They told me it could not be done...

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GraphiteDak
GenIII

6/21/2004
23:49:24

Subject: They told me it could not be done...
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Earlier this year my company vehicle I had (don't have any more) was a 2000 GMC with the 4.8 Liter engine in it. At one point it started missing really bad. So I used my old school technique to unplug each coil one at a time to find two dead cylinders.

So. I stopped at the local mechanics shop (our company has a full mechanics shop of like 10 to 15 guys to maintain and repair the fleet) and they told me unplugging the wires would result in the O2 sensor being ruined and the injectors would have to be replaced to repair.

Well. I didn't want to leave my truck there to have to drive a temporary one so I got home that night and removed the injectors. I took the plugged ones and used compressed air (100+psi) at the inlet using a simple air nozzle with a rubber tip. While I held it against the injector I had two little allegator style jumpers on the coil. One to +12V of the battery and the other in my hand to repeatedly and quickly touch the - of the battery. While I did this junk shot out of the injector. After doing it a few times I re installed the injectors and the truck ran better than it ever did since I got it!
And within a day the CHECK ENGINE went off and stayed off.
Nothing happened to the O2 sensors. I figured those guys were full of sh*t because I've fixed friends cars where they had coils go bad and not fire on cylinders for miles and those O2 sensors were fine when I installed new coils.

Well. The other day I was fixing my aunts Saturn. It used to belong to my younger bro in law so that's why it is Ricer yellow with the anti roll bar, etc.

So anyway I'm putting in a used steering column because the other one was trashed. The car had been stolen and recovered and had a short ever since.

So When I start it when I was done with the steering column I noticed it missing very badly. Pulled the plug wires one at a time and found the #2 cylinder dead. My Aunt barely touches the gas when she drives so she didn't even notice! How can a 4 banger running on 3 not be noticed????

So I pulled the plugs. The #2 was oil fouled to hell!So I installed NEW plugs and it STILL missed on #2!
So I was then worried about mechanical problems so I grabbed my trusty compression gauge.
Well, it had about 140 PSI so it was DEFFINITELY in good order. That left FUEL as the problem. So I pulled the fuel rail and that #2 injector and did the trick mentioned above. Takes about 5 minutes.
Put it back in and I've never seen this car run so smooth. Even with the A/C on it was smooth and it never was before.

My point of sharing this is that I've done this TWICE now and it worked great. So if someone tells you to get new injectors try blowing them out with high pressure air. All you have to lose is a already plugged injector!
Just remember to only pulse the 12VDC to the injector coil for a split second each time or you may burn it right out. Do that while holding the air to the inlet.

daffydak
GenIII

6/22/2004
00:40:28

RE: They told me it could not be done...
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d@mn graphite!! is there anything you CANT do LOL!!! thats just another reason i need an air compressor!!! :-)

those other non fouled plugs, look a little hot too...

Dan

MOPAR=More Power!!

ZenDak
Dodge Dakota
JOIN HERE

6/22/2004
07:55:26

RE: They told me it could not be done...
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coolness - how long would be too long to hold the 12V to the injector? I take it you probably just want to 'tap' it against the battery,,,but would it really hurt the injector to hold it longer?

Bob Lincoln
Dodge Dakota
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6/22/2004
09:23:42

RE: They told me it could not be done...
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Since it's a dead short across the injector's solenoid coil, more than 5 seconds at a time is risky. The FSM for my Daytona lists that as the time interval to use when dumping fuel pressure to work on the system.

The mechanics were right to warn you that unplugging the wires COULD result in damage to the O2 sensor, from running rich. It COULD happen, not guaranteed to.

Kowalski
GenIII