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2005 chevy trailblazer_ls
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Discussion Starter · #1 ·
So, my 05 TB has just seemed constrained. I remember when I got the truck it was a rocket and sounded fantastic, now it gets up and moves but it sure does not feel as quick as it did. Heck, before the truck felt within a couple HP of breaking the tires loose, now it sometimes does (with part throttle) but full throttle not so much, not exactly a loss of power at full throttle, but there isnt anything more after about 1/3 throttle. Oh, and the wonderfull intake roar of before, isnt so wonderfull. I dont know how to describe it, insted of the war cry, its now more of a gereatric moan.

So I replaced the spark plugs (AC Delco), no difference. Air filter is recently new and looks great. The fuel filter is not servicable. And I just cleaned the TB.

Also.
Rough idle, not horrible but you can feel the engine running
Surging on accleleration. If you can it in first the truck acclerates at different ammounts as it revs out, untill 5k (not 4k like it used to be) then it jumps ahead a little faster.
If pushing hard the truck stinks. I occasionaly notice it when driving, but running at around 30mph in first for about 3 min or so, when you stop the truck there is a definate sulfer smell.

The truck is at the dealer, f-ing AGAIN, pardon the rant!
Sound like a bad O2? Milage is decent, 21 Highway, down from 23, and I have seen 25, mixed is mid 15's, down from high 16's.
Or might it be a clogged cat? Sounds like a maybe, but with 55k?
Oh, and the truck does not overheat, exactly, but it is the first truck where the temp guage will DROP if the RPM's are pushed higher. Run in OD ~2kRPM and 210 on the guage, kick it down a gear and run ~2500RPM and it runs under 200.

I know the dealer is going to say alternator (getting its 4th, 1st lasted 50k, 2nd 5k, and the 3rd about 10 minutes) because thats what it is in for now. But I feel I have to force feed my dealer step by step repairs to get anything done.

Should I force them to check the cat? Can they check the O2 if it isnt throwing a code?

Thanks!
 

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'But I feel I have to force feed my dealer step by step repairs to get anything done.'

If you feel this way, you need a different shop to work on your truck. Find a good independant shop you can trust near you, and take all of your service work there. Every bit of work. Develop a relationship with them, and they will treat you right.

Back to your present issue; are there any codes in the computer?

-- Dan Meyer :coffee
 

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2002 chevy trailblazer_lt_ext
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WOW! 4 alternators in 55,000 miles?!? I think you've got an electrical problem that could be related to your poor performance issues. If the PCM isn't getting good power, then it can't manage the engine properly. This would also mess with the 5VDC reference voltage that almost every sensor on the engine uses to report values back to the PCM.

I would like to think the dealer would notice that 4 alternators in 55,000 miles is quite excessive and would start to look at why they keep failing...

Just my :m2:.
 

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Discussion Starter · #8 ·
Thanks for the replies.

As for dealers, this is the one I bought it at and one of the better service centers. The one closer to me gave me a worse feeling about having my truck worked on.

The first alternator "failed" at around 50k, nothing terribly supprising. The second had phase go out and wouldnt charge above 2500, and then failed completely. I'm convinced the third was bad out of the box. The fourth just went in today so time will tell.

So, as a matter of fact I just got back from the dealer. They fixed the alternator and said they didnt notice any driveability concerns, and couldnt get it to stink. Of course, they only hooked it up to the computer and the computer said everything was fine (George, no CEL). So I took the tech for a drive, ran it hard up a couple hills (still surging on accel), kept the RPM's up and drove it into the lot. Then I reved it out and got out of the truck, HORRIBLE sulpher stink, tech then promptly said that that was normal because I was running it hard :eek: . SO after a discussion that turned into a mild argument, that I feel bad about and appoligized profusely for, they agreed to keep the truck and look into it some more. My biggest complaint was the tech was convinced that if the scanner didnt say there was a problem then there wasnt, and that if the O2 was bad it would certainly throw a code.

I suppose it could be an electrical issue, and that has burned up the alternators. Any ideas on areas to look?
 

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I'm still leaning toward an electrical problem. This would cause the computer to improperly control fuel delivery, causing your engine to run rich. (sulfur smell) Possibly a bad ground somewhere in the electrical system? Internally bad battery? Corroded battery terminals?

However, it could also be clogged injectors. I could also be a partially clogged cat as previously suggested. The dealer can run an efficiency test on the exhaust that will rule out the cat.

Keep us posted...
 

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Discussion Starter · #10 ·
Dealer called, said the truck is done, couldnt find anything wrong (big supprise, they never find anything wrong).

When I took the tech for a drive he hooked up the scanner and said that everything was looking good as far as fuel delivery. Today they looked at the truck and did a cat test, said that at 3000 RPM the cat had a very low PSI, less than 1PSI IIRC, so its not bad. Although, they rounded the O2 sensor off trying to remove it so they put in a new one.

I was reading up last night and found that a sulphur smell is not uncommon, especially if you use cheap gas (we do) and dont run it hard that often (I run it hard, the wife does not, she does 90% of the drive with it) so maybe the condition is normal.

I'll take it for a ride tomorrow after I get it back, but I expect to have the same problems. The truck is going to a different dealer after this though.

Any other ideas?
To reiterate
Low power
Good throttle response at low throttle input, not so good at high throttle input
Bucking when going downhill with Cruise on (and No, its not normal, I had the "normal problem and this is the same thing only 10x as violent)
Oh, occasional low idle when starting
and sometimes an almost stall when taking off, almost always happens if I just reversed, say like heading out of the driveway.

Cam position sensor, maybe?
 

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Discussion Starter · #11 · (Edited)
Oh, and to answer your questions.

Battery is OEM, but I used the 1yr old same group battery from my Sonoma to test if it was the battery, problem still exists. When the dealer replaced the last alternator they said the battery was bad, said it wouldnt take a charge and wouldnt not even fire up the load tester, wanted $200 to replace the battery. I said that the battery had taken a charge the night before, it had started the truck at least 6 times without the alternator working, ran the truck for more than 30 minutes without the alternator working, and still started the truck like normal, it certainly should at least show up on the load tester. They said they would test the battery again, never heard anything else about it. BUT, knowing that they would mention the battery again I switched it with my truck battery and had it tested, it works fine and showed 20CCA OVER the rating when tested.

Cleaned the cables

Cleaned the ground to frame, but not yet the ground to motor, thats next.

Are the symptoms somewhat falling into a ground issue? I have NO problem putting a new battery in and replacing the cables. I do dislike how the ground is exposed right next to the front drives side wheel and my cable was green with corrosion, but since its exposed it will look like that within weeks of instilation.
 

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2004 gmc envoy_sle
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Same Ole Sh**

And I just cleaned the TB.

You said it all when you cleaned the Throttle Body....The TB is electronically controlled....electric motor instead of a throttle cable as in the older vehicles.
The electric motor is very sensitive to "changes".... If you didn't follow the normal procedure that GM recommends that is your problem....GM says to disconnect the Battery, unplug the el. motor before removing the TB....once removed you have to be very carefull not to get the "el motor" out of "place" or sync or the TB will have to "re-learn" the position etc...etc....
This was in a technical service bulletin at the local GM shop....I had the SAME problem several yers back when I tried to clean the TB....I asked a friend who works at the shop mentioned above and he looked it up for me. I simply put up with the poor idle, surging and all things you are having... for about 100 miles give or take...then once it "re-learned" It was fine.
I would just drive it awhile before I did anything major. It sounds just like the problem I had.
GOOD LUCK
 

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Discussion Starter · #13 ·
And I just cleaned the TB.

You said it all when you cleaned the Throttle Body....The TB is electronically controlled....electric motor instead of a throttle cable as in the older vehicles.
The electric motor is very sensitive to "changes".... If you didn't follow the normal procedure that GM recommends that is your problem....GM says to disconnect the Battery, unplug the el. motor before removing the TB....once removed you have to be very carefull not to get the "el motor" out of "place" or sync or the TB will have to "re-learn" the position etc...etc....
This was in a technical service bulletin at the local GM shop....I had the SAME problem several yers back when I tried to clean the TB....I asked a friend who works at the shop mentioned above and he looked it up for me. I simply put up with the poor idle, surging and all things you are having... for about 100 miles give or take...then once it "re-learned" It was fine.
I would just drive it awhile before I did anything major. It sounds just like the problem I had.
GOOD LUCK
Sorry, I may have mislead you there.

All these symptoms have been going on for quite a while, in an affort to solve the problem I cleaned the TB. The clean TB has about 30 miles on it, the truck has been doing this for at least that last 5000. After cleaning the TB there was no change in how the truck ran.

Thanks for the input, thats good information to know.
 

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...Are the symptoms somewhat falling into a ground issue? I have NO problem putting a new battery in and replacing the cables. I do dislike how the ground is exposed right next to the front drives side wheel and my cable was green with corrosion, but since its exposed it will look like that within weeks of instilation.
Have the battery load tested at AutoZone (they do this for free) and shake the battery around while the test is in progress. This should rule out an intermittent bad cell.

After you clean the grounds, (and any other battery connection) coat the surface of the clean wire terminal, bolt/screw, and mounting surface with dielectric grease. This will prevent corrosion.
 

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Discussion Starter · #15 · (Edited)
Got the truck back from the dealer this morning, and as you can guess, the problem still exists. Another "We didnt notice anything wrong". I'm done with this dealer. Looking at the service centers close by and it seems there are four, the one very close to me that I dont trust that much, but that is based on one visit, the dealer I go to, one a fair distance away (40+ minutes) and a Saturn garage. Anybody think the Saturn garage is a really bad idea? They seem like my best bet right now.

Thanks for the tip on shaking the battery, thats a good tip. However, both my OEM battery and the battery out of my truck are showing the same symptoms, its possible that both are bad in exactly the same way but I think that is unlikely.

Hopefully cleaning the cables will solve the problem, and thanks for the tip on the dielectric grease.
 

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Thanks for the tip on shaking the battery, thats a good tip.
No problem.

However, both my OEM battery and the battery out of my truck are showing the same symptoms, its possible that both are bad in exactly the same way but I think that is unlikely.
I agree- highly unlikely.

Hopefully cleaning the cables will solve the problem, and thanks for the tip on the dielectric grease.
No problem.
 
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