I have a 94 blazer full-size with a 5.7 in it. I failed my e check because the hc and no were high. How do i fix this! Thanks!


Hc=152.9
no=1316.3
these are the readings

 

your egr is probably not functioning or the passages are plugged up. Was it originally a 5.7, or did somebody swap it in on you? The 4.3's had a linear EGR, but the 5.7's had backpressure EGR (vacuum actuated) until obd-II.

Remove/inspect/replace the vacuum lines from TB to EGR solenoid and solenoid to EGR valve. A cracked or plugged vacuum line will prevent the valve from opening.

Clean/test the EGR valve. Blowing through one hole, you should only be able to blow while manually pushing the diaphragm up (engine vacuum draws the diaphragm up when the PCM activates the EGR solenoid)

Rebuild the TB (EASY; kits with all the gaskets are like $30-$50 depending on what's included). The TB passage might be clogged. Get a can or two of throttle body cleaner or carb cleaner.

Last resort is the EGR passages in the heads may be clogged. HTH..

 

It's a fullsized blazer...the 350 was already in it!!!...i swapped out the old one for one out of a 95 1500 chevy pick up!same engine...i was told to put in a can of sea foam or rubbing alcohol and run it on the freeway before testing again. What do you know about any of these things!...thanks

 

The Seafoam probably wouldn't hurt, but I would also do the things that helo said.