initial timing setting
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Joined: Oct 2001
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From: Lake Ronkonkoma, N.Y.
initial timing setting
I'm not sure if I should post here or the ECM board so I’m going to post both (sorry) I have 1 question.
I have a 91 z28 with a 383, zz-409cam, AFR 190cc heads, 30#lb SVO injectors @32 psi, custom TPiS Prom for current setup(I know, I know planning on getting into prom burning when I get the money to buy the stuff), Msd 6al and blaster coil, accel distributor.
I was having trouble getting the car to start, I had to step on the pedal to get it to turn over and when it did it ran bad bogged down and detonated. So I lowered the fuel psi down to 32psi from 55psi. I set the timing @ 8* btdc. Now it doesn't bog down, afterfire, backfire, or detonate. But it still won't start on it's own. I adjusted the idle stop all the way out, which I know is not good to do. I'm going to put the fuel psi back up to around 39-42, and adjust the idle stop back a little bit. Ok after all that here's my question.....
****If I have to advance the timing to let's say 10 or 12* btdc to get the car where it will start and idle on it's own, will that throw off the entire timing chart that is preprogrammed into the Prom?***
Thank you in advance to all that reply ....Dan
I have a 91 z28 with a 383, zz-409cam, AFR 190cc heads, 30#lb SVO injectors @32 psi, custom TPiS Prom for current setup(I know, I know planning on getting into prom burning when I get the money to buy the stuff), Msd 6al and blaster coil, accel distributor.
I was having trouble getting the car to start, I had to step on the pedal to get it to turn over and when it did it ran bad bogged down and detonated. So I lowered the fuel psi down to 32psi from 55psi. I set the timing @ 8* btdc. Now it doesn't bog down, afterfire, backfire, or detonate. But it still won't start on it's own. I adjusted the idle stop all the way out, which I know is not good to do. I'm going to put the fuel psi back up to around 39-42, and adjust the idle stop back a little bit. Ok after all that here's my question.....
****If I have to advance the timing to let's say 10 or 12* btdc to get the car where it will start and idle on it's own, will that throw off the entire timing chart that is preprogrammed into the Prom?***
Thank you in advance to all that reply ....Dan
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Joined: Jul 1999
Posts: 10,907
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From: The Bone Yard
Car: Death Mobile
Engine: 666 c.i.
You may have to go "inside" the eprom to adjust Injector PW while cranking. Stock, the base timing is 6* and that should be what you are using. If you find that you NEED to set the base timing to 8* or higher it too shows you need a new eprom.
As for "what will happen" if you need to set the base timing to 10* to get it to fire...if it is too much, you will get detonation when in WOT or high load situations.
As for "what will happen" if you need to set the base timing to 10* to get it to fire...if it is too much, you will get detonation when in WOT or high load situations.
Last edited by Grim Reaper; Apr 5, 2003 at 08:47 AM.
Thread Starter
Junior Member
Joined: Oct 2001
Posts: 89
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From: Lake Ronkonkoma, N.Y.
If the car runs correctly after starting, but while cranking and at low idle doesn’t get enough fuel, then I need to raise the PW of the injectors during start mode correct?
I was thinking that I could test this theory by, Cranking the engine and then have someone pull down on the TPS lever without moving the throttle plates. That would give the ECM an indication to raise the PW?
I’m going to put the Timing @ 6* btdc and work around it. Is any one familiar with the zz-409 cam? I don’t think it’s radical of a cam to give me such low rpm problems, but maybe it is?
If anyone has any other advice, or insight as to what I should look at or do, to fine tune this engine, please take a minute to post it. It will be GREATLY appreciated. I plan on getting everything to read out and tune the prom myself in the near future but as for now I’d like to be able to drive the car around. Meanwhile I will continue to search the boards, for tuning tips. Thanks again to all who reply….Dan
I was thinking that I could test this theory by, Cranking the engine and then have someone pull down on the TPS lever without moving the throttle plates. That would give the ECM an indication to raise the PW?
I’m going to put the Timing @ 6* btdc and work around it. Is any one familiar with the zz-409 cam? I don’t think it’s radical of a cam to give me such low rpm problems, but maybe it is?
If anyone has any other advice, or insight as to what I should look at or do, to fine tune this engine, please take a minute to post it. It will be GREATLY appreciated. I plan on getting everything to read out and tune the prom myself in the near future but as for now I’d like to be able to drive the car around. Meanwhile I will continue to search the boards, for tuning tips. Thanks again to all who reply….Dan
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