454 Mag MPI ran great ..... but only to 4000rpm
10-23-2006, 10:57 AM
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454 Mag MPI ran great ..... but only to 4000rpm
RE: Baja 232 w 454 Mag MPI
Just got the boat back from the shop. The engine got a valve job and new maniforlds.
First time out on the water, it started up great, idled perfectly and ran really smooth. Started building speed, and a 2800rpm, got an alarm. Killed engine, reset alarm and went back out to try again.
This time no alarm, but full throttle was now only 3000rpm. Throttled back and then up and upped full throttle to 4000rpm. Never did get above 4000rpm's even though the engine ran perfectly, no unusual sounds or vibration.
Mechannic scanned engine and indicated a knock sensor alarm had occured. Cleared alarm condition and said to try again. Same result (4000rpm) occured.
Any ideas would be appreciated ......
Just got the boat back from the shop. The engine got a valve job and new maniforlds.
First time out on the water, it started up great, idled perfectly and ran really smooth. Started building speed, and a 2800rpm, got an alarm. Killed engine, reset alarm and went back out to try again.
This time no alarm, but full throttle was now only 3000rpm. Throttled back and then up and upped full throttle to 4000rpm. Never did get above 4000rpm's even though the engine ran perfectly, no unusual sounds or vibration.
Mechannic scanned engine and indicated a knock sensor alarm had occured. Cleared alarm condition and said to try again. Same result (4000rpm) occured.
Any ideas would be appreciated ......
10-23-2006, 11:40 AM
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Re: 454 Mag MPI ran great ..... but only to 4000rpm
Mechanic checked knock sensor, throttle linkage and used timing light to confirm timing. Said all appeared OK and to try running again. Same thing occured .....
Most interesting part, the engine felt much smoother and even more powerful than prior to this service. The only problem seems to be max RPM at WOT.
Most interesting part, the engine felt much smoother and even more powerful than prior to this service. The only problem seems to be max RPM at WOT.
Last edited by StillHaulin@63; 10-23-2006 at 11:42 AM.
10-23-2006, 11:59 AM
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Re: 454 Mag MPI ran great ..... but only to 4000rpm
I would try fuel filter, my engine was doing the same thing this summer at about 4100rpms it felt like it was cutting out .
hope this helps
hope this helps
10-23-2006, 11:59 AM
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Re: 454 Mag MPI ran great ..... but only to 4000rpm
Mine did the exact same thing last week after I replaced the head and manifold gasket.. I set the timing at Top Dead Center (opps).. Ran great, sounded fine.. Just would not run over 3000rpm. The moment it would not get up on I realized my mistake and advanced the timing by hand till she ran 4900/5000rpm. – I’ll hit it with a light next spring.
But double check what was removed or replaced. Timing, Spark plug wires.. Why did you replace the manifold? Did you upgrade in performance?
But double check what was removed or replaced. Timing, Spark plug wires.. Why did you replace the manifold? Did you upgrade in performance?
10-23-2006, 12:05 PM
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Re: 454 Mag MPI ran great ..... but only to 4000rpm
Originally Posted by masi242
I would try fuel filter, my engine was doing the same thing this summer at about 4100rpms it felt like it was cutting out .
hope this helps
hope this helps
Simply felt like full throttle was now at 4000rpm.
10-23-2006, 12:08 PM
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Re: 454 Mag MPI ran great ..... but only to 4000rpm
Check your fuel pressure at the rail. My Scorpion is doing the exact same thing and only has 20psi at the rail and I am told it should be 43 psi. Waiting on fuel pump to get her.
10-23-2006, 12:08 PM
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Re: 454 Mag MPI ran great ..... but only to 4000rpm
Originally Posted by 2 Trick Rick
Mine did the exact same thing last week after I replaced the head and manifold gasket.. I set the timing at Top Dead Center (opps).. Ran great, sounded fine.. Just would not run over 3000rpm. The moment it would not get up on I realized my mistake and advanced the timing by hand till she ran 4900/5000rpm. – I’ll hit it with a light next spring.
But double check what was removed or replaced. Timing, Spark plug wires.. Why did you replace the manifold? Did you upgrade in performance?
But double check what was removed or replaced. Timing, Spark plug wires.. Why did you replace the manifold? Did you upgrade in performance?
BTW .... Replaced maniforld with stock Mercruiser due to leak.
No upgrade involved.
Last edited by StillHaulin@63; 10-23-2006 at 12:50 PM.
10-23-2006, 12:09 PM
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Re: 454 Mag MPI ran great ..... but only to 4000rpm
Originally Posted by Wahoo ATV
Check your fuel pressure at the rail. My Scorpion is doing the exact same thing and only has 20psi at the rail and I am told it should be 43 psi. Waiting on fuel pump to get her.
Thanks .....
