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87 tbi issue after tune up truck died!!!! UPDATE BLAZER IS RUNNING!!!!
- Thread starter isaac
- Start date
well guys thanks for all my fellow k5'rs i would just like to thank all of you guys that helped me out! i took out the old ignition control moduel had it tested at the autoparts store and whamo it was the problem. got a new one swapped it out and the truck runs like a champ! so have one final question somoene was telling me having my timing set to 0 degrees could be an issue since we are at 5500 feet above sea level here in albuquerque new mexico is that true? and if so what should i set my timing at? thanks again all.
isaac
isaac
Stomis
Professional Amateur
Timing shouldnt be 0*. It should be 4-7* depending on exact year of truck for TBI with the ECM wire unplugged on the firewall.
4xcrazy
3/4 ton status
timing SHOULD BE 0*, the computer compensates fully on which way it needs to go.
with the wire unplugged
well i hope i did it correctly i put the timing at 0* with the wire unpluged just like the book says. but i have had a couple of people tell me to set it to 4* due to the higher elevation. so i guess i will run it at 0* and see how it runs....
4xcrazy
3/4 ton status
mine's been set at 0* forever, and it's also been through several different elevations over it's life, never had ANY issues with the way it runs,.
Thunder
3/4 ton status
Timing should be at 0 degrees. With bypass disconnected. The MAP sensor can sense ambient air pressure. ECM knows what elevation you are in and adjusts fuel/timing accordinaly.
You can add more initial timing usually up to 4 degrees. But if the fuel pressure is too low you can get detonation, The ECM will see this Thur the knock sensor. ECM will keep reducing timing in 1 degree incriments up to 20 total degrees. Till detonation goes away. So there is no real advantage to setting the timing over 0. unless you have an adjustable fuel pressure regulator and can tune the fuel pressure for the more advance added.
You can add more initial timing usually up to 4 degrees. But if the fuel pressure is too low you can get detonation, The ECM will see this Thur the knock sensor. ECM will keep reducing timing in 1 degree incriments up to 20 total degrees. Till detonation goes away. So there is no real advantage to setting the timing over 0. unless you have an adjustable fuel pressure regulator and can tune the fuel pressure for the more advance added.
Stomis
Professional Amateur
Last time this was up for discussion I checked all data and it said between 3-7* depending on year. I guess it really dont matter at all seeing as how the computer will take it out to as advance as it can go with no detonation correct?
Thunder
3/4 ton status
Every TBI truck I have ever seen says 0 degrees. It is clearly stated on the emissions sticker in the front of the engine compartment on the radiator support.
Dont know about all Data's info
Like i said you can set more inital timing but you should use a scanner or ALDL to monitor knock counts to see if you are rich enough at higher RPMs to keep from detonating. As long as you are not detonating and the ECM is not pulling timing. You will get a little better performance at WOT.
I run around 13 PSI fuel at 4 degrees advance for best combo on MPG and performance.
Dont know about all Data's info
Like i said you can set more inital timing but you should use a scanner or ALDL to monitor knock counts to see if you are rich enough at higher RPMs to keep from detonating. As long as you are not detonating and the ECM is not pulling timing. You will get a little better performance at WOT.
I run around 13 PSI fuel at 4 degrees advance for best combo on MPG and performance.
K5dreamer
1/2 ton status
silly carb guys trying to tune EFI 
Thunder
3/4 ton status
silly carb guys trying to tune EFI
EFI is infinitely more tunable than a carb... maybe you should look around and get out of the stone age.
K5dreamer
1/2 ton status
EFI is infinitely more tunable than a carb... maybe you should look around and get out of the stone age.
lol got it backwords buddy, im a devoted follower of computer controlled fuel delivery. I was stating that most often its the older guys used to tuning carbs that bring up the altitude issue, and suggest rejetting the throttle body (yes ive actually heard that suggestion) or adjusting the timing for the altitude despite the computer controled ignition system.
