98 454 Mag Mpi mid range missfire
05-14-2019 | 02:50 PM
#42
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05-14-2019 | 07:50 PM
#48
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From: Slidell, La.
I have the same engines. Mine (oddly both) were bogging/Missing above 4000 rpms. Noticeable loss in power and sounded like the engines were grunting over 4500 but with no additional power.
I had 2 issues over a period of time. Both similar to what you are seeing.
1. Vacuum lines were hard and leaking. they are supposed to pull vacuum on the fuel regulator to restrict the bypass on the fuel rail to supply the extra fuel needed at higher RPMS.
2. This lil bastard caused me grief for 4 years!! Loss of power above 4K. Finally had a TPS issue borrowed a scanner and found knock sensors on both engines. It was locking the timing above 4K to protect the engines. Had to replace 1 sensor and clear them. Runs like champ! Get a programmer to rule it out! Looks like you may have used the lil merc flashing reader, but I would rather see it on the read out.
I had 2 issues over a period of time. Both similar to what you are seeing.
1. Vacuum lines were hard and leaking. they are supposed to pull vacuum on the fuel regulator to restrict the bypass on the fuel rail to supply the extra fuel needed at higher RPMS.
2. This lil bastard caused me grief for 4 years!! Loss of power above 4K. Finally had a TPS issue borrowed a scanner and found knock sensors on both engines. It was locking the timing above 4K to protect the engines. Had to replace 1 sensor and clear them. Runs like champ! Get a programmer to rule it out! Looks like you may have used the lil merc flashing reader, but I would rather see it on the read out.
05-14-2019 | 10:39 PM
#49
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Joined: May 2019
Posts: 24
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I have the same engines. Mine (oddly both) were bogging/Missing above 4000 rpms. Noticeable loss in power and sounded like the engines were grunting over 4500 but with no additional power.
I had 2 issues over a period of time. Both similar to what you are seeing.
1. Vacuum lines were hard and leaking. they are supposed to pull vacuum on the fuel regulator to restrict the bypass on the fuel rail to supply the extra fuel needed at higher RPMS.
2. This lil bastard caused me grief for 4 years!! Loss of power above 4K. Finally had a TPS issue borrowed a scanner and found knock sensors on both engines. It was locking the timing above 4K to protect the engines. Had to replace 1 sensor and clear them. Runs like champ! Get a programmer to rule it out! Looks like you may have used the lil merc flashing reader, but I would rather see it on the read out.
I had 2 issues over a period of time. Both similar to what you are seeing.
1. Vacuum lines were hard and leaking. they are supposed to pull vacuum on the fuel regulator to restrict the bypass on the fuel rail to supply the extra fuel needed at higher RPMS.
2. This lil bastard caused me grief for 4 years!! Loss of power above 4K. Finally had a TPS issue borrowed a scanner and found knock sensors on both engines. It was locking the timing above 4K to protect the engines. Had to replace 1 sensor and clear them. Runs like champ! Get a programmer to rule it out! Looks like you may have used the lil merc flashing reader, but I would rather see it on the read out.
https://www.ebay.com/itm/ECU-Chip-Tu...-/272270940170
