7.4 MPI very sluggish
#1
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7.4 MPI very sluggish
i have a 1998 7.4 MPI that is a turd out of the hole takes forever to get on plane had a computer hooked up to it tonight and at wide open throttle the timing advance is only 15 degrees total if i ease into the throttle the advance will go up to 26 degrees total but after a certain point it drops to 15 the engine only has 200 hours on it i have changed computers, throttle bodys with the iac and tps, and distributors and nothing seems to make a difference base timing is set at 8 degrees BTDC it does not miss and there are no codes i lost about 10 mph from the old engine ( which i blew up ) to this one and i am pretty sure i will get that back once i get it running right anyone have any ideas ?? thanks Ed
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#2
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Fixx
i have a 1998 7.4 MPI that is a turd out of the hole takes forever to get on plane had a computer hooked up to it tonight and at wide open throttle the timing advance is only 15 degrees total if i ease into the throttle the advance will go up to 26 degrees total but after a certain point it drops to 15 the engine only has 200 hours on it i have changed computers, throttle bodys with the iac and tps, and distributors and nothing seems to make a difference base timing is set at 8 degrees BTDC it does not miss and there are no codes i lost about 10 mph from the old engine ( which i blew up ) to this one and i am pretty sure i will get that back once i get it running right anyone have any ideas ?? thanks Ed
#3
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according to the computer the knock sensor is working but not sensing any detonation so it doesnt appear to be retarding the timing we took a hammer and was tapping the block by it and could see it working i have also tried premiun fuel and it didnt make a difference on another board someone said maybe it is a fuel delivery issue i never checked the fuel pressure but i will this weekend on the water
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#4
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i found this module that is bolted to the back of the engine called a spark advance module but it is not going to be easy to get to to change it kind of wondering what some one elses thought is on this if it could possibly be the problem
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Fixx
have you had your injectors cleaned? their are screens in the top of them and after they get plugged with cotton from the filter and causes the motor to go lein..send thsm out and have them back flushed and new screens put in them..you will loose about 1000 rpms if their plugged up..
#7
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my boat is a 272 baja and since i have changed engines this summer due to a major brain fart on my end the best i have gotten out of it is 48 going with the current on the saint clair river everytime i change something on it it has been getting slower to the point i couldnt get it over 9.5 mph last weekend only thing is mine doesnt miss a beat it will hit the rev limiter out of gear but wont get out of its own way under a load
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my boat is a 272 baja and since i have changed engines this summer due to a major brain fart on my end the best i have gotten out of it is 48 going with the current on the saint clair river everytime i change something on it it has been getting slower to the point i couldnt get it over 9.5 mph last weekend only thing is mine doesnt miss a beat it will hit the rev limiter out of gear but wont get out of its own way under a load
#9
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have you had your injectors cleaned? their are screens in the top of them and after they get plugged with cotton from the filter and causes the motor to go lein..send thsm out and have them back flushed and new screens put in them..you will loose about 1000 rpms if their plugged up..
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#10
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but that is why i bought my boat for the fuel injection i hate carbs i have had way more problems with them in my lifetime than i ever have had with injection until now
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