What could possible be wrong.
Im used to se my BLMs change a bit during idle. But now its crazy.
My BLM's are changing between 118 and 150 during idle. It climbs up and down..

No vaccume leaks that I could find. And the trend is the same no matter what i put in the VE tabel.
The only thing I changed on the car, is that I put on the stock CAT, and installed a hayfire ign box.


Missfire, bad 02 ?

Tomorrow I will pull the plugs.
Any ides?

Thanks

 

Even with the stock 02 in the stock location at a prolonged idle under certain conditions, I have seen the sensors cool down. This will drive the BLM value up richening the mixture. The overich mixture will then still be burning as it leaves the cylinder, whcih on the stock setup will heat up the exhaust in the manifold which heats the 02, driving the BLMs back down which leans the mixture and cuts the heat, and it repeats the vicious cycle. My stock G20 van with the LE9 (truck L69 equivalent) feedback carbed engine was bad about doing this with its stock 1 wire non-heated o2 sensor.

 

Is the car in closed or open loop when this happens.
When did you change your o2 sensor last time ?
The o2 sensor shall be changed every ~45000km

If the car is in Closed Loop it shall be on 128 (+/-)3 in BLM (L-term) and INT (S-term)..

Hows your injectors ? How do the car run ?

 

Hi A. had a nice vacation?

O2 changing- NBO2 varies some depending on temp. I logged the EGT compared to NBO2 and WBO2 and you could see it very clear.

Air leak? How close the the collector gasket is the O2?

Missfire can caurse any sort of problems, I know but you should here it miss? Pull the plugs, if you like you can email me a logg file and spark plug pictures, I have done a lot of reading about sparkplug reading this summer.

/N.

did you sort out your other problem? was it stall saver?

 

I use a heated 02 at the collector of my hooker headers. The 02 is only 2 year old with 1242 miles on it.
Right now the cars idle is stabel, and I can hear no missfire. But I can feel it not running smooth during slow, low rpm driving.
Something is not right. I will com back after pulling the plugs.

THanks

 

Update.

Plugs look ok, a bit on the rich side.
I noticed a trend. When the car is cold the idle is fine.
Then when the car enter closed loop the first time , the BLMs are dead on. But as temp rise so does the BLM. And the engines idle get worse and worse.
I can smell gas so im definitely NOT lean. Its the other way around.
And it doesnt matter what i put in the VE tabel. So this must be something mechanical. I took of the cat and replaced that with a strait pipe. But no change.
Also I noticed that the car gets in and out from closed loop. It never did that before, as I use a heated 02. And I have verified that I have 12v at the censor.
My bet is a bad 02 censor,that shows "ok" value when warm. But the hotter it gets, the more error it shows.
What do you think?

And can i use any kind if 3 wire 02, or does it have to be a ac delco?

Thanks

just a notice. The car does not consume any coolant. Or get hot to fast etc.

 

They are not very expensive so its worth a shot.

I have used AFS-74 and some OEM market from "hansen racing" and they worked good. I have heard bad things about "biltemas"

/N.

 

If youre way rich that will kill the o2 sensor to...
I would put my money on a new o2 and go from there, you got a heated 2 from www.tpiparts.net fast shipping and most times you dont have to pay customs and taxes..

 

 

Changed the 02 to a 3 wire bosch unit. Now its fine.. Thanks for the help..

 

Sounds good to hear