!!i need help!! [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: !!i need help!!


PITBULL
09-03-2011, 05:21 PM
My 2002 trailblazer was working just fine a couple weeks ago besides my bad bcm issues but recently it starting acting up the thing is if it sits for a few hrs like over night or a work day when i start it it seems fine put it in gear start to accelerate and it starts bogging down unless i floor it but when let foot off gas it bogs down again and sometimes dies but if shut off and restart it runs fine. just replaced fuel pump assembly and feul filter ystrdy and didnt help. not air filter either checked that 2. anyone know what the prob could be?:hissy:

Ralph_T
09-03-2011, 09:34 PM
My 2002 trailblazer was working just fine a couple weeks ago besides my bad bcm issues but recently it starting acting up the thing is if it sits for a few hrs like over night or a work day when i start it it seems fine put it in gear start to accelerate and it starts bogging down unless i floor it but when let foot off gas it bogs down again and sometimes dies but if shut off and restart it runs fine. just replaced fuel pump assembly and feul filter ystrdy and didnt help. not air filter either checked that 2. anyone know what the prob could be?:hissy:

Any check engine light codes?

PITBULL
09-03-2011, 09:52 PM
Any check engine light codes?

No check engine lights on dash but that could be due to the bad bcm i think i have, not sure about codes havent had it scanned.

Ralph_T
09-03-2011, 09:59 PM
No check engine lights on dash but that could be due to the bad bcm i think i have, not sure about codes havent had it scanned.

Why do you think you have a BCM issue? It would be helpfull to have some background on this issues you have been having. The more info the better.

PITBULL
09-03-2011, 10:10 PM
Why do you think you have a BCM issue? It would be helpfull to have some background on this issues you have been having. The more info the better.

well i bought the truck last winter a few weeks later it wouldnt start in the morning then it wouldnt start after work dead battery read something online bout a short in starter replaced that still went dead then got new battery at end of winter so it got warm havnt had dead battery issue since then volt meter started wigglin around while driving, and when i pass someone at night i notice my headlights flickering like crazy and when start to slow down or step on brakes lights go dim for a second. people have told me thats a sign of bad bcm. theres a bunch of little black boxes on the side of bcm case next to the barcode and mine says red whats that mean? if i buy a used bcm and dont care bout mileage and stuff do i have to reprogram it at the dealer?

PITBULL
09-03-2011, 11:30 PM
Why do you think you have a BCM issue? It would be helpfull to have some background on this issues you have been having. The more info the better.

as far as the new issue im having with it bogging out its never donr this before. so when i wake up to go to work it starts up just fine then starts to idle alittle lower than usuall then when put in gear and lightly accelertrate it starts to bog out and wont shift if i put the pedal to the floor it will come alive and go like a bat outa hell but as soon as i let go of gas it goes back to boggin out and if i step on brakes or slow down it will die sometimes or when put in park it will idle real ruff but if i shut it off and simply restart it it runs just fine when it runs funny like that it does smell like a bad catylitic converter but to me that dont make sence cuz i can just restart it and its fine if its the cat you would think it would do that all the time not just at first then restart and be fine.:bonk:

christo829
09-03-2011, 11:59 PM
How many miles on your truck? I didn't see that mentioned.

Whoever has been telling you it's the BCM is not very familiar with this platform. What
you described as the vehicles previous behavior is typical of either a parasitic drain or
a failing battery. These trucks are really picky about their voltage level. You didn't say
how old the previous battery was. Anything over 4 years can be suspect. Even then, a
new battery can fail, or be poorly connected.

Bad grounds or a flaky ignition switch can also cause erratic behavior.

In any case, once you replaced the battery, you reset the PCM. Your subsequent description
of the vehicle's behavior is typical of a dirty throttle body. There is a very
good write up here on Trailvoy for doing a proper clean up job. $5 and half an hour
can rule that out.

Depending on your mileage, plugs and O2 sensor could be tired as well. If you or the previous
owner didn't keep up on oil change intervals, your camshaft position actuator solenoid could be
clogged and not responding properly. That screws up timing,

So, if we can get some more detail about mileage, maintenance, behavior with AC on
or AC off, at idle in park, at idle in gear, what your rpms are at idle, etc, we might be able
to narrow down the cause (or causes).

Good Luck!

Chris

Ralph_T
09-04-2011, 12:00 AM
well i bought the truck last winter a few weeks later it wouldnt start in the morning then it wouldnt start after work dead battery read something online bout a short in starter replaced that still went dead then got new battery at end of winter so it got warm havnt had dead battery issue since then volt meter started wigglin around while driving, and when i pass someone at night i notice my headlights flickering like crazy and when start to slow down or step on brakes lights go dim for a second. people have told me thats a sign of bad bcm. theres a bunch of little black boxes on the side of bcm case next to the barcode and mine says red whats that mean? if i buy a used bcm and dont care bout mileage and stuff do i have to reprogram it at the dealer?

Are you still running on the original alternator becasue it sounds like it's not charging correctly? Low voltage will cause all sorts of mayhem with the electronics.

Ralph_T
09-04-2011, 12:01 AM
as far as the new issue im having with it bogging out its never donr this before. so when i wake up to go to work it starts up just fine then starts to idle alittle lower than usuall then when put in gear and lightly accelertrate it starts to bog out and wont shift if i put the pedal to the floor it will come alive and go like a bat outa hell but as soon as i let go of gas it goes back to boggin out and if i step on brakes or slow down it will die sometimes or when put in park it will idle real ruff but if i shut it off and simply restart it it runs just fine when it runs funny like that it does smell like a bad catylitic converter but to me that dont make sence cuz i can just restart it and its fine if its the cat you would think it would do that all the time not just at first then restart and be fine.:bonk:

Sounds like a bad O2 sensor.

Ralph_T
09-04-2011, 12:05 AM
How many miles on your truck? I didn't see that mentioned.

Chris

Very good points Chris. We need to be mindfull of newbs jumping on here asking jump>to>this conclusion type questions. We need to remind ourselves that we need a full workup on the vehicles prior to providing advice. You questions were very good. And I am afraid many of the newbs who post here think we have all the answers. We might, but only if we know the previous maintenance and miles and condition of engine/body, etc.

Good stuff.

barniejekyl
09-04-2011, 12:17 AM
Has the throttle body ever been cleaned ?

PITBULL
09-04-2011, 12:24 AM
Very good points Chris. We need to be mindfull of newbs jumping on here asking jump>to>this conclusion type questions. We need to remind ourselves that we need a full workup on the vehicles prior to providing advice. You questions were very good. And I am afraid many of the newbs who post here think we have all the answers. We might, but only if we know the previous maintenance and miles and condition of engine/body, etc.

Good stuff.

My truck has 126,000 miles, the body is in great shape. the battery that was replaced was a little over a year old, i have the original alternator, new battery, new starter, new fuel filter, and new feul pump assmbly. as far as the way it was takin care of before me idk i got it from a dealership that i now dislike very much we shall not name names! i put a aftermarket stereo in it but it doesnt matter wether i disconnect it or not same electrical probs either way. i saw a thread earlier today that i now am going to clean throttle body idk if its ever been cleaned before. i cant tell you what it runs like with air on cuz my blower motor crapped on me a month ago. but when idling funny it runs at bout 5 to 600 rpm.

PITBULL
09-04-2011, 12:35 AM
the only other thing i could say is that a couple days before it started running funny i had accidently left my key turned on to the on position for bout 5 hrs while i was at work truck still started no dead battery and no probs till a couple days later if that helps at all.:weird:

Ralph_T
09-04-2011, 12:43 AM
My truck has 126,000 miles, the body is in great shape. the battery that was replaced was a little over a year old, i have the original alternator, new battery, new starter, new fuel filter, and new feul pump assmbly. as far as the way it was takin care of before me idk i got it from a dealership that i now dislike very much we shall not name names! i put a aftermarket stereo in it but it doesnt matter wether i disconnect it or not same electrical probs either way. i saw a thread earlier today that i now am going to clean throttle body idk if its ever been cleaned before. i cant tell you what it runs like with air on cuz my blower motor crapped on me a month ago. but when idling funny it runs at bout 5 to 600 rpm.

Have you had the charging system tested properly? This includes the alternator output function. That's really the only thing I can think of that you have left to check. the aftermarket stereo wiring would be my primary concern however. This is a big gottcha.

PITBULL
09-04-2011, 12:55 AM
Have you had the charging system tested properly? This includes the alternator output function. That's really the only thing I can think of that you have left to check. the aftermarket stereo wiring would be my primary concern however. This is a big gottcha.

no i havent had it tested. the aftermarket deck is wired w a scoche adapter that i was told was for my truck with the little black box for adjustible door ding. what exactly is a big gottcha the charging system or stereo wiring?

PITBULL
09-04-2011, 12:58 AM
i put the stereo in this spring after the drained battery issuse during winter

Ralph_T
09-04-2011, 12:59 AM
no i havent had it tested.

You have your answer. We really can't proceed with troubleshooting unless we know the health of your electrical/charging system. Please let us know how it goes.

PITBULL
09-04-2011, 10:58 AM
You have your answer. We really can't proceed with troubleshooting unless we know the health of your electrical/charging system. Please let us know how it goes.

thanks i will get that tested and try some of the other things suggested also and let you know how its going as i go along. Dont get me wrong i may be a newb to this site but im no stranger when it comes to vehicals i have a 1981 monte carlo i built from ground up. (hands on every nut and bolt) and it runs like a top. but when it comes to all these computers and things in new cars it gets frustrating. my first question was just to get this very helpfull convo started again thankyou this has helped alot now i have an idea where to start so we can get this figured out and i can go back to enjoying my truck and most of all have a happy wife again lol.:laugh:

petevw
09-04-2011, 12:52 PM
Part of the poor idle problems may be from when you changed the battery.

You have a lot of miles on that TB, and you have no idea if or when the throttle body was cleaned. In general, they should be done every year or so, or if you put a lot of miles on it.

In your case, when you replaced the battery, the PCM probably went back to it's factory default setting (the computer thought the throttle body was new & clean). Since it was (and still is) probably pretty dirty, that may be the cause for your poor idle, etc.

Disconnect the battery, remove the throttle body from the engine, and clean with throttle body cleaner and an old toothbrush. Re-install and reconnect battery.(make sure battery was disconnected for at least 35-40 minutes).

This may solve some of the drivability issues.

PITBULL
09-04-2011, 01:09 PM
[QUOTE=petevw;1123023]Part of the poor idle problems may be from when you changed the battery.

you make a good point except i changed the battery months ago and this prob started last week. Im going to get a new air filter and clean throttle body later today to hopefully fix the prob but if not at least rule it out. i may even be able to get my electrical system checked today like suggested earlier

blackcoog
09-04-2011, 01:28 PM
i cant tell you what it runs like with air on cuz my blower motor crapped on me a month ago..


I know this isn't going to help the issue at hand, but I thought I'd throw you a pointer. I thought my blower motor had crapped out too... turns out the blower motor RESISTOR and the harness to it had turned into a pile of molten goo.

Also, after I had that goo-ball (yes, that's a technical term) under the dash, the short from it was plenty to make a lovely smell of burning plastic and a dead battery....
Check that, it's most likely going to be the cause of one of your problems (the "dead" blower motor) :thumbsup:

http://forums.trailvoy.com/showthread.php?t=32751 (How-To)

PITBULL
09-04-2011, 01:34 PM
Check that, it's most likely going to be the cause of one of your problems (the "dead" blower motor) :thumbsup:


sounds good il check that today also. is it an easy fix? where do i look to see if thats the case?

blackcoog
09-04-2011, 01:36 PM
Check that, it's most likely going to be the cause of one of your problems (the "dead" blower motor) :thumbsup:


sounds good il check that today also. is it an easy fix? where do i look to see if thats the case?

http://forums.trailvoy.com/showthread.php?t=32751 :D

It's under the dash on the passenger side. Took me approx. 15 minutes, and I had to splice in a new pigtail, too.

PITBULL
09-05-2011, 10:15 AM
Sounds like a bad O2 sensor.

ok so i cleaned the throttle body ystrdy by following instructions to the tee off of a thread here on trailvoy.( thankyou ) it still didnt fix the problem seems to have gotten alitlle better but still boggs out now i want to try the 02 sensor but when i asked the parts guy the prices on it he asked if i needed the upstream or downstream one if i do have a bad 02 wich one would you think it is? didnt have enough time to check electrical ystrdy because some drunk dumped his bike and ran from the cops into the woods behind my dads house.

christo829
09-05-2011, 11:12 AM
ok so i cleaned the throttle body ystrdy by following instructions to the tee off of a thread here on trailvoy.( thankyou ) it still didnt fix the problem seems to have gotten alitlle better but still boggs out now i want to try the 02 sensor but when i asked the parts guy the prices on it he asked if i needed the upstream or downstream one if i do have a bad 02 wich one would you think it is? didnt have enough time to check electrical ystrdy because some drunk dumped his bike and ran from the cops into the woods behind my dads house.

Sounds like some excitement you could have done without! Hopefully they caught the
guy.

You'll want the upstream sensor. The downstream one acts mainly as a check against
catalytic converter performance. Upstream gets the most material thrown at it, and tends to
break down faster.

Cheers-

Chris

PITBULL
09-05-2011, 11:19 AM
Sounds like some excitement you could have done without! Hopefully they caught the
guy.

You'll want the upstream sensor. The downstream one acts mainly as a check against
catalytic converter performance. Upstream gets the most material thrown at it, and tends to
break down faster.

Cheers-

Chris

thanks Chris il grab that one and see if it solves the issue. Oh they caught him alright the dog just followed his trail of clothes he left! nothin like a naked drunk in back a squad car huh:woohoo: