Testing fuel injectors? How?

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Hey guys. My mechanic says I've got a bad injector, but wants to charge me an additional 300.00 pull the plenum off my 94 Grand prix with a 3100 to find out. I can get the plenum off myself with no trouble, but how does one
go about testing the fuel injectors? I put a long screw driver on each injector while the car is running, and left the tick-tick-tick that each injector makes .. one is slightly less .. powerful than the rest, but I'm not sure if that is a clear indication of an injector failure or not .. help!
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What does he think is wrong with the injector?
Electrically, you can test the resistance.
For leakage, you can remove the injectors and fuel rail as an assembly, run the fuel pump, and wait.
For clogging, well, depending on the injector, hard to find.
If you have a misfire on a specific cylinder, you could swap the injector with another cylinder and see if the misfire moves to that cylinder.
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The injector isn't opening all the way. I'm getting a 'lack o'fuel' miss. Basically a miss but no gas smell out of the exhaust. What's the best way to test resistance?

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You check the injector's resistance by disconnecting the connector from the injector and measuring the resistance of the injector across its two pins (on the injector, not the wire) with a digital multimeter. I don't know if I'd trust an analog ohmmeter, but I suppose it should work.
I'd go the swapping injector route. Find out which cylinder is misfiring, swap that one injector with another cylinder, and see if the misfire moves. If the injector is "not opening fully" as alleged, the resistance check should still be good.
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Not sure mortal man has the equipment to properly check an injector. I thought they should be around 12 ohms but that's only one check. They can have the right resistance buy still be partially clogged. How much do you trust your mechanic? If you want to DYI, I solved a misfire problem in a 98 Montana by installing a set of reconditioned injectors from www.lindertech.com There's a bunch of places selling recond. injectors but I read of this outfit on another board. Not sure of cost for the 3.1 but it was around $150 +/- for the 98.

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Get the set, as suggested. It costs about the same as ONE new injector and those all fail eventually. GW
DonW wrote:

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The problem is that I don't have the funds to replace all the injectors at once. For 6 @ 70.00 (for new) That's almost 500.00 :( I don't plan on having the car much longer.

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but your going to pay 300 to have them looked at? then replaced if nessacery?

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Already paid 250 to have my 'miss' looked at ...

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If someone charged you that:
Then told you it was an injector. With all due respect, you were "BUNGHOLED!"
Refinish King
PS What ever happened to customer, not servicing the customer?

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believer in this stuff but it worked for my wife.
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Been there .. done that :)

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<snip>

How did you get *her* to drink it? Did she work any better? Hmmmmmmm, maybe ill try some on mine....
RK (sorry,lol......Not)
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Not to pick a nit but that's just over 400 dollars (420). I'm sure your point still stands on that anyway though.

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hehe .. 420.00 plus gaskets, bandaids, and money for the cuss jar = $500.00
wrote:

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True true.
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How about this: yank one plug at a time and bend the electrode shut, shorting it out. Put it back in and run engine, if it runs worse, obviously not that cylinder, move plug to next, etc. until you find the suspect cylinder/injector and service just that one. Comments?? Tom
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Never do that. If anything remove the spark plug wire from the plug. Hold it with something with rubber grips (such as pliers), pointed at something like an exhaust manifold. To which it will arc, rather then to your hands.
It's basically a dead cylinder test. Driving on a dead cylinder is something to avoid. It can be anything from a hole in the piston, to a valve that is stuck closed. Some time's it's just a fouled out spark plug, a bad terminal on a DIS or distributor tower, or even a bad plug wire.
Knowing which cylinder is dead is a good starting point. Yet with fuel injectors, you may have one dead. Yet find out 2 or 3 are below the required readings. With injectors you should First check for pulse with a noid light (signal from ECM). Then check pulse voltage. After that test all the injectors.
Two injectors with issues will cause an engine to run bad, yet it may seam like it only has one injector down. Charles
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Hmm ... seems really cheap for an injector at that place ... How long have you had those injectors?

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Replaced them in Jan 04 & about 6000 miles ago.

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