Hey guys, got a dilemma i can't seem to figure out. Last week my truck started running rough, not really bad though. At first i almost mistook it for me lugging the engine, because it would only do it under load in 4th or 5th gear. This past weekend it got significantly worse, its got a misfire under all conditions, idle and under load. No CEL on display at any point. So, i started with the basics, getting air obviously, next i moved to the spark. Along with a burnt wire (which i replaced, but it did not fix the issue) I noticed the by removing no.3 wire from the dizzy resulted in no change in idle, where as all of the other wires would change the idle. So, replaced that wire as well, along with the plug. No change. Moved on to the cap and rotor, replaced them, no change. At this point i conducted a brief compression test which yielded 145 on no.3 and 144 on no.1, so compression is good. At this point, I am feeling as though i have either a fuel injector issue or valve adjustment issue, neither of which i am a fan of. I doubt there is, but can anyone tell me of a way to pinpoint which one it might be before i rip the manifold off? Thanks guys.

Justin

 

Hey man. I bet it's an injector. Can u see if the plug is still securely on the injector? Do u have a mechanics stethoscope to put on the suspect injector to check if it's operating? I checked ur profile to see what motor u have but did not see it. I did notice u are a fellow upser though. I'm a driver out of the aliso viejo building In Orange County, CA. R u a driver?

 

Nah YotaWorx, i'm a big bad supervisor lmao

Thanks for the advice, i didn't even think to put a stethoscope on it, i have one laying around too. I apologize, i spaced on the motor, 3.slo!

 

Well no more luck today, got an ear to the injector, or i should say as close as i could (god i HATE HATE HATE this manifold), and it seems to be working okay… I can hear it clicking, thats about it. Found a few vacuum leaks, one at the intake elbow and one at the egr valve that i fixed, but still no change. Sometime this weekend i'm going to pull the manifold, how would you test an injector out of a car to make sure it is working, or can you even do that? I'm trying to eliminate everything i can before i tear into doing the valves.

 

Found Thooks write up on testing injectors, guess thats what i will be doing this weekend.

https://www.yotatech.com/forums/f116...s-home-239660/


EDIT- After doing more research, i am 90% sure its an injector. If i am getting spark (which i am), and my compression numbers are good (which bad #'s would indicate a burnt valve or rings), and no vacuum leaks, i am only left with fuel delivery. Since it is only on that one cylinder, i feel like i can make a pretty educated guess as to what it is. Ordered a set of flamethrower's injectors, guess i'll be seeing how well they do sometime next week.

 

I was confident it was an injector problem, but i would have never of suspected it was this bad (no.3 is the right one.)-



changed the filter the other day after all this had started, must have gotten past the old filter… The whole thing was full of dirt.

 

Just to close this thread out, installed the flamethrowers today, smooth as silk idle, and tons more usable power everywhere. Super impressed and happy with the results!