MPFI problems

[2000tahoeZ71]

well my motor with 192k on it started misfiring 3 and 4. Read the plugs and it looked like Oil and coolant. Replaced the motor and cranked it up ran great for 15 seconds and then started misfiring, 3&4. Pulled injector and 3&4 were sputtering. I replaced the original spiders in January 2014 with a brand new Delphi mpfi system. Looks like I spent 2 grand for no reason as the injectors were bad. What is the likelihood that two injectors would go out simultaneously? Should I do any troubleshooting before I spend 330 bucks for a new AC Delco MPFI system? I tested the injectors on the old one by connecting wires to their pins from a 12 volt source, which makes me believe the problem is in injector and not a computer problem btw.

 

[SunlitComet]

if you had oil and coolant in the cylinders then you had engine mechanic issues so replacement was justified. you should not have either in there.you can plug in the the newer one and run a injector balance test with the right scan tool. if triggering 3 or 4 also triggers the other you will need to verify with noids without injectors plugged in to see if both still activate at the same time. if so you have a wiring or pcm issue.

 

[2000tahoeZ71]

Well, I took number 2 and 4 and gave them 12volts from an outside source. 2 sprayed fuel like I wouldn't believe while 4 barely sputtered. I just ordered a new set of injectors, this time I went with the AC Delco version. Don't know if it really matters as I have heard they both made by Delphi. Who knows, really pissed that they went out after less than two years.

 

[SunlitComet]

both are actually the delphi builds but branded differently for marketing reasons.

 

[2000tahoeZ71]

Well the delco was about 60-70 bucks cheaper so I went with them this time. Maybe I'll have better luck. Just really hard to believe that two injectors went out at the same time.

 

[SunlitComet]

using good fuel and filter?

 

[2000tahoeZ71]

Ac Delco pump, Delco filter about 10k ago. Always run 87 with ethanol as its dang near impossible to find ethanol free, and didn't give me any better mpg vs the extra cost. Most of the 87 comes from one local distributor around here and seems to be good quality for what it is.

 

[SunlitComet]

http://pure-gas.org/