texFCturboII

iTrader: (17)

Just started about two days ago after running out of gas (Gas gauge busted last week):

While driving, especially cruising at low RPMs the thing bucks like crazy. AFR's lean out, and i have to either floor it or slip the clutch to get around the neighborhood. When accelerating aggressively it runs ok, except for mega hesitation at 3k-4k rpms. Even above 3-4k rpms there is hesitation before boost, leans out, bucks, etc.... regardless of engine temps. No hesitation before...

Starting, I have to give it gas and get the rpms up above 2-3k at first, nurse it for a few seconds to get it to not die. Sometimes it cranks forever, acting like its flooding almost catching but not quite, then finally catching and starting up.

I just started a new 9-5, I haven't had any time for the car, taking the train to work... I've got time this weekend to throw at it. Any ideas?

TPS?
Fuel pump?

will test compression as well, but its a newish rebuild...

being broke and owning a 7 sucks.

Mods listed in sig.

Thanks for the gander.

Justen

iTrader: (12)

I'd try replacing the fuel filter first, especially after running the tank dry.

tweaked

iTrader: (4)

Check your fuel pressure. you may have a pump going bad. It's doubtful that it's the filter unless you have been running lots of shitty gas. Toyota proved that fuel filters are good for over one million miles. that's why their filters are so hard to get to. It is possible your tank has rust and it is collecting on the fuel pickup screen. It could also be the fuel pressure regulator. Or low voltage to the pump.
It's best to start with a pressure gauge.

texFCturboII

iTrader: (17)

Ok, thanks. Will do when I get time this weekend.

Osirus9

iTrader: (10)

+1

also, they're cheap and easy to replace (2 bolts and under the brake booster, also have a bucket ready for when the gas drains from the lines). so all around good starting point imho

SpikeDerailed

iTrader: (7)

I lol'd

texFCturboII

iTrader: (17)

Ok, sock filter was fine, not clogged. The in-line filter is almost brand new, so I doubt that is it....

I've yet to hook up a fuel pressure tester to it, but I did check the voltage at the fuel pump....

Test leads to B and L/W on the fuel pump connector in the hatch strut tower, i get:

idle: 5.4V
cruise: 5.8V
full throttle: 9.3V

looks like I am rewiring the fuel pump over the week.

texFCturboII

iTrader: (17)

Correction, that is the B and Bu wires that were tested....when it first starts up it sits at around 10 volts, but drops to around 5V after a little bit. I'm thinking with voltage that low that I may be looking for another alternator as well.

texFCturboII

iTrader: (17)

New battery, good spare alternator (tested good at the store anyway) and the fuel pump has been re-wired. Starts right up, the lean issue is gone and it drives smoother, much more rich all across the board. I'm going to have to tune that out. However, my volt gauge is still reading low, under or just over 13V while cruising.

And now I have an oil leak somewhere around the oil pedestal, grrrrrrr.

texFCturboII

iTrader: (17)

So, yea. Just drove it about 20 miles tonight. It kept a constant 12v. Started up after the first 10 miles no problem, lights were bright. Other than that it drove like a dream. Oil pressure was great, temps were great, A/F readings were great.

texFCturboII

iTrader: (17)

My best guess as i slept and thought last night is the alternator? The gauge works just fine, and before I swapped this one on the voltage with the previous, shot alternator was acceptable, high 13's to low 14's. The store tested the currently installed alternator, and the voltage regulator is ok according to the tests, but could it be limiting the voltage output to 12V? I simply don't know, just throwing it out there. I thought I remember Icemark saying that these cars needed a minimum 13.1V to keep everything running and battery charged, but I'm not seeing any drop from 12V in the battery after a long drive.

This alternator is a s4, the previous one was a s5. It's nice having stock wiring back into play (less points of failure.) but it's not nice having to worry about low voltage. Could bad grounds be causing this as well?

hiroichi1515

iTrader: (17)

Hey, look at your rtek log while the car is going and see if the battery voltage matches what the battery voltage is reading there out of curiosity.

After I did the fuel pump rewire my gauge moved up, but it didn't read nearly the same as battery voltage until I rewired the cig lighter to pull power from the batter with a relay attached. It seems that took a load off somewhere even though it wasn't in use and the gauge went up even further.

Osirus9

iTrader: (10)

why did you downgrade from an s5 to an s4 alternator? they wiring is different for these alternators as well as their amp output. Your low voltage could be simply that the s4 alternator does not put out as much power as your old s5 one did.

hiroichi1515

iTrader: (17)

I guess, you could just through the old s5 one back on, I don't think you ever mentioned it was bad. That is what I am using now as well.

Osirus9

iTrader: (10)

He did say it was bad. but why not return the s4 alt to the store, change the wiring back to the way it was and get a rebuilt s5 alt? That's what I'm running and I don't have low voltage issues anymore.

texFCturboII

iTrader: (17)

I'm not running anything but a 40amp electric fan.... no A/C, no power steering, no stereo, no electric windows, nada. Why not go with an s4, it was sitting in my storage anyways, so sfree alternator is better in my mind.

However, something is up with the fan now, I burnt out a relay controlling it via Arghx's relay write up.... gotta investigate that as well now. When it rains it pours.

50 mile drive this morning, read 12V the whole time. I'll check the rTek when I get back home tonight.