I made a couple of changes to my lb9. the car runs good but I think is running a bit lean (wot).

here is the list of things i changed
Tes headers and 3" cat back
1.6 rollers rockers
Msd AL, coil, and wires
AFPR at 51 for now.
bosh III injectors
crank pulley
K&N

Afther installation the car runs notisable stronger but I geting knock retard at to 2 to 4 of it, some times up to 7 but rarely. My o2 sensor was reading .700 at 47psi. I then bumped the psi to 50.5 and o2 readings jump to .780. I think(wot) acording to the tunning section in the forum it should be reading between .850 and .900. I don't want to raise the fuel press anymore. I car idles great (.200 to .450 o2 sensor @750 rpms) so i don't think i have a vac leak. I also played with the timming but not much difference now set at 4 degress with the computer disconected

Can my stock computer not compansate for my changes? do i need a new chip?

thanks in advance for the help.

 

What year car/ecm system is it?

Car is probably going abit lean with the 1.6 rockers. Those leaned out my L98 a good bit for some reason. More airflow allowed into the motor now so may change the tune abit, especially if its a speed density car.

Is the o2 sensor is working properly? Fresh sensor? No air leaks with the exhaust? That can skew readings. Fuel pressure holding constant?

How are you measuring the timing retard? Do you have tunerpro or some scanner?

If there are no leaks in the exhaust and no other mechanical issues/sensor errors and it is going lean (check spark plugs at WOT can help verify things), then sounds like you could use a new chip tune with just abit more PE mode at the rpms its going lean. Shouldnt be hard to do.

 

It's a 1989 M5 It has the stock computer and prom. I don't think a have a leak on exhaust have checked couple of times. My idle at start up goes to about 1100 rpm them once hot drops to about 750 - 800 steady i have not found any vacuum leaks. Also I use an Autoxray to check the O2 sensor and knock retard. I also just replace the fuel pump with a walbro.

thanks,

 

Seems like slightly high idle speed for a 305 but not horrible I guess. Is the IAC closing at idle to only a few step counts or so?

Usually the stock chips are set around 6 deg timing at idle without the EST wire connected for computer control.

I'd keep it around that but since the o2 is looking abit lean, i'd look into getting tuning equipment and start playing with your own chips. Then you can play with timing in the chip as you see fit.

Injectors ohm out to 14-16 ohms or so when warm?

 

I have not checked the IAC. Injectors checked Ok. I will replace the old vacuum lines today see if I get any improvements. At idle when warm my injector pulse is between 1.7 and 1.6. Alos at what rpm should my idle be at?

thanks,

 

I would have thought closer to 650-700.

 

Thanks,

 

Could depend tho, not sure what the stock bin settings are for that year/manual trans. Stock L98 ARAP bin commands 575-600 rpm as idle and thats about what mine was.

 

Well,

I checked the Idle steps and i get between 58 - 60, one of the parameters on the xray calls for 800rpm cold and 750 warm, I don't know is that is the bin you mention. car is ussually runs about 50rpm over it.

Either way i will look into what i need to make my own adjustments to the prom. I really appreciate the help you gave me.

thanks once again

 

50-60 steps when warmed up is alittle high but not horrible. Most guys tend to tune for 10-20 to allow some room for movement either way. I'm not sure what a stock car would normally see, I dont remember what mine did.

 

Well,

I going to get some tunning equipment and go from there. I'll let you know how it goes.
thinking about getting the autoprom.

thanks,

 

Orr89RocZ

first of all thanks for your previous help. If you can do you mind giving me your opinion on which way i should go with tuning equipment. I have been looking at the APU-1, the EBL and diypnp. I know that the Diypnp will convert my current system to S/D, but it seems like a plug and play deal. The car is not my daily driver so I don't mind taking more time to learn about any system I choose. Also in the future i might go with a 406 sb N/A I have already built.

thanks for any ideas you can give me.

 

EBL with PFI mod all the way. It is the easiest way to go and probably the best way to tune.