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2004 chevy trailblazer_lt_ext
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Discussion Starter #1
Hi!

I've got a problem with my 2004 Trailblazer and ended up having it towed to an auto shop I've never used before. I talked to the guy yesterday who said the problem solved like my catalytic converter. I told him I just replaced it last October (2009) and he told me I had two? Can anybody help me out and tell me how many catalytic converters are on 2004 Trailblazer (EXT) with a 4.2 liter L6 engine. I think the mechanic isn't being on the up & up with me.

Thanks in advance!
 

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2004 gmc
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There are two O2 sensors but only one cat. What problem caused you to get it towed? Did you have a SES light and what code was present?

Once a mechanic lies like that, all confidence flies out the window.
 

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2004 chevy trailblazer_lt_ext
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Discussion Starter #3
I was headed down the road after refueling. I stopped at a stop light and when I went to pull away from the light, I pushed on the gas, got a RPM rev but very little acceleration. I pulled off, turned off my engine and let it sit for 5-10 minutes. I was able to do a three-point turn to turn around, got on a side road and got up to 20 mph. Stopped at a stop sign and then got next to nothing (I think my speedometer actually read 0!) I pulled to the side of the road and called Triple A. No lights at all came on.

It's a high mileage vehicle (177,000 miles). I replaced the transmission about 18 months ago and it only has about 50-60K miles on it. The catalytic converter was replaced by my regular mechanic last fall and has been driving fine since. I'm kinda thinking I need to have it towed to the guy who I trust.

The mechanic where it was towed to said it's either the cat or the fuel pump. I talked to my regular mechanic this morning who said he inspected the fuel pump last fall (cause he thought that was the problem) but it was fine.


Thanks!
 

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2004 chevy trailblazer_lt
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The mechanic may be misinformed or just took a cursory look under the truck. I wouldn't write him off quite yet. (But the caution flags should be waving in your mind right now!)

It is insanely easy to find out if it's the fuel pump or not. It takes less time to perform the test than it takes to read this sentence. Literally. No, really.

You screw on a fuel pressure tester to the Schrader valve just in front of your fuel filter, turn the key to ON (but not start) and read the pressure. If it is about 50 to 60 psi, it's probably not the fuel pump. If it is below that, it probably is the fuel pump.

Fuel pumps wear out. They have bearings in them that wear and there is an especially high failure rate of fuel pumps right after getting a full tank of gas. Just because it was fine last fall doesn't mean it is fine now.

You can ask the mechanic how much he would charge for a fuel pressure test. (It takes literally five minutes. You can buy a fuel pressure tester at any auto parts store for $50 and do it yourself too.) Then get him to tell you what the pressure reading was. Then let us know.

If the fuel pump is good, it takes about 10 minutes to test the cat. They remove the front oxygen sensor and replace it with an exhaust backpressure gauge. They read the pressure at idle and again at 2500 RPM. (Pressure should be 0 psi at idle and no more than 4 or 5 psi at 2500 RPM.)

Those two tests will, #1 confirm or eliminate the fuel pump and the cat; and, #2 tell you right away if the mechanic is trustworthy.

The best thing, of course, is for you to take this information (don't tell the mechanic that you know it though) and stand over him while he does the pressure readings.

Good luck and let us know what happens.
 

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2002 gmc envoy_slt
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Unless there was something weird in that tank of gas, converters don't just suddenly fail like that and take time to gradually clog or melt. Only if the CEL was blinking or lead or something else in the fuel, would it suddently clog to the point of no power. If you were fine just before that fill up, there's something else at play here. When it gets that bad with no power at all, a bad converter should set a code for insufficient converter efficiency or something like that. (I forget the code number of hand, but it took a few weeks for mine to gradually clog up to that point).

Its also easy enough to tell, temporarily pull the pre-cat O2 sensor and take a very brief trip around the block.....does it run a whole lot better? (If so, the converter is shot, if not its something else....you can also just loosen the converter to manifold flange bolts to allow gas to escape and prevent CEL errors for the O2 sensor not functioning).
 

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2004 chevy trailblazer_lt_ext
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Discussion Starter #6
Just to let everyone know.... the vehicle ended up getting towed to the mechanic I trust and unfortunately, it seems I've killed 2 transmissions in it now :( (which unfortunately, is the first thing I thought when it started giving me problems last week.)

This transmission didn't lose a gear (when it was replaced in 2008 I lost 3rd gear). This has something to do with pressure. The tow truck driver told me he actually drove the vehicle onto and off of the flatbed. It's fine when the engine's cold.....but doesn't work at normal operating temperature.

Now, the question is..... rebuild the transmission (AGAIN!) or buy another vehicle?

Anybody got a EXT Trailblazer with low mileage they want to sell to me real cheap, by chance?

Thanks for all the advice!
 

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2002 gmc envoy_slt
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If the motor is sound, its cheaper to drop a built 4l60e in than to buy a new vehicle. Around here there are shops with 'built' units for around $500-$600 with core/trade, that's not installed obviously. The built units have a stronger sun-shell (which is usually breaks and you loose 3rd), Corvette servos and the like.....what I'll most likely do when the time comes and swap the unit at my brother's garage. (Unless he's up on rebuilding 4l60s, but being a Ford guy, I doubt it).
 
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