Only 400 mV @ idle, need help!!!

[cabech984]

Well, I finally got my Hybrid Firebird running. My only apparent problem so far is that Im only getting O2 readings of 400 mV @ idle speed. It will occasionally go to 520-570 mV. I am running;

3.8L ( .030" bored)
208/208 cam
Fuel pressure @ 43 psi w/ line off
zero boost (breaking in)
#55 Injectors w/ low imp ECM
TT Chip
TE44
Autolite 24 plugs gapped @ 32
70mm TB & Upper plenum


I think everything is connected right, it runs on its own, can the cam sensor cause any problems w/ fuel? @ 25 ATDC, the voltage was 7.03vdc. I am running a mix of 5 gallons 94 octane, 3ish gals of 87. I am thinking it is on the crappy fuel but, still want to make sure before I actually drive. Any help is appreciated, let me know if I need to mention anything

 

[SouthernCal GN]

O2s should be rather rich at initial start-up; once you hit closed loop, the O2s should bounce around.

What are your BLM and INT #s at? TPS setting?

 

[cabech984]

BLM & IT are both @ 128. TPS is .42 at idle. Does the cam sensor sound like it is in time? It takes no time to fire up the engine and it runs around 800-825 rpm. I think it is close, guessing that the crappy fuel mix is to blame. Maybe I should go get 5 gals of 110??

 

[johnplogii]

At idle the o2 Mv should be .450 give or take & it will bounce around. The .700-.800 readings are what you want at full throttle.

 

[cabech984]

At idle the o2 Mv should be .450 give or take & it will bounce around. The .700-.800 readings are what you want at full throttle.

Oh, I see!!! well sounds like I am close, perhaps .050 mV are on the table b/c crappy fuel??? Looks like I may get to drive it today afterall! Cool!!

 

[johnplogii]

I have never had a car that sat right on .450. They will bounce around alot. If it goes above .450 and below .450 your doing really good. readings in the 300's to 500's is perfectly normal in my opinion.

 

[mikestertwo]

TT chips use an open loop idle. Take the car out and let the chip "Learn". I'm sure after a few engine cycles things will settle down.

 

[SS/GNX]

What O2 sensor (brand) are you running?

 

[Blazer406]

TT chips use an open loop idle. Take the car out and let the chip "Learn". I'm sure after a few engine cycles things will settle down.

What he said.... when you first crank it for the first time.... all the BLM cells are 128..... as you drive it...... maybe a few hours.... these values will change..... except for the BLM cells that are programmable through Eric's Chip....

It sounds right to me..... drive it a little and report back...

 

[cabech984]

What O2 sensor (brand) are you running?

Using a Bosch O2 sensor.

On TT's website, it says the O2 mV should be 780-820 at idle. Are you saying that after a few drives they should go up from the 430's Ive got now?

 

[Pablo]

.450 represents around 14.7:1 air fuel ratio


this is around what you want for idle and part throttle. The narrow band o2 sensor will never be accurate enough to completely rely on it being accurate down to .050

.500 for idle is fine.

The higher o2 numbers quoted are for richer air fuel ratios associated more with WOT.

Let me re-iterate.. the stock narrow band sensor is next to WORTHLESS for accuracy. The only place it is even near accurate is at 14.7:1 which like i said is around .450. Anywhere else is just a guess.

Its like licking your finger and holding it up in the air to determine exact wind speed and direction.

 

[cabech984]

OK, OK, it seems to be running fine, just trying to make sure. I think I burnt out the starter solenoid switch as well as there is a slight knock.

 

[Blazer406]

OK, OK, it seems to be running fine, just trying to make sure. I think I burnt out the starter solenoid switch as well as there is a slight knock.

Slight knock.... That doesn't sound too good to me....

Has the 02's changed any at idle?

 

[cabech984]

Slight knock.... That doesn't sound too good to me....

Has the 02's changed any at idle?

Yes the O2's are almost constantly moving up & down.

I dont know about the knock thing, it comes and it goes, never constant at any RPM. It reminds me of an unprimed lifter but not too sure. I ran it last night and it had a constant 40 psi of oil pressure. I had to take off the gauge b/c the fittings were leaking pretty bad. I'll have to put the gauge back on and figure it out.

 

[GNVYUS 1]

Like Pablo said, the stock narrow band sucks for dead on accuracy. Don't worry about idle MV's, your BLM is great at 128 so drive it around and use that to determine how your car is doing. Your other settings look good.

Why would you waste your time and money mixing in 87 octane on a performance turbo car?? Yes mix 110 if you want but be aware that your 02 will die way sooner due to the lead so get a Denso Stainless 02 as your back up because you are going to need it.

If you are worried about your cam sensor get the Caspers Cam Tool, easy as hell to set up right the first time.

 

[cabech984]

Like Pablo said, the stock narrow band sucks for dead on accuracy. Don't worry about idle MV's, your BLM is great at 128 so drive it around and use that to determine how your car is doing. Your other settings look good.

Why would you waste your time and money mixing in 87 octane on a performance turbo car?? Yes mix 110 if you want but be aware that your 02 will die way sooner due to the lead so get a Denso Stainless 02 as your back up because you are going to need it.

If you are worried about your cam sensor get the Caspers Cam Tool, easy as hell to set up right the first time.

Well, the car had a 3.1 on it before this engine, there was 87 octane (less than 3 gallons) from it. I added 5 gallons of 94 octane.

The mV's were terrible under throttle, O2 cross counts were almost zero, car sputtered, misfired, etc while on the throttle. Could the 02 sensor be bad? I'm using a Bosch that I got with the engine.