o2 sensor showing 0 cross counts and 47 mv at idle?

[d0n_3d]

I'm trying to resolve a major idling problem with my car. First of all...the car wants to die every other time I come to a stop or let off the throttle completely under normal cruise...I hooked up t-link yesterday and noticed my o2 sensor was reading 0 cross counts and between .025-.047 mvs at idle warmed up at 160...when you push the pedal the cross counts would show up and mvs would go up...but then go back to the original values of 0...well i figured it was the o2 sensor causing the problem so I yanked it out and threw in a brand new one...same thing!

car is running pig rich...blms are locked at 150 and i have replaced all my vacuum lines and the entire motor has been re-sealed (new intake gasket, headers, head gaskets, etc.)

all sensors on the car are new or 1 year old...tps is set at .42 at idle and iac counts at 20 fully warmed...

is there a way to check the o2 sensor circuit or is my ecm bad? the ecm is factory original...

 

[JDSfastGN]

double check all the seals along the intake, make sure the egr is tight and the bracket isnt cocked. Retigten all the plenum bolts as well. The 02s sound like there is a pretty big exhaust leak before the sensor. Check all the grounds on the back of the heads, as they can make all the sensors act funny and give weird readings. Mine had recently come loose and my BLMs were pegged and 02s were acting funny as well. Good luck with it man.

 

[Eric Stage I]

A BLM at 150 means the idle is lean. The computer tried to add fuel, but hit the upper limit and can't add any more. That's why the O2 is so low at idle, and that's why it won't idle right and tries to stall.

Are you using a stock type maf, or a Translator setup? What does the airflow read at idle when the O2's are low?

Regards,
Eric

 

[fast eddie]

iac to high,try for 0-10 at idle

 

[d0n_3d]

Originally posted by Eric Stage I
A BLM at 150 means the idle is lean. The computer tried to add fuel, but hit the upper limit and can't add any more. That's why the O2 is so low at idle, and that's why it won't idle right and tries to stall.

Are you using a stock type maf, or a Translator setup? What does the airflow read at idle when the O2's are low?

Regards,
Eric

forgot to mention that...using right now (temporarily) a stock ac delco maf sensor and the readings are 4-5 GPS at idle fully warm...tried 2 stock mafs and the same reading occurs...

i am also no longer the egr setup...have a block-off plate installed with a gasket and some sealer...using stock pcv setup...and I know I have no exhaust leaks because i have brand new gaskets on the headers and the turbo to header connection...all new vacuum lines as well! I am going to double check the intake manifold towards the back where the seal is...going to see if air is coming out that seal...

 

[Eric Stage I]

You could try and temporarily disconnect the PCV and block it off, just to see the effects on the BLM. The stock PCV doesn't always work right...even the A/C Delco ones.

Eric

 

[WarpSpeed]

You didn't mention if that was a genuine AC delco purple wire O2 sensor?

 

[d0n_3d]

does not matter which o2 i throw in there...

 

[d0n_3d]

OK I can't find any leaks anywhere...checked all around the intake manifold...no leaks there...no exhaust leaks...no vacuum leaks (all lines are new!)...egr plate is sealed...brand new o2 sensor, good working maf sensor, most everything else is brand new on the car...it's either a bad ecm or it's something internally that I did not see even when I tore everything part over the winter...everything has been re-sealed...

in extreme cases like this...can't I just get a chip setup where it locks the BLM and INT at 128 all the time??? wouldn't that cure the problem? that's what I had before...I was running the extender chip and it's the only chip out there that cures my problem...car runs 100% excellent and smooth when I run an extender chip setup...I am only running the stock style stuff right now until I save some money for a new setup for my new injectors...

 

[Lee Thompson]

ground wire

On the back of the head is a small tan wire that is the ground for the O2 sensor. Make a new wire, ground it to the intake and run it inside and piggy back it onto the existing tan wire where it goes into the ecm. Hopefully that is your problem.

 

[ijames]

Don, what do the blm and O2's look like cruising at 55-65 mph steady speed? Are they still unhappy, or do they behave?

 

[tttype]

Exact same problem

Don, have you solved this problem ?
I am having the exact same problem.
New rebuild, Pegged idle BLM, low O2 at idle, new AC O2 sensor.
No easily found vacuum/exhaust leaks.

Just about to replace all hoses & egr gasket with hopes of improvement.

Ran hands around header flanges & turbo connection on cold running engine & found no exhaust leaks. Anyone have a different method.
Also sucked some atf through a vacuum hose & saw no obvoius smoke leaks.

Funny we are both having same problem of fresh rebuilds.

Darrenl

 

[bruce]

Originally posted by d0n_3d
(new intake gasket, headers, head gaskets, etc.)
all sensors on the car are new or 1 year old...tps is set at .42 at idle and iac counts at 20 fully warmed...
is there a way to check the o2 sensor circuit or is my ecm bad? the ecm is factory original...

Sounds like you may have used a sealer that was no in fact O2 sensor safe.

Just have Joe burn you an open loop chip and see if it runs OK, without out going closed loop.

If it does, drive it a couple hundred miles, and then put a NEW DELCO O2 sensor in it, and the old closed loop chip.

BTW, just using a silicone based aersol to clean/ lube weatherstripping is enough to poison an O2 sensor. They hate any form of silicone, or even being NEAR it.

 

[tttype]

New info

Problems I'm having;
-very rough idle w. stalling
-pegged @150 BLM
-very low O2( stuck below 100mv at idle, 7-800 cruise), but lots of cross counts

have no vac/exh leaks

So today swapped MAF.
02 started to read better 200 then 800,200 etc. GOOD ,but once in closed loop still get maxed BLM.

Swapped out JL chip with Turbo tweak chip & idle is good. BLM's dont get maxed either .BUT its a open loop chip.
Seams like BLM is locked at 128.
So has this cured problem OR only covering up the BLM issue by locking them ?

The original Maf read the exact same flow 6gr, idle , 12gr 2g RPM ,18@ 3g ,27@ 4g. so why would it change the O2 readings ?
I doubt the MV were actually 60mv @ idle with BLM pegged @150.
Car took a few seconds to spool up so must have been real rich.

???

 

[Eric Stage I]

The Turbotweak is not an open loop chip. It will switch to open loop at idle after certain conditions are met. The BLM is still allowed to learn, but you have to drive around a bit for it to learn. The BLM's are not locked at 128 (except at WOT).

Regards,
Eric