I recently installed a BBK 78mm TB/Plenum, and did everything exact. But shortly after install the check engine light comes on, went to O'reilly's and got bank 1&2 lean codes. so after research I have done everything to hopefully correct this. I readjusted the throttle stop, cleaned the IAC and TPS, set the TPS voltage to .98, went through several drive and idle cycles, relearned the idle several times, and checked for Vacuum leaks. I still get a check engine light when idling for banks 1&2 lean codes.

From what I have asked before the stock fuel system should easily readjust for all of my minor mods???

I am planning on buying a tuner, and AFR guage next month but don't have the money yet.

any help or ideas is greatly appreciated.

thanks,

 

With that big of a throttle body u really need a "tune" to get it right. I don't think u can really fix it with tweaks

 

I am hoping to get the Sniper system middle of next month, I am just trying to make sure this lean code isn't bad enough to do damage. But it only sets off at idle, and doesn't ping or anything under acceleration.

 

Yea, you probably need to get a tune for that much air flow...

 

Last night I installed an AFR guage from AEM, and here are my readings.

At Idle the guage peaks out after it reaches 18 and goes blank???
Cruising at any speed (25-85mph) it bounces around 14.5???
Moderate accel hovers around 13-14???
Hard accel between 12-13.5???

I still don't have a Tuner yet, but are these numbers fairly normal or do I have a major problem?

 

Those AFR's are definately normal except at idle.

After the car and gague o2 are warmed up you should also be around 14.5 just like your cruising AFR.

 

Well your a/f shouldnt go over 13:1 at WOT...thats just not good. And the other values seem slightly lean and at idle i think is probably a decent bit lean. Not 100% sure though but i dont think the gauge should ever max out or you have a problem. just look it up on google and search what ideal a/f ratios are for different situations like idle and light/moderate acceleration and stuff.

 

Do you think I have a problem with anything, or just a lack of a tune to keep up with airflow mods?

I don't yet have the $$$ for a tuner(and can't decide which one to get), but don't want to cause damage until then.

 

The very lean AFR at idle leads me to believe there is a small vacuum leak after the MAF.

As to the "more air" notions, there is no truth to that at all; as all a larger TB and more efficient plenum do is allow the engine to pull air in more easily, at throttle openings larger than whatever the most the old PB could open.

The MAF records this added flow and the PCM will adjust the mix to hit it's target AFR, other than the normal things one would do when tweaking a tune there's nothing that needs to be changed to accommodate a larger TB or upper plenum. You should disconnect the battery to clear the KAM and forse the PCM to learn new idle air trims.

When you adjusted the throttle stop screw did you do it like this?

Also I am a bit confused as to why and how you adjusted the TPS, as it is not adjustable (nor does it need to be adjusted) on the EECV (eek-5) system.

The EECV system reads the TPS voltage at startup and continuously when the engine is running, and saves the lowest observed value as indicating closed throttle--this called a reverse latch (ratch) function, and the ratch voltage becomes the basic for all other TPS signal interpretation.

 

Yes, I adjusted the throttle stop from that exact link that I found in other posts( a few times), I also have disconnected the battery several times. I have checked for vaccuum leaks with a can of carb cleaner, but I will triple check again this weekend.

Thanks for the help!