so what i've got hppening is that at idle im looking at my tbi and its puddling mass amounts of fuel on my mostly closed butterflies, like a hairsbreadth open actually and im thinking that at that low of an lv8 load, the lowest infact that it can be it should not be pumping that much fuel through those injectors because it just seems like a dumb waste of fuel and that seems stupid because isnt that the point of F.I., more controll and less waste?
should it be spraying this heavy at idle sitting still in park? it a considerable puddle on the butterflies and if i start to drive it off that wont it just mostly fall in and puddle up in the manifold and then feed the cylinders un evenly?

 

Was the motor cold at the time? Thre will be more fuel when the motor is cold to richen things up.

If you have access to a scantool or winALDL you can redo your min air adjustment. At idle most of the air the motor needs is being supplied by the idle air control. The passages for the IAC pass under the butterflies and allow the air to pass right by. With this there wont be much air going past the butterflies. Because of this, the fuel dist. wont be as good

There is a screw on the tbi that determines how far the throttle blades are open at idle. Its covered by a brass plug. Punch it out to get access. With the motor warm and idling slowly turn the screw to open the throttle blades while watching your IAC counts on the scan tool. Shoot for about 15 to 20 IAC counts at idle. With the throttle blades opened a bit, more air will go past the butterflies and the high velocity air shears and atomizes the fuel. With the throttle open a bit maybe there wont be little lakes of fuel in the tbi.

BTW, tbi is SD, not MAF. It uses the manifold pressure to determine load.

EDIT: there usually shouldnt be that much fuel sitting in the tbi. Does teh car run ok? Any codes?

 

ses light has come on once in the time i have been driving the car and it went off since then.
cars been running great other then one odd tank where i got 100 less miles out of it the the usual 280. pulled a 15.9 at the track i think its doing okay.
two questions though.
where is that brass plug
how much diff does adjust the tv cable make
oh and one more,,
will fuel go shooting out if i take off my tb to clean it, how much pressure is the fuel line under when the car is off?

 

Standing in front of the tbi, the plug will be on the right side in front of the linkages. Actually, looks like its aluminum or something. You should be able to peirce the plug around the edge with somethign small and sharp and pry it out. As for the fuel pressure, no gas will shoot out when you unhook the lines, just make sure to remove the gascap first. If there is pressure in the tank, itll puke fuel back through the lines.

 

I don't mean to hijack the thread, but a question. Why do you want the IAC to be controlling very much air at idle? I noticed the same thing where there was gas dripping around and the butterflies were only open a sliver.

Besides that, I was trying to get my off-idle throttle feel to be better. The pedal is/was kind of hard to press starting from idle, and my theory was that this effect would be less if the butterflies were open more to start and less air was going through the IAC. I think this makes sense. So what I did was adjust the idle screw until my IAC was just barely on (and then rebend the TPS). Is there a reason why I'd want more than just a little IAC?

I think my throttle feel off idle is better this way, but I haven't had time for a test drive yet.

 

The main reason to not have the IAC open is to get the air to flow through the bores where the gas is being injected. Its the shearing from the air that helps to atomize the fuel.

I dont think itll help with the pedal feel as thats really caused by the vacuum itself.

Oh, no need to rebend the tps. The ecm automatically uses the lowest tps reading as its baseline. Just dont get too carried away with how far the throttle is open.

 

My question was why should it be set up with any IAC air at all. I tuned it down so the IAC was barely on at idle (can't remember numbers right now).

I guess I'll find out. Intuitively, it seemed like there would be less stickiness if air is already flowing around the butterflies a little, as opposed to them being essentially closed with a lot of vacuum force across them - then you have to "break the seal" when you try to come off idle.

Are you sure on a 7747? My idle was surging around until I fixed the TPS. It was saying 7% or something like that. It was happy when I got it down to 1%. There's an entry in the bin too, something like "max idle TPS".

It does make sense that it would just figure it out from the minimum value it ever sees, but it doesn't seem to work that way.

 

this is all somewhat related, toyed with that screw today and got the idle down and i have two questions
1) should the injectors pulse, it seems as though they pulse like a strobe effect.
2)i put a brick on my go petel to see if it was opening the blades all the way and it was only opening them like 9/10ths of the way how do i adjust the throttle cable to fix this