Donzi 377 scorpion timing/idle issue
08-06-2021 | 11:33 AM
#21
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08-06-2021 | 11:35 AM
#23
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From: On A Dirt Floor
08-06-2021 | 11:41 AM
#24
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From: On A Dirt Floor
https://www.mercruiserparts.com/bam/...31458/2725/120
You can see IAC (GM pintle type) from frt of tbody with Flame Arrestor off. You can plug with your finger or etc too.
Give me a ring when you have time
08-06-2021 | 04:00 PM
#25
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Okay. I have the diagram /parts microfiche
https://www.mercruiserparts.com/bam/...31458/2725/120
You can see IAC (GM pintle type) from frt of tbody with Flame Arrestor off. You can plug with your finger or etc too.
Give me a ring when you have time
https://www.mercruiserparts.com/bam/...31458/2725/120
You can see IAC (GM pintle type) from frt of tbody with Flame Arrestor off. You can plug with your finger or etc too.
Give me a ring when you have time
08-06-2021 | 09:47 PM
#27
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What’s up guys. So this may be a long one, but anyhow. I bought a boat back in may that had a cracked block on the port side. The starboard side runs fantastic. Smooth responsive no codes, service mode with a paper clip method works well. Even with a scanner too. I verified in service mode I have 8 degrees BTDC. Engine runs like a champ. Looks original with boat saying 440 hours but ecu reads 280.
now, onto the port side. Removed the engine. Found out it is a 383 already with the WRONG compression. Was upwards of 10.3/4:1. Luckily I did some math to find that out before getting a new block, piston combo. Had the machine work done and they assembled the long block. I did lifters, intake manifold and dressed it. Compression is 9.1:1 now which factory is 9.0:1.
I am have a very hard time trying to set timing on the new engine.
key on. Insert clip. Start, try to get base time where it needs to be. Even 5-6 the more is very responsive BUT out of service mode the idle increases?? I can only get about 1 degree and idle stay at 750 fully warmed up out of service mode. Is there any reason why increasing timing would increase idle?? I’m thoroughly confused. I’ve tried swapping throttle bodies. Map sensor. All from the good engine that runs. Similar results.
I did forgot to mention that I had to have a cam custom made to the original specs which I found same lsa 114. Same lift etc.
vaccumm on good starboard engine is 16 at idle
new engine is 10-11 at 0-1 degree BTDC.
VOLTAGE is 13.x
the map sensors read at 5hg diff as well. Would this maybe be a vaccum leak im chasing? To cause this issue??
when I get timing to 7 degrees idle is now up to 1500ish.
maybe I am doing something wrong?
Any and all advice would be greatly appreciated.
now, onto the port side. Removed the engine. Found out it is a 383 already with the WRONG compression. Was upwards of 10.3/4:1. Luckily I did some math to find that out before getting a new block, piston combo. Had the machine work done and they assembled the long block. I did lifters, intake manifold and dressed it. Compression is 9.1:1 now which factory is 9.0:1.
I am have a very hard time trying to set timing on the new engine.
key on. Insert clip. Start, try to get base time where it needs to be. Even 5-6 the more is very responsive BUT out of service mode the idle increases?? I can only get about 1 degree and idle stay at 750 fully warmed up out of service mode. Is there any reason why increasing timing would increase idle?? I’m thoroughly confused. I’ve tried swapping throttle bodies. Map sensor. All from the good engine that runs. Similar results.
I did forgot to mention that I had to have a cam custom made to the original specs which I found same lsa 114. Same lift etc.
vaccumm on good starboard engine is 16 at idle
new engine is 10-11 at 0-1 degree BTDC.
VOLTAGE is 13.x
the map sensors read at 5hg diff as well. Would this maybe be a vaccum leak im chasing? To cause this issue??
when I get timing to 7 degrees idle is now up to 1500ish.
maybe I am doing something wrong?
Any and all advice would be greatly appreciated.
08-09-2021 | 10:18 AM
#30
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Joined: May 2021
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before the other engine had a miss it was doing 52 at 3400 rpm on the gps
FIXED! : IAC was not moving. had a bad connection with one of the wire. went right into service mode now and timing set! Took it out on the water. now the other engine has a miss.i cant win. pretty heavy miss. used a tester and all wires are firing. injectors where just freshened up and had a great bill of health. wonder if rocker or spring broke. 450 hours on this engine. Was planning on doing top ends over the winter.
FIXED! : IAC was not moving. had a bad connection with one of the wire. went right into service mode now and timing set! Took it out on the water. now the other engine has a miss.i cant win. pretty heavy miss. used a tester and all wires are firing. injectors where just freshened up and had a great bill of health. wonder if rocker or spring broke. 450 hours on this engine. Was planning on doing top ends over the winter.
Last edited by hypforlife32; 08-09-2021 at 11:09 AM.
