# Engine misfiring (fuel injector?)



## TheBrownRobert (Aug 28, 2007)

A couple weeks ago, injector #4 died. I bought a refurbished one off of rockauto.com and managed to install it without removing the fuel rail or air collector. The car hasn't run right since. It runs perfectly smooth while in neutral, but it misfires intermittently while driving. It sputters slightly while accelerating between 20 and 30 MPH, and it bucks and kicks when maintaining 40 MPH or faster (this is especially annoying when cruising with the overdrive on).

I've replaced the spark plug wires, I've cleaned the spark plugs, distributor cap, and rotor, and I've mixed fuel injector cleaner into my current tank of gas. None of this has had an effect. Before installing the refurbished replacement, I tested its resistance (11 Ohms = OK) and lubricated the O-rings.

What could be causing this problem? The car ran perfectly fine before the old injector died...


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## TheBrownRobert (Aug 28, 2007)

I found the problem. Removing the old fuel injector caused the gas to drain out of the fuel rail and flood the intake. Cranking the engine after installing the replacement injector forced the excess fuel through the exhaust and into the emissions system, which caused either the BPT valve or the EGR valve—or both—to malfunction. I'm not a mechanic, but from my basic understanding, these valves are responsible for recirculating exhaust through the air intake under certain conditions to make use of unburnt fuel (such as when the engine is under a load). This explains why the engine ran fine while in neutral but ran poorly while driving. All I had to do was remove the L-shaped line that connected the EGR/BPT valve to the exhaust and it magically made the car work right again. I hope my state doesn't start testing emissions...


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## Chunkylover (Dec 29, 2011)

So you mentioned you replaced your injector with out taking everything off. did you just remove the 2 screws and the injector came out? did you depressureize the fuel line before you did this? just wanting to avoid dumping fuel in the cylinder. Any help would be appreciated.


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## rogoman (Dec 16, 2004)

Chunkylover said:


> So you mentioned you replaced your injector with out taking everything off. did you just remove the 2 screws and the injector came out? did you depressureize the fuel line before you did this? just wanting to avoid dumping fuel in the cylinder. Any help would be appreciated.


To perform any maintenance on the fuel system assembly, like replacing injectors or hoses, first remove the fuel pump fuse. Now start the engine up; after it dies, crank the engine over several times. It's now fully depressurized. Be sure to put the fuel pump fuse back in when you're done.


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## pandapdq (Apr 16, 2013)

All due respect, but why did you buy a refurbished injector? Was it that much cheaper than a new one?


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## Chunkylover (Dec 29, 2011)

pandapdq said:


> All due respect, but why did you buy a refurbished injector? Was it that much cheaper than a new one?


I found a reman injector for $40 and the new one is $80. I just want to know if it is possible to take it out and how difficult of a job is it without taking the intake manifold off. Any body done this?


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## rogoman (Dec 16, 2004)

Chunkylover said:


> I found a reman injector for $40 and the new one is $80. I just want to know if it is possible to take it out and how difficult of a job is it without taking the intake manifold off. Any body done this?


Replacing a fuel injector normally is fairly easy:
- Unplug the harness connector.
- Remove the small two hold-down screws and the bracket.
- Using a very large screwdriver, place it under the harness connector of the injector.
- Gently apply pressure with the screwdriver. The injector should pop out.

If it won't come out, pull the entire fuel rail off the intake manifold without removing the hoses or the other harness connectors and push the injector out.


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