ChopperbobII
Austin, Tx
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My friend and I were trying to figure out why his 8.1 eng on his
Alegro was missing. We hooked up my code reader and no codes.
He took it in and it turned out that the injectors were fouled causing
the missfire. They replaced all the injectors and cleaned the rails becouse they couldnt find new ones. Why didnt it throw a code?
Bob
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jesterdog
Texas
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Joined: 05/04/2007
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Maybe because it can't sense for that condition? The spark was working. The injector was firing (but nothing was coming out). I would have thought that at some point the O2 sensor would have sensed too rich exhaust.
These are just guesses...
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Gale Hawkins
Murray, KY
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Joined: 07/22/2007
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ChopperbobII wrote:My friend and I were trying to figure out why his 8.1 eng on his
Alegro was missing. We hooked up my code reader and no codes.
He took it in and it turned out that the injectors were fouled causing
the missfire. They replaced all the injectors and cleaned the rails becouse they couldnt find new ones. Why didnt it throw a code?
Bob
Mention to him about doing a google search on Sea Foam to prevent this in the future. I think the quality of fuel is going down instead of up.
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amxpress
Clayton, NC
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I have successfully cleaned injectors without having to replace them. If they are OK electrically and just restricted, they could have been flushed with a good injector cleaner.
If they were that bad, he might consider replacing the fuel filter, too.
The previous response of adding Sea Foam...good idea to add a quality in tank injector cleaner to keep it from happening again. If it does, flush them, don't replace them.
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Daveinet
il
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If there is no fuel at all, it will not make it rich or lean, you just have one cylinder that is doing nothing. Its as if that cylinder does not exist. If you have an injector sit for a long period of time, it can stick shut. Most of the time, we think of injectors that get clogged and stick partially open which the computer would sense. But if the injector is stuck closed, or if no fuel is passing through, the computer does not see it. I suspect because it is a motorhome, that it sits unused sometimes, which made the injector stick. Often a wack with a screw driver handle and it will be perfectly fine.
All the after market fuel injection systems will tell you that it is very common for new injectors to stick shut. Its a normal procedure the first time you fire it up to have to smack a few injectors to knock them loose. Mine all worked the first time, but that is not always the case.
Dave
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spamtownr
Austin, MN
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Joined: 02/15/2009
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$5 says it either the back 2 plug wires... most likely 5 or 7. It could be 6 or 8 also.
Rog
04 Newmar Mountain Aire
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spamtownr
Austin, MN
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$5 says it either the back 2 plug wires... most likely 5 or 7. It could be 6 or 8 also.
If it were me I would start looking at the misfire count and see which cylinder shows up. You will need a good scanning tool to get this type of info.
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lfeather
Titusville, FL
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spamtownr wrote:$5 says it either the back 2 plug wires... most likely 5 or 7. It could be 6 or 8 also.
That's exactly what I was thinking!. I had that engine and it missed frequently and every time it was the back plug wire melting. Replaced them three times before I traded for a diesel.
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jesterdog
Texas
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Daveinet wrote:If there is no fuel at all, it will not make it rich or lean, you just have one cylinder that is doing nothing. Its as if that cylinder does not exist. If you have an injector sit for a long period of time, it can stick shut. Most of the time, we think of injectors that get clogged and stick partially open which the computer would sense. But if the injector is stuck closed, or if no fuel is passing through, the computer does not see it. I suspect because it is a motorhome, that it sits unused sometimes, which made the injector stick. Often a wack with a screw driver handle and it will be perfectly fine.
All the after market fuel injection systems will tell you that it is very common for new injectors to stick shut. Its a normal procedure the first time you fire it up to have to smack a few injectors to knock them loose. Mine all worked the first time, but that is not always the case.
Yeah, makes sense. I don't know what I was thinking about burning rich...less fuel means lean. LOL! No fuel means no burn. Thanks for the info about rapping the injectors witha screwdriver...
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dezertcamper
San Diego
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spamtownr wrote:$5 says it either the back 2 plug wires... most likely 5 or 7. It could be 6 or 8 also.
If it were me I would start looking at the misfire count and see which cylinder shows up. You will need a good scanning tool to get this type of info.
Good advice as this is a problem with the 8.1 in class A RV's that have tight dog houses and dont get good air flow.
But my question to you is, did you read what the original poster wrote? Becuase he said they had a misfire that did not throw a code, and the scanner did not pick this up. And once diagnosed it was found to be a faulty injector.
So go ahead and send me that $5 please! LOL!
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