Frustrated with ScanMaster readings!!

[Dreamcar86]

Just when I think I have a grip on these cars I find myself back at square one. Problem is my block learns, they are at 146 and I cannot find the problem. There does not appear to be any vacuum leaks and this problem just presented itself. I have read and read and do not know where to look. Is there any documentation out there that explains how to trouble shoot and find the problem?

Any and all help greatly appreciated.

 

[ikle]

I am new to these Buicks but I would pull the vacuum lines off of the vac block and put vacuum to each line to see if they all hold vacuum,if there is no vacuum leak detected then i would replace the gasket for the vacuum block(it might be bad)Do you have the stock vacuum block?There might be a slight crack in the vacuum block its self.Just my two cents,still learning about these awesome cars.I'm still trying to figure out why mine are a little low 116 BLM's,good luck I hope this helps
ikle

 

[ikle]

Another thing you could look at is fuel pressure to low.My BLM's where once at 160,then I noticed that after my car warmed up (10-15min.)the fuel pressure would slowly drop about 12 pounds.I replaced my fuel pump with a Red Armstrong pump from Cottons,even though my pump only had about 100 miles on it,but was 4 years old and everything was ok.Just a thought,I also read that a guy on this site had high BLM's(160)and he found a vacuum leak behind the a/c controler inside the car,I guess these gremlens can be anywhere!
ikle

 

[Otto J]

What is your o2 doing normally?
don't rule out a bad o2

 

[bmackinnon]

What is your o2 doing normally?
don't rule out a bad o2

+1 ... and what's your fuel pressure doing... is the high blm at idle only? PCV correct? Injector condition? My high bl's were due to gunked up old injectors... many causes possible... need to start going thru the list....

 

[Dreamcar86]

What is your o2 doing normally?
don't rule out a bad o2

Now that you say that my stock O2 may be on its way out. I am so used to looking at the wideband that I overlooked what the ecm is reading. If memory serves you want the O2's to be jumping all around at warm idle and mine stays put.

+1 ... and what's your fuel pressure doing... is the high blm at idle only? PCV correct? Injector condition? My high bl's were due to gunked up old injectors... many causes possible... need to start going thru the list....
Today 01:13 PM

Fuel pressure is holding steady at 42 (line off)

I am new to these Buicks but I would pull the vacuum lines off of the vac block and put vacuum to each line to see if they all hold vacuum,if there is no vacuum leak detected then i would replace the gasket for the vacuum block(it might be bad)Do you have the stock vacuum block?There might be a slight crack in the vacuum block its self.Just my two cents,still learning about these awesome cars.I'm still trying to figure out why mine are a little low 116 BLM's,good luck I hope this helps

I will check the lines again however all my vacuum lines are new and my vacuum block is aluminum with brand new gasket.

Thanks for the input! Now to continue the search.

 

[87NAT]

Just becasue your lines are new doesnt mean there isnt a leak somewhere down the line. Put a handheld vacuum pump on each line and see if it holds.

 

[Dreamcar86]

The frustration mounts

Took a day off work to try and figure out where the problem lies. Got the mighty vac out and went to town. Started replacing all the vacuum lines again and replaced vacuum check valves. Did find one thing that has me scratching my head. Dropped the glove compartment door and pulled the orange vacuum line off and connected the mighty vac when I started hearing a sucking noise coming from the thermostat controls by the radio. Is this normal and can it affect the BLM readings? Not sure what direction to go.

 

[bmackinnon]

Now that you say that my stock O2 may be on its way out. I am so used to looking at the wideband that I overlooked what the ecm is reading. If memory serves you want the O2's to be jumping all around at warm idle and mine stays put.



Fuel pressure is holding steady at 42 (line off)

Did you replace the O2 sensor? Are the cross-counts cycling? Fixed number at idle is not a good sign... and a bad o2 will most definitely affect bl's.

And my earlier question revolved around the blm TABLE... are you just looking the the idle blm? or are the bl's too high thruout? you have to watch the scanmaster bl number while you are under load to see the other bl's.... like going up a long, steep hill with moderate boost/throttle for instance. MUCH easier with powerlogger or direct scan. FP question was asking if your fp is rising lb. for lb. with boost, not just idling...

 

[Dreamcar86]

Did you replace the O2 sensor? Are the cross-counts cycling? Fixed number at idle is not a good sign... and a bad o2 will most definitely affect bl's.

And my earlier question revolved around the blm TABLE... are you just looking the the idle blm? or are the bl's too high thruout? you have to watch the scanmaster bl number while you are under load to see the other bl's.... like going up a long, steep hill with moderate boost/throttle for instance. MUCH easier with powerlogger or direct scan. FP question was asking if your fp is rising lb. for lb. with boost, not just idling...

Yes, I was referring to the idling BLM's however they are fluctuating under load. Is this a good sign? Fuel pressure is good under boost and the BLM's do go down under a load. The o2's seem to be reading correctly under load as well. Tomorrow I will take it out and log a run on the PowerLogger and watch both o2 readings as well as cc's. Looks like there is more work tomorrow.

 

[87NAT]

There is one vacuum line that goes into the cabin behind the glove box for your HVAC controls and doors. From there it branchs off to each of its deadends. I had a vacuum leak on the A/C control head switch. Pulled my hair out for a few weeks trying to figure out my high BLMs. If the mighty vac does not hold vacuum at ANY of it points.... then there is your culprit.

 

[bmackinnon]

From your last post, this is sounding more and more like a simple vac leak. Will the PL display the entire BLM/INT table that's currently learned in like Direct Scan will? They (bl/int) are a table based on load (lv8?) vs. rpm. If only the idle bls are high, it's likely just a vac leak.

 

[Dreamcar86]

There is one vacuum line that goes into the cabin behind the glove box for your HVAC controls and doors. From there it branchs off to each of its deadends. I had a vacuum leak on the A/C control head switch. Pulled my hair out for a few weeks trying to figure out my high BLMs. If the mighty vac does not hold vacuum at ANY of it points.... then there is your culprit.

Bingo! There it is. There is a switch with multicolored vacuum lines going to it and when I pump the mighty vac it is leaking. Guess I need to replace the switch.

BTW - I spoke with Julio AKA Razor today and he gave me some excellent suggestions regarding high/low BLM's.

Step 1. - remove vacuum block and place a nitrile/latex glove between the throttle body and vacuum block and replace the two set screws. If this does not change the BLM's then go to step two.

Step 2. - Try setting the fuel pressure up and see if that lowers BLM's. If not then the work begins.

In my case and 87Nat's it is (was) a vacuum leak at the A/C control switch.

Hope this may help others as this can be very frustrating.

Thanks to all who replied to this thread.

Happy Spooln'!

 

[87NAT]

Glad to help. Sharing info is whats its all about.:smile: