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  • Name
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    The only "Shire" in the USA !
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    Formula Firebirds, Old GM ( EMC and EMD)2 stroke diesel trains
  • Drives
    GMC 2500HD Firebird Formula 455

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Formulabruce's Achievements


Enthusiast (6/11)



  1. Adding a capacitor ( noise suppressor) is an old trick that used to work well, and may just fix this. ( credit to Pizza) The Body control module ( all cab functions) GROUND is UNDER the truck, on the DS, right under the DS door on the CAB mount Extension facing the REAR of the truck. These ground wires need to be removed and cleaned well, and frame cleaned. After put some waterproof GREASE on it.. Did you do this ground?
  2. My vote get some THROTTLE BODY Cleaner ( ONLY use specific Throttle body cleaner) pull off the air intake giant hose clamp, and hose, and clean, clean, clean, and back side of the throttle plate too. All it takes is a Little dirt to cause this.
  3. The problem lies with whats called a Ground loop. The radio, for lack of a better term, is using the speakers as a ground. Pull the radio. If you used an adapter pigtail, make sure you Solder the power and ground leads. Check the ground wire size, make sure its same as power. Check the ground wire ( truck off, key out) coming to the radio, to truck ground with a ohm meter. I turn on the beep on my meter, so I don't have to look at the resistance. Probably a NEW ground wire from the chassis of the radio, to a GOOD truck ground, ( possibly one of the 2 cigar /12 volt outlets below) will do the trick. Good luck!
  4. BCM Ground. Driver side CAB Extension mount ( just under the DS door) On the mount, facing rear are a bunch of wires grounded to the mount. Remove, clean WELL, then grease/woolwax after re installing. Cost... about Free... Still have issues? Grounds at back of engine to Firewall..
  5. I only use Dex 3 compatible, and ALWAYS re use the original Rubber pan gasket on the 4L80E. the aftermarket gaskets are folded paper. ter originals are rubber with metal inside and very durable. Im not sure the 1/2 ton HD gets a 4L80 though...
  6. Get a good used 6L90. You'll need a harness and a controller to run the 4l80, and the link to the current truck harness will not match. Even making the 4L80 a manual shifting trans will still cost more and then youll still need a lock up connection. Call these guys. The 6L90 IS actually a more rugged transmission. whats wrong with it? https://www.justchevytrucks.com/
  7. So, did you do the grounds on the frame extension below the drivers side door, facing the rear of the truck? If not, better get those wires and frame clean, and cover it with marine grease after.
  8. Check the grounds on the brakes. some controllers are more sensitive. The grounds are usually a metal magnetic disc that moves and tightens the arms/shoes. These, and the area they ride on can get rustly
  9. DOT 4.5 is THE Highest you can go. It has a slightly higher boiling point, still synthetic.
  10. When replacing, I use "Copper" Never size to add a 3rd dissimilar metal between the threads. I get no corrosion of any type. There are brackets to hold the manifold tight on the DS rear if you want a quick fix, but it bolts to the back of the head.
  11. Does this have a 2500 HD cooling set up, or is it the 1/2 ton electric? Clutch on fan can cause this if the 2500 type. time for pics and more facts
  12. No Bose in AA pillars or Console, only 6 speakers and that's 2 in the front doors and one each in back doors. The Sub is NOT available with a regular cab , OR a split front bench seat. So , if ordered, its priced according to your seating. I believe you could order the bose, even with front buckets, and NOT check the "Sub" box, and get what you have, which is very common by the way.
  13. I have had to repair the wiring to the 4wd on or off sensor on WT's . right at the sensor it can get brittle.
  14. And I would agree. The 3.73 was available with a Diesel in a HD as well. I suppose one could have ordered a 3.73 truck, but its odd to have a Towing package and HD coolers. I have seen some 1500HD set up like this with the semi floater rear and the non straight frame in the rear. Typically a 2500 has a bent style rear frame like the 1500HD( 1500 HD only available in Crew cab ) Typically a 2500HD will have a big straight 'C" channel at the rear.
  15. I have seen new aftermarket coils do this.
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