Okay, what sensor(s) determine the BLM? I'm running the WinADLD program and with the car on but not running (cold) the BLM is 128 (normal). When I run the car it shoots up to 149 almost instantly.
From what I understand, the BLM shouldn't go up that high (Lean condition) and that it shouldn't move off of 128 until the engine has warmed up.

So, either I have some bad sensors (which ones?) or my ECM may be shot (I hope not!!). I don't think the car is running lean, though I guess that is a possibility as well. I'll pull the plugs here soon to see what they look like to check that possibility.

So, what sensors contribute to the BLM number, and any suggestions on checking them?

Thanks in advance

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87 GT 3.4 V6 Fiero Automatic

not real sure about the ECM functions, but I think the O2 & Coolant Temp Sensor (CTS) are the ones to look at. I dont think it should goto BLM untill you hit 180*. You say it goes into BLM right away, I would guess the CTS is bad. The CTS is the one that goes into the front of the intake manifold, near the pulleys & egr solonoid. Does your WinADLD give you CTS readings?

anyways, I always wanted to make the cable & try out WinADLD, hows it work for ya? is the cable as easy as it looks to make? maybe another thread....

Well both the O2 and the CTS sensors seem to be giving out the proper data. Which is part of why I'm puzzled by all this.

WinADLD seems to work okay. Only problem is it's slow, only updates every 1.5 seconds. I don't know if that's a constraint of the program, or the interface.

*edit*
Some more notes. The INT does go up as well, but it takes a few minutes. The BLM is instant.

Vacuum line question. The EGR relay connects to a device with three vacuum lines running from it. One big one that goes under the airfilter (purge line? What's it do?) the other two run one to the TB the other to the EGR. At idle there is no vacuum on any of these at all. Is this correct?

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87 GT 3.4 V6 Fiero Automatic

[This message has been edited by Banner (edited 09-17-2002).]

two of the 3 hoses on the EGR solenoid will not have vacuum on them at idle.that solenoid is controlled by the ECM.The larger hose coming off the single nipple goes to the air cleaner just to keep dirt out of the solenoid(one of the common causes of failure of the solenoid)

So the one coming off the TB should have a vacum on it then? (The other one goes to the EGR, the big one to the air cleaner).

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87 GT 3.4 V6 Fiero Automatic

BLM is a long term fueling compensation derrived from what the ECM has learned about the engine over a period of time. It is stored in memory and used as soon as the engine is started. The integrator is a short term compensation that adjusts rapidly for current conditions. The INT does not start working until the system has reached closed loop. When the engine is running in closed loop the BLM should stay fairly constant with only slow changes. The INT will be continually changing. If you are running the 3.4 with a stock 2.8 fuel system, that would likely explain the BLM of 149. FYI there are several BLM cells for varying RPMs and loads.

[This message has been edited by rockcrawl (edited 09-17-2002).]

Banner,

That 1.5 second update is the best the ECM can do. Not the software's fault.

http://www.customefis.com/GMEFI.html

quote Originally posted by opm2000: http://www.customefis.com/GMEFI.html

EXCELLENT ARTICLE.....Recommend all read!

Phil

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GTDude
OVER 25 years GM experience

Phil,
What we all really need to do is develop some guidelines or use references for those who have the ALDL software. I recently got a cable from Racin'Rob and downloaded the software. Next to the factory service manual, this may prove to be the most usefull tool a Fiero owner can have.

David Breeze

Well, I put in the injecotrs from the 3.4 and it appears that the BLM number has gone down. The INT is extremely low most of the time now.

However the idle problem has gotten considerably worse, if you punch the gas will idling it will stall as well (I adjust the idle screw and think I got that taken care of however).

I will take the car out a few more times to see if the computer gets better at idling, but right now it will idle down to 500 then up to 1500 rpms. Doesn't do this all the time, but it will start into doing it until the IAC kicks in and stops it. I'm going to look at the data and see if I can spot anything. Someone did tell me to put in the O2 sensor from a 3.4 motor, don't know if that will give different readings, but I may try that next.

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87 GT 3.4 V6 Fiero Automatic

Banner, You're barking up the wrong tree. Everyone knows that BLM stands for the Bureau of Land Management. Stop screwing with your engine and call your congressman.

Banner,

If BLM of 128 is the target, then BLM of 149 meant you were running lean. Lean means short on fuel for the given airflow. To enrich the lean condition you would want to give more fuel flow. This would be by increasing fuel pressure if you have 2.8 injectors. Or you could do it by switching to the 3.4 injectors.

Is that right?

Exactly what is your BLM now, with 3.4's?

What did you find out about the 3.4 O2 sensor? I suspect that is bogus info, somehow. New sensor might be better. The O2 sensor simly measures O2 and gives that info to the computer, which strives for stochimeteric balance.

The BLM limits in the V6 ECM are 120 and 150. The BLM's can only be evaluated at a steady state (idle, cruise) with no TPS change. WOT doesn't matter since the O2 is not used. The INT will move around normally.

If the ECM is unmodified, the right injector would be around 18.1 lbs/hr.

Just an FYI.

I was looking at the sensors for the 2.8 and the 3.4 and found that the MAP sensor and the Oxygen sensor are the exact same on both engines. So is the Coolant temperature sensor.

The Knock Sensor is different (even though it looks the same)

The Air charge temp sensor is different, but that looks like a form/shape change.

So for the most part I don't think that changing any sensors (unless they are bad) will affect the running of the engine, 2.8 vs 3.4.

How many 3.4 people with 87's or earlier have put in the chip from an 88? Just curious.

Thanks!

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87 GT 3.4 V6 Fiero Automatic