I recently bought a 98 blazer and engie light came on. i changed cap, rotor, plugs, wires, egr valve.
the code that it was given me was P0402 (i believe thats the code) but it was for the egr valve. So i replaced the egr valve and the
problem seemed eo get worse. When i go to leave my house for a fire call it hesitates really bad the 2 blocks i have to drive
now after awhile of driving it does it on and off. and my engine service light is still on and its still the erg valve code. I was told at the
dealer that they think its a bunch of carbon build up and they would need to take apart the top of the motor to clean out/.
Does anyone have any ideas or have seen this before? thanks
Gary

 

First of all, clear the codes and then drive it for a bit and read to see if there are new codes. Then another cheap thing to replace would be the fuel filter. Not sure what else could be causing this since you replaced the plugs and wires, cap and rotor. What did you gap the plugs to? (Should be set to .06in. of a gap) Also what plugs did you replace them with, you need to run platinum plugs preferbly the AC Delco Platinum Plugs.

-Lenny

 

I have cleared them 3 times and it comes back after 5mins of driving, the plugs were pre gapped they were bosch platium 2, Its the same code that keeps coming up. it seems as it got worse when i added the new EGR valve. cuz before it only did it ever so often, now its when ever i start teh truck up.

 

Well the problem could lie in the spark plugs, because supposedly our trucks don't like anything other than regular platnium plugs (only one tip) and seem to prefer the ACDelco Platinums.

Also I would clean out the IAC with some electrical parts cleaner and the MAF sensor also with electrical parts cleaner, also yould replace the PVC valve (like $5). Other than doing those first I don't know what else to suggest.

Also depending on the mileage it could be that you need a general overall engine tuneup, take a look at this thread it should help you on what to replace/clean. Also a fuel filter is a cheap possible fix that if nothing else, once everything is back to running right will help with better gas mileage (better flow of gas to the engine). You might even have clogged fuel injectors so I would run a bottle of fuel system cleaner through a tank of gas (can be found at WalMart or any car parts store). I would just try a bunch of these, cheap ones at first then work your way up, checking after each one is done till it gets fixed. Another possibility if you are still getting a bad EGR valve code is that the replacement one was defective.

-Lenny

 

When i changed the plugs it was after the new EGR and ran the same but i will look into those. also when i had the truck in the shop for a new tranny they did a fuel system flush which cost me 2 legs an arm and my kidney..... they said it would fix it but ya it didnt.. I got a fuel filter from napa, had dad order the AC platnium plugs. I'm gonna clean the IAC in the morning and go from there
thanks for all the info.////....

gary

 

Well, you may want to pull off the EGR valve again and see about attempting to knock some of the soot loose from the supply tube. I have used a 1" diameter brass pipe cleaner with a long handle to loosen the carbon debris from the inlet tube, then just started the truck with the EGR valve off to purge the line. Just a word of warning, it'll be LOUD!!

Also, a gasket is available with an integrated screen over the inlet to the EGR valve to prohibit carbon chunks from stopping up the EGR valve.