Running lean?

[Eriol]

Hey, I was wondering if I could pick your brains for advice on this problem. I've back-burnered my "popcorn" problem because of it, I'm approaching the deadline of a meet in just over a week.

My car seems to be leaning out under hard acceleration. When I mash the go-pedal and the turbo spools up, it will start pulling hard for about one or two seconds, and then just kind of settle back and wheeze its way up the tach.

I've had a few fuel problems since I bought the car. The first time I tried to start it after installing the turbocharger, the fuel pump was dead. I replaced that with a refurbished one (I'd already spent my budget on the car and turbocharger), and found tons of rust in the gas tank.

A couple of weeks ago I installed a new gas tank, along with a new pump sieve and fuel filter. Much to my dismay, it's still running like crap.

A voltmeter on Vf has it running at 5 volts most of the time, and the exhaust smells pig rich. Under part-throttle acceleration it will drop to 3.5v, 2.5, and then 0.

The longer I let the ECU "learn", the worse it runs. When I reset it it will run decent at first, and slowly get worse. Here's what happens when I monitor Vf after I reset it: it will run at '0' for like 5 minutes (always does on startup). Then it will stay at 2.5 until I goose the gas, when it climbs to 3.5v. After driving it starts spending most of the time at 5v.

I just replaced my O2 sensor, and that hasn't helped. The old O2 sensor I pulled out had a white glaze on it -- it was black when I installed the turbocharger 8 months ago.

This weekend I plan on checking my fuel pressure and timing -- anything else I should look at?

I've searched the forums and scoured the TSRM, but nothing has really jumped out as a solution (unless my 'new' fuel pump or filter are the problems, in which case I'll be pissed!)

Thanks in advance -- sorry for the long post.

[Eriol]

Oh, it's bone stock and has never thrown a code.

[1987supraomega]

hey i've got the same problem so if you find out what the cause is let me know

[Idealsupra]

ugh i posted before but read what your wrote wrong....

i would start at the fuel pump...maybe a clogged fuel filter as well...leaky injectors if you are smelling gas...

check the easy stuff first...

[Eriol]

1987supraomega: damn, I skipped over your thread when I was searching because you said you shimmed your wastegate, but there is some good info in there. I'll let you know my results.

Idealsupra: that was some good info you posted before, so I'll let it stand for anyone else that's searching.

"the fuel pump is supposed to run 6volts normally...until i believe its
50% throttle and then it switches to 12volts..."

I'll definitely check that out.

I am fearing that the problem might be the fuel injectors, since they might have been exposed to some 3-year-old gas when I was checking out the car. It generally seems to run pretty smooth, though. Do you have some injectors from one of your parts cars you'd be willing to sell me, if that is the problem? :)

[Idealsupra]

1987supraomega: damn, I skipped over your thread when I was searching because you said you shimmed your wastegate, but there is some good info in there. I'll let you know my results.

Idealsupra: that was some good info you posted before, so I'll let it stand for anyone else that's searching.

"the fuel pump is supposed to run 6volts normally...until i believe its
50% throttle and then it switches to 12volts..."

I'll definitely check that out.

I am fearing that the problem might be the fuel injectors, since they might have been exposed to some 3-year-old gas when I was checking out the car. It generally seems to run pretty smooth, though. Do you have some injectors from one of your parts cars you'd be willing to sell me, if that is the problem? :)


1) just let it be known those readings would be what the FUEL PUMP is seeing...NOT the ecu... i thought the readings you had were from the fuel pump and not what the ECU is reading...so i misinterpreted it.... but anyways yeah ;)

2) bad gas wouldnt REALLY fuck up injectors...i would check for leaks...i had a leaky injector oring and it caused me to run lean up top...i fixed it and ran perfectly.... also...you could try running some xylene through the system...just pour some into the gas tank and let it run through the system and do its job...you can find xylene at any paint supply shop.

3) if it comes down to it... i DO have two sets of stock 440s...however as with any used injectors...they MIGHT be better then what you have...they might be worse...all i can tell you about them is they came off two perfectly running (fuel wise) cars.... so if you want/need them...we can work something out...

also i saw you tried to send me a PM on SF....sorry my box was full...gets like that quick lol... let me know if you needed anything or if you were just confirming that you got the tracking number....and that stuff should be getting there tomorrow as well...and let me know any problems you might have with condition of stuff...

thanks man

jayson

[Eriol]

Did you have a gas smell in your engine when you had the leaky o-ring? I have no leaky gas smell.

What would xylene do? Clean things out? I've run fuel injector cleaner (the stuff you buy at gas stations) a couple of times, and that didn't help.

Thanks for the replies, man.


1) just let it be known those readings would be what the FUEL PUMP is seeing...NOT the ecu... i thought the readings you had were from the fuel pump and not what the ECU is reading...so i misinterpreted it.... but anyways yeah ;)

2) bad gas wouldnt REALLY fuck up injectors...i would check for leaks...i had a leaky injector oring and it caused me to run lean up top...i fixed it and ran perfectly.... also...you could try running some xylene through the system...just pour some into the gas tank and let it run through the system and do its job...you can find xylene at any paint supply shop.

3) if it comes down to it... i DO have two sets of stock 440s...however as with any used injectors...they MIGHT be better then what you have...they might be worse...all i can tell you about them is they came off two perfectly running (fuel wise) cars.... so if you want/need them...we can work something out...

also i saw you tried to send me a PM on SF....sorry my box was full...gets like that quick lol... let me know if you needed anything or if you were just confirming that you got the tracking number....and that stuff should be getting there tomorrow as well...and let me know any problems you might have with condition of stuff...

thanks man

jayson

[Idealsupra]

Did you have a gas smell in your engine when you had the leaky o-ring? I have no leaky gas smell.

What would xylene do? Clean things out? I've run fuel injector cleaner (the stuff you buy at gas stations) a couple of times, and that didn't help.

Thanks for the replies, man.


yeah i had a gas smell when i had the leaky orings...but it wouldnt hurt you to do a visual inspection at the least...

the xylene will basically clean everything out pretty well...its a much better option then the normal crap at auto stores IMO...

:rant2: hehe i just like this smiley and noticed it lol

[Eriol]

yeah i had a gas smell when i had the leaky orings...but it wouldnt hurt you to do a visual inspection at the least...

the xylene will basically clean everything out pretty well...its a much better option then the normal crap at auto stores IMO...

:rant2: hehe i just like this smiley and noticed it lol

Cool. I'm not going to dig down to that fuel rail unless I have to, but if I do I'll check that out.

As for the PM:

"I was just going to say that I'm surprised the stuff got here so quickly! I might even have a chance to put the fenders on before the meet, if I have time left over after I get my fuel issues worked out.

Thanks, man -- I'll let you know when I get a chance to check the stuff out."

Your PM box on SF is still full. :P

[aye mate]

I had the same problem not too long ago. I jumpered the fuel pump resistor to make it run a constant 12v and it cured my problem. But you should replace the fuel filter if it hasnt been done.

[Eriol]

UPDATE: well, the fuel pressure check pretty much checked out, so I took my injectors to an injector shop here in town to get cleaned and flow-tested. Hopefully I'll get them back tomorrow.

4 of my spark plugs, which have 2500 miles on them, had a white glaze, and two had a black film -- so I'm thinking the injectors were the problem.

This shop (linman's technology or something like that) only charges $35 to clean and test the set -- can't beat that.

[Eriol]

Linder technical services. Watch out if you go there - they replaced one of my injectors without asking me if I wanted to do so, and charged me like $115 for it. Seemed like good work though.

The car is running smoother, but Vf and E1 still reads 5 volts all the time. I ran a 16.03 at IRP tonight, so it's not too bad though.

Since a fuel pressure regulator.. well, regulates the fuel pressure, couldn't I just drop a Walbro or MKIV fuel pump in there, keeping it running stock? I might try that, or try replacing my fuel filter -again-.

[aye mate]

A 16?! You're a turbo right? I hope thats a typo.

[shaeff]

I ran a 16.03 at IRP tonight, so it's not too bad though.

Since a fuel pressure regulator.. well, regulates the fuel pressure, couldn't I just drop a Walbro or MKIV fuel pump in there, keeping it running stock? I might try that, or try replacing my fuel filter -again-.

i sure hope that 16 is a typo!

and make sure you drill out the J-tube!!! (and it wouldnt hurt to get an aftermarket FPR)

-shaeff

[Eriol]

i sure hope that 16 is a typo!

and make sure you drill out the J-tube!!! (and it wouldnt hurt to get an aftermarket FPR)

-shaeff

Nope, 16.03, and yup I'm a turbo. That was my first time racing, though, so the car could probably have been .2-.3 seconds quicker. Why, what are our cars supposed to run bone stock?

And what's a j-tube?

[shaeff]

Nope, 16.03, and yup I'm a turbo. That was my first time racing, though, so the car could probably have been .2-.3 seconds quicker. Why, what are our cars supposed to run bone stock?

And what's a j-tube?

we run 15's stock. N/A's run 16's stock if i remember correctly.

you should have been about a second quicker.

the J-tube is bolted to the driver's side of the block. its a metal fuel return line shaped like a J. it has a restriction in it (a pinhole for gas to go through) when we upgrade fuel systems, we drill it out to let fuel flow more freely.

edit: heres a crappy pic of it in the TSRM. you dont want to remove it (unless you have the hardware to replace it) you just want to drill out the restriction. it's #8.

http://www.cygnusx1.net/supra/library/TSRM/em/EM_67.html

-shaeff

[mk3forme]

I have not heard of that mod Shaeff. What size do you drill it out too?

[Eriol]

The fuel return line? the thing that plugs into the FPR? That could cause problems?

Al Jordan was telling me about drilling out the pulsation damper for more fuel flow tonight.


we run 15's stock. N/A's run 16's stock if i remember correctly.

you should have been about a second quicker.

the J-tube is bolted to the driver's side of the block. its a metal fuel return line shaped like a J. it has a restriction in it (a pinhole for gas to go through) when we upgrade fuel systems, we drill it out to let fuel flow more freely.

edit: heres a crappy pic of it in the TSRM. you dont want to remove it (unless you have the hardware to replace it) you just want to drill out the restriction. it's #8.

http://www.cygnusx1.net/supra/library/TSRM/em/EM_67.html

-shaeff

[aye mate]

Buddy of mine ran a 14.7 with intake and exhaust. So I would say 15.1 with stock everything!

[Eriol]

Yeah... I dyno'd it today for some reason, and it confirmed my ass-dyno. Good and strong until about 3000rpm, and after that the torque just kind of peters out. Or more generally, good and strong until right around when the turbo starts kicking in full force, and then it just kind of peters out.

The idea was I would be able to hook my car to the dyno's wideband setup and get a more accurate idea of what my car was doing, but that ended up not happening for various reasons.

I'd post the dyno chart, but you guys would probably laugh me off the boards. :)

[aye mate]

ehh go ahead and post it up someone might be able to help you out...some guy posted a stock mkii dyno sheet once...that was kinda funny.

[Eriol]

ehh go ahead and post it up someone might be able to help you out...some guy posted a stock mkii dyno sheet once...that was kinda funny.

Yup, stock MKII dyno sheet... that's probably about what mine looks like. :icon_roll

http://i7.photobucket.com/albums/y258/suck4ss/dyno1.jpg

[shaeff]

I have not heard of that mod Shaeff. What size do you drill it out too?

sorry for replying so late! :(

you'd want to drill it out to the diameter of the pipe. the j pipe is there to retain fuel pressure incase your fuel pressure regulator craps itself. with the walbro fuel pump, there is no need for the j pipe because the walbro pumps lots and lots of fuel!

-shaeff

[Eriol]

OK... sorry if this is a stupid question, but how do I check the voltage being fed to my fuel pump? Someone at the meets the other day was telling me I should check it at the resistor in the front, but I don't really see anything there to probe in to. I can't find anything in the TSRM about it, either.

I learned many years ago that it can be a bad idea to just start poking at a circuit with a voltmeter without knowing what you're doing...

[Eriol]

Well, I tried the 12v mod and it didn't like it... ran like crap for about 10 seconds and then died.

This weekend I'll try to test the fuel pump voltage, and double-check my TPS.

[Shawndude]

OK... sorry if this is a stupid question, but how do I check the voltage being fed to my fuel pump? Someone at the meets the other day was telling me I should check it at the resistor in the front, but I don't really see anything there to probe in to. I can't find anything in the TSRM about it, either.

I learned many years ago that it can be a bad idea to just start poking at a circuit with a voltmeter without knowing what you're doing...

There is a "FP" (fuel pump) terminal in your diagnostic box by the battery under the hood. Stick the red voltmeter lead into it, and ground the black lead of the voltmeter to something (the battery ground is right there).

But by the time the power gets all the way back to the fuel pump, you can count on 1-2 volt drop from your readings depending how old and crusty your wires are.

[Eriol]

There is a "FP" (fuel pump) terminal in your diagnostic box by the battery under the hood. Stick the red voltmeter lead into it, and ground the black lead of the voltmeter to something (the battery ground is right there).

But by the time the power gets all the way back to the fuel pump, you can count on 1-2 volt drop from your readings depending how old and crusty your wires are.

Oh, sweet, that's easy. I already have a wire run to the block for checking VF. Thanks!

[Eriol]

Hrm... Fp and ground give me 11.25v at idle and 13.5v under hard acceleration... is that right?

I unplugged the fuel pump, jumpered Fp and +B, and checked the voltage at the fuel pump connecter, and it was getting 12.25 volts. :dunno:

I am not running the 12v mod.