backfiring through the intake
#1
backfiring through the intake
96 f250 351w. I pulled the heads off this motor to replace the gaskets. While I was doing so, I put on short tube headers, removed smog stuff due to it being rusted off, plugged holes in back of the heads, New plugs, wires, cap, rotor, y-pipe and 1.7rr. Before I did any of this, the truck ran better than after I "fixed" it. I pulled the codes and get a lean code, but I'm sure it was in there from before due to busted ypipe and leaky manifold gaskets.
I got this thing together thinking that I'm going to have a stout little motor, but this thing is gutless and idles rough. I still have the exhaust leak at the y-pipe, but I cannot see that causing the issue. Fuel pressure is at 38 psi at idle
I got this thing together thinking that I'm going to have a stout little motor, but this thing is gutless and idles rough. I still have the exhaust leak at the y-pipe, but I cannot see that causing the issue. Fuel pressure is at 38 psi at idle
#2
Sounds like timing isn't right. I would be sure that the rotor inside the dizzy is facing towards #1 on the cap when the #1 piston is at the "Compression" stroke. Use a piece of tissue paper and plug the plug hole till you find it.
Have you checked that the plug wires are correct for the firing order? I believe this year engine uses 1-3-7-2-6-5-4-8 order.
Let us know what you find.
Have you checked that the plug wires are correct for the firing order? I believe this year engine uses 1-3-7-2-6-5-4-8 order.
Let us know what you find.
#3
#5
I made sure that all push rods were seated properly before torqueing the rocker arms down to 14 ft-lbs. I did not however rotate the motor to where the valves were closed when I did it. I was told since the lifters are hydraulic, I did not have to do so. Could this be my problem?
I did remove the cap and wires and changed them they are on correctly. All sensors and connectors are on and good connection.
I did remove the cap and wires and changed them they are on correctly. All sensors and connectors are on and good connection.
#6
I made sure that all push rods were seated properly before torqueing the rocker arms down to 14 ft-lbs. I did not however rotate the motor to where the valves were closed when I did it. I was told since the lifters are hydraulic, I did not have to do so. Could this be my problem?
I did remove the cap and wires and changed them they are on correctly. All sensors and connectors are on and good connection.
I did remove the cap and wires and changed them they are on correctly. All sensors and connectors are on and good connection.
this is incorrect. even though they are hydraulic, if the lifter is on a cam lobe it will have to compress the spring regardless of lifter style in order to seat the rocker (im sure you noticed this). this will make the torque measurement inaccurate. I always just tighten them down good-n-tight rather than use a torque wrench. there is no reason to turn the motor over to net your 14lb torque rating, as good and tight is plenty good enough, especially on a low rpm application such as this.
any codes?
#7
So what I did with the rocker arms " should" be okay not to cause a problem? I'll probably pull the intake and valve covers just to check and make sure.
I had 2 codes. One was an always lean code and the other was for the spout. I plugged the spout in and confirmed that it was advancing with throttle and it was.
I had 2 codes. One was an always lean code and the other was for the spout. I plugged the spout in and confirmed that it was advancing with throttle and it was.
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#8
Timing Marks
The timing marks are there. Take some middle grade sandpaper and sand the harmonic balancer until you find them (do NOT use one of the magic rust remover sprays). Once you find them, if you have a scribe, go over them lightly, if not, ehh. Get some liquid paper and go over them gently with a paper towel handy in case you go outside the lines. You should be able to see them great under the light.
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