Like the title says, I had a P0305 before which is why I figured it was the original poppet injectors because they had 200K miles on them. I bought and swapped in the MPFI upgrade but when I cranked it up I got a P0300 after a little while of driving. Has a pronounced miss at idle and a shutter down low but levels off at higher speeds. Have replaced the distributor, wires and plugs as well. Any suggestions are welcome.

 

Update: Took everything apart again and put it all back together. Now I've got P0303. Seems like roving gremlin...

 

What brand of distributor did you use as a replcement? What brand of cap and rotor? Are all of things things new and AC Delco? Did you use dielectric grease on all of the connections and inside the cap?

Did you check your cam retard after reinstalling the distributor? Should be 0 but specs allow for +/- 2 degrees.

 

Distributor, rotor, cap and wires was Ac Delco and was zeroed out when installed. Spark plugs are Autolite double platinum. The MPFI kit was Standard Motor Products.

 

Well, from there you may as well check out this thread:

https://blazerforum.com/forum/2nd-ge...eakdown-88305/

Post all 4 numbers and by then perhaps The Captain or Les will check in on the thread

How did the old plugs look when you removed them?

 

They were carboned up pretty good but I was disappointed to find Bosch +4 plugs. The last receipt I have for spark plugs from the previous owner was 2005 and 100K miles.

 

I would double check and make sure none of the pins were bent when plugging the connector back into the top of the spider assembly too...

 

The good Doctor gave you some very good advice, on all counts!


We have to assume that your vehicle is at least a 1996, due to performing the fuel injector upgrade. Knowing the "vitals" helps us a lot when it comes to diagnosing problems After we know the year, make, model, 2 door, 4 door, transmission, 4x2 or 4x4, then we can get very specific with diagnosis & repair procedures, and give you correct part numbers.


First of all, the "basics" need to be correct. Autolite and Bosch are great plugs... when they are used where they belong... certainly NOT in a 4.3L GM. These engines are very fussy when it comes to secondary ignition parts, and the fuel delivery system. Distributor cap, rotor, & plugs all need to be AC Delco. Plug wires need to be a good quality name brand, (AC Delco, Belden, Denso, Autolite). NOT a store brand, (Duralast, Master Pro, Driveworks, Carquest, etc).


What manufacturer and model number of scan tool are you using? We can help you better with the diagnostics if we know what you're working with. Any idea how many miles are on the oxygen sensors? Don't let me sidetrack you here, we still need all 4 readings for the fuel pressure and leakdown.

 

99 Olds Bravada 4-door
4.3 v6
4L60e
AWD
Distributor, rotor, cap and wires are Ac Delco. Plugs are Autolite double-platinum. I'll check into getting a set of Ac Delco spark plugs tomorrow, gotta get the pressure gauge tool for the fuel pressure check. I'm at a loss with the O2 sensors as far as their concerned.
Using the Automatic obd adapter and an ELM 327 obd adapter with Torque Pro.

 

This above!

Torque pro is pretty good software for many things. If you want to also get Car Diagnostic Pro from Amazon ($8.95) that will allow you to do cam sensor retard with your existing OBD2 adapter. Torque Pro does not have the ability, but is easier to use. Captain will be asking you to verify cam sensor retard eventually.