Trying to "lean out" your car with only a stock ecu is a waste of time and energy.

 

Is this the radiator switch which *should* be hooked up?

As for the variable resistor (potentiometer), I've got that centered. My idle air mix screw is only backed out about 1/2 turn! Every other car I've looked at it's backed out a good 4 or more turns.

Just put another O2 sensor in tonight, that got my O2 code to go away, but I'm sure this one will be killed from the overdose of fuel here shortly.

Thanks for the help, I think we're starting to head in the right direction

 

Yep, thats where the rad switch *should be*. Had mine installed and hooked up , but didn't realize that w/ a koyo it sees no coolant flow anyway

 

Update, soldered the wires leading to the switch together, now the ECU thinks it's always closed. Waiting to see how this & the next/next few tanks of gas go, & we'll see if things have been solved, or if I'm on to the next issue. Thanks!

 

Next update: as of soldering water temp switch wires together, & driving, I did 238 to a tank, requiring 13.5 or so gallons to fill up-- this was 17.8mpg. Driving style was a mix of city & interstate, w/ AC on over 50% of the time. I filled up again, on thursday, and about 70 miles in, went to a neighborhood garage sale, where I found a timing light for $2.

I never truely set my timing after the rebuilt-- and it was set a bit 'tarded. I advanced it to 0* TDC, the stock spec. Noticed ALOT more power than I'd had before. While I was working on it, I decided to also *properly* set my idle, so a smooth 750 rpm. At about the 130 mile mark on this tank, I built a green lamp checker, to indicate whether or not I'm sitting in closed loop. I found that my previous driving style kept me in the rich control setting while accelerating, and was able to correct this by going on the closed loop lamp.. a HUGE help! Anyway, I'm now at 235 miles on this tank, and the needle hasn't hit the 2 tick marks on E yet... I'd say I've burned 11 gallons of gas thus far. I really think I can get close to 20mpg on this tank, which was primarily revs up to redline & just all around fun driving. It will be interesting to see what happens next tank, as this car is definitely fixed MPG wise.

Probably the best thing about this tune up, besides the increasement in efficiency & money left in my wallet, is the fact that the car's actually the fastest it's ever been, having the timing properly set.

Good luck, hope this can help someone else enjoy their car more.

 

If you soldered the two wires to the temp switch located at the bottom of the radiator that should tell the ECU that the coolant temp is always above 62 degrees which should cause the car to rev to 3000 or so each time you cold start the car at least. Since you live in Florida this might not be a problem, but if you lived in a colder climate it would not be a keen idea.

 

Right, indeed. For whatever reason, my car doesn't do the 3K warm up when I start it. Incase you missed it (this sentance NOT intended to be rude lol) this car has an S5 motor/S5 intake manifold, all else S4. Emissions are removed, including fast idle cam (which is soon to go back on, as it stalls when cold now that timing & idle are properly set). But for whatever reason, this car doesn't do the 3K warm up. I'm assuming part of that system was embedded in the rats nest, and by removing that i now prevent it from happening. I'm curious to know, what enables the engine to rev that high? is it the BAC going wide open?

Thanks!

 

On an S5, the AWS and the BAC contribute to the 3000 rev upon startup, and the Fast Idle Cam would be independent of the 3000 rev mechanism.

Since your engine is a S5 but are using S4 sensors I guess you are using an S4 ECU. If this were the case then the S4 uses the Air Bypass solenoid in concert with the BAC to create the 3000 startup rpm.

 

That explains it, then. Thanks bud!

 

Ill be connecting those sensor wires before I leave town! I get about 270/tank w/ almost exclusively highway driving.

Before I upgraded injectors, got rtek and had those clowns screw up my diff I got 355/ tank on my best run. Hopefully I can get over 300/tank just messing w/the sensor and setting timing. Then I'll see what I can do about creating a "highway tune".

 

The Water Temp sensor wires being connected together will tell the ECU to initiate the 3000 rpm rev for 17 seconds upon startup. It also affects the Relief solenoid as to whether the air being pumped into the ACV via the air pump is sent to the exhaust ports or dumped into the air silencer which vents the air to the atmosphere. This should have no affect on gas mileage as the system is for emission purposes only.

 

s4 n/a has a more agressively rich tune under low RPM/high load mapping, the S5 is a little more leanient so a way to adjust fuel will give you better mileage, otherwise ******* the engine is going to get you even worse mileage.

stop listening to people about the O2 sensor, it does little to nothing for 98% of your driving time. but the rich issue will throw a code for the O2 sensor pointing you where you need to look, which is for possible vacuum leaks or too much fuel from the pump/regulator or faulty AFM/variable resistor/pressure sensor/timing out of adjustment/TPS out of adjustment.

 

hacks.

mine gets about 300ish on a full tank but i have this problem with my tank where i cant get that last 1/4 tank. so i drive around on 3/4 of a tank most of the time. i do a lot of highway driving as well.

 

you guys have to remember that the S5 has a bigger gas tank, so it goes further on a tank, so you need to quote MPG.

 

S4 T2 here w/ full emissions removal, so I haven't noticed any of these "symptoms"

355 miles, put in 15.018 gallons = 23.6 mpg

At that point I hadn't done anything to the car, I'm sure a tune up and a tune would help. My "550s"came back as 580s after being cleaned, so I'm sure that's not helping, but I'm not going to tune anything until I get my ic finished and replace this bound up diff which im sure is also hurting mpg.

 

I get really good highway mileage. Full tank will take me 250 miles at 80-90 mph average highway driving speed.

Now on the street, I average 10mpg. Unfortunately, that is where most of my driving takes place.