Cascade Crew

305 302eater · Posted: Wed May 16, 2007 2:36 pm Post subject: Over fueling problem

OK i have had this problem for a long time. Just want to see what you guys might think would be the problem. OK so i have rebuilt my throttle body have a spacer on it have a tbi chip and the rest of the listed stuff in my sig... i also have headers without a o2 senser. but i was over fueling just the same with my stock exhaust... Any input would be awesome guys...

Thanks Tim

Twilightoptics · Posted: Wed May 16, 2007 2:58 pm Post subject:

What do you mean by "overfueling"?

305 302eater · Posted: Wed May 16, 2007 3:06 pm Post subject:

OH ok over fueling meaning i have a cloud of fuel following me around... And it runs like crap till it warms up, misses and everything. But when i pull my plugs they are fine... No carbon or anything... ?

Dewey316 · Posted: Wed May 16, 2007 3:24 pm Post subject:

How are you running it without an o2 sensor? Get a stinking sensor in there, so it can actualy make proper fuel adjustments.

Twilightoptics · Posted: Wed May 16, 2007 5:35 pm Post subject:

Xophertony · Posted: Wed May 16, 2007 9:39 pm Post subject:

once you get an o2 in there and are no longer driving around with your ECM in "soft fail" mode you can diagnose any other problems. more then likely you were running rich (overfueling) before due to a failed o2 sensor, thats why removing it made no change. replacing it with a new one may solve your rich condition. so +1 to what they all said.

iansane · Posted: Wed May 16, 2007 9:45 pm Post subject:

I was running without an o2 for awhile after I swapped to LTs because I wired it wrong and gave the ecm a full 12v. Ooops!

It ran like shat up until it the ecm finally ignored the o2 and then it just ran like less shat.

I'd ditch the onesizefitsalltbichip.

305 302eater · Posted: Thu May 17, 2007 6:41 am Post subject:

ok guys so no help, i know well enough that i'm should have a o2 there but like i said it made absolutly no difference with it the or not ask dylan... when i had my stock exhaust i replaced the o2 a number of times after rebuilding my tb and it still ran rich... rich enough that i could shoot fire out the back when my exhaust would pop from my exhaust leak... But thanks anyways...

91RSVert · Posted: Thu May 17, 2007 7:06 am Post subject: Re: Over fueling problem

Xophertony · Posted: Thu May 17, 2007 7:23 am Post subject:

305 302eater · Posted: Thu May 17, 2007 7:39 am Post subject:

Tony i just said i had replaced the o2 a number of times with my ecm having little responce to it.... I have full length headers and bolt ons like under drives smog delete ac delete dual snorkel... all i can think of right now... I will try and put my stock chip back in and see what that does for me... I realize that i should have a o2 sensor hooked up in order for my computer to adjust... It just bairly did in the first place... I did a full rebuild in the tb everything except replace the injecters... they are spendy suckers... mine seem to have a alright spray pattern though... just a lot of fuel.... and when i'm racing my car i can see a cloud of fuel behind me from take off till i hit about 3k then it seems to deminish... and every time i shift it comes back for a split second then i goes away... anyways it has had this problem a couple of years now.... Just was trying to see if you guys could come up with any ideas that i haddent already...

Dewey316 · Posted: Thu May 17, 2007 7:51 am Post subject:

There are other things to check, but really, the reason we all jumped on the o2 sensor, is that without it, the car is never going to run right. I would put the stock chip, and an 02 sensor in first, then see how it does. If it is still really rich, check the fuel pressure, make sure it is in the 10-13 psi range. Also check for vacume leaks. The small vacuum line that connects to the MAP, can also get cracks in it, check that as well.

91RSVert · Posted: Thu May 17, 2007 8:18 am Post subject:

Underdrives wont really affect the fuel mix to even worry.
smog delete will affect the mix
ac delete wont
dual snorkle, slightly
headers will

you did not replace injectors upon rebuild. Was asking that to see if you got wrong ones. As well, now I noticed you said you had this problem before.

My tbi smokes when I get on it too. Hook everything back up like it should be. Make sure its got a good tuneup and everything is correct, then learn to start burning your own chips. It appears not many mods throws the TBI ecm outta wack, unlike MPFI/TPI ones.

Twilightoptics · Posted: Thu May 17, 2007 8:26 am Post subject:

Headers will make lean.

If you want your EFI to run right period, you have to have an O2.

Now something we all didn't mention was that when you floor it, the computer doesn't look at the o2. If that's where you are rich there are a few simple possible problems:

1: Too much fuel added in the chip
2: Bad ignition system up to an incl. spark plugs
3: Fuel Pressure too high

iansane · Posted: Thu May 17, 2007 8:41 am Post subject:

Demon · Posted: Thu May 17, 2007 9:02 am Post subject:

Quasi-Traction · Posted: Thu May 17, 2007 9:30 am Post subject:

I'll join the croud and say either burn your own chip, or go back to the stock TBI chip.

Paul, how do you figure you go leaner with headers?

Twilightoptics · Posted: Thu May 17, 2007 9:43 am Post subject:

You allow more flow. Means you get more air into the cylinder. The computer only adds the pre-determined amount of fuel for the given throttle position, map value, and RPM. Thus more air, no extra fuel = Lean.

You'd only see it on the top end for the most part.

Demon · Posted: Thu May 17, 2007 10:46 am Post subject:

you're only getting more air out of the cylinder though, not in...
after I put my ported TB on, I noticed the car running a little less rich, but still, its really rich ... the only point in time I think its actually running right is up above 3500rpm ... but this is why I require a tune ... my computer still thinks I'm running stock manifolds and I'm not, so its trying to compensate by putting more fuel into it to compensate for the extra flow out while keeping the same flow in.

for his chip, its programmed to run rich to begin with, and after headers, its going to run even richer still ... add to that the lack of O2 and theres no way at all for any compensation to be made anywhere.

at least that is how I view it... comparing the two engines, of course, is a vast difference, but I believe it still works out about the same in that area.
his chip though should be a much quicker and less expensive fix once he gets the O2's in

Dewey316 · Posted: Thu May 17, 2007 11:28 am Post subject:

More air out = more room for air in. It increases the VE, that is why you pick up HP with headers, it increases the efficency of the motor. As the efficiency goes up, you need to compensate for the greater pumping ability, with more fuel. Thus why putting headers on, will lean things out at WOT, especialy in the higher RPM range.