ohhh yes timing
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Joined: Nov 2002
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From: Corpus Christi Texas
Car: 1990 rs, pride and joy
Engine: 305 tbi
Transmission: t-5
ohhh yes timing
Today i go to check my timing for the first time after i changed spark pulg and wires. I disconnect the tan with black stripe wire and it reads at 0*. ALso when i disconnected the wire i notice the car ran like crap actting like it wants to die then come back. So i re connect the wire and notice that the timing marks are way off. I mean it doesn't even line up with the little degee marks on the engine. A good inch or two after it. Any comments of why it would be way? I have a 305 tbi 90 rs
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Joined: Nov 2002
Posts: 161
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From: I am all around you
Car: Formula
Engine: 5.0L
Transmission: 700R-4
When you replace the timing chain/gears there are markings on the gears that have to line up...sometimes these gears get put on backwards or upside down (I have found two like that myself)...You will have to time it by ear...advance the timing until you can hear knocking when you accelerate or rev the engine, then back it off until you get the best power/gas milage, which ever you are going for...alittle time consuming but definately better than dissasembling the front of the engine to fix the gears...then again I could be way off in my diagnosis, I think you could still benefit from adjusting your timing the way I described...good luck
Uh, no,
what you have described is perfectly normal
When you disconnect the ESC wire the engine is running purely off of the timing advance you have mechanically dialed in at the distributor. When the ESC is connected the ECM takes over and dials in the advance that has been preprogrammed in the chip for that RPM, MAP pressure, vehicle temp, etc. This will usually be around 20 degrees give or take a few degrees depending on vehicle, operating conditions, chip, etc.
The reason it wants to die when you disconnect it and run it at zero is that the car doesnt like 0 degrees of timing at idle, that is why GM engineers programmed much more than that in the chip (when you plug it in it goes way up).
When you adjust base timing you add or subtract timing to the whole rpm and load range.
While zero is the factory setting (for TBI cars anyways) youll probably want to add a little bit more than 0 for better performance.
Try 4
what you have described is perfectly normal
When you disconnect the ESC wire the engine is running purely off of the timing advance you have mechanically dialed in at the distributor. When the ESC is connected the ECM takes over and dials in the advance that has been preprogrammed in the chip for that RPM, MAP pressure, vehicle temp, etc. This will usually be around 20 degrees give or take a few degrees depending on vehicle, operating conditions, chip, etc.
The reason it wants to die when you disconnect it and run it at zero is that the car doesnt like 0 degrees of timing at idle, that is why GM engineers programmed much more than that in the chip (when you plug it in it goes way up).
When you adjust base timing you add or subtract timing to the whole rpm and load range.
While zero is the factory setting (for TBI cars anyways) youll probably want to add a little bit more than 0 for better performance.
Try 4
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