still burning too much gas...

[SuperK]

I am guessing you are talking about your muffler? My flowmaster on my b6 got really hot, I would assume the KL would put out more heat... Clogged cat/resonator/muffler? something restricting flow? do you have a lot of exhaust volume/velocity out of your muffler? I dunno if that was already discussed cuzz SuperK is all confused as to what has and hasn't been checked/done after a million pages.

[wytbishop]

That's actually a very good question. ^^^

[mikeinaus]

the exhaust is a little over a year old and id be extremely surprised if it was clogged. it has quite a bit of velocity/flow from it and doesnt sound clogged. i do have fairly thick (probably hollow) stainless steel tips so they might add to heat dissipation, but even the exhaust gas doesnt get very hot. i cant comment during revving but at idle its hot, but its cold enough i can hold my hand on it indefinitely without getting burned, it also feels quite damp to the touch. i tried doing this to a accord at school that had been driven for like 10 min and it was unbearably hot compared to mine...


on a side note i had the exhaust off the car last august there wasnt anything disrupting it, even the cat looked fairly clean at the time.

[Nd4SpdSe]

thats my cell phone so i dont have macro on it... the plugs are maybe 7 months old? my vacuum gauge is extremely sensitive to throttle, especially in higher gears. its weird cuz it acted completely different with the old chipped ecu. very slightly throttle changes, were talking barely increasing in speed puts the vacuum close to 5 in 5th gear. fyi im sitting around 15.5l/100km on the first 60km of this tank

You gotta have some smartphone or something pretty new cause those are nics pics for a phone. My LG Shine Plusisn't a fancy phone and it was free, but it does have a macro mode on it.

A sensitive throttle/vacuum gauge is a good sign, but you should be sitting around 10in-mg around 100km/h, maybe even at 120.

The extra fuel that you're consuming is definitely not being burned. My guess is that it's going straight through the engine and out the tailpipe somehow.

If he was running rich his plugs would be coated in black soot, if he was dumping raw fuel, his plugs would be wetter than your mom last night. Those plugs are perfect, nice and golden, straight out of the oven, baked to perferction.

[Redline322]

It's a little bit of a long shot, but have you checked your thermostat? Unless you are on the highway for a long period of time or in very cold temps, you might not notice it. It could keep your engine in warm-up mode, using more gas in the process. It wouldnt take much of a temp drop to cause it to drop back into warm-up mode on the highway, but you wouldnt notice it in stop and go traffic and your car would warm up and idle normally when parked due to not enough cold air going through the rad to cool it quick enough to counter the heat the engine produces.

[wytbishop]

I agree those plugs are perfect, which means whatever is being burned is at a nice A/F ratio. But it's going somewhere and if 50% more fuel was being burned at a proper A/F ratio he'd be making 260whp.

How can fuel leave the system?

A) Injected into the cylinder and burned.
a1) It is burned at a good A/F ratio and proportionate energy is extracted from the fuel.
a2) It is burned at incorrect A/F ratio; less energy is extracted and symptoms of a rich A/F ratio are detected.

B) Injected into the cylinder and not burned.
B1) Injected into cylinders which are not firing (not sure how that could happen) ...Passes through the engine and out the exhaust. Liquid fuel would be present at the exhaust tip along with a very strong smell. Plugs might not be so wet (seriously not funny Mike...btw) as the air would be constantly flowing through the engine as well.
B2) Injected into the correct cylinders...super rich, CAT would clog, very strong smell of fuel in the exhaust would be detected.

C) Leaking out.
c1) Leaking from the tank...you'd see it on the ground where you park.
c2) Leaking at the filter, fuel rail, FPR...you'd see/smell it in the engine compartment.
c3) Leaking from the vent return line perhaps? Would only leak when the engine is running and would be less noticeable.

Fuel is leaving the fuel tank and not being burned. Figure out where it's going and you'll find the answer.

Check the fuel return line.

[wytbishop]

It's a little bit of a long shot, but have you checked your thermostat? Unless you are on the highway for a long period of time or in very cold temps, you might not notice it. It could keep your engine in warm-up mode, using more gas in the process. It wouldnt take much of a temp drop to cause it to drop back into warm-up mode on the highway, but you wouldnt notice it in stop and go traffic and your car would warm up and idle normally when parked due to not enough cold air going through the rad to cool it quick enough to counter the heat the engine produces.

I get 9L/100km and he's getting 15+L/100km. Do we think that warm up mode would account for a 60-70% increase in consumption?

[wytbishop]

Looking at the diagram below and thinking about the fuel system in the simplest terms...the fuel pump moves fuel to the fuel rails through the filter, fuel hits the FPR and pressure builds.

The PRC solenoid controls the fuel pressure by opening and closing the FPR. According to the troubleshooting guide when the PRC solenoid is off there is vacuum at the FPR and the only time it is on is at hot start. On my ZE there is no PRC solenoid. The FPR operates directly off the IM which tells me that fuel pressure is directly related to IM vacuum. Fuel that is vented by the FPR goes directly back to the fuel tank.

Does your engine have a PRC solenoid? If so try removing it and connect the FPR directly to a vacuum source on the IM. I would also trace the return line back to the tank and make sure it's not venting fuel to the ground.

The only truly open component in the system is the charcoal canister. If the two-way check and the check and cut valves are both stuck open you could have fuel pouring into the canister but I think you'd notice that.

[mikeinaus]

I replaced the thermostat recently with no change. I have also tried with and without the prc without any noticeable difference. I'll have a look at the return line, but I've had the car on a hoist quite a bit and havnt noticed any leaks, or any signs of leaks. I want to have a look at any drag in the system. If the plugs are good it has to be burning properly. If its not leaking then there has to be some kind of drag somewhere. Either in the brakes, bearings or something internally in the tranny.

[Nd4SpdSe]

If the plugs are good it has to be burning properly. If its not leaking then there has to be some kind of drag somewhere. Either in the brakes, bearings or something internally in the tranny.

I was going to elaborate on it, but I gotta run in 10, but in short, I totally agree

[wytbishop]

you wouldn't happen to have like...1000lbs of cargo in the back would you?

[SuperK]

fine, I'll stop sitting in the back seat, sheesh.

[mikeinaus]

you wouldn't happen to have like...1000lbs of cargo in the back would you?

nope. all i have in the trunk is maybe 10-15lbs of tools/oil and stuff like that, my fiberglass sub box in the spare tire well, the sub and 2 amps. total weight im guessing would be maybe 100lbs give or take 15lbs. then i have my rx8 seats which are quite heavy, with all the motors in the drivers seat its probably close to 80 lbs, then maybe another 30lbs of random stuff in the back seat. ive added quite a bit of weight over stock but i dont think its a significant enough amount to affect mileage that bad.

my jack is broken so i cant check much at home atm, however my front wheel bearings were replaced in august and i recently rebuild/lubed by calipers a couple months ago. im also having even brake pad wear at a normal rate. if there is a drag it has to be in the rear wheel bearings (doubtful they can drag very much without being obvious) or something to do with the transmission. the reason im mentioning the transmission is it makes a weird noise, kind of like a cat meowing when i drop the clutch hard or on steep hills or run over the neighbors cat in the alley... i believe that has to do with possibly the pressure plate or maybe the mating surface with the flywheel and the clutch friction material (stage 1) but doubt its significantly affecting my mileage.

[wytbishop]

I gave this some thought a few days ago and it seems to me it would have to drag pretty hard.

I can't help but think that anything that dragged that badly would a) be pretty o vinous and b) probably be severely damaged by said dragging.

[Daninski]

Have you adjusted your Idle screw yet (top of throttle body)? I fooled with mine and found if it's screwed out to far the engine will run sluggish when starting off. This would cause excess fuel to be dumped when starting off or idling. To set the idle jump TEN and Gnd then using a separate tach (not the one on your dash) screw it in till the engine runs rough then out until the rpm sits at 650. The rpm will go to 700 once you remove the TEN Gnd jumper. You could go out and see how many turns out it's set at by screwing it in and back to where it is now. Should be about 3 to 3.5 turns out. My 5 cents