1989 Iroc Z 5.7L 89k miles, bought the car drove it 90 miles home. Tuned it up and ran it, went 14.87 @ 92.91 on a 2.2 60'
I never checked the timing, I never felt confident doing it because I wasn't well read on EFI so I just assumed it was stock.
Well I am going to the track this Friday, have read up on timing on TPI motors, and decided to bump the timing up from stock. I bought a timing light, unplugged the EST wire and checked the timing. It doesn't show up on the timing tab. If the timing tab were longer, I can only guess that it was set at 15 or 16 degrees initial. I think that can't be right, and borrow my dad's high dollar timing light thinking mine was a POS. Sure enough, timing is set to 15/16* initial.
I am excited to run it on Friday, I retarded it 6* to 10* initial and it picked up a ton of top end
. I also swapped my converter to a 2800 converter so I am hoping to post some better times this go around.
And I guess the moral of the story is this was probably a case of "time it by ear", I can't imagine why else the initial would be that far off. I never noticed the car pinging but I always run good gas in it.
I never checked the timing, I never felt confident doing it because I wasn't well read on EFI so I just assumed it was stock.
Well I am going to the track this Friday, have read up on timing on TPI motors, and decided to bump the timing up from stock. I bought a timing light, unplugged the EST wire and checked the timing. It doesn't show up on the timing tab. If the timing tab were longer, I can only guess that it was set at 15 or 16 degrees initial. I think that can't be right, and borrow my dad's high dollar timing light thinking mine was a POS. Sure enough, timing is set to 15/16* initial.
I am excited to run it on Friday, I retarded it 6* to 10* initial and it picked up a ton of top end
. I also swapped my converter to a 2800 converter so I am hoping to post some better times this go around.And I guess the moral of the story is this was probably a case of "time it by ear", I can't imagine why else the initial would be that far off. I never noticed the car pinging but I always run good gas in it.
So out of curiosity, was I running a ton of total advance with it set like this? I know on a non computer controlled setup, if I was running that much initial that would have been well into the 40's for total advance. Would the computer have prevented that from happening?
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built91Z28
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Feb 22, 2013
I'm not real educated on EFI, but I think that it would have tried to advance it into the 40's at high rpm. But I think there is a knock sensor that would have retarded it if it sensed knock.
The computer doesnt actually know what the timing is actually at at any given time. Its assuming its set to factory and advancing from that assumption.
The computer doesnt actually know what the timing is actually at at any given time. Its assuming its set to factory and advancing from that assumption.
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The computer doesnt actually know what the timing is actually at at any given time. Its assuming its set to factory and advancing from that assumption.
That's exactly what I was thinking.Originally Posted by built91Z28
I'm not real educated on EFI, but I think that it would have tried to advance it into the 40's at high rpm. But I think there is a knock sensor that would have retarded it if it sensed knock.The computer doesnt actually know what the timing is actually at at any given time. Its assuming its set to factory and advancing from that assumption.
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Quote:
The computer doesnt actually know what the timing is actually at at any given time. Its assuming its set to factory and advancing from that assumption.
Yep. - These OBD1 computers/sensors are kinda late to sense knock though, and when they do they pull a metric-crap-ton of timing out in an instant to save it, thus the power falls off exponentially. Originally Posted by built91Z28
I'm not real educated on EFI, but I think that it would have tried to advance it into the 40's at high rpm. But I think there is a knock sensor that would have retarded it if it sensed knock.The computer doesnt actually know what the timing is actually at at any given time. Its assuming its set to factory and advancing from that assumption.
I bet your cruising speed timing was in the 50-60* range with that much initial.
Quote:
I bet your cruising speed timing was in the 50-60* range with that much initial.
WOw Originally Posted by Shagwell
Yep. - These OBD1 computers/sensors are kinda late to sense knock though, and when they do they pull a metric-crap-ton of timing out in an instant to save it, thus the power falls off exponentially. I bet your cruising speed timing was in the 50-60* range with that much initial.
lol