MAF Pipe Diameter

DClipse · May 5, 2008, 11:48 AM

I'm still having issues with the fueling. The car wasn't running perfect even with the stock injectors and ECU. Everything is hooked back up and after a few days now, it started acting up again. The mechanic says it's because of the pipe diameter. We used the 2.5" pipe when we made the kit. I have to find out the exact size and convert it to suck thru set up also. Would that be the issue, cause the car goes down to mid 10's when I stop at the lights and then climbs up to 14's? Sometimes it will die out.

**otter** · May 5, 2008, 12:03 PM

Dying front O2 sensor? The stock MAF pipe is 2.5".

Do you have a tactrix cable so you can log and see if anything seems off?

DClipse · May 5, 2008, 12:16 PM

I changed to brand new O2 sensors. The only codes are bank 2 too rich and misfire. It's not misfiring like before. I know the afr's are messed up, cause the tune was according to a dying maf. Now the new maf is in and the tune is all over the place. Which is ok, but I ran rich before and wasn't making the car die out. If the pipe is 2.5" then I'm not spending anymore money to fix something that won't work anyway. It could be different on the Eclipse though.

$MIVEC$ · May 5, 2008, 01:10 PM

Where is the MAF located on your piping?

DClipse · May 5, 2008, 01:13 PM

Stock position, about 6-8 inches from the throttle body. It's just sitting upside down so it looks cleaner.

DangerousDan · May 5, 2008, 01:52 PM

how far from the BOV is it? could it be sensing air bouncing off the throttle plate or maybe air going through it backwards altogether? this was an issue I was told to be wary of when pressurizing the MAF, but it was more towards directly after you come off the throttle.

+1 on the tactrix cable, from my last phone call (she still hasn't called me back

) CAN bus support should be out or was immediately forthcoming. I didn't ask so I

for sure; it wasn't the topic of discussion

**otter** · May 5, 2008, 02:12 PM

Quote:

Originally Posted by DClipse

Stock position, about 6-8 inches from the throttle body. It's just sitting upside down so it looks cleaner.

Do you think the issue could be because you're pressurizing the MAF when you're not supposed to?

DClipse · May 5, 2008, 02:40 PM

Dan might have a point there. Maf is only about 2-3 inches from the bov. The reason why I had to buy a new maf was cause of a bov that was open at idle. I'm guessing it does the same when you let off the gas. But anyway we will be converting it to a suck thru set up. I'm just waiting on a Greddy BOV to arrive. So Ralliart pipe is 2.5"? And how much would it affect if it was a bit smaller?

DangerousDan · May 5, 2008, 07:27 PM

I was gonna suggest recirculation as a way to slow the transition, but thought it might hamper your efforts to find the root problem if that's not the cause

if it takes three days to show up you are a long way away by trial and error

mounting it upside down would make it more susceptible to moisture, just like an o2 sensor. I'm not sure how much condensation would affect it though.

the MAF has been pressurized before, otter. thunder-rush did it for sure, and I am sure there are others.

edit: also, try putting the BOV in different places to see if there is a change.

more grasping at straws though, I'd look into more data logging options before too long

doesn't always help, but it can't hurt

DClipse · May 5, 2008, 07:42 PM

It only took couple of days for the fuel trims to settle. Now, any change should be visible right away. I'm kind of unsure of what to do next, cause they told me that even after putting the new maf in and running the stock injectors and ecu the AFR's were still all over the place. There's something seriously wrong somewhere and they're saying it's the maf pipe diameter, and they want to keep going. Of course this is costing me a lot of money, and I don't wanna keep spending if the car is ****ed. I need to get the Evoscan.

$MIVEC$ · May 5, 2008, 10:46 PM

If it helps qlitv's solved the rough idle and being to rich by pressurizing the MAF. After testing a few things the maf pressurization was the last resort and it worked

DangerousDan · May 6, 2008, 06:16 AM

his is already pressurized.

well, put the stock airbox back on and test it out.

I took otters word for it and didn't measure, but 2.5 what I remember as well. oversized MAF pipe would, generally speaking, only lean it out unless the turbulence was real bad

DClipse · May 6, 2008, 07:44 AM

I guess it's not really pressurized at idle, or when I get off the throttle. That's when the bov stays open. Now that the warm weather is here, it seems about .25" open. It could be the reason for my troubles. We'll see how it goes with the new one.