust to that heat shield under the car that is easy to forget to reinstall. It is supposed to help the oxygen sensor ground properly, but some believe that it isn't necessary to have it. I installed a new oxygen sensor and connected the ground strap at the same time and it fixed the problem(not sure which one did it). It wouldn't hurt to start with reconnecting the ground strap before buying any new parts.

 

[viperkd77]

wow, i didnt even think of that. I actually pictched that ground strap bc it was pretty beat up. Im guessin i can make a new one with some 4guage power wire and 2 connectors???? I know the one end attached to the frame, but i cant remember where the other end goes? Would it be on the 02 sensor or weld it to the new pipe or wut?? Let me know, thanks. Im still considerin gettin dsmlink to because of the deal im most likely getting. thanks

 

[95FlamingTalon]

You can make one if you want, but I found stainless steel braided ground straps exactly like that at Napa for cheap. It should connect the frame of the car to the exhaust. I connected mine with one of the nuts on one of the exhaust clamps. I can't guarantee this will fix your problem though, but I think it's worth a shot trying. Getting dsmlink will definately show you if your o2 sensor is at fault in any way. It is definately $600 worth of tuning and diagnostic tools.

 

[viperkd77]

ok. here we go. I did another boost leak test. leak at the throttle body seal. replaced w/ 1g throttle body and same air idler controller. Now i have a massive leak there bc the gasket is not in correctly and i have to take it all apart again and reinstall it. However, no leak from throttle body seal and now bigger throttle body. No leaks newhere else. Got dsmlink w/ecu outta sold 2g. Put the ecu in, it is socketed,etc. all good there. correct cord, etc. used my friends labtop bc he has a serial port, but he i guess has 1g software. The dsmlink seems to not be connecting now as the connection is timed out. do i need to dload 2g software or soemthing. is this a common problem???? I still dont know if the 02's could be bad or not. But i had a boostleak and i hear that even a lil leak like that can do alot with richness,etc. Now i have a huge leak thouh that i created and my idle is wack. But, how do i fix this dsmlink so i can get this thing tuned and see if nething else has created this problem of low mpg and horrible power. thanks

 

[viperkd77]

ok, have a capture on dsmlink at wot. if ne1 wants to view it (if even possible), i can send it to u and u can analysis it. It runs better, we leaned it out a lil so the air/fuel is aobut 10.5 to 1 ratio in the higher rpms. thanks

 

[gimpybrad]

Would the ground strap still be needed if I am no longer using the rear o2? I no longer have a cat and my rear o2 is simply tied to the bottom of the car. Which i didn't think would hurt the engine, it's basically just there to see if the cat is working, am I correct in my thinking. PS. Still waiting to install the new front o2, it is currently 34 degrees outside with a good layer of frost.