well i was wondering, i saw that vin decoder site on here, and decided to check it out, BUT what i was wondering, is when i do the engine swap, do i have to change the VIN to match the engine and new check digit?

I was also wondering about something else... i noticed today that my truck was running rich. and i know the EGR is out, so i was wondering if the EGR being out, if it would make my truck run rich..

and one last thing, how do you reset the computer on our trucks?

 

No, you cannot change your trucks vin. If you're into classic cars, thats the meaning of the term "numbers matching"... whether or not the engine, transmission, etc matches what the vin says it should be.

I don't know if the EGR will make it run rich or not, your o2 sensor could be giving out. One questions though... does your truck get up to running temperature? If not, it is still in its open loop, which defaults it to run rich.

To reset the computer, unplug power to it for 10-15 minutes or so. If you really want to completely reset everything in it, leave it unplugged overnight.

 

yeah it does, it usually overheats at first (only for like the first few min, but i have a 180 thermo on the way), and then cools down to running temp. i was thinking the o2 sensors too, mainly because the engine has burnt up so much oil for so long, that i bet those things are caked... and also i was thinking thats why my EGR crapped out, would i be able to just clean it and hope it functions properly?

and as for resetting the computer, i saw somewhere (cant remember where) that to reset a computer, you have to disconnect the negative battery cable, turn the key to "start" for 15-20 seconds and then reconnect the battery, start the vehicle, let idle for 15-20 seconds, shut the vehicle off, and then you can start it and drive it normally. the only reason i asked you guys, was because i wanted to know if it was a different way...

 

Here's a basic run-down of how the ECM works... Imagine the ECM has a hard drive like a PC, that stores instructions on what to do with a specific vehicle. These instructions are like "general rules" for any vehicle and will run the vehicle, but not well. The ECM also has flash memory, like the RAM in your PC, which takes input from the various sensors and "fine tunes" the set of instructions stored in the hard drive to your specific vehicle and how you drive it. For instance, if you like the upper rmp range, it will fine tune the air/fuel maps and spark timing to run best in the upper rpm range and vise versa if you like driving in the lower rmp range. Also, if you live at high elevation or sea level, it will fine tune the maps accordingly.

If you think about it like a PC, if you put your PC on standby, the RAM is stored for when you come back and turn it on. That is like turning your car off. If you shutdown your PC, it will clear the RAM, which is like unplugging power to the ECM in your truck. If you leave power unplugged to the ECM for 15+ minutes, it will reset the RAM and clear all stored data. Then you will have to warm your truck back up and drive it around for 20 miles or so (I've heard all different numbers here) in whatever driving habits you will be driving with most, so the ECM can "re-learn" what was cleared from the flash memory.

 

makes sense, i was just making sure...

 

Im not trying to take your thread but does anyone know what kind of computer the 87s have if any

 

is it a carb or TBI? if its a carb, theres no computer, but if its TBI, im not sure on the part number, but any computer from '87-'91 will run the truck

 

It is carbed but theres some things (not sure at the moment) that ive read that say the carb is "computer controlled" but I dont really know

 

If there is a computer on carbed it may be for the ignition timing or for the choke or emission controls. That's all I could think of.