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2004 chevy trailblazer_ls_ext
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Discussion Starter #1 (Edited)
Good evening all.
This is my first time posting; I have been able to find solutions to my problems and answers to my questions simply by utilizing the search function.

Up until Now.

Tonight, on the highway at approximately 60 MPH, I temporarily lost all power. It was akin to a clutch with severe slippage; eventually the engine caught up with the RPMS.

It sputtered, shuddered, and abruptly died at the red light at the tip of the off ramp. It did fire right back up, but again, it acted like it was self destructing.

The SES light came on, and I used my code reader to see what codes were being thrown.

I read the following codes: PO134, PO130, PO134 again (a previous time), and PO171.

I had read the codes a few days earlier "just for the hell of it" and there were no stored codes and zero incompletes. (I had purchased the truck less than a month ago with 143K miles on it and was curious).

Some Google research revealed that it COULD be the Secondary Air Injection Check Valve malfunctioning. I was about to buy a replacement part and decided to visually verify the part I was ordering looked the same as the part already on the truck.

To my surprise I found the part was not there at all, rather there is a milled block/plug bolted on where the part should have been...

This appears "factory-like",. that is to say it looks to be professional, almost like it came from the factory.

Can this be correct?

JUST figured out this is a California car - does that matter???

Any assistance/guidance/wisdom you can provide would greatly appreciated.
 

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2006 gmc envoy_slt
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31 Posts
look at the frame rail under the drivers side, is there a pump there ?


could be possible that some one had "deleted" the SAIS on it...

also, have you cleaned your Throttle body ?
 

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2004 chevy trailblazer_ls
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17 Posts
Mine is actually the exact same way, and I'm getting the secondary error code on one I just bought. Looked at it to start testing things and mine has the same milled block. Somebody has to know what's going on here? Seems like it cant be a home done fix job, especially if its going to trigger a check engine light.

So thoughts? Is this part not present on an 04 TB?
 

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2005 trailblazer_lt
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112 Posts
IIRC the secondary Air Pump system wasn't installed on all GM360 trucks. IIRC it might have been just been used on the 04 & 05's. My 04 had it and my 05 has it. I've pulled that block off plate from a couple of junkyard GM360s for my own use in the future. The Secondary Air system is kinda' prone to failure and many times people will just remove the bad part and install the block off. A replacement pump is about $45 & a replacement AIR solenoid is around $90,... but the block off only costs a few bucks.

To "fix" it completely you've got 2 options: Pay to have the code check removed from the PCM ,... or pay for replacement Secondary AIR parts when they fail. ( MOST of us are 'cheap' and will just drive it till it HAS to be "fixed" ! )


:cool:
 

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2004 chevy trailblazer_ls
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IIRC the secondary Air Pump system wasn't installed on all GM360 trucks. IIRC it might have been just been used on the 04 & 05's. My 04 had it and my 05 has it. I've pulled that block off plate from a couple of junkyard GM360s for my own use in the future. The Secondary Air system is kinda' prone to failure and many times people will just remove the bad part and install the block off. A replacement pump is about $45 & a replacement AIR solenoid is around $90,... but the block off only costs a few bucks.

To "fix" it completely you've got 2 options: Pay to have the code check removed from the PCM ,... or pay for replacement Secondary AIR parts when they fail. ( MOST of us are 'cheap' and will just drive it till it HAS to be "fixed" ! )


:cool:
Well I have the unfortunate luxury of living in Portland and we have to pass emissions to register our vehicle. This means a check engine light keeps me from being able to register and drive my car. This means I'm at he point where it does indeed HAVE to be fixed.

My vehicle is an 04 TB LS. If my PCM has the check for a SAIS it seems like it would have had the actual system originally installed otherwise why have the code.

So what do I do now? Do I have to reinstall an entire SAIS in to my vehicle? Im not sure what you mean by removing the code check, can I have someone program the PCM to not look at the SAIS? I've never heard of that have no idea where I'd go for that or how much that would cost.
 

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2005 trailblazer_lt
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112 Posts
Installing the block off was something the PO did to be able to use the truck, not caring about the inspection because they probably had some time left on the 'last' inspection sticker. If your getting a check engine light your truck OBVIOUSLY should have the Secondary Air installed. If the parts are not there - than OBVIOUSLY someone removed them. Rather than fixing it properly ( spending $80 on a solenoid ) they cheaped-out & slapped a block-off on it ( $5). They sold it knowing this & yes,... now that you own the truck, it's your problem.

Yes; To pass the state inspection you will either have to re-install the parts that the PO removed,..... or have your PCM re-programmed not to perform the SAI check.

Took me about 2 seconds to SEARCH these for forums to find info on PCM programming. search = "Keyword(s): pcm, programming"

https://forums.trailvoy.com/showthread.php?t=108785&highlight=pcm+programming

A little effort goes a long way.


:cool:
 

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2004 chevy trailblazer_ls
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Installing the block off was something the PO did to be able to use the truck, not caring about the inspection because they probably had some time left on the 'last' inspection sticker. If your getting a check engine light your truck OBVIOUSLY should have the Secondary Air installed. If the parts are not there - than OBVIOUSLY someone removed them. Rather than fixing it properly ( spending $80 on a solenoid ) they cheaped-out & slapped a block-off on it ( $5). They sold it knowing this & yes,... now that you own the truck, it's your problem.

Yes; To pass the state inspection you will either have to re-install the parts that the PO removed,..... or have your PCM re-programmed not to perform the SAI check.

Took me about 2 seconds to SEARCH these for forums to find info on PCM programming. search = "Keyword(s): pcm, programming"

https://forums.trailvoy.com/showthread.php?t=108785&highlight=pcm+programming

A little effort goes a long way.


:cool:
Thanks, I do search the forum instead of just asking blindly for help hence how I found this thread from 3 years ago instead of just starting a new one. If a problem or idea is brought up in a thread though its fair to ask about it right there to the person who brought it up. I do appreciate the response though.

I also do get all your obvious remarks, but the fact that you also mentioned it is sometimes factory installed and other times certain ones simply don't have a SAIS has me thinking of a number of possibilities.

But the biggest thing that confuses me is that this is a milled aluminum block. If as you say its done to as a bypass then it's a factory created band-aid that will trigger a check engine light always so that doesn't seem like something that would actually be done. If this is an at home bypass to just drive the vehicle it seems like it would be a rough DIY plug or something installed there. Not a machined factory created part?

Or better yet why even remove the faulty check valve to begin with? I dont think a bad check valve is going to keep the car from driving, just going to cause a light, so why would you go out of your way to remove it and replace with a plug if the light is still going to be on?
 

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2004 chevy trailblazer_ls
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Actually I guess if I'm reading it all correctly the idea is the SAIS existed on 04 and 05 trucks, they decided to stop using it so on later vehicles.

Then rather than a redesign they started shipping them with these blocks from the factory where the check valve use to go. Then they programmed the PCM to not look for a SAIS so the block wont cause a check engine light on those vehicles?

And now people are actively removing SAIS from their old vehicles and taking these blocks from newer cars in junk yards to plug their Check Valve hole, although I'm not sue why even do this unless the check valve actively prevented your car from driving. Then after this people are all just driving with a permanent check engine light on.

Or they're doing all this then going out and paying someone to reprogram their PCM to eliminate the check which also seems like it would be pretty illegal as it bypasses an emission requirement.

Just trying to fully understand. Seems like a bit of a stretch that this is a regularly done thing by people but I dont know so I guess it's possible?
 

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2005 trailblazer_lt
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Thanks, I do search the forum instead of just asking blindly for help hence how I found this thread from 3 years ago instead of just starting a new one. If a problem or idea is brought up in a thread though its fair to ask about it right there to the person who brought it up. I do appreciate the response though.

I also do get all your obvious remarks, but the fact that you also mentioned it is sometimes factory installed and other times certain ones simply don't have a SAIS has me thinking of a number of possibilities.

But the biggest thing that confuses me is that this is a milled aluminum block. If as you say its done to as a bypass then it's a factory created band-aid that will trigger a check engine light always so that doesn't seem like something that would actually be done. If this is an at home bypass to just drive the vehicle it seems like it would be a rough DIY plug or something installed there. Not a machined factory created part?

Or better yet why even remove the faulty check valve to begin with? I dont think a bad check valve is going to keep the car from driving, just going to cause a light, so why would you go out of your way to remove it and replace with a plug if the light is still going to be on?
Here is a picture of the block off I pulled off a 2006 ( I thinik is was an 06 anyway ) :



When the SAI system, fails in my 05 I'm going to install this factory block off. No. I didn't cut A "rough DIY plug or something",... it's a DIY modification using factory parts. I could have cut a piece of metal to make a block-off but why bother when it took 2 minutes to unscrew the factory block off from a junk truck ?? The SAI was not used on the early GM360, they GM engineered it into the 04-05, but re-engineered the I6 engine again without SAI after finding it to be a flawed system; seems to me to be pretty easy to understand.

Maybe the original SAI solenoid was causing the truck to run crappy because it was always stuck open - or because it was stuck fully closed, maybe it was physically broken causing an exhaust leak. Your asking questions that only the PO can answer,.... and that have no relevance anyway. You've got a SAI check engine light and need to fix it for inspection. The block-off installed on your engine might as well be a failed solenoid - your still dealing with the same issue.


Like I said: when dealing with your SAI problem you've got options,

1) leave it as is and fail inspection,
2) replace missing/bad parts to clear the code
3) re-program your PCM not to check for SAI operation.

:cool:
 
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