IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => General Buick Tech => Topic started by: Scoobum on July 13 2017, 02:27:19 PM
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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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Are the BLM'S working at all? 128 is default.
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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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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.
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Are you saying its at 128 at WOT or idle.
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128 at idle. It's jumped from 118...so something's amiss.
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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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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.
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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.
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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.
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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.
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Track isn't open till next Friday. I use VP race gas. It's as clean as a whistle.
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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.
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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.
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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.
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Run some smoke thru it and see where the leak is if any at all
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sounds like it fixed itself....ever yone else wants 128 and you got it!
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I've never bought into the 128 crap. Steve, you and I both know if the BLM's rise out of nowhere...then something's up. That's why we have scan tools...to monitor this stuff. It's raining as usual, so nothing will likely get checked today. If that big yellow thing in the sky comes out I'm gonna check for exhaust leaks...and slap in a new PCV valve and 02 sensor.
I want everyone's input on this. I've stated here before that my opinion of Felpro head gaskets is that the quality level has slipped. I think I read a post from Paul from MAGNA state the same thing. The fire rings are literally egg shaped. Is it possible the combustion could travel across the open deck and head to the fire ring and eat away at it...with the higher combustion pressure forcing the fire ring towards the intake side...causing an air leak and making the BLM's rise.
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Given the wide range of correction provided by the ecm, blms are not all that significant within the greater scheme of things and people tend to forget that blm are ignored at wide open throttle. I find them most useful if there is a sudden change from the normal range indicated by the ecm meaning something has changed in the car. A change of 10 can be attributed to both ambient conditions as well things like fuel pressure or leaks. It's all a guess by the programmer initially anyway.
I agree with Paul, I think Felpros went down hill several years ago. That's why I always suggest the VR's on the average car.
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I race this car in temps in the 40's to 90's...and the BLM's stay locked at 118...so it's not that. I swapped out a bunch of vacuum lines. I'm down to an exhaust leak...or a headgasket on the way out on the intake side. I monitor this engine like a hawk. Max boost has been 25 PSI and always on a safe tune without a hint of KR. I'm gonna be pissed if this is a headgasket going south.
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After about 17 years of being beaten on hard, my son's T is pressurizing the radiator a bit when it is cranked up....I guess the hgs are beginning to seep
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Update. I checked the nuts on both sides where the crossover bolts up...and they're snug. Proper igniton module is installed. BLM's still at 128. Now riddle me this. I removed 2 vacuum hoses from the steel lines. First the one going to the EGR...which I have capped...as I did away with it. BLM's stayed at 128. I removed the one going to the one way check valve...BLM's at 128. Should the BLM's not have gone up with the huge vacuum leak?
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Is this the idle blm block that is off?
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Is this the idle blm block that is off?
Yes
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what about the higher cells? Are they also higher than before?
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what about the higher cells? Are they also higher than before?
Steve, I have lots of PL files from recent track outings. I'll have a look and post back tonite. Thanks for your help on this one. It's got me stymied.
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Steve, I have a spare ECM we can try if you think that could be an issue. I've seen them do some stupid things. I'm ordering a new 02 sensor tomorrow morning. It'll be here Tuesday.
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I would start with a new O2 sensor just for the heck of it..mainly because the O2 sensor is the reading that the ecm uses to decide what the blms should do
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Should the BLM's not have gone up with the huge vacuum leak?
The INTs should move quickly. If they spend a lot of time elevated, the BLMs should follow.
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Just finished straightening up the garage...and found 2 new Denso 02 sensors still in the packaging. Think Glen had a half price sale on these awhile back and Dan Keller and I bought a bunch. Steve, it's pouring rain again. I'll get a PL file in the morning so I can make a comparison of the cells. I'll swap the new 02 sensor in then as well. Thanks for the help guys.
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Should the BLM's not have gone up with the huge vacuum leak?
The INTs should move quickly. If they spend a lot of time elevated, the BLMs should follow.
I'll check that tomorrow as well...thanks.
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INT = short term fuel trims
BLM = long term fuel trims
What does your wideband say? if it is 14.5 to 14.9 is it even worth sweating? Also, don't some of those fancy new chips have locked BLM cells?
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Here it is boys and girls. With a fresh Denso 02 sensor...the BLM's have returned to 118. Thanks for everyones help.
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Good new, now go beat the piss out of it, And don't join that 13second club from Toronto.
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for some reason, I find it funny! :D
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What's wrong with the thirteen sec club? Other than they probably need to stop spending on cool guy parts and do some tuning.
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you got that right. cool guy parts don't work.