Please Help!! #4 injector not firing

[MurdokGST]

I was driving home and car started running on three cylinders. Plugs and wires checked out OK, Ithought it was a bad injector, but I switched with working cylinde and it fired. Upon further inspection I found that the wires on the #4 injector harness were shorted to each other. I put in another injector harness, but I'm still running on 3 cylinders...Is ther anything else that could have gotten damaged from the short? I've been searching the site all day, but can't find any answers...someone please help...I'm going crazy and miss my car.

 

[turboholic]

-You might want to check the ECU.

 

[niko]

any oil on that plug?

 

[GTM]

Originally posted by turboholic
-You might want to check the ECU.

Wouldn't that throw a code and light on the instrument cluster??

He said he swapped injectors around but didn't mention if he swapped spark plugs. It's possible as the injector harness was taking a dump it wiped out the spark plug on that cylr by running too lean??

BTW what caused the harness short?? Where??

Cheers,
GTM

 

[MurdokGST]

There was oil in that spark plug well and the plug was oil fouled. I have since put in all new plugs and wires. The short was right were the wires went into the clip 4 the injector. Logged it and only came up with the faulty injector circuit code...everything else seems to be working...does anyone know where the injector resistors are? I wouild like to know before I start digging through the harness out in the cold(brittle wire and all).

 

[GTM]

Originally posted by MurdokGST
There was oil in that spark plug well and the plug was oil fouled. I have since put in all new plugs and wires. The short was right were the wires went into the clip 4 the injector. Logged it and only came up with the faulty injector circuit code...everything else seems to be working...does anyone know where the injector resistors are? I wouild like to know before I start digging through the harness out in the cold(brittle wire and all).

Hmmmm, off the top I don't see the relationship between the oil and the injector wire. Certainly a compression check if nothing more as reassurance subsequent damage has not occured.

I can't help with your resistor location anyone else????
..............

I'm inclinded to think the oil leak is from the plug well ring gasket which caused someone to become less than gentle with the injector harness and caused the short. I've not looked at the circuit but the resistors could be inside the ECU in which case you may be screwed.

Cheers,
GTM

 

[MurdokGST]

I found resistors they look fine as far as I can tell...I'm leaning towards computer being shot...anyone know if the short could have got computer being that the negative wire goes to the computer? I hooked up test light and it lights up on both wires and only lights up on positive wire of known working injector harness...I fear its the ecu..any other ideas would much be appreciated

 

[GTM]

Originally posted by MurdokGST
hooked up test light and it lights up on both wires and only lights up on positive wire of known working injector harness...I fear its the ecu..any other ideas would much be appreciated

The fact it lights on both wires tells you there is an _open_ circuit in the return ground system. You can pin-out the harness connector to the ECU with an Ohm meter which hopfully will tell you it's in the harness and not in the ECU. After that you might get lucky and find a burned cap. or transistor which you can replace otherwise you will be looking for a used or rebuilt unit.

Cheers,
GTM

 

[turboholic]

Originally posted by GTM
Wouldn't that throw a code and light on the instrument cluster??

-So now you think MurdokGST should look into the ECU?

 

[niko]

replace valve cover gasket and sparkplug gaskets. just had same problem now runs great.

 

[MurdokGST]

PUT In a good working ECU and I'm still running on 3 cylinders....I'm ready to light this damn thing on fire

 

[GTM]

Originally posted by MurdokGST
PUT In a good working ECU and I'm still running on 3 cylinders....I'm ready to light this damn thing on fire

Did you ever check the continuity on that #4 injector circuit all the way from the ECU connection? Any chance you got the polarity swapped when the wires were burned?

Cheers,
GTM

 

[BISHILVR]

try swapping the igniton module (power transistor) out just for the heck of it....

 

[MurdokGST]

I checked for continuity and it checked ou OK...I also replaced the harness to the injector with a new one(I triple checked that I hooked up th wires right) That is why I replaced the ECU...I know the oneI got works because I watched the guy pull it from his car that was running perfect and it is the right on for my exact car. I'm going to do a compression check if it ever warms up because it is 5 degrees and I don't have a garage. I still think it is electrical though just because of the results from the logger. I just don't know anymore

 

[GTM]

Originally posted by MurdokGST
I checked for continuity and it checked ou OK.
...
I'm going to do a compression check if it ever warms up because it is 5 degrees and I don't have a garage. I still think it is electrical though just because of the results from the logger. I just don't know anymore

Oh geepers, don't tell me I got snookered again. When you get in a car you need to listen how it cranks... all cylrs with the same compression or one that sounds weak. You had the plugs out and you knew something was going on with that cylr so if your seat of pants wasn't adequate then a compression chk was in order just for that cylr would have told you yeah or nay. Basics first, then look for additional problems.

Cheers,
GTM