At wits end with high BLM's, putting up the Guru Signal

[DonnieShort]

Where to start?.....

Firstly, Fp set to 43-44# line off, T+ set properly on, on, off, off, base setting to 3½"maf 0 normal idle. Doesn't change but a point or two down when putting it on rich idle, but goes up quick when set to lean idle. Vacuum is 17 at ilde.

Over the last few weeks I've been trying to troubleshoot a high blm problem. Usually they are well within range 132-136. But over the last couple of weeks they have jumped dramaticly, to the tune of pegged at 160 at idle

Things I've already done:
I went by Razor's procedure and started off by eliminating the vacuum portion by putting flat gasket material under the vac. pod closing off vac. to everything. It still was at 160. Went around the engine with 2 cans of carb spray around all the usual places tb, plenum intake etc. nothing. I put the maf directly to the tb eliminating the intake tract, ic, turbo etc. that checked out fine, no changes yet still at 160. Ran a can of Top Engine cleaner through it and it looked like I had a little smoke from the ds header ( ATR piece that's been welded 5 different times over the last 6 years ) so I put on a new gasket, Felpro 1400 replacing a copper gasket and still nothing. Turned out to be oil smoke where the valve cover bolts had worked loose and leaked down on the flange. Changed the oil and filter put in a new o2 and that helped a little but it eventually it creeps back up 160. Put in a new fuel filter, still no change. I ran a compression test for the heck of it and it looked like this:
#1 - 145
#2 - 149
#3 - 145
#4 - 145
#5 - 150
#6 - 145

Pretty good for a 113,000+ mile car
So with all that being said, where do I go from here? What is the most logical thing to do next? I do have some Turbo Link files that I can share if anyone would like to look at them. One is a 15 mile or so trip back to the house and 2 more are some idleing and staging it up some in the driveway. Please help!!!

 

[Razor]

First.. keep hand guns away from vehicle

Get a probe/stethescope and listen to your injectors. make sure they all sound tick tick tick. If any sound erratic.. that can be the cuase.

If you plugged all the vacuum ports on top of the TB and reset comp..let it learn and it went to 160.. then its a big leak.

Remove the egr and block off the ports. Reset ecm.. retest.

IAC gasket missing or leaking?

IAC numbers 20-25 at idle?

Is it an AC Delco O2?

Swap in a known good GM MAF.

Swap computers...

Swap chips...

Is it only the idle cell that is bad on your BLM? When you drive and cruise are they normal? When you decel? When you accell?

If all the above is done and problem is still there... your in trouble.

This will keep ya busy..

Keep at it.. you'll find the problem.

 

[Steve Y]

Donnie turn the FP up some if you want to.

Does the car idle well? If so, don't worry about it. I wouldn't give it a second thought. Maybe it is sucking air through the throttle blade shaft area which is a common problem. It is a known problem from day one when these cars were made that some of them will run high blm at idle for that reason. Nobody was real concerned.

Also, maybe the injectors are a little lean at low PW.

Bottom line is that the blm's are doing there job and if the car runs good, forget it.

Good luck.

 

[TurboDave]

Donnie

I didn't see in your original post if you checked the exhaust manifolds and crossover for leaks.
Leaks in the exhaust system anywhere pre turbo will cause the BLM's to shoot up to the top limit.

 

[DonnieShort]

Originally posted by TurboDave
Donnie

I didn't see in your original post if you checked the exhaust manifolds and crossover for leaks.
Leaks in the exhaust system anywhere pre turbo will cause the BLM's to shoot up to the top limit.

All the exhaust has checked out. Thing is, I've had exhaust leaks over the years and pretty bad ones, but the blm's never did anything like this. Leaks I've had before sent blms maybe to high 130's, maybe 140 and that was with the ds header cracked around every primary ( ATR ) so bad that I don't know how it was even staying together:eek

Steve , I've added fp, took away and nothing is really helping it. But here's the deal, if I don't get this fixed I'm going to have to change the oil at 300 mile intervals because the oil is very gassy smelling. I changed it just the other day and in a few weeks time it was smelling pretty bad so it's possible I could even be higher than 160.

I'll do some more checking. I have to take a break from it for a day or two. I have no evidence of this, but why do I feel that it's the intake gasket??

 

[Steve Y]

Gassy smelling?

Maybe 1 injector is malfunctioning. I had that happen once, a long time ago. Put about a pint of gas in the oil.

Keep an eye on your level.

How about checking the plugs after you leave it idle for a while....

The car doesn't feel like it is missing, does it?

 

[Rickracer]

If BLMs are that high.....

....and the oil is being diluted with fuel, it almost has to be a MAF or O2 issue. Something is telling the puter the motor is lean, and the puter is adding all the fuel it can. If these cars had a MAP sensor, I'd tell you to look there. I've seen MAPs cause similar problems, particularly in FoMoCo products.

 

[klrv6]

I found my high BLM

I was having issues with my BLMs pushing 140. I thought the crossover was completely sealed, turns out after I removed the pipe and sealed with a bead of high temp RTV, I was now working on how to get rid of the low BLMs. Even if it looks tight, remove and seal it!!

 

[Razor]

Running top engine cleaner will show you your exhuast leaks.

I had one I chased for three weeks. Ended up not having a gasket between the TB and plenum.

Had another one blown EGR gasket. Thats another port to block off completely.

O2 sensor picks up the info.. computer makes a correction..Inbetween you have a lot of stuff. It can be a tough problem.

Chuck Leeper gave me this advice once, get a legal pad.. write down everything it can be.. then put it on your windshield and start checking stuff off.

I had a brand new set of injectors(50's) that were bad.. I pulled my hairs for 6 hours.. returned them, got a different set.. bam.. problems went away.

Dont think becuase something is new..it cant be bad.

Oil change after 100-200 miles. You'll kill the bearings.

 

[streetknight]

Don't mean to rob the thread, but I'm having similar problems. My first blm cell is pegged at 160. I spoke with Razor the other day and I did the blocking off the vacuum block this evening, then reset the computer. I then proceded to watch DS to see when the car would go in Closed loop. IT NEVER DID. I'm new to these cars and might be missing something, but I let the car idle for 30-40 minutes and it got as hot as 180 degrees and NEVER went into closed loop. The only way it would is if I held the throttle over 1400 RPM's. Then it would say closed for about 5-10 seconds and then go back OPEN. When it was closed at part throttle the 2nd blm cell started shooting up to around 145.

My EGR is blocked off. I'm going to put in a new o2 tomorrow. I was hoping that blocking the vacuum block would rule out bad vac lines, but since no closed loop I don't know what to do.

HELP!!! Reynolds is in a few days.

Thanks,
Benji

 

[Razor]

I'll be at Reynolds, if you need help getting it figured out.

I'll bring some goodies.

Some chips may not go into closed loop until the car is driven. And reset the computer after every change and let it relearn.

Use the mity vac to test your vac lines.

 

[DonnieShort]

I don't belive that it would be the maf. The car runs too good and idles too well. Plus it's a 3½" LS1 sensor, doesn't seem they go bad very often. But I'll swap it with another just to be sure.

I'm going to re check the egr and see what that does. This problem has been a little while coming on. Numbers were in the mid 130's t0 137 for a little while and has gradually gotten worse. The o2 is definatly seeing something and dumping more fuel to correct it. 160 has to be a big leak and I'm leaning toward it being something with the intake gasket, but I'll re check everything before I do that. I've got a set of heads I want to put on and would like to do all of that at the same time.

 

[SpeednV6]

Try changing chips. I use 3 different chips and get different blm's at idle. Chip #1: 128 at idle, Chip #2:150 at idle, and Chip#3: 160 at idle.

 

[DonnieShort]

Originally posted by SpeednV6
Try changing chips. I use 3 different chips and get different blm's at idle. Chip #1: 128 at idle, Chip #2:150 at idle, and Chip#3: 160 at idle.

The chip I have is the same one I've had for over 4 years ( Extender ) without any problems at all. Do chips ever go bad?

 

[SpeednV6]

The chip doesn't go bad unless static electricity zapped it, but that's not the case. An example: My Red's chip idled at 150, I called Red up and told him about it. I sent it back and then it ran at 128. He said he did something to the chip.
2nd example: My PTE chip idles at 150 and a homemade chip idles at 160. I don't know why, but it seems that the program of the chip obviously affects the chip and idle blm's. I could be wrong, but I don't change the tune...only the chip.

 

[ThikStik]

Thing is, at one time, he had ok blms with this existing chip. So something changed. Have you tried disconnecting one inj at a time? And it sure seems that a plug would be dark l How about checking for corrosion on ecm pinouts...mine were very corroded.

 

[Razor]

Swap in a stock GM MAF and a regular chip see what happens.

You can get a chip with an open loop idle that reads 128 all the time at idle. Those I get scared off.. cuase you get a problem.. really hard to tell. The thrasher will idle at 128

Buick 101, swap electrical parts first.. then start of finding whats cuasing the issue.

 

[DonnieShort]

When I pulled the plugs to run a compression test they all looked very good. I'll try and swap the maf out. I can use one my dad has on his LT1 Corvette and see what happens.

 

[quikv6]

Second

I second the MAF swap completely. I had blms at
160....but my idle was great and the car ran smooth. Swapped a GM maf...blms went to
120's

 

[wiked87gn]

keep us updated and tell us how this one turns out and what the fix to your high blm's was..