Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner
1 - 18 of 18 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter · #1 ·
So I have a 2005 Trailblazer that recently started acting up. While riding at 30-40mph, the vehicle will surge. You can notice the RPMs going up and down. Had the throttle body cleaned and the vehicle put on an analyzer and no codes showed up of any kind. Vehicle has 60,000 miles on it.

This was not happening until recently. Only bulletin that the mechanic can find on this is that "It is a known issue with no resolution". I don't have the bulletinn number, but surely there has to be a solution to the problem. Gm is not Microsoft is it?

Anyone experience this problem and find a solution? I researched the forum but did not seem to find a solution to this issue. If I missed something, a link would be most helpful.

Thanks.
 

·
Banned
2004 gmc
Joined
·
26,181 Posts
You may need to drive around with the analyzer recording everything when the bug happens, looking for a sensor that starts varying for no reason. Have to catch it in the act , not just look at the computer in the shop. Probably not the accel pedal or throttle body, since those have two redundant sensors that always have to agree or it throws a code.

But maybe the MAP, ECT, or something else where there's only one of them.

Sounds like a subtle and potentially expensive bug to troubleshoot, I agree.
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #3 ·
So had the trailblazer on the highway tonight and it has no power. barely could get it to 60mph. Hauled out to pass someone and had to pull back in. foot to floor and nothing. Barely could maintain 60.

So this really sucks...do i have a major trans/engine problem...or some stupid sensor? Ideas would be appreciated as this is going to cost me big time in diagnostic.

btw the idea of analyzing while driving...shouldn't it contain the historical codes in memory/ Cause there are no codes showing what so ever.
 

·
Banned
2004 gmc
Joined
·
26,181 Posts
Sensors usually throw a code. Bad head gaskets and valves, for instance, usually don't.

Internet forum guessing can't POSSIBLY substitute for professional hands-on diagnostic work with the proper gauges and tools. I think you're beyond anyone's ability to help remotely.
 

·
Registered
2005 chevy trailblazer_ls_ext
Joined
·
2,667 Posts
I agree with Roadie and the others.

Unless you want to start throwing money at parts! In which case -
I guess I'd start with new spark plugs. Yes they are suppose to be good until 100,000 miles, but I changed mine around 50,000 miles and it made a huge difference. This gave me back most of my lost power. Here the plugs are about 6 or 7 bucks a piece - so it might cost you an hour of work and 50.00.
I really didn't have any surging, but very slow take off, and it took a lot of throttle going up hills or on ramps, and my MPG dropped some.

But if I were to take a guess (and this is ONLY a guess) your symptoms sound to me like it could be a cat. converter getting plugged (assuming your vehicle has one - I don't know what vehicles for other countries have in the way of emission equipment).

Also - what does your temperature gauge read? It should be right in the middle. If it's reading too low you can and usually will have a loss of power (ask me how I know) :)


That being said I still think you would be better off finding a good mechanic or dealership to diagnose your problem(s). It might really be cheaper in the long run.
Without any codes from the PCM at best we are taking a stab in the dark so to speak!
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #7 ·
Thanks for the advice and it is going back to the shop tomorrow.

Problem is that I have had "professional" advice and got the "it can't be fixed line".

I am beginning to suspect the cat.

I know it could be major engine stuff (fingers crossed) but I am hoping that with 60,000 miles, these engines last longer than that.
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #9 ·
So, anyone want to know what the problem was?
.
.
.
.
.
.
.
.
.
.
.
.
Anyone?
.
.
.
.
.
.
.
.
.
.
.
.
.
Are you sure?
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
You are going to have to read a lot of useless information to get to the bottom of this issue.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Cat melted.
 

·
Banned
2004 gmc
Joined
·
26,181 Posts
Ummmmm, melted cat may not be the cause, just an effect. Of misfiring, bad injector(s), plug, valves, etc. Make sure you know WHY the cat was damaged before rejoicing. (Sorry to be the voice of caution.)
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #15 ·
Ummmmm, melted cat may not be the cause, just an effect. Of misfiring, bad injector(s), plug, valves, etc. Make sure you know WHY the cat was damaged before rejoicing. (Sorry to be the voice of caution.)
Nope..appreciate that!

How about a cracked manifold? I had that repaired about 2 weeks ago and it was probably like it for three months. Would that cause this possibly?
 

·
Registered
2006 chevy trailblazer_ls
Joined
·
374 Posts
:iagree: Had a 95 Blazer (apparently notorious for overfueling problems) and burned through 2 cats before I found out that the CPI spider was leaking... sad because that model got the most horsepower of all the blazer models.
 

·
Registered
2005 chevy trailblazer_ls_ext
Joined
·
2,667 Posts
Ummmmm, melted cat may not be the cause, just an effect. Of misfiring, bad injector(s), plug, valves, etc. Make sure you know WHY the cat was damaged before rejoicing. (Sorry to be the voice of caution.)
I don't know - have we ruled out poor design? 60,000 miles seems awfully soon to be having bad injectors or valves. Granted could be a bad plug - but I would think the o/p would have noticed the miss - which most people here would say SHOULD have set a code.
 

·
Registered
2005 chevy trailblazer_lt_ext
Joined
·
1 Posts
surge / hesitate same

I've had this issue since I was at about 45,000. Mechanic told me he couldn't find a problem. At about 85,000 miles happening more often, again mechanic says no codes and in his test drive he couldn't get it to do it. Husband thought I was crazy too until it happened to him. Now at 98,000 I'm pulling my hair out. Headlights flicker dim/bright even stalled when I slowed for a construction zone, but immediately restarted in N while still rolling. Spent enough money on diagnoses...I love the car...but the issues drive me crazy...husband says it's my last new car. Guess I'll check cad. conv.....
:bonk:
 
1 - 18 of 18 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top