BIC DDP and test pipe questions

[Compton74]

So as title states I have a BIC DDP, and just put a test pipe on my 3 inch hks exhaust ( not sure the name of it but it's the one that looks stock and is quiet). Now my question is Fuel mileage has greatly suffered after I took the cat off and put the down pipe on. Nothing else was done to the car at all, and my driving habits haven't changed at all. Could either one of these 2 items cause a fuel issue? Car is a 91 with lex/550 57trim. Thanks for the help

 

[radiod]

Did something happen to the O2 sensor when being pulled and put back in? Was the wiring and clips for the O2 making a good connection and not fried from hanging above a turbo/exhaust manifold with no heat shields on it? First thing I'd test with a noticeably large drop in fuel economy is the O2 sensor.

 

[Compton74]

Well when I installed my original drift motion 3 inch down pipe before the BIC DDP I noticed the plug easily fell out so I replaced it with a weather pack connector, which normally never fail but I'll check it out regardless. Thanks for the input I'll come back and let yu know what i find.

 

[Compton74]

So checked the o2 sensor and everything was fine, checked the plug and connection, and even checked codes just to make sure I wasn't missing anything, and still getting less then par mileage. Any Other things I can check?

 

[RazoE]

Not sure but let me know cause I'm getting consistant 12 mpg, even on the freeway with the same downpipe and no cat..

 

[gsxr141]

i too am getting crappy gas mileage. while i too have a bic ddp and catless 3" exhaust, i don't think that's the problem.

 

[shipkiller]

well you have 550cc and you are not tuned

 

[Compton74]

well you have 550cc and you are not tuned

I beg to differ, the original reg reimer mod states only 550s and a lex afm. Don't think there is much tuneing capability with the stock computer. Now the only reason I'm bringing the issue up to begin with is because with the drift motion 3 inch down pipe gas mileage was fine, as soon as the cat came off and the DDP went on gas mileage went in the crapper. I can throw the cat back on but I highly highly doubt not having a cat is at fault. But then again its hard to put a downpipe at fault as well. Guess I'll have to put the DM down pipe on and see if mileage changes, if so the down pipe is at fault.

 

[TrqMnstr]

I bet I can tell what it is, it's a rare condition called "Lead Foot". It's a mild condition that affects most vehicle owners after installing a performance part. My diagnosis, you like the way DDP sounds so you're on the gas a little heavier than normal. That or a vac leak.

 

[Compton74]

Lol ^ I keep trying to convince myself that its not that

 

[SupraCorwin]

I switched from a 3" dp and high-flow cat to a 3" ddp and no cat. Didnt notice a difference at all, my mpg is still in the mid 20's

 

[MKIIINA]

did you reset your ecu after installing the new ddp? might be the ecu relearning still.

 

[STREET90]

Compton, (black cressida) you got me concern, about this as I also have a downpipe on its way, I barely get 200 miles on a full tank, but then again I'm running a w58 with 3.93 rear end

 

[TrqMnstr]

"Lead Foot" is nothing to be embarrased about. Just be up front about it before any sexual activity. Ollz!!! In all seriousness though. Fill your tank reset your trip meter and calculate your mpg. Those modifications you have should not affect mpg's that drastically. Like I said before you might want to look for some vac leaks also.

 

[radiod]

I'm driving with a boost leak right now and getting 16mpg ONLY IN CITY DRIVING. Full turbo back 3" with the BIC DDP and cat delete. Getting mileage that low means something else is happening. When everything is working good on my car I can get ~18mpg in city, easy 21+mpg if I do some highway driving.

 

[shipkiller]

why are you driving with a boost leak??

 

[radiod]

It's my DD and I haven't been able to pressurize the intake to find it. It doesn't leak under vacuum. Everything still runs fine, just running a bit rich and cutting early/boosting low.

 

[TrqMnstr]

It's my DD and I haven't been able to pressurize the intake to find it. It doesn't leak under vacuum. Everything still runs fine, just running a bit rich and cutting early/boosting low.

I'm driving with a boost leak right now and getting 16mpg ONLY IN CITY DRIVING. Full turbo back 3" with the BIC DDP and cat delete. Getting mileage that low means something else is happening. When everything is working good on my car I can get ~18mpg in city, easy 21+mpg if I do some highway driving.

Uhh no. You have a leak. Of course you gonna get bad mileage

 

[radiod]

I know I'm getting bad mileage, I'm saying that. I'm saying I'm getting bad mileage and they're getting significantly worse, so something else is wrong on their cars. Never said my mileage was good, thus the...when everything is working good on my car I can get ~18mpg in city, easy 21+mpg if I do some highway driving.

 

[Compton74]

Compton, (black cressida) you got me concern, about this as I also have a downpipe on its way, I barely get 200 miles on a full tank, but then again I'm running a w58 with 3.93 rear end

Mike your only getting 200 a tank? There's something wrong then man. I get at least 300 a tank