i did an oil change the the other day, i finished and as i left my shop my truck had no power,acceleration very poor, it took forever to get to 90 km, and my engine light started to blink every once an a while, i checked codes on it an i got code for multiple misfire, and i have two codes sayin rich fuel mixture. i have 99 blazer 4.3 auto, and i also have heard that puttin bosch plugs in could possibly screw up the ignition module and coil is this true and is there any way to test this.

 

Plugs won't screw up anything. Plugs are plugs when new. Some just last longer and perform better than others.

What codes were present. I'm assuming P0300, but what were the other two rich mixture codes?

 

ya i got p0300 - random/multiple misfire, and p0175 b - bnk 2 sys. too rich, p0172 - bnk 1 sys. too rich and just today i got p0152 - o2 sens. b2 s1 ckt hi volt. hope to hear back thx

 

And all of these codes popped up after an oil change??? Did you hit any wires during the work? I would look for a loose or disconnected ground.

 

You might also check around the oil fill tube to see if you accidently created a vacuum leak by knocking off a vacuum hose.

 

sorry no i already had p0300 i got the other three after the oil change.i checked to see if i might of hit somthin and there was a hose partially off but thats it.two months ago i put in boshe plugs and i just heard they were crap so i took them out an today i put in ac delco platnium spark plugs, but when i took out the boshe plugs most of them were black and brown and coverd in crap, huge gaps,and just totaled. my truck still has a nasty idle, around 500rpm and shakes the truck, ive done spark plugs,again, wires,cap,rotor,pcv valve,cleaned tb,cleaned maf sensors,did oil change. any other ideas

 

did you clear the codes since all the new parts were installed? and did you check fuel pressure? (even tho says rich) and you might want to check the FPR to see if its shot as alot of ppl say they start leaking or dumping fuel into the engine ...

also did you change the fuel filter?

thats all i got for now lol

 

i did clear the codes now and all i got left is the random/multiple misfire p0300 now, i have changed my fuel filter, buti have not checked my fuel pressure yet, or the fpr, so i will try those thanks for the ideas.

 

bad pick up (crank shaft sensor ) located in distributor. replace distributor if you do this your self make sure the new distribtor matches the repacement exactly.the problem is the orientation of the rotor to the drive gear.

 

bernie... There is quite a bit wrong with your recommendations. The "pick up" or crank shaft sensor (CKP - crankshaft position) is not located in the distributor, but rather on the front timing cover down near the harmonic balancer, but I doubt that is the issue at hand. If you are talking about the CMP (camshaft position) sensor, then that is located in the distributor, but does not require the full on replacement or even removal of the distributor to replace the CMP sensor.

Now, about your statement on the orientation of the rotor to the drive gear... Some drive gears have been known to crack and cause erratic timing and that would require the removal of the distributor to properly diagnose, however, the drive gear is available separately for much less than the cost of a new distributor.

Since this thread is quite similar to another thread where all possibilities were ran through, I'll link to the other thread for the benefit of the OP.

The dreaded PO300 CAUTION LONG POSTas123

Long read, but lots of useful information and trouble shooting steps. Try not to get caught up in replacing components to start. Read through the whole thread and go over the diagnosis properly before replacing things.