lean idle, rich wot, NO boost leak. any thoughts?

[chrislockhart]

550 injectors with lex afm(adjustment screw backed all the way out), walbro, afpr.
idle at like 18 a/f, partial load 14.7, wot at about 10 a/f at 12 psi.
also hit fuel cut at like 13psi. every thing screams boost leak but i just tested it with no leak!? im going to test again tomorrow for the hell of it.
sooooo i was thinking maybe dirty maf?

 

[chrislockhart]

swapped maf sensors with my friend same result. boost leak tested it again (with engine/piping warmed up) at 25psi no leaks. i noticed last night in the rain it seemed to be running a little bit richer idle 16a/f and i could boost a little bit more befor hitting fuel cut... no idea why. im going to check the connection from maf all the way to computer i guess...

 

[AJ'S 88NA]

Try posting in the gte section, will probably get more response.

 

[hvyman]

Moved. Don't start two threads. Just ask a mod to move it. Thanks.

Don't clean the afm.

Your lean idle is prolly from the screw being backed out. Screw it in.

Under boost on stock Ecu you will see 9-10:1 all day long. It's tuned for safety.

Also should get something to tune more with.

Are you getting code 34?

 

[shipkiller]

o2 sensor getting old maybe?

 

[hvyman]

Dont post if you dont know in the tech section please. O2 is not used at wot tho his afr look normal for a stock ecu under wot. With the lex afm screwed out all the way lots of unmetered air is coming in without the ecu knowing.

 

[GrimJack]

There are a few critical details left out here as well.

1. How did you check for boost leaks, exactly?
2. Have you checked for codes?

 

[chrislockhart]

sorry about that i thought i was in the gte section thanks hvyman.

i know the screw being out will give me a lean idle and can only raise my fuel cut and make me run leaner at wot so im not concerned about that.

i boost leak tested with everything from the turbo inlet to the engine under 25psi with throttle open and every thing at near running temp.

i haven't checked for codes because the check engine light is not on. it come on for a second when i hit fuel cut and then goes away.

if it were only a matter of it running 9-10 wot i would just drop the fuel pressure, (im only looking for 10.5-11). but the real the problem is i am hitting fuel cut at only 12-13psi. so it seems to me the ecu thinks its getting more air than it really is and is pushing the injectors to max duty cycle and then hitting fuel cut.

i was running 16-18 psi on my old motor and never hit fuel cut with everything the same except now i have RC 550s and JE pistons lol you can prolly guess what happend to my old motor...
i do plan on getting an apexi neo or something like that but regardless this problem needs to be fixed. i shouldn't see fuel cut until at least 20psi or so

can loose connections cause the problem im seeing?? thats all i can think of

 

[shipkiller]

Dont post if you dont know in the tech section please. O2 is not used at wot tho his afr look normal for a stock ecu under wot. With the lex afm screwed out all the way lots of unmetered air is coming in without the ecu knowing.

exactly, if his WOT is fine and the ecu doesn't use it over 70%load, it would affect idle and partial load afr but not WOT.
wasn't I clear?

 

[Dan_Gyoba]

Just a note here, but a leak that would cause lean at idle wouldn't need to be a boost leak, per se, since it would have nothing at all to do with the charge pipe from the turbo to the throttle body. A leak in the hose from the accordian hose, across the front of the 3000 pipe and to the ISC valve would do that, since there would be a bunch of unmetered air in there, for whicht he ECU would not inject fuel. This would become a slight vacuum leak pre-turbo, but as soon as there's any REAL airflow through the AFM, this leak would probably go unnoticed. It's only significant at idle where it might make up a sizeable portion of the air entering the intake manifold.

As such, checking the charge pipe from turbo to throttle body wouldn't catch this leak, even if present.

 

[chrislockhart]

exactly, if his WOT is fine and the ecu doesn't use it over 70%load, it would affect idle and partial load afr but not WOT.
wasn't I clear?

my wot is NOT fine. that is my ONLY problem. 16 a/f idle is not a problem. i just mentioned it for trouble shooting sake.

Just a note here, but a leak that would cause lean at idle wouldn't need to be a boost leak, per se, since it would have nothing at all to do with the charge pipe from the turbo to the throttle body. A leak in the hose from the accordian hose, across the front of the 3000 pipe and to the ISC valve would do that, since there would be a bunch of unmetered air in there, for whicht he ECU would not inject fuel. This would become a slight vacuum leak pre-turbo, but as soon as there's any REAL airflow through the AFM, this leak would probably go unnoticed. It's only significant at idle where it might make up a sizeable portion of the air entering the intake manifold.

As such, checking the charge pipe from turbo to throttle body wouldn't catch this leak, even if present.

my entire engine has been checked under 25psi. turbo to exhaust valves. i know what your tryin to say, but like i said im not concerned with the lean idle.

all i need to know is how the hell can the ecu think its getting more air than it really is.
(EXCLUDING A BOOST LEAK AND EXCLUDING A BAD MAF SENSOR)
what other options are there because i cant think of any besides lose wiring. but even that doesnt make since to me because it is a wave signal not a (resistance) signal and if that signal is broken for even a short time then i would think the ecu would just shit out and not give me any fuel while there is no maf signal... or it could be opposite as a safety thing i have no idea

 

[CajunKenny]

Two things:

1. The TCCS stores codes even if the CEL is not on.

2. For Pete's sake...it's an AFM! NOT a MAF!

 

[chrislockhart]

but do you think a stored code that isnt important enough to leave the light on would show the cause of my problem? and if it did what code do you think it could possibly be?? ill check tomorrow but i highly doubt ill find any other code besides 34...
and ya i guess technically it is an afm lol i never really put much thought into it...

 

[Dan_Gyoba]

Except that I thought it had been already addressed that the 10-12:1 AFRs at WOT are absolutely normal for a 7M-GTE with the stock TCCS, even if you aren't running a Lexus/550 setup, and therefore, it's also absolutely normal when you are. Personally, I'm hoping for 11-12:1 AFRs at WOT under boost.

As for the lean idle, I would be worried about 18:1 AFR at idle, since it would indicate that there is possibly a leak somewhere. Also, as per my earlier post, the leak probably is NOT anywhere from the turbo to the exhaust valves, but rather somewhere between the accordian hose to the ISC valve. This is actually kind of important, since the air coming in here isn't just unmetered, it's unFILTERED. It's also going to be passing that stuff in when you're not at idle, but instead of coming in through the ISC, it'll go through the turbo as well.

14.7 under partial load basically means that your O2 sensor is working, and the TCCS is able to compensate with O2 sensor feedback to get your proper AFR.

Other than that, low base fuel pressure could cause a lean idle, though that would tend to affect WOT as well.

So, given that the WOT AFR is perfectly normal, the only problem left is FCO at 13 PSI. Yes, a code that doesn't leave the light on could well cause this, (Though most likely you'll get something like turbo overpressure code.)

There are proceedures for testing FCO in the TSRM, but things to understand are what CAUSES FCO. FCO happens for a few reasons, so start looking at them.

The AFM isn't directly the cause for FCO, though it does have a bearing on it. The TCCS shuts down fuel when the injector duty cycle gets too high. Injector duty cycle is based on metered air flow in conjunction with the learned value from the engine operating under partial throttle in closed loop mode.

Injector duty cycle will be higher if the injectors are not putting in as much fuel as they should be. Low fuel pressure could do this.

I'd check fuel pressure, and that the fuel pump resistor/relay assembly is working as it should, as well as general fuel pump operation. Possibly a full-time 12V mod would be a test of that assembly.

Alternately, maybe your injectors aren't flowing as well as they should, and so are needing a higher duty cycle in order to deliver the fuel that they need.

I suppose that it's also possible that the AFM has an issue, perhaps partially blocked, and is overreporting to the TCCS, but that would probably result in much lower AFRs.

 

[hvyman]

Try doing q boost leak with the throttle closed. That way the pipes can hold pressure instead of going out the exhaust. Also run soapy water over all the connections.

 

[chrislockhart]

my lean idle is the result running a lex afm with the adjustment screw all the way out. i am not concerned with that.
i dont have an accordion hose i have a hard pipe. I HAVE NO LEAKS FROM MY AIR FILTER TO MY MUFFLER. my fuel pressure is just a hair under stock, regulated with an aromotive regulator, walbro 255 pump running 12v full time, jtube removed, brand new RC 550cc injectors.
my WOT is NOT normal. i said my gauge only goes to 10. i know it is well below 10 before it hits fuel cut.

the ecu is acting like it thinks its getting more air than it really is and is pushing the injectors to max duty cycle and then hitting fuel cut. so the reason i posted here is to try to get just one single alliterative reason for this BESIDES a leak of any kind and BESIDES a bad afm.

---------- Post added at 03:40 PM ---------- Previous post was at 03:36 PM ----------

Try doing q boost leak with the throttle closed. That way the pipes can hold pressure instead of going out the exhaust. Also run soapy water over all the connections.

i have tested with throttle open and closed. and have plugged the muffler to check for exhaust leaks just for the hell of it... i will try the soapy water. it just seems a leak to small to notice without soapy water shouldn't cause this big of a problem...

 

[Supra mn]

I'm having almost this exact same problem.
Recently installed:
550s (cleaned and flow tested by DM)
Lex afm with stock electronics
New tps (calibrated per tsrm)
Used 60-1 Ct-26 upgrade by Albert
Aeromotive AFPR
Walboro 255
DM Intercooler kit with spearco intercooler and Knockoff hks BOV

I'm having all the same problems metioned in this thread, except i don't fuel cut at 13 psi (or at all up to 16 psi for that matter).
Idle is high 17-off the gauge (18 being the highest itll go) afr. Normal driving is 14.7ish. WOT is 10, which like he said, is actually lower, but the gauge wont go past 10.
On cold start, it will idle in the mid 13's, move to mid 14's, then 15.9-16.4 until warm.

My idle vacuum is -15. So I must have a vacuum leak somewhere, but can't find anything.

I have horrible compressor surge, so a synapse BOV is on it's way.

Another thing I notice is somewhat of a stumble or misfire at idle. My guess is that's how the engine runs when its super lean, because I only notice it with the afr higher than 18. The tach moves up and down maybe 50-100 rpms. When I let off the throttle while driving, and the afr goes up into the 18s, it feels like engine braking.

I installed the lex afm with the screw all the way out. Fuel pressure set at 33 psi with vac hose on. I know this is too high, yet my idle was still high 17's+.
I turned fuel pressure up to about 38, and that changed nothing.
I turned fuel pressure down to about 30 and put the lex afm screw all the way in. This helped my idle, but not by much. It idled at mainly 17.0, but would go up to off the gauge every once in a while.
At this point, I was alright with the idle, and tried to tune WOT. So I lowered fuel pressure to 23 and left the afm screw all the way in. This gave me the same idle, and WOT starting at 11.5 and dropping to 10 by 4k rpms.

This was the best I could get it, and although 23psi fuel pressure is within tsrm standards, it seems a little low.
I have checked for boost leaks up to 20 psi from the turbo inlet to right before the throttle body and found none. I replaced the throttle body gasket when I installed all this, so that's not leaking. The injector o-rings and insulators were all replaced when flow tested.
Every hose coming off the accordion hose has been replaced.
I can't think of anything else, I've pretty much listed every problem I've noticed. (which is a lot longer list than I was thinking it was..)

Any help would be appreciated, but please don't tell me to buy an SAFC or go standalone. The car is getting garaged soon, so by the time I got that in the mail, got it all wired up and ready to tune, it'd be pointless.

 

[ATL88Supra]

bottom intake manifold gasket,injecter holes(bad O-rings/to small/large), PCV system-any open or oil leaks from the block is a boost leak unless piped correctly and sealed and the list go's on you have a vac/boost leak

 

[3p141592654]

You need to adjust the deadtime compensation to match the RC550s. Unfortunately, you can't adjust it since its burned into the firmware of the ECU. Have you measured Vf at idle. It will tell you what the ECU is doing to compensate.

 

[Nick M]

idle at like 18 a/f, partial load 14.7, wot at about 10 a/f at 12 psi.

So what is the issue? Aside from a lean idle and having all that bypass from the screw?

Except that I thought it had been already addressed that the 10-12:1 AFRs at WOT are absolutely normal for a 7M-GTE with the stock TCCS, even if you aren't running a Lexus/550 setup, and therefore, it's also absolutely normal when you are. Personally, I'm hoping for 11-12:1 AFRs at WOT under boost.

Well, about 10 is normal, even high 9. But he has the screw all the way out causing too much air to bypass. 14.7 at a partial load is what it is supposed to do. That keeps the catalyst in its operating range.