Rough idle running rich maybe
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Mountain Pass
Joined: Apr 2015
Posts: 247
Likes: 0
From: Conroe,TX
Rough idle running rich maybe
Ok hope this does not turn into a long post but want to give as much info as possible to maybe help you guys narrow it down.
My truck is a 1990 F250 HD has 5.8 351w with Comp cam with new springs on heads cannot remember the number but was recommended by Conaski also shorty headers, recently rebuilt have 9000 miles on the rebuild, oil changed and broke in properly with zinc added for break in. It had new plugs,cap,rotor,wires and all that stuff when you rebuild.
In the beginning I had the computer go so I replaced it with one from a yard and fixed the one I have but the one from the yard is still in the truck.
I was not getting any codes but still had a high idle issue so replaced the TPS,Coolant sensor and temp sending unit for the gauge along with a good cleaning of the throttle body. I have not replaced the MAP or the EGR I did away with the air injection stuff but kept the components hooked up to keep from a CEL Also replace all vacuum lines.
Seemed that I fixed that then about a month back it just started well kinda running rough not bad but just a rough idle kinda dismissed that well then I started getting a shudder which happens I think when it shifts to OD the truck will shake if I push the OD switch it will kinda goes away, but I think it just makes the RPMs highs so the shudder just smooths out but is still there. I looked around then and found a spark plug cap hanging off so checked all those and the coil tip broke so replace the coil also.Also it has been mention to me that it smells rich, maybe I am immune LOL
One other thing is that here recently the CEL has been flickering when it warms up and the shudder does not get bad till it gets a little warmer also.
I am currently offshore I get off and home Christmas Day and I plan on retrieving what codes are there and will post those.
One question I have is when I rebuilt the motor I do not recall an O2 sensor again I will look for one when I get home but again I do not remember one being there or hooking anything like that back up when I installed the motor.
Sorry for being long winded but would rather give to much info than not enough. TIA
My truck is a 1990 F250 HD has 5.8 351w with Comp cam with new springs on heads cannot remember the number but was recommended by Conaski also shorty headers, recently rebuilt have 9000 miles on the rebuild, oil changed and broke in properly with zinc added for break in. It had new plugs,cap,rotor,wires and all that stuff when you rebuild.
In the beginning I had the computer go so I replaced it with one from a yard and fixed the one I have but the one from the yard is still in the truck.
I was not getting any codes but still had a high idle issue so replaced the TPS,Coolant sensor and temp sending unit for the gauge along with a good cleaning of the throttle body. I have not replaced the MAP or the EGR I did away with the air injection stuff but kept the components hooked up to keep from a CEL Also replace all vacuum lines.
Seemed that I fixed that then about a month back it just started well kinda running rough not bad but just a rough idle kinda dismissed that well then I started getting a shudder which happens I think when it shifts to OD the truck will shake if I push the OD switch it will kinda goes away, but I think it just makes the RPMs highs so the shudder just smooths out but is still there. I looked around then and found a spark plug cap hanging off so checked all those and the coil tip broke so replace the coil also.Also it has been mention to me that it smells rich, maybe I am immune LOL
One other thing is that here recently the CEL has been flickering when it warms up and the shudder does not get bad till it gets a little warmer also.
I am currently offshore I get off and home Christmas Day and I plan on retrieving what codes are there and will post those.
One question I have is when I rebuilt the motor I do not recall an O2 sensor again I will look for one when I get home but again I do not remember one being there or hooking anything like that back up when I installed the motor.
Sorry for being long winded but would rather give to much info than not enough. TIA
Thread Starter
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Mountain Pass
Joined: Apr 2015
Posts: 247
Likes: 0
From: Conroe,TX
Ok so lets try this again, I know punctuation is not my strong suit or maybe no one has a clue but I know that's not true. Lets try this is there a O2 sensor on a 90 F250 HD 351W
Fleet Mechanic
Joined: Jan 2013
Posts: 1,305
Likes: 8
no worries, your post was quite readable.
a lot of people are celebrating the winter solstice, but eventually one of the real gurus will be along.
until then ... yes, your truck came from the factory with an oxygen sensor, but now that you have aftermarket headers it may be missing ? that would certainly explain a rich condition.
also, a flickering CEL is not healthy. try pulling codes.
a lot of people are celebrating the winter solstice, but eventually one of the real gurus will be along.
until then ... yes, your truck came from the factory with an oxygen sensor, but now that you have aftermarket headers it may be missing ? that would certainly explain a rich condition.
also, a flickering CEL is not healthy. try pulling codes.
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