52172

iTrader: (2)

My car started to lean out at certain rpms mainly @ 4.5 lbs of boost and randonly throughout the rpm range. We have checked the fuel pressure and it is stable so that is not the cause. Car still is running the MAF and we have swapped MAF's and problem still persists? The tune was never messed with so what else could be causing the leaning out? Could an 02 sensor be causing it? Before the leaning out I picked up a few trouble codes and they were bank 1 and 2 too rich and another one that said something like bank 2 slow response time?? Any help is appreciated. Thanks

52172

iTrader: (2)

no one has any ideas?

OreoLt1

iTrader: (11)

If it's an O2 issue you need to somehow use a scanner to watch the millivolts for the pre O2's and ensure that they are functioning properly.

I would also double check the MAF.

What's the fuel psi? I would try an injector drop test also. Just because you have sufficient fuel psi. doesn't mean you have the fuel flow/volume that you need.

Is the engine running smoothly or does it feel rough like it has a miss? If rough, possible stuck injector, vacuum leak, MAP sensor, restricted fuel system.

52172

iTrader: (2)

motor is running smooth. I am not sure what the pressure is? Thanks for the input this is a little out of my league, but will pass this on to my mechanic since he was a little stumped. What exactly is the injector drop test? My injectors and fuel system are all brand new.

OreoLt1

iTrader: (11)

Injector drop test is where you pressure up the fuel system and record the fuel psi., then if you have a scanner (Snap on Modis or a OTC Genisys) look under functional tests and look for injector drop test. This lets you activate and pulse each injector individually. Once you have tested a injector record the fuel pressure and figure the amt. of psi it has dropped. After testing reset the fuel pressure to what the original psi. read before testing and test each injector individaully untill all are tested.

The results will show you if you have a stuck open, stuck closed or clogged injector based off of the differences in the amt. of psi. that the injector flowed per millisecond or whatever the time the injector is activated.

If you don't have a scanner OTC sells a remote handheld box that performs the same as a scanner. You connect the box to the batt. and you have a connector that will plug into an injector.(You may have to rig up your own connector to fit your injectors depending on vehicle) The box lets you pulse the injector by millisecond or second. Follow the same procedure as if you had a scanner and record your results.

Your tech. should know what a inj. drop test is.

RooRnZ28

iTrader: (14)

something weird is wrong..... is there like a certain rpm it leans out at, or anything like that? or does it just happen randomly

52172

iTrader: (2)

it definetly is something weird since it is not obvious to my builder/ turbo specialist. The leaning is most pronounced at 4.5 lbs of boost, but it does happen at other rpms and times other than that, but the only pattern we see is the 4.5 lbs of boost.The whole fuel system/ tune is all new. The leaning out is very weird it only happens spuradicaly throughout the rpm range and not all the time. It is more pronounced under boost obviously since there is more of a hp drop there. My builder has been trying to diagnose it for four days now and he has not been spending all of his time on it either. Car ran great for 1500 miles and now this problem came about. WTFK what the problem is. I can't wait till he figures it out. I am just trying to find the best way for him to get to the root of the problem without waisting a bunch of time. I appreciate the input. Thanks

W8N2SQZ

iTrader: (6)

What fuel system set-up do you have?

I agree and would also scan to check how well the 02's are switching. I have had old 02's in the past that would switch really slow and sometimes freeze at any given millivolt.

Does your tuner have the ability to change OS's on the car so you can cut out the maf and even run without the 02's to see if the problem persists?

I also log fuel pressure on my car with EFI live, do you have the abilit to do this?

Glenn

52172

iTrader: (2)

Thanks Glen. My fuel system consists of an a-1000 pump with a factory sumped tank with all new -10 feed line with billet fuel rails and a -8 new return line and an aeromotive FPR. Since I was getting those too rich bank 1 and too rich bank 2 codes with the slow response time codes I am thinking what your idea of the problem might be right. I know my tuner/builder has the ability to ditch the maf and 02's and run it that way, but not too sure as to why he has not tried that yet already if it is not too labor intensive. I know he has tried another MAF sensor and the problem was still there.

shoemike

iTrader: (25)

is this a problem you are seeing with your own wideband?
i just had some very similar symptoms , and it was just a bad wideband sensor.

W8N2SQZ

iTrader: (6)

Another good point Shoe!

Has all of your testing been performed with the same wideband? Could you check it with another WB?

Changing the OS does take some time but if he is going to spend days on trying to figure the problem out, than maybe it is worth the time spent to change it over. Especially if you plan to run more boost later, a 2 or 3 bar set-up is the way to go.

Glenn

RooRnZ28

iTrader: (14)

hmm....did you say it was throwing some codes?

52172

iTrader: (2)

it is not a problem with my wideband the car is losing power from the leaning out. Yes it is throwing some codes and they are bank 1 too rich and bank 2 too rich and slow response time switching bank 1 and 2. Do those codes mean the 02 sensors are bad? Thanks

99FormulaM6

iTrader: (21)

he can tune it in OL and keep the maf if you want. then you just wont have the o2s anymore to worry about them

52172

iTrader: (2)

I don't think it too big of a deal to change the 02's. I am sure he is about to figure it out on Monday I don't think he has spent too much time on my car he is busy with lots of projects and is just fitting me in. I havn't spoke with him since wednesday. On monday I will call him and talk to him about the 02's. Isn't it better to have it running in CL rather than OL?

RooRnZ28

iTrader: (14)

if its throwing any o2 sensor codes, then i think you should change them to some bosch 131111's, and see if that was your problem.

any faulty sensor can make the car run wacky... its happened to me too many times.

52172

iTrader: (2)

Maybe that is what I will tell him to do and I am sure he will agree. The 02 sensors have 115K miles on them. How much do the bosch ones run?

02NBMFormula

iTrader: (6)

could be a vacuum leak post maf that lets out already metered air.

52172

iTrader: (2)

That makes sense. Wouldn't the boost drop if there was a vacume leak post maf though? The boost is holding steady @ 10lbs? I need to talk to him again and see what he has ruled out thus far. Last time we talked he had only ruled out the MAF and fuel pressure.

RooRnZ28

iTrader: (14)

i think they run $60-$80 a pair if you get them online. not sure which site to get them from, but search bosch 13111 and it will come up! i'm running them without any issues.