Jump to content

bad misfire at idel


Recommended Posts

ive got a 94 with 263000 on it and it started to miss a while back. the temp was about 30 degrees cooler on the exhaust manifold on the 6th cylinder so i thought it was injectos so i replaced all of them and got 50 horse while i was at it. well not it has gotten worse and i assume thats because the bigger injectors make it more noticable. im not sure what else it could be. ive cracked the lines at the pump and they all drop the same in idle when i do. its worse at idle around 1100 and you can tell the lose of power when you drive down the road. plus it just sounds horrible and has a lope to it. any ideas on how to fix thos or even where to start. ive changed the fuel filter about 1000 ago all the air was bled out of the lines from the pump to the nozzels after i was done and im not sure where to go now. anything helps

Link to comment
Share on other sites

They sound exactly the same when you crack each one? Do it again but crack them at the injectors one at a time. There is something at 1100RPM that makes everything more noticable than other RPM's. It's fast enough to make the noise really loud but not fast enough to smooth it out. Mine did the same thing when I put an injector together wrong, but you said you have new injectors. I would like to see if cracking them at the injector changes anything, sometimes air gets in there and has a hard time getting out which. How did you measure #6? With an IR gun? How does it start when the engine is cold?

Link to comment
Share on other sites

i dont personally but i can get it checked

--- Update to the previous post...

cracked all the lines at the injectors and its still missing but i got underneath it and it noticed some fuel towards the back of the engine like its leaking diesel somewhere i just cant seem to place it it looks like its comeing from somewhere below the fuel filter but not the filter itself. its not a major leak but could it be enough to miss?

Link to comment
Share on other sites

The only thing under the fuel filter is the lift pump/fuel heater. Is it leaking around that? Could be leaking out all your pressure causing all the low power issues.

Link to comment
Share on other sites

If you are getting the fuel spraying when you crack #6 injector line then you need to look deeper into the engine. The next step would either be a compression check or just pull the head and see what the damage is. If you do not get fuel out of the line then you need to get the pump looked at. The fuel leak under the truck will not cause one cylinder to miss fire consistently. You would have a random miss from an air leak that would be worse under load. Tom

Link to comment
Share on other sites

They should all spray. I would let the 3 foam and they should only do that for well not very long with it running. Let them do it again for eh 30 seconds. If they never start spraying a constant stream then something is wrong.

Link to comment
Share on other sites

×
×
  • Create New...