Author Topic: BLM's Up-Why?  (Read 9198 times)

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Offline Scoobum

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BLM's Up-Why?
« on: July 13 2017, 02:27:19 PM »
So last week I'm at the track...and the car fell on it's face...likely the ignition module. I come back in and turn the boost down from 23 to 20...and it sails through the 1/8th traps no problem. I save the file...and then run through the SM and the BLM's are up to 128 from 118. I get back to the trailer and the vacuum hose that goes onto the one way check valve is off. I reinstall it...and assumed the BLM's would return to 118. PL file shows no lean condition...no KR...and the boost stayed at 20 PSI. I swapped in all new vacuum hoses...but the BLM's remain at 128. I'm gonna check the exhaust flange crossover nuts tomorrow. Open to suggestions as to what's going on. BLM's are normally 118.
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Offline reality

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Re: BLM's Up-Why?
« Reply #1 on: July 13 2017, 03:39:21 PM »
Are the BLM'S working at all? 128 is default.

Offline 1KWIKSIX

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Re: BLM's Up-Why?
« Reply #2 on: July 13 2017, 03:44:16 PM »
Brad,
Please correct me if I'm wrong, but I don't believe that BLM's at 128 would be a concern.
I understand that readings of 128 +/-   10 are (118 to 138) are often considered in the normally acceptable range.
However, since your car is being pushed pretty hard while running down the 1/8 or 1/4 mile,  I'm of the same thought as you that you'd want it closer than that.


If your BLM's are 118, means you are rich and fuel is being pulled to compensate.
128 shows that you are bang on the money. At least that's my understanding of things.


What does your Power Logger show for BLM's in all 16 cells?


Be sure your O2 sensor is not crapping out as the ECM bases its reading on a properly functioning O2 sensor.
Any exhaust leaks or cracks in your system ? These could also contribute to adding fuel by the ECM to compensate.
Lastly, changing your vacuum lines is a good idea....they often get brittle and leak which would also be a contributing factor.
I alway use hair spray on my vacuum hose barb ends and use mechanics safety wire to snug them down , just to be sure they don't blow off prematurely.
If you've got access to a smoke machine I think that would tell you conclusively that there are no other vacuum leaks.


dave

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Re: BLM's Up-Why?
« Reply #3 on: July 13 2017, 03:48:37 PM »
128 isn't default...it's the current reading. Yes...128 is perfect...but the car normally runs at 118...and has suddenly jumped to 128...so something's up. It's currently raining...as usual...so I'm done for today. Gonna slide under it in the morning and check the exhaust nuts on the crossover. I had that DS header welded 15 years ago. I may just pull it for inspection. I also run header gaskets...so one may have burned through.

02's and CC's are moving around...but I can slap a new 02 sensor in it. Any chance the PCV is fukd?

Rad is at it's normal level...and the oil is clean. Engine is running smoothly.
« Last Edit: July 13 2017, 03:55:15 PM by Scoobum »
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Offline reality

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Re: BLM's Up-Why?
« Reply #4 on: July 13 2017, 04:06:44 PM »
Are you saying its at 128 at WOT or idle.

Offline Scoobum

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Re: BLM's Up-Why?
« Reply #5 on: July 13 2017, 04:26:43 PM »
128 at idle. It's jumped from 118...so something's amiss.
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Offline reality

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Re: BLM's Up-Why?
« Reply #6 on: July 13 2017, 04:36:50 PM »
Did you have the computer unplugged
 or battery cable off if so then the blm will stay at 128 until it relearns


Pull a vacuum hose off and see if the blm jumps up slowly

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Re: BLM's Up-Why?
« Reply #7 on: July 13 2017, 04:58:50 PM »
The ECM was not unplugged. The BLM's jumped at the track. It's developed a vacuum or a pre turbo exhaust leak. I swapped in new vacuum lines...with no change.
Hard work pays off, dreams come true. Bad times don't last, but BAD GUYS do!

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Offline TexasT

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Re: BLM's Up-Why?
« Reply #8 on: July 13 2017, 07:33:25 PM »
How are the O2 readings ?  maybe a new fuel filter or something in the tank like that hose from pump to sender has developed a little leak and not delivering the fuel it was.
Anything else you goofed with?

I like the check the manifolds above.
Rich

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Re: BLM's Up-Why?
« Reply #9 on: July 13 2017, 07:47:34 PM »
Rich, I swap a new fuel filter in every year...but I could toss in another one...they're cheap. I could drop the tank out and check on things. Got lots of time on my hands. PCV valves are cheap too. I haven't touched anything other than what I mentioned. The BLM's jumped up when it blew that hose off at the check valve.
Hard work pays off, dreams come true. Bad times don't last, but BAD GUYS do!

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Offline TexasT

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Re: BLM's Up-Why?
« Reply #10 on: July 13 2017, 07:49:19 PM »
Put a gauge on it and make some passes. See if it is up. But yes filter is cheap. Do you "strain" your fuel when putting it in?
I'm guessing the tank isn't new. No telling what kind of floaters are in there.
Rich

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Re: BLM's Up-Why?
« Reply #11 on: July 13 2017, 07:51:24 PM »
Track isn't open till next Friday. I use VP race gas. It's as clean as a whistle.
Hard work pays off, dreams come true. Bad times don't last, but BAD GUYS do!

RIP Scott Hall AKA Razor Ramon

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Re: BLM's Up-Why?
« Reply #12 on: July 13 2017, 07:53:32 PM »
Slicks are on the car. I could boost it up in the driveway and watch for the fuel pressure to rise with boost. New pump in it last summer. Fuel pressure gauge is on the A pillar with the boost and knock gauge.
Hard work pays off, dreams come true. Bad times don't last, but BAD GUYS do!

RIP Scott Hall AKA Razor Ramon

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Re: BLM's Up-Why?
« Reply #13 on: July 13 2017, 07:57:57 PM »
Boosting it in the drive might work but I think and actual top end run is more realistic with the volume. If the pump cam supply the
 and keep the pressure up you are in business.

Maybe you should disconnect the orange wire and see if the blm goes back to your "normal". It might have "learned" too much with that vac hose off.
Rich

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Re: BLM's Up-Why?
« Reply #14 on: July 13 2017, 08:11:39 PM »
I swapped out the ignition module today...so the battery was disconnected. I followed Erics directions for cranking up a new chip. BLM's remain at 128. They did drop to 125 for about 30 seconds...but went back up to 128. Weird...to say the least.
Hard work pays off, dreams come true. Bad times don't last, but BAD GUYS do!

RIP Scott Hall AKA Razor Ramon

 

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