Engine/Transmission (1998.5 - 2002) New 275s bad?

[oldiron]

I installed a set of 275 injectors this afternoon and now have a miss, very noticeable at idle and less so at higher RPMs but still there. The install went very well, pulled the transfer tubes back, old copper washers out, new ones in, everything torqued properly, even #6. The injectors were new in the box but could there be a bad one? The truck did have a bad lift pump for an unknown number of miles before installing the gauges and had a slight uneven idle with the stock injectors so are the 275s amplifying an existing condition? Any ideas appreciated, thanks.

 

[McDowra]

possible but not likely. loosen line one at a time to find one missing. Check install if it looks ok swap with another hole. If miss follows injector its bad, if not check transfer tube.



Tim

 

[oldiron]

Good news, I got an IR thermometer today and checked the exhaust temps. Found out one was way cooler than the rest. Bad news, I pulled the transfer tube and everything looked ok but it still misses badly. Good news, at least it's #1 and easy to reach. Tomorrow I'll pull the valve cover and move around the injectors. Question, Can I reuse the copper gaskets that I just put in with the new injectors?

 

[Big_Daddy_T]

Is it possible some small debris got into the tube?

 

[CFAR]

Didn't they recommend replacing the injector tubes when putting in new injectors on the 98. 5-99 years???

 

[thejeepdude]

Originally posted by CFAR

Didn't they recommend replacing the injector tubes when putting in new injectors on the 98. 5-99 years???

I didn't change the tubes on my '99, and my 275's worked flawlessly from the beginning... no misses, no leaks.

 

[oldiron]

Well I swapped #1 and #3 which evened out the IR temp readings but it still sounds just as bad. At low speed you can feel the surge but it seams to smooth out at higher speeds. It pulls stronger than before and now hits 31 lbs boost but the idle and low speed suck. What's the story on the new injector tubes?

 

[thejeepdude]

Originally posted by oldiron

Well I swapped #1 and #3 which evened out the IR temp readings but it still sounds just as bad. At low speed you can feel the surge but it seams to smooth out at higher speeds. It pulls stronger than before and now hits 31 lbs boost but the idle and low speed suck. What's the story on the new injector tubes?

I don't see how it could be the injector lines if it runs better than it did after moving the injector. If the line was causing the low temps in #1, it would still be low in #1 after moving the injector. In fact, after re-tightening them an aditional time, theoretically the condition should worsen. I am more inclined to think it's the injector. I would switch it again with #2 and see if anything changes. It seems to me it could be possible that the injector has a slight defect that may be intermittently vary it's output with each install. This could show up as more or less performance when you put it in #2, but at least it's one more datapoint to look at which may or may not tell you the problem. OOooor there's an entirely different problem altogether... just throwin out ideas.

 

[oldiron]

It's raining today so not much getting done. I did crack 4 of the 6 lines with the truck running. I get a consistent change in the miss with 3 of the cylinders but with #3, my suspect, there is a change but not nearly as much as the others. Sounds like one of the new injectors is "lazy". This weekend I'll stick one of the stockers back in that hole and see if everything is happy.

 

[oldiron]

Yup, one of the new injectors is bad. I pulled it out, swapped in an old one and the miss is gone. Unfortunately I bought these two years ago so I wouldn't ask for a replacement but I'm sure someone will sell me a single. Thanks to everyone who helped out.

 

[thejeepdude]

Originally posted by oldiron

Yup, one of the new injectors is bad. I pulled it out, swapped in an old one and the miss is gone. Unfortunately I bought these two years ago so I wouldn't ask for a replacement

I would! Depending on who you bought them from, they should be glad to replace a bad one if you're just now installing them. If they do say no, you're no worse off than you are now.