Check Engine Code (air-fuel ratio lean malfunction)

[Silv89t]

Hey guys my car flashing a code 25 for air-fuel raio lean malfunction. Not sure what's causing it to do that. If anyone out there has face this problem can you let me know how you fix yours. Maybe I can start there and go from there on..before this happen I had knock sensor code (52) and the air-fuel malf code(25), I had a vacuum leak, one of the sensor valve broke right on top of the powersteering pump, found that and bypass it, remove the pump because my pump was bad. I thought that was going to fix but then came back with only the air-fuel malf code and not the knock sensor code. Please let me know. thank you

Seng

 

[jetjock]

That's a nice post. Would've been better with the code though...

 

[Kevin]

what code #

 

[Silv89t]

Sorry didn't know the code top of my head. Updated post

 

[Kevin]

fix that code 52...most likely wiring.
fix the vaccuum leak.
Fix that broken sensor dont bypass it..

---------- Post added at 10:04 PM ---------- Previous post was at 10:01 PM ----------

read these
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=27
http://www.supramania.com/forums/showthread.php?100760-code-25&highlight=code+25

 

[Silv89t]

Thanks for the link,
well after I bypass the leak code 52 went away and the car ran better. Couple days later code 25 came back and when I start the car cold the car idle crazy like miss firing, idle goes up and down...

 

[mkiiichip]

explain how you bypassed the PS idle up please

 

[Silv89t]

In the middle side of the intake pipes (connects to the turbo), there's a vacuum lines that goes down to the valve with two valve sticking up on top of the PS pump...then from there route back on the other side then that line that goes across and to the motor and down to the rack in pinion. There will be pressure to through the rack so you can turn the car smoother..

 

[mkiiichip]

just as i thought, you have just created a constant (and fairly large) vacuum\boost leak.

This line does not go the the rack. it is originally used to raise the idle momentarily to compensate for the load put on the motor from the PS pump creating pressure to turn the wheels.

if you don't want to fix it properly (which includes dealing with what ever you have going on with the pump and replacing the idle up valve). then just block off both hoses that originally went to the PS idle up valve (so no air can leak from either end (after this if your car stalls while sitting still and turning the wheel you should know why))

hope this helps a little

-mkiiichip

 

[Silv89t]

Oh okay it's call the idle up valve, thanks I didn't know that. Well I'm not sure where that other line goes to but I never touch it so it should in at the right place. I know it supposely make sure that I can get pressure so it's much easier to turn the wheels. That case can I just replace that idle up valve without having the pump there..I'm still waiting for a new pump..plus new PS lines(one is leaking). What do u mean by stalls while sitting and Turning the wheels? I don't get it..
But thanks for the respond

 

[ben1984j]

Oh okay it's call the idle up valve, thanks I didn't know that. Well I'm not sure where that other line goes to but I never touch it so it should in at the right place. I know it supposely make sure that I can get pressure so it's much easier to turn the wheels. That case can I just replace that idle up valve without having the pump there

No, that valve operates off of fluid pressure (generated by the pump). No pump = no pressure.

Because of this, what he said about stalling while sitting and turning the wheels won't apply. This would only happen if you had an operational P/S system but no idle-up valve. Basically, when you turn the wheels while at rest, the pump has to work really hard (produce maximum fluid pressure). Since the pump is driven by the engine, this massive load on the pump will lower engine idle RPM.

The idle-up valve solves this problem - it is designed to open when there is sufficient pressure in the system (again, when the pump is under heavy load). When it does open, it lets additional air from the intake (accordion hose) directly into the manifold, bypassing the throttle body. This extra air increases idle so the car doesn't stall out, etc. when you crank the wheel at low speeds.

But like I said, there's no use for the valve until you have a working pump. In the meantime you should follow mkiiichip's advice and cap off the lines that went to the idle-up valve, to keep from having a vacuum leak.

 

[Silv89t]

Thanks Ben1984j
Okay that was well explain about the idle up valve. Okay i will try and block off both end to see if that solves the problems, if not I can go from there...I didn't know that's how the idle up valve operates..So even tho I bypass it, there is still a leak because without the idle valve and the pump there's no use?

 

[Silv89t]

hey thanks guys i blocked both end and now the car sounds alot better. I mean like my blow off valve sounds totally different now after that, it blows air out sooner when rev the motor. Alot more like normal now hope this will solve the problems.

 

[hvyman]

nice seng.

 

[Silv89t]

nice seng.

Hey thanks Kyle, just wanted to have my car running good so I can start smoking some ppls...lol j/k
I feel alot happier if my car runs wonderful...

 

[ben1984j]

hey thanks guys i blocked both end and now the car sounds alot better. I mean like my blow off valve sounds totally different now after that, it blows air out sooner when rev the motor. Alot more like normal now hope this will solve the problems.

You're welcome, good to hear you got it fixed!

 

[Silv89t]

Well actually I try posting this tread up on SF and there were couple guys who help but not as much people wanted to share...SM basically saved me thanks to all you Mk3 driver who help shre their idea. plus I figure they havent ran across that problem. Prob Most of the guys on SF are MKIV driver...anyways like both site plus cencal too...

 

[Silv89t]

Damn my code 25 came back on. think it might be the O2 so I testing the O2 the other day, but didn't have an needle (analog) voltmeter so I skip to the digital volt meter part. Warmed up the o2 sensor at 2500rpm and got 4.39 volts, pos(+) at VF1 and neg(-) at E1 on the Diag plug. Any suggestion thanks

From the diagframe on the TRSM Online, the O2 shoulde be replace from the case that has voltage when tested from terminals VF1 and E1

Note: when the code came back on my car kinda jerk A bit while I'm on the gas and when starting cold the car idle up and down (fluctuating) until driving then goes back to normal..