BLM- Long term fuel trim?

[steveo]

hey.. so wait a minute here

if you disconnect the alternator and it runs better, and your BLMs become correct, the first place you need to jump is that it could be but a bad rectifier and/or regulator causing fluctuations in voltage, which totally screws everything.

questions:

- what happens if you say run jumper cables from another running vehicle, running off its alternator, while yours is disconnected?
- is this an internally regulated alternator, or external? are you sure?
- is your alternator bracket painted? are the bolts coated?
- do you perhaps have an oscilliscope or a friend that owns one....?

afaik any gm ecm should operate correctly from probably 10.5 volts to 15 volts. just because the voltage is ok on a dc multimeter doesn't mean it's clean enough.

[rudder2fly]

hey.. so wait a minute here

if you disconnect the alternator and it runs better, and your BLMs become correct, the first place you need to jump is that it could be but a bad rectifier and/or regulator causing fluctuations in voltage, which totally screws everything.

questions:

- what happens if you say run jumper cables from another running vehicle, running off its alternator, while yours is disconnected?
- is this an internally regulated alternator, or external? are you sure?
- is your alternator bracket painted? are the bolts coated?
- do you perhaps have an oscilliscope or a friend that owns one....?

afaik any gm ecm should operate correctly from probably 10.5 volts to 15 volts. just because the voltage is ok on a dc multimeter doesn't mean it's clean enough.

I thought this too! The alternator on the truck was original and had 180,00 miles on it. So I bought a rebuilt alternator from NAPA which is a single wire internal regulator alternator. The bracket is non painted. Still same problem. So I decided to eliminate the wiring. I hooked the output wire directly to the postive post of the battery. I disconnected the single excite wire (brown wire) and went directly to the postive post of the battery. I then ran a ground wire directly from the alternator case to the negative post of the battery. Same problem. The motor will idle but not smoothly and it surges badly above idle. When all this started (truck would not crank had to use starting fluid) then would run, I went to the fuel pump checked pressure and it was 10# at the TBI. So I decided to put in a new fuel pump ( a new AC DELCO) this pump showed a little more pressure 11#. Yes I was smart enough to cut a trap door in the bed so I won't have to drop that 36 Gal tank again. My friend says why don't you just get another truck, well I can't afford another truck, I burn wood and use the truck in the woods, I am the 2nd owner had this truck 20yrs, it's been a good one, and frankly I am not going to let this beat me!!! G.S.

[rudder2fly]

I thought this too! The alternator on the truck was original and had 180,00 miles on it. So I bought a rebuilt alternator from NAPA which is a single wire internal regulator alternator. The bracket is non painted. Still same problem. So I decided to eliminate the wiring. I hooked the output wire directly to the postive post of the battery. I disconnected the single excite wire (brown wire) and went directly to the postive post of the battery. I then ran a ground wire directly from the alternator case to the negative post of the battery. Same problem. The motor will idle but not smoothly and it surges badly above idle. When all this started (truck would not crank had to use starting fluid) then would run, I went to the fuel pump checked pressure and it was 10# at the TBI. So I decided to put in a new fuel pump ( a new AC DELCO) this pump showed a little more pressure 11#. Yes I was smart enough to cut a trap door in the bed so I won't have to drop that 36 Gal tank again. My friend says why don't you just get another truck, well I can't afford another truck, I burn wood and use the truck in the woods, I am the 2nd owner had this truck 20yrs, it's been a good one, and frankly I am not going to let this beat me!!! G.S.

Outside temp was a 45deg when I started the truck. Alternator chg 14.3v coolant #215C open loop. Is this correct? INT-BLM numbers at 128. Oxy at 698, eng spd 625,MAP 2.65, IAC 145. Prom ID is 24F5. The coolant at operating temp was 61C. So the number went from 215 to 61? That looks backwards to me? I don't know yet how to put this chart up but I will give you the numbers and maybe you experts can put a chart to them. Engine hot; 1.18, 0, 2000rpm,61, 1.63, 143, 172, 800to100,140to56,14.1v, 83, learn control engaged, tcc unlocked,close loop. Here are the numbers with the alternator not charging; 1.12, 0, 2125rpm, 61, .76, 132, 147, 800to100, 100to20, 11,5v, 13, LCE, TCC UL, closed loop. I want to explain while the truck will run at 12volts or less it does not run perfect. It does not surge, will accelerate lite throttle or heavy throttle, but is a little rough at idle and the idle is up at 1500-1600rpms. The idle will drop back to 1000rpms in neutral in say 8 seconds. Its hard to look at this screen and drive too!! The oxy numbers are all over the place, they do not steady out with a steady throttle. So still trying to figure this program. GS.

[damanx]

Do you know how to make a log?

At the top of TunerPro, there are some buttons that look like regular buttons on a cassette player for example. Once TunerPro is connected to the ECM, you can then make a log. When you are ready to stop the log, press the stop button and a window will open up and you can select the name and where to save this file. It will be an xdl file.

You can name it whatever you want. Once you get that done, you can add it as an attachment here by selecting the "go advanced" option, then select the "manage attachments", then select the file and upload it.

As far as your problem with the alternator, I could not tell you what my opinion is about it, other than possibly a ground broken somewhere allowing regulator noise to affect the ECM, but this is merely a guess.

[rudder2fly]

Do you know how to make a log?

At the top of TunerPro, there are some buttons that look like regular buttons on a cassette player for example. Once TunerPro is connected to the ECM, you can then make a log. When you are ready to stop the log, press the stop button and a window will open up and you can select the name and where to save this file. It will be an xdl file.

You can name it whatever you want. Once you get that done, you can add it as an attachment here by selecting the "go advanced" option, then select the "manage attachments", then select the file and upload it.

As far as your problem with the alternator, I could not tell you what my opinion is about it, other than possibly a ground broken somewhere allowing regulator noise to affect the ECM, but this is merely a guess.

Well I hope the file is here! GS.

[damanx]

Does this log have you connecting and disconnecting the alternator while it's recording?

Just a quick run through that log, and something might be wrong with my tuner pro, but your spark advance looks like it's jumping all over the place on it's own.

Also noticed a MALF code 15 for Coolant Sensor Low.

[rudder2fly]

You can see where I disconnected the alternator it's less than 12v about half way thru the recording. Connected it's 14+ volts. I replaced the coolant sensor last nite it's a NAPA TS4052SB. My question is does the coolant sensor start a high number like 205C in open loop then drop down to 62C in closed loop? How did you read my file? All I see are all kinds of marks. Is this what is called HEX and how do I change this into letters and numbers?