Since I already upgraded the front end with MOOG part , and got an alignment so the maintenance is complete thus far, just awaiting the time to do a tune up . What I'm tryin to do is do other upgrades that will give me both a performance boost (best bang for your buck) and also a mpg boost to boot. I've looked into possibly getting a pcm tune or flash , but where should I go for that I only know about Blackbearperformance since I used them with my 99Tahoe and it worked great . What about an exhaust system, is there any decent upgrades other than a kit that I could look into ? And, some form of intake upgrade either a k&n drop in or a full CAI. Outside of this I've been considering just getting a bull bar and put some Kc's on the front of my blazer since I drive on a lot of back roads and I haven't found a bulb I like that would make the stock fog lamps bright enough to make them worth trusting .

Don't know much about these trucks or how to get performance or mpg improvements so any help would be greatly appreciated

Chi_Town

 

I have a '03 Blazer 4WD also. So I am looking forward to hear what answers you get on Upgrades on your '03. BTW do yourself and your fellow forum posters who want to help you a big favor. Always post your year, model, and whether 4WD or 2WD. I know you may say , well , I posted that last time,so surely they remember. No, they don't. I have been here for only a short while. One thing is certain sure. When it comes to tune up parts like plugs, wires, O2 sensors, etc. always use AC Delco or Delphi parts. Yes, I know , other brands may have a better buy or a big name, but don't fall for it. This AC Delco/Delphi is esp. true for the fuel pump and harness for the fuel pump. And remember , the 4WD or 2WD is a critical factor when it comes to getting a correct answer to your questions. HTH, Jim in SC 2003 2 door Blazer LS with 4WD and all stock.

 

Save your money on the CAI. It's all sales hype and a total waste of money. Instead, like Jim mentioned, spend the money on AC Delco parts, especially plugs, distributor cap & rotor. Denso oxygen sensors have a faster response time, and they are cheaper than AC Delco sensors

 

Went with the Denso 02 as you directed me to do so Captainhook, and I ordered the AC delco tune up stuff (plugs,wires,cap/rotor) off rockauto. I was just looking into other avenues that I may consider because I really want to try to push 20mpg out of my blazer minimum, this whole 15-18mpg is getting old since i'm only getting about 240-260 a fill up =/ and 80-90% of my driving is on country roads which are paved at 55-65. So I figured maybe a pcm upgrade would be sufficent, wont bother with the cai, I just put a new drop in Fram filter about 5k ago so I'll just let that run out and probably get a k&N drop in . The only issue I have with the blazer is the check engine light is on due to a vac leak towards the back of the blazer, but I'm not exactly sure what I'll have to run the code again and see what comes up .

As for the blazer it's a 2003 5dr 4x4 115k 3 owner ( i'm the third owner ) previous owner was my step parents , and before them was the dealership they bought it from .



Chi_Town

 

Curious as to how you know there is a vacuum leak at the rear? Anyways that is where the fuel vapor canister is; check the hoses going to it, probably one of them is split and just needs replacement.

I have had two Blazers, a '95 and currently a '02; both got the same mileage, same as yours. I tried the cold air intake and performance spark plug wires....no change except in the weight of my wallet!
I never tried the Denso O2 sensors...could you let me know if that makes any difference?

I have investigated several times what it would take to put dual exhaust onto a 4x4, 4dr Blazer and have given-up eveytime.....fuel tank is just in the way. Thought maybe headers would help, but never got anywhere and expect that any gain would not be enough to offset the cost and effort to install.

If you try something, let us know how it goes.

 

The oxygen sensor I bought is the Denso, having great success with it , and the code that is coming up for my 03 are (P0449 ,P0455) . I do need a tune up so I will just make sure to order the plugs and wires Captain told me about to keep that end stock since I know the GM 3800 is really picky with plugs and wires, and running anything but stock could result in thrown codes or rough idle . I still haven't heard anything about a K&N drop in, if anyone has seen any improvments in either mpg or performance ? Or is it just the fact of never having to buy another filter ? Also I was thinking exhaust kit or maybe just doing a different muffler, either way are there any differences in improvements other than sound on either upgrade ?


chi_town

 

This is a perfect example of why DTC's must be diagnosed and repaired in the order they are received. Then perform a drive cycle to confirm the repair. The P0449 is an electrical problem with the EVAP vent solenoid. More than likely that is what's causing the P0455, (large EVAP leak). This will help diagnose the problem:

 

Hey Captain Hook, thanks so much for posting that video! I love having a great big chunk of information and that guy definitely delivers it. Awesome.

I'm wondering if anyone has the VCM pinout diagram for a 2003 Blazer LS, 4wd, 4 door?

I got the P0449 code. Before seeing this video I had already replaced the solenoid, and unfortunately the SES light is still coming on after I clear it. I checked voltage at the solenoid connector and have good +12 from the pink wire and no ground from the white until I turn on the car, then the white connects to ground...but with a LOT of resistance. I'm not sure if it should really have that much resistance or not.

I pulled the plugs from the back of the VCM because I'd like to check continuity of the white wire from the plug-at-vent-solenoid to the plug-at-VCM, but I don't have the pinout of the VCM. There are a lot of pinouts online from pre-2000, but those don't much look like they match mine. So I'm hoping somebody has the 2003 VCM pinout lying around.

BTW, if this counts as hijacking this thread, I apologize...it seemed on point.

Thanks for anyone that can help.
Chris

 

Chris, provided the 8th character in your VIN is "W", the orange wire should show battery votage with the ignition in the RUN and START positions. The white wire goes to pin #45 at the PCM. Disconnect the PCM and the vent solenoid connectors, resistance end to end must be less than 5 ohms.

EDIT: My 2003 schematic shows the feed wire as being orange BUT, it comes from the ENG 1 fuse, and several pink wires are fed by that same fuse, so it might be pink at the vent solenoid

 

Hey Captain, thanks for getting back to me.

The 8th character in my Vin is X...so, don't know exactly what that means for your advice. Strangely, the orange wire shows battery voltage even if the key is not in the ignition (and it stays hot through any key position). But that side of the connecter is not my problem.

I can't figure out which pin in the VCM harness would be pin 45. The harness is two macro connectors, one of which is blue, the other green. Each macro connector holds two sets of 40 pins each. On the VCM itself are letters that indicate that the green connectors are A and B, and the blue are C and D. So I'm guessing that pin 45 would be in the B connector, but I'm not sure which side I should start counting from, and in the top or bottom row of pins.

Thanks,
Chris

EDIT: No wait! I just found on the VCM body numbers that indicate which pin is which, so I think I'm good. We'll know after I test continuity.