Cascade Crew

RSFreak · Posted: Sun Apr 21, 2013 9:48 pm Post subject: Found the problem...

Injector #1 is not firing. Now gotta find out why. Can I use a multimeter on the plug to see if it is getting juice? I don't want to frag my harness or ecm by randomly jamming probes into things. Very Happy

fiveoformula · Posted: Sun Apr 21, 2013 9:56 pm Post subject:

Shouldn't be any problem if your just checking for power and ground, just make sure it's doing the intermittent miss thing when you check. Then maybe check it again when it's not doing it.

iansane · Posted: Mon Apr 22, 2013 9:05 am Post subject:

Been awhile since I messed with tpi but isn't it powered all the time and the ECM provides ground?

O'Reilly has a 'noid light rental set, btw.

Alphius · Posted: Mon Apr 22, 2013 11:48 am Post subject:

RSFreak · Posted: Mon Apr 22, 2013 12:32 pm Post subject:

Did the spray test on the header tubes. #1 stayed wet. Pulled the plug wire and attached spare plug. Started car. Plug fired. Pulled injector wire. No difference in idle. Injector plug is in good shape.

MrMike98 · Member Joined: 18 May 2010 Posts: 231 Location: Bremerton

try a couple cans(2 tank full) of good injector cleaner.........
u might get lucky.

Alphius · Posted: Mon Apr 22, 2013 3:17 pm Post subject:

Stick a multimeter on the injector and see what it's resistance is compared to a couple other working injectors on your car.

Just unplug the injector and measure the resistance from one terminal to the other.

chevymad · Posted: Mon Apr 22, 2013 4:32 pm Post subject:

If that's all the testing you've done, all you know is that you have a miss. Definatly do an ohm check on that injector though. Also if you can use a screwdriver or something to listen to the injector vs a working one. Working one will have a sharp click to it. Non working you'll hear clicking but it'll just be engine noise.. won't be sharp.

Pull that spark plug and look at it. Could be fouled. If it looks ok swap it with a known good one. Check compression if you have a tester.

Firing a spark plug when its under pressure in the cylinder takes more voltage then firing one just connected to the wire. It's still possible to have a bad plug wire or plug even though it fires fine. I like to swap the wire with another cylinders, same with the plug.. if the miss moves you know what's wrong.

RSFreak · Posted: Mon Apr 22, 2013 8:22 pm Post subject:

Pulled the plug, didn't look fouled, replaced it anyway. Still have a miss. Sad

I'll check the resistance tomorrow.

aaron_sK · Posted: Tue Apr 23, 2013 5:36 am Post subject:

My money is on a bad wire, or maybe a bad pickup coil.

Steve's mechanic put his stethoscope on each injector and didn't hear a dead one, and jostling the wires around "fixed" the problem.

BluFbdy · Posted: Wed Apr 24, 2013 6:22 pm Post subject:

You gotta ohm out that injector, if they're multec style its possible the varnish is gone, the only way to tell is to check it, if its on point with the others then I would try to clean it, no sense in cleaning a shotty one

As far as jostling wires around when my coil wire from the dizzy was shot it stopped the entire thing from firing, just for s's and g's check that injector

RSFreak · Posted: Wed Apr 24, 2013 8:44 pm Post subject:

Twilightoptics · Posted: Thu Apr 25, 2013 10:02 am Post subject:

And you still haven't taken ten seconds to ohm the injector?

aaron_sK · Posted: Thu Apr 25, 2013 11:24 am Post subject:

Remember, this is a John repair.

Once you've taken two years to do a weekend engine swap, taking a week to ohm out a set of injectors is nothing. Wink

Twilightoptics · Posted: Thu Apr 25, 2013 5:42 pm Post subject:

Or swapping two plug wires. LOL

How do you know the spark plug is firing? Is your head in the combustion chamber? :OP

RSFreak · Posted: Thu Apr 25, 2013 9:31 pm Post subject:

chevymad · Posted: Thu Apr 25, 2013 10:02 pm Post subject:

Or it could just plain not have enough voltage to arc anywhere.

Paul's right. Just as I was explaining too, there's a different voltage requirement when the plug is in the cylinder then when its out. The voltage may be high enough to arc through a weak spot in the wire. The wire may have such high resistance that the very little spark actually reaches the plug. Also possible that the resistance of the wire + the resistance of the plug gap under compression is high enough that the spark never leaves the coil.

All easy to rule out just by swapping the wire around with another cylinder. Misfire moves.. you've found the bad part.

Ohming the injector will at least tell you if the electrical coil in the injector is good. Injector can still be plugged or stuck though. One of those tests that if it passes.. you still don't know if the part is good. But if it fails you know its bad.

RSFreak · Posted: Fri Apr 26, 2013 8:20 pm Post subject:

chevymad · Posted: Fri Apr 26, 2013 9:32 pm Post subject:

Makes no difference John. Unless you have a scope that can read the voltage in that wire in comparison to the others.. then you have no clue whats happening. Swap the wire. Only way to test at home.