BLM's at 90, strange O2 readings

Mark E.

Member
I am working on a car getting it ready for smog. I have helped with this car for years and it usually has zero issues.

When I put Direct Scan on to check the numbers, cruise BLM's straight to 90 and seem to want to keep dropping.

Immediately upon cold startup the O2 cross counts go 0-255 in 5 seconds and stay like that over and over until it lights off. Then the O2's barely go to 750 mv, around 1/2 way on the Direct Scan analog gauge. It looks rich so the blms drop and drop.

My other cars have very low cross counts until the sensor lights off and then over 800mv max reading or over 3/4 on the Direct Scan analog gauge.

This is about the only strange thing I see on Direct Scan. Drilled out restriction in return line so fuel pressure drops properly with vacuum. Swapped ecm, chip, coil/module, tightened grounds at back of head, Cleaned all grounds, new O2 sensor, changed negative cable and added a fat ground to the frame. Pulled injector harness for inspection. Ohmed out fine. I have had this car at my house for a week and am running out of ideas.

HELP!!!!! Any ideas appreciated. If the strange O2 readings are not it, most popular throw some money at it idea is injectors. But they hold pressure with key off no problem. it has 009's and could use a set of 60's anyway.
 

Eric Stage I

TurboTweak Guy
Make sure the chip matches the injectors. Get the full part# on the injector as there are 2 different 009 injectors. What kind of chip?
If all that checks out, then it could be a bad MAF.
 

Mark E.

Member
Old school 009's. 3-289-81382. Same chip I have always used. Tried others with no change.

Swapped to a stock Maf to bypass Translator and idle blms dropped also. Usual is Impala maf and Translator.

Chip consultant is here now. We can also try another.
 

Eric Stage I

TurboTweak Guy
Yeah, definitely not 009's, which was a Lucas 42lb injector.

The 3102 is a Siemens 55lb injector.

So, if you're using a 42lb chip, that's a problem.
 

Mark E.

Member
Got a 55 smog chip and what do you know, everything is fine.

Thanks for the help.

This was a good one to make sure I stay humble LOL.

Later, Mark
 
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