First off, Hi and thanks for being here! I got a ton of questions I hope someone can help me with. My husband has a '93 S10 Blazer 4.3L Vortec. Last spring it started to idle funny and after I found out he's never done a tune up, I did that. Plugs, wires, roter button and distributer. Then he told me his SES light was on so I got out my trusty paper clip and run the codes. Replaced the IAC valve. This just keeps getting worse AND because it doesn't want to start, diesels, blowes big puffs of black smoke when I give it gas, I can smell gas when it starts and is getting about 7-8 miles per gallon I think it's the CPI unit. Does this sound right? What I want to know is how hard is it to take the plenum off and replace the CPI unit? I'm not the worst mechanic but not the best and need to know if I can do this or not. I also would like to know if the hoses can be replaced or if I have to replace the whole unit and do I need a gasket for the penum? When and if I do this I need to make sure I get everything I need in one shot. I just got married and moved to Florida so we know no body down here. This is the only car we have and I can't go back to Autodrones after I get everything tore apart. THANK-YOU-SO-MUCH!!!

Rosetta

 

Hi, I just did the job 6 months ago, and it is not hard at all. Just make sure you de-pressurize the fuel system (chiltons will show you what to do) and yes you need a gasket for the plenum. I would definately replace the hoses, because they are failure prone. Also dont forget the O rings for the fuel line fittings. It really isn't that hard to do, and should only take a couple hours at the most. Just get a chiltons manual, and it will walk you through step by step.

My local parts store had a gasket set just for this procedure, if you have an autozone, or advance auto, they may have one too. Good luck!

 

it could be your EGR valve that is plugged.... i had the same problem a while back and it happens alot... all that carbon is left over from when it wasnt tuned propely...and now that it is tuned, the carbon deposits are breaking off and now plugging up the EGR valve allowing it to not close.


the EGR valve is directly under the air intake. there are two bolts... one on each side.. you might need to remove the compressor support bracket to get the EGR valve out... just clean it.. get all the carbon out and make sure that you can push it in and it comes out by itself... if there is not any free movement.. get some CARB cleaner... dont use break cleaner (too harmful to the parts inside the valve) spray the cleaner inside and out...let it soak.... i take a air crompressor and lightly blow the valve inside and out until its dry... then i check it again for free movement..


hope this helps


and good luck

 

Thank You! I have the EGR valve off and cleaned. Thought I'd try that first and see(less expensive). I have a Haynes manual but I've always done better just taking things apart. Just wanted to say thanks again.

Rosetta

 

Has the cat ever been replaced? You could be expierenceing a plugged cat.
What happens when you disconnect the O2 sensor? Does it smooth out? If so, your O2 sensor is shot. The computer will go into a defualt mode if it isn't getting a signal from the O2 sensor. It'll run nice and smooth, howver your gas mileage will suck big time.

Check those out as well.

 

I've put the EGR valve back on and all's well there. Checked the O2 sensor and that's fine. Went to Advance and got a CPI unit. My husband had the oil changed last week and it's about a quart over with gas. Thanks for all of your help. This truck is REALLY nice and I'm trying to at least get it back to what it should be. I'm gonna see if I can't get some pictures up for you to see.

Rosetta

 

All done! Wasn't as hard as I thought it would be! There was something I thought was weird. My haynes book said that when I pushed the valve in to let the pressure of the fuel system gas would come out. I got nothing. How bad was that? I know all of the hoses on the CPI unit were so brittle they broke off. It's running great now just gotta chane the oil.
Thanks,
Rosetta

 

Nice work! Feels good to save $400+ by doing it yourself doesn't it?