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2004 chevy trailblazer_lt
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Discussion Starter · #1 ·
Hello all, I have an '04 trailblazer with 4.2L. Within the past week it seems to run sluggish around 1500-2000 rpm, no power. If I give it more gas it'll down shift and power is back, seems normal at the higher rpms (almost like hitting the power band in a two stroke dirt bike). I have an aftermarket "Scan Guage" pluggedinto the obdII port all the time to monitor gas mileage, trans temp, coolant temp etc.... Seems like it's a bit on the hot side lately as well, 211-220 f where it was usually 206 f before with normal driving. The temp still shows 200-210 on the instrument cluster though; normal... I put new plugs in about a year ago, Bosch Platinum, fuel injector cleaner, installed a new radiator in January (the trans line into the radiator was leaking at the fitting on the radiator regardless of what I did. I wound up by-passing the radiator and using auxillary cooler for trans fluid only). The trailblazer ran fine after all this though and only started acting sluggish recently. If anyone has had similar issuess and found a fix I'd appreciate any advice.
 

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2004 gmc envoy_slt
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These engines like AC Delco Iridium 41-103 plugs.

Since have a Scan Gauge, check the performance of the O2 sensors. The upstream sensor should be fluctuating between low voltage (~100mv) to high voltage (~900mv), and the downstream sensor should remain fairly steady at about 750mv.

What is the mileage on the truck?
 

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2003 chevy trailblazer_ls
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Hello all, I have an '04 trailblazer with 4.2L. Within the past week it seems to run sluggish around 1500-2000 rpm, no power. If I give it more gas it'll down shift and power is back, seems normal at the higher rpms (almost like hitting the power band in a two stroke dirt bike). I have an aftermarket "Scan Guage" pluggedinto the obdII port all the time to monitor gas mileage, trans temp, coolant temp etc.... Seems like it's a bit on the hot side lately as well, 211-220 f where it was usually 206 f before with normal driving. The temp still shows 200-210 on the instrument cluster though; normal... I put new plugs in about a year ago, Bosch Platinum, fuel injector cleaner, installed a new radiator in January (the trans line into the radiator was leaking at the fitting on the radiator regardless of what I did. I wound up by-passing the radiator and using auxillary cooler for trans fluid only). The trailblazer ran fine after all this though and only started acting sluggish recently. If anyone has had similar issuess and found a fix I'd appreciate any advice.


If you replace the o-ring on the cooler line fitting and the line is not damaged it won't leak.
 

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2004 chevy trailblazer_lt
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Discussion Starter · #5 · (Edited)
"If you replace the o-ring on the cooler line fitting and the line is not damaged it won't leak."

Yeah, I thought the same thing. At the time I did verify that the oring was still on the fitting and the line appeared ok it continued to leak.....
I included that info in case it could somehow affect or cause my current problem which was loss of power.

If you have any suggestions for what might be causing that please share. I appreciate your input.
 

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2003 chevy trailblazer_ls
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"If you replace the o-ring on the cooler line fitting and the line is not damaged it won't leak."

Yeah, I thought the same thing. At the time I did verify that the oring was still on the fitting and the line appeared ok it continued to leak.....
I included that info in case it could somehow affect or cause my current problem which was loss of power.

If you have any suggestions for what might be causing that please share. I appreciate your input.
No sir, it would not effect the running.
 

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2008 gmc envoy_sle
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"If you replace the o-ring on the cooler line fitting and the line is not damaged it won't leak."

Yeah, I thought the same thing. At the time I did verify that the oring was still on the fitting and the line appeared ok it continued to leak.....
I included that info in case it could somehow affect or cause my current problem which was loss of power.

If you have any suggestions for what might be causing that please share. I appreciate your input.
hi,

no check engine lights on , is that correct? no codes.

lets start with obvious, throttle body. when was last time it was cleaned or looked at?

what about thermostat?

and as for plugs, take one out and look at its condition. Envoyboy2004 is correct these trucks seem to run better on acdelco iridium.
 

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2004 chevy trailblazer_lt
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Discussion Starter · #8 ·
Ok, it just stalled on me in traffic a bit ago. Threw a code P0606. I was stopped at a light and when I went to take off it stalled. Had to put it in park, take key out then back in to start back up. I had been driving it today and it would drive fine then occasionally have the low power issue ( sounded like extra chatter from under the hood when experiencing the low power, not loud but just extra noise). It seemed fine driving back home tonight. So this is definitely an intermittent problem.
 

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2008 gmc envoy_sle
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Also, I cleaned the throttle body, it wasn't really that dirty.
I see that there is a is TSB #3164A that covers the problem.

SERVICE ENGINE SOON LIGHT DUE A DIAGNOSTIC TROUBLE CODE P0606 DIAGNOSTIC TROUBLE CODE, OPERATE IN REDUCED ENGINE POWER MODE, AND POTENTIALLY STALL

hopefully someone can chime in and provide the tsb.
 

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Discussion Starter · #11 ·
Ok, this has something to do with my AC. When AC is on I experience the low power and hear the chatter. I'd say it's the compressor but I just put a new one on two years ago and have zero issues with it cooling. Could it be the clutch? Again, I can't believe it's be the compressor (used right amount of pag, right type, condenser, drier and orfice tube as well we're replaced as well) but if it is, what I want to believe is irrelevant I guess
 

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Discussion Starter · #12 · (Edited)
Ok, this has something to do with my AC. When AC is on I experience the low power and hear the chatter. I'd say it's the compressor but I just put a new one on two years ago and have zero issues with it cooling. Could it be the clutch? Again, I can't believe it's be the compressor (used right amount of pag, right type, condenser, drier and orfice tube as well we're replaced as well) but if it is, what I want to believe is irrelevant I guess
I did a test drive and the AC is Definitely part of the problem. I drove it quite a bit today w/AC off and had no issues at all. As soon as I turn the AC on it was like tossing an anchor with a chain out the window and the slapping sounding chatter from under the hood began. Is it possible for a compressor to still function but put more demand on the engine to the point where the symptoms described earlier in this post occur? Has anyone ever heard of this before? If I have to replace the compressor I'll do it but I'd like to rule out any other possibilities first if I can. Thanks for any feedback you can give.
 

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check the condition of the compressor pulley and bearings.

if the compressor pulley bearings are failing, it would be loud, and yes, it would still function.
 

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Discussion Starter · #14 ·
check the condition of the compressor pulley and bearings.

if the compressor pulley bearings are failing, it would be loud, and yes, it would still function.
Put a stethoscope on it yesterday and the noise is definitely coming from the compressor. With engine off and turning the compressor by hand you can hear it tick every revolution. Ordered new compressor, will see if that fixes it in a couple weeks.
 

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Discussion Starter · #15 ·
Installed the new compressor yesterday and it appears that was the issue. I had a hard time believing that a bad compressor would cause that kind of power drain or that the serpentine belt would bear that kind of load but everything is kosher now. I did have debris caught in the orfice tube screen but I didn't get any thing else while flushing the system.
 

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You will always have some debris at least some mushy stuff on the orifice tube.
The key is how much and how imbedded it gets. If you don't have a restriction showing on gauges then it's not plugged enough to matter.
Compressors are all junk and have been for well over 10 years now.
You are often better off getting a factory one from a junk yard than a reman or "new" one at parts store.
Even Napa, last time I checked, ones were still really just factory air/4 seasons,everco/murray....whatever they call themselves now.
I remember going through so many R4 ones on Blazers and conversion vans.
Some would hum and slightly vibrate as soon as you installed and spun them.
AC on paper is such a simple system but in reality it is a pain in the rear.
Just had two town cars this month that were fine but then got high side restriction. One kicking off on safety pressure switch at over 350-375 the other just high at almost 300. The first would almost stall engine when it kicked on.
 

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Oh, BTW

BTW, don't mind the 1st post thing. Hello all!!!
Long time lurker.
I have a thing about joining the most official forum I can find when I buy that type of vehicle.
Hovercrafts, limos, fire trucks, sport bikes, Town Cars, and now add Trailblazer to the mix. Just got one for my wife a couple weeks ago. Replacing a 2000 Expedition with 5.4. We used to have almost matching 87 2 door Blazer with 2.8 and 89 2 door Jimmy with 4.3 and digital dash. No real probs with either of those for the few years we had them.
Anyway, I work on a lot a cars for people and there are a slew of TB and Envoys around here but I have only had 2-3 ever come to me that I can remember. AC issues I think.
So all this reduced engine power and TPS drilling rivets to replace vs whole throttle body is now to me.
I have always heard the 4.2 inline was a good engine and they all raved about its power when it cam out. I'm not really impressed. It might be great at half to full throttle. I wouldn't know. I'm an old guy in a Lincoln who typically impedes most people. The 4.2 doesn't seem to have to torque I would like once it is in 3rd or overdrive and you hit a slight incline etc.
Kind of like my zx-12r vs zx-11. You could short shift the 11 and be in high gear at 40 mph and just roll the throttle and fine and smooth. The 12 had to be down shifted at least 2 gears id not 3 all the time or it would bog and buck.
I do enjoy driving the Trailblazer though. It is easy to go fast in and feels firm in its stance. I have a 98 Durango with 5.5 susp lift and 6 body lift with 38 inch tires and it is really close to same interior size but a lot easier to get into.
The Durango has the wimpy 5.2 318 and I have no idea about gearing I assume factory but it has plenty of go and smooth torque on slight hills. Up Country I think is lift. Absolutely smoothest riding lifted truck I have ever been in. I went from a 91or 92 Ram Charger with 6 inch Superlift susp and 35 inch tires and it was typical rough truck ride. I drove the Durango from Texas to Ohio like a sedan.
BTW, also....I talk (type) a lot.

Great FORUM!!!
 

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2008 gmc envoy_sle
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Installed the new compressor yesterday and it appears that was the issue. I had a hard time believing that a bad compressor would cause that kind of power drain or that the serpentine belt would bear that kind of load but everything is kosher now. I did have debris caught in the orfice tube screen but I didn't get any thing else while flushing the system.
glad you figured it out and its all good now.

approx how much was the compressor and what brand is it?

might help others who have same issue.
 

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Catalytic converter

Good evening Folks,

I haven`t been on here for a while and just now interestingly found this thread!

Fact is, I also own a 2004 Trailblazer LTZ with the traditional 4.2L engine and have experienced a similar loss of power- issue in my vehicle just about two weeks ago! There are only about 119,000 km on the vehicle which equals about 74,000 miles. I am driving my Trailblazer close to Frankfurt, Germany in the city, rural roads and autobahns. The car is in excellent condition and gets serviced on a regular Basis.

As I was wanting to pass someone else on the Highway lately, it became evident that the pick-up upon pressing the gas pedal wasn`t what it used to be. I could pass, however the rpm´s went up to 4,500 and stayed at about 4,000 revolutions at 140 km/h (86 mph). The automatic shifted down way too late compared to previously as I went off the gaspedal a little. Checked the max. Speed and it was only a littel bit higher - 150 km/h (93 mph). Normal Vmax is over 120 mph (this is Happening once in a full year...no worries!)
ABSOLUTELY NO CODES!! (MDI, formerly the "TECH2").

Summing it up, the power loss is most evident at higher speeds but I did notice the pick -up is also somewhat worse also at City Speeds, especially going uphill. Iridium plugs (AC-DElCO) were put in at only 7000 km less, as was an air filter, a K&N. Since there is no massflow sensor (MAF) in this 4.2, this part is not part of the discussion (eg. contamination by the K&N filter oil)!

Nevertheless, for now we replaced the K&N for a normal AC air filter. Several knowledgable mechanics suggested it is most likely a plugged catalytic converter with the inside beeing melted - in this case, you will not here any noises while banging against the converter. There will be a silent but massive outflow obstruction, so that the exhaust fumes will not be able to be set free.

So, the most obvious things will be checked next week, this is the throttle Body - however, a clogged converter ist ranking number one currently, as this will not set any codes!
Worst case is the engine dies or runs iradically at idle or a red light. Mine runs fine at low rpms, but again, there appears to be a mild loss of power upon acceleration here as well!
Most other conditions will set a code (e.g. "lean" mixture), that would include an inadequate fuel pressure as well, I would experience more "symptoms".

Once I know more, I will let you know! "Backpressure testing" through the O2sensor hole is not widely done over here and the Manometer kit with the Adapter kit for the o2 sensor thread are not available in Europe,unfortunately.
They might do Endoscopy (look inside the catalyst), but that appears impossilbe as the converter is past a 30-40 cm Long pipe.

Any Input or further ideas on how to efficiently check the converter for obstruction and more generally on behalf of our power loss issues are very welcome!

Cheers,
Klaus :tiphat
 
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