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

 

[viperkd77]

piper, please aim me. i see u have ideas on a sub setup in your trunk as well. But ne ideas on my mpg with dsmlink now?

 

[PieEyedPiper]

I like the idea of re-installing a grounding strap. Minimal work for potentially large pay off. It always gives me piece of mind to put things back to how it was intended to be by the mitsu engineers. I've seen grounding issues do scary stuff to cars so I'd definitely try it.

As for DSMlink, I'm not familiar with the file format they use, but if you can post a log on here I'd be happy to help interpret it for you - provided I'm able to read it. Does DSMlink allow you to export the log file into excel or a simple document readable by any windows computer?

Oh yeah don't forget we only need RPM, Timing, Knock (yay DSMlink), o2's, and TPS.

 

[95FlamingTalon]

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.

Yeah, the ground strap grounds the front o2 sensor as well. The rear o2 sensor is only good for setting off the check engine light, it doesn't effect engine operation.

 

[viperkd77]

when i get the chance, i get new grounds straps or soemthing (maybe find the old ones) and put them on . ill let u all know. thanks, Karac

 

[PieEyedPiper]

when i get the chance, i get new grounds straps or soemthing (maybe find the old ones) and put them on . ill let u all know. thanks, Karac

*cough* and DSMlink logs..

 

[viperkd77]

how to send the log, it is like 10 pages in word???

 

[PieEyedPiper]

PM me, I'll give you my email and I'll sift through it.
The log is one pull, 2k to redline right?
I'm sure theres just a bunch of needless info in the log if its 10 pages.

 

[viperkd77]

how do i put the logs in a from where i can send them to u. thanks

 

[viperkd77]

nevermind, i didnt see u replied and tha tthe thread turned into 2 pages, im a rere

 

[viperkd77]

my pm's arent working for some reason, so just email me and ill check it and then ill ahve ## email so i can sned the logs to u someway

 

[viperkd77]

hey, still havent gotten my car on a lift to look and put a ground strap on. I ahvent been home from school. Also, i stl d have dsmlink logs if i can send them to ne1 somehow. Car runs well at wot. I dunno if this exhaust could have nething to do with me having an a/t. They dp is close to the transfercase. My overdrive seems a little sluggish and i know that is very useful for mpg. thanks

 

[Midnight DSM]

hey, still havent gotten my car on a lift to look and put a ground strap on. I ahvent been home from school. Also, i stl d have dsmlink logs if i can send them to ne1 somehow. Car runs well at wot. I dunno if this exhaust could have nething to do with me having an a/t. They dp is close to the transfercase. My overdrive seems a little sluggish and i know that is very useful for mpg. thanks

I wouldn't worry about the DP being too close to the transmission. You have been going in the right direction with what you have been looking at already i.e. O2 or ground strap. An exhaust alone isn't going to change any MPG other than the fact that it sounds cooler now so you are into the gas pedal a little bit more. Go through the steps in your head, of removal and installation of the new exhaust. It has to be something that was either removed, left unplugged, or something in this area. Ground strap sounds like an easy solution and you don't need to find a lift to get that fixed. If you were die hard you could even use your factory jack to lift one corner of the car and install the strap. The strap goes about midway under the car from one of your exhaust clamps to the frame (any grounding position with a bolt)

 

[adidalax]

Car runs well at wot.

so it only runs like poo-nanny when you arent @ WOT?

 

[viperkd77]

true. like poonanny when not under wot. also, yea, i need to jsut get udner the car annd take a good look around the front and rear 02 sensors, could be soemthin stupid. Gas mileage seems to be gettin even a lil worse now even after leaning it out on link. Myabe even though my front 02 is reading voltage, it is going bad??

 

[adidalax]

im pretty sure its your front O2 sensor then. i believe when you're at WOT, you'll be in closed-loop. Just change the sensor out!! That heat from the torch coulda screwed the sensor....

 

[viperkd77]

i hope that is the case. Itll cost me a lil money, not much, but at least itll fix this mess. What do u mena by closed loop? when its not wot is it open loop?

 

[adidalax]

i hope that is the case. Itll cost me a lil money, not much, but at least itll fix this mess.

That's probably the issue, and yes...it is cheap. Might as well try it anyway

What do u mena by closed loop? when its not wot is it open loop?

Check this thread out...

http://www.dsmtuners.com/forums/showthread.php?t=126507&highlight=closed+loop

 

[viperkd77]

hey, havent done any ground straps. However, i disconnected the harness on the front 02 and did a log. I drove around the block and a constant .04volts for the front02voltage came up on dsmlink. The car smoked alot and ran a little more rugged. Maybe the 02 sensor is fine and it is the ground strap or exhaust leaks, etc? ne more suggestions. TPS voltage or soemthing? I ahve no idea.

 

[redeclipse7782]

I thought the o2 sensors have there own ground wire built into them? My ground strap is disconnected and my gas mileage is fine.