Possible Causes For System Too Lean - Toyota Nation Forum : Toyota Car and Truck Forums

BustaRice · 03-02-2004, 08:31 PM

I've searched up a couple threads on running lean but haven't found the definite answer to my solution.

I started getting System Too Lean when I got my supercharger installed. Some threads stated that it is because of too much air coming in then fuel... and I am using my stock air box as well.

The only modification that I did to it was blocked off my airbox silencer/resonator and also removed the wheel well white box that looks like it collects air as a reservoir.. I'm pretty sure some of you know what box I'm talking about.

Well I did that mod to increase the sounds obviously but after my supercharger that sound increase is all gone so it doesn't seem like that mod is useful anymore.

My question is.... I always thought that this mod was only for sound and not much extra air increase. I could put it back but the lower box is a big hassle to put back on... if most of you feel that that is the culprit than I will put it on... but I don't wanna change it if that's not the problem.

Thanks and hopefully someone knows what i'm talking about.

oh ya.... i am using the stock pully and trd air filter... nothing else is modified.

Nick · 03-02-2004, 09:24 PM

what leads you to say you were running lean? plugs coming out white? detonation?

BustaRice · 03-02-2004, 09:30 PM

when i went to autozone and ran the scanner it came out with System Too Lean on Bank 1

I also got EGR flow excessive.... but that might be somethin else...

Nick · 03-02-2004, 09:33 PM

odd, i'd get some mixture gauges and monitor each bank seperately,

i would have thought for sure it would have been the injectors/regulator not spitting out enough fuel, those injectors aren't all that big, not much of a margin for you s/c guys

how lean was it? did it trip a cel? or is that just what the scanner told you, cuz on f/i'd engines the mixtures can get pretty scary with stock fuel systems

BustaRice · 03-02-2004, 09:49 PM

well when i initially got that error i resetted my ecu and the CEL came back with the same errors. then i used the scanner at autozone and deleted the codes... then after awhile the CEL went on again.

during this time i was running without an IAC check valve so i'm not sure if that's a culprit either. but today i finally found a correct valve and have it pointed away from the engine and i will reset the ECU once again but i'm not that hopeful that my problem will be fixed that easily but if so then that's great.

any suggestions..

***Phi*** · 03-02-2004, 11:34 PM

So was the IAC valve the problem?

BustaRice · 03-02-2004, 11:35 PM

no idea yet... the code is gone because it's resetted but i will see after awhile if it pops up again because it usually takes awhile before the CEL shows up.... so it's too soon to tell..

but i didn't really do much so i'm not sure if that's the problem.

***Phi*** · 03-02-2004, 11:44 PM

Quote:

Originally posted by BustaRice
I also got EGR flow excessive.... but that might be somethin else...

Code P0402 right?

This might provide some help (scroll to the bottom);
http://www.toyotanation.com/showthre...404&forumid=10

BustaRice · 03-03-2004, 12:03 AM

regarding the p0402... i got that info on teamsc3 thread already but thanks anyways.

although... i am not familiar with mechanic terms so that write-up about p0402 is very confusing... i'm going to take that to my mechanic who installed my s/c and see what he has to say about it maybe he can root out the problem.

until then... i hope the too lean problem is something small like what i did to my airbox.