Chevy Nova Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
219 Posts
Discussion Starter #1
What is the best way to determine if you have a fuel injector problem...any one have any ideas on troubleshooting these?
 

·
Registered
Joined
·
1,559 Posts
coponova said:
What is the best way to determine if you have a fuel injector problem...any one have any ideas on troubleshooting these?
The first thing they teach you when you go to school for carburetors is that "85% of all diagnosed carburetor problem are not in the carburetor." I would say that number is much higher when it comes to fuel injection. People seem to forget that under the EFI is the same engine that was under a carburetor. A lot of the same basics still apply. For some reason, they assume their plugs & wires should live for ever and they must have an EFI problem. Modern EFI is very reliable. It's usable service life commonly exceeds the life of the car.

As for your question. Let's assume you have a dead skip that cannot be cured with new plugs, wires, cap, & rotor. You should be able to isolate the skip to one cylinder by doing a cylinder kill test (or by the one spark plug that does not match the rest). Pull the valve cover and verify that all the rocker arms are moving. (You could have lost a cam lobe.) Next do a compression test. (Notice, all of these are test you would do with a carburetor.)

Still got a dead cylinder? Use a stethoscope, wooden stick, or a long screwdriver to listen to each injector at idle. Each injector should make a very distinct ticking sound. If one is silent, it could have failed. You will need a "Noid Light" to verify that there is an electrical pulse at the injector plug. (Be advised. The last time I found a silent injector, a squirrel had bitten the wire into.)

From there, it's hard to offer any advise without some specifics of what you are working on and what type of problem you are encountering.
 

·
Registered
Joined
·
219 Posts
Discussion Starter #3
Hey tpinovaII,

Thanks for the detailed response. I am currently working on my truck, a 97 Dakota. It has a 2.5 liter and about 1 weeek ago started running pretty rough and the idle was rough as well. I hadnt done a tune up in a while so I replaced the plugs, plug wires, cap and rotor. This didnt seem to help any. \

I had a similar problem with an old neon, that turned out to be clogged injectors, and due to the age and milage on the truck (95k), I figured maybe the same thing.

The clog I found on the neons injectors was rust from in the fuel rail that all the gum out in the world would not have fixed.

Again thanks for your response, and if you have any ideas, based on this information let me know.

Ed
 

·
Registered
Joined
·
1,545 Posts
this may or may not be the problem but it is an answer, very specific and without trying to solve a problem....but to test an injector, other than taking it out and having it flow tested it called an injector drop test...you need a special tool that plugs onto the injector and what you do is put a fuel pressure gauge on, key it up to run the pump and make pressure then you push a button on the drop tester (something like 20 3ms pulses or whatever the specific one uses) then you see how much the pressure drops on the guage for each one...start it up maybe each time or every other so its not just dropping a ton of fuel in there, obviously a clogged injector would show little or no pressure drop


is the check engine light on, does the bulb in the check engine light work, initial key up it should come on for a few seconds...

last time fuel filter changed?

air filter/MAF not obstructed?

check the basics first
 

·
Registered
Joined
·
219 Posts
Discussion Starter #5
I went through and checked pretty much everything that was recomended...put everything back together and I do get the check engine light. It indicated error code 43 which is:

43: Misfire detected in multiple cylinders. **

I have replaced the plugs, plug wires, cap, rotor, checked the injectors, fuel pressure, and air intake. Not sure what to do next.
 

·
Registered
Joined
·
219 Posts
Discussion Starter #7
new2novas said:
seems like coil and/or module to me...can you get data stream on your scan tool
I dont have a scan tool, I was using the key turn method. Is it possible I routed the plug wires in such a way that it could be causing this problem? I read about a similar issue on a dodge web site, but there was no info on the proper way to have them routed. I thought I put them in the same way I took them out.
 

·
Registered
Joined
·
219 Posts
Discussion Starter #9
Is there an easy way to test the coil? It still wants to stumble at idle now, evan after messing around I have done.
 

·
Registered
Joined
·
1,151 Posts
What error code are you gettin now?
And you can usually test the resistance in the coil with an ohmmeter.
 

·
Registered
Joined
·
219 Posts
Discussion Starter #11
I am still getting just error code 43, and I just checked the coil, I got a short, around 1.2 ohms.
 

·
Registered
Joined
·
1,151 Posts
Ummm, is that outside the acceptable range? Cuz it sounds pretty close to what I would guess it should be.
 

·
Registered
Joined
·
219 Posts
Discussion Starter #13
I would guess so. Never had to check one before.
 

·
Registered
Joined
·
1,151 Posts
If you have a Haynes or Chilton, itll have the acceptable resistance in there, but Im fairly certain 1.2 ohms is acceptable, so thats not the problem. Anyways, now youre saying that it misses at idle but smoothes out at higher rpms?
 

·
Registered
Joined
·
219 Posts
Discussion Starter #15
CDJr said:
If you have a Haynes or Chilton, itll have the acceptable resistance in there, but Im fairly certain 1.2 ohms is acceptable, so thats not the problem. Anyways, now youre saying that it misses at idle but smoothes out at higher rpms?
Yeah, it has even stalled out on me when it is just idlling.
 

·
Registered
Joined
·
1,151 Posts
I think the fuel filter would be the next thing I would check.
 
1 - 16 of 16 Posts
Top