I did the "pull each wire off the distributor" trick and cylinders 2 and 5 did not register any rpm drop. There is no noticable smoke of any color coming from the exhaust at low idle and I'm not losing a significant amount of oil or water. I plan on running a compression test once I pick up a tester and there is spark but I'll probably buy new plugs just in case, but I'm just wondering whats everyone's experience on injectors failing? Basically, how likely is it that 2 injectors or the wiring to them have failed? The car has about 120k miles and is of course a 91 L98.

 

My wife's old Beretta dropped two injectors within a year. It was about the same mileage. It kicked on the SES light, but the car didn't run horribly - just a little rough.

Take a long screwdriver and hold the blade against the suspect injector(s). Put your ear to the handle and listen for it clicking (clicking = OK). Check a couple to compare, if you're unsure. It's easy to tell a good one from a bad one.

It sound wierd, but it works.

 

It idles rough, but feels decent at speed. Theres no SES light on. The injectors may just be clogged. I can get an injector wiring tester but I don't know where to get an injector tester. The rough idle started immediately after I changed the fuel pump. I plan on changing the injectors in a few months anyway, but hopefully I can wait until then. Fuel economy is crap when your down 2 cylinders.

Anyone know where to get an injector tester?

 

The Beretta was an OBD-II car - ours are OBD-I, so I don't know if we'd get a SES light.

I wouldn't drive it too much more, if it's down 2 cylinders. It could cause damage that will cost more to fix than the injectors. Try the screwdriver trick, and find / replace the bad injectors.

You might have picked up some crap when changing the pump out - have you replaced the fuel filters? Also how is your fuel pressure? It should be about 43psi, and able to hold it for a while once you shut down the engine?

You might check NAPA, autozone, etc, for a tester (if they exist other than an actual flow bench).

 

As far as the injectors just pop the wires off of them and see how much resistance you get from the injector. Compare all the cylinders and if there are injectors with half the resistance of the others then you know what the problem is.

Also did you consider that it could be spark related? Wouldnt hurt to pop the cap off and look underneath at the points to make sure everything is okay

 

Cap, rotor, plugs, and wires are all less than 4 months old. They are definately getting spark, but it might be weak. I'm gonna change the plugs just to be sure. The fuel filter is new also, changed a few weeks before the pump was. Fuel pressure is normal. As far as I can tell, I'm either losing compression, spark, or the injectors are malfunctioning somehow.

According to my book, there should be a tool that you hook to one injector that when activated will cause it to fire for a specified amount of time. You then read how much fuel pressure drops from each injector. They didn't have it at autozone, but I'll try NAPA.

 

I ran compression with the engine cold and all cylinders were very close, between 190 and 200 PSI. I remembered that the misfire happened most prominantly at normal operating temperature so I let it idle for 10 minutes. Then after burning my hand a few times I let the engine cool for 20 minutes or so and ran compression again and got the same results for cylinder 5(didn't recheck 2).

I did the screwdriver to the ear trick and heard clicking on all injectors, even after disconnecting them. I presume this is because they are so close together and I was hearing the adjacent one.

While observing the injectors I noticed that 2 of them looked different than the other 6. They were a lighter green on top with a polished looking bottom side, while the others were a darker green on top with a grey bottom. These 2 anomalous injectors just so happend to coincide with the cylinders that were misfiring. I checked their resistance and got 14.3 ohms for cylinder 2 and 8.0 ohms for cylinder 5. I then checked the injectors for cylinders 1 3 and 4 and got 18.0, 17.6, and 18.0 ohms respectively. I didn't check the other injectors because I figure I found my problem. Obviously injector 2 is bad and injector 5 is really bad. The car runs pretty good when cold though. Would an injector problem like this be effected by heat this much?

 

14.3 is borderline that alone wouldnt make the car run that bad, but it should probably be replaced, and ya the other one is dead. As far as it messing up when hot remember the car starts with the computer in either open loop or closed loop i forget, then when it warms up it switches into the other. So the computer acts differently. Time for some new injectors and you should be good to go. I strongly advise against mix and matching injectors tho. www.racetronix.com is based out of toronto but if you call and talk to jack he can get you a set of flow benched injectors for less then you would pay for 2 at the dealership

 

Closed loop is when the vehicle heats up and the only difference is that the computer uses the reading from the O2 sensor. The only way I see this effecting cylinder 2 (with 14.4 ohms) is that cylinder 5 misfiring is causing a false reading (rich or lean) from the O2 causing the cylinder 2 injector to add more chaos to it's already incorrect spray.

 

that answer works for me. Glad i could help you find your problem. Had an injector randomly die on me last year and took a while to figure out what the problem was, actually went through 2 dif mechanics neither of which found it eventually found it myself

 

You should have the fuel injectors checked and if thats not it your ecm is fried.

 

I tested them myself. Low resistance = a short circuit = bad injector.