Thread: Well I'm just about out of ideas

Replaced the cat today, it WAS extremly clogged, there was black **** pouring out of it when I took it off. Threw a 3" DP on there too while I was at it. BUT...my gas mileage still sucks at about 12mpg or less and the idle is still rough. I know I have polys but I've been in cars with polys before and it was nothing like this. I'm pretty much out of ideas as to what could be causing this. Only code is for the o2 because the DP doesn't have a bung. Someone suggested to me the other day it could be the tune...any ideas?

Front 02 sensor is not plugged in? That would make it run rich.

The front o2 is plugged in and working good.

how is your tune set up? what do your LTFTs look like? are you running mega rich to compensate for the boost since you have nothing but a downpipe?

Originally Posted by Bio248

how is your tune set up? what do your LTFTs look like? are you running mega rich to compensate for the boost since you have nothing but a downpipe?

My KR levels were surprisingly low so we didn't have to chenge anything to compensate. I'm not sure how everything's set up because I had fastkatt do it I don't have my own tuner. It idles at about 1k in park too if that help anything.

high idle can come from a few things. a vacuum leak is a good first guess, but it wouldnt be smooth if that was the case. were any of your plugs ever smashed or anything? are you burning oil? how does the car run overall?

Originally Posted by Bio248

high idle can come from a few things. a vacuum leak is a good friend guess, but it wouldnt be smooth if that was the case. were any of your plugs ever smashed or anything? are you burning oil? how does the car run overall?

No I'm not burning oil and my sparks are fine. In idle it runs like **** but normal driving and in boost it runs perfect. I'm pretty sure I've fixed all the vaccum leaks already but I guess it can't hurt to check again. Last time it ended up being a loose bolt in the supercharger and a bad T, and all the lines looked good.

what about misfires? are you logging any?

Maybe a MAF on its way out? I'd plug it at idle and see if that changes anything.

Originally Posted by bluegtp91

Maybe a MAF on its way out? I'd plug it at idle and see if that changes anything.

MAF is on the list of things I already tried, replaced that with a new one a couple months ago. And bio no, there's no misfires.

shot o2 sensor up top?

Originally Posted by bluegtp91

shot o2 sensor up top?

Scanner readings from the o2 sensor are good. I'm stumped lol

Is your egr valve stuck open at all?

Originally Posted by 01GTP

Is your egr valve stuck open at all?

GOOD GUESS!

seriously, thats a good idea.

Hook up a scan tool and see what it says for the position at idle should be 0%.

That's one thing I actually haven't tried yet, I'll look at it tomorrow thanks guys.