Rebuilt motor and the problems I am having

[Crimsin]

I had my 4.0 rebuilt in December. I bought a cam from Delta cam that was slightly bigger than the stock, stage 3 super six heads, headers, and the bigger throttle body. The truck has never run smooth. Twice I have had to take the truck in to have air leaks fixed. This last week I had the intake replaced, because the mechanic claimed the intake was so old it would keep going thru seals. The mechanic claims that my barely over stock cam is what is making my truck run rough. I talked to Delta, and they say its highly unlikely.
Has anyone else had this problem? I need to figure this out, I am running out of money to try and get this truck to run right

 

[swynx]

how is it running rough? like it wont idle? does it run down the road fine? is it rpm dependant?

i had a high idle and crappy mileage for awhile, tryed replacing the intake manifold gaskets 3 times before i finally smeared gasket maker on both sides and got rid of all my problems.

the cam shouldnt make it run rough, just sound better and have more go-go juice.

 

[willy]

Sounds like you need a new mechanic

 

[Crimsin]

It runs rough at idle. When it goes down the road it moves out

 

[RonD]

Assuming clean fuel injectors

Lets start with that vacuum leak thing

Warm up engine to operating temp, temp gauge should be above 1/3 but below 1/2
If not then you have a bad or the wrong thermostat, 192 or 195degF is correct one.
180degF is bad.

Now at operating temp and idling at 600-700rpm
Unplug the IAC Valve wires
Idle RPMs should drop to 500 or engine may stall, either is good it means no vacuum leaks.
If idle stays above 700 then you have a leak......OR, someone has been playing with the Anti-Dieseling screw on throttle linkage, it is NOT an idle screw, should be adjusted with IAC Valve unplugged and engine warmed up so idle is 500 or less.

So RPMs stay high and Anti-Dieseling screw isn't the issue, start by unplugging each intake manifold vacuum line and plugging that port with your finger, if idle drops you found the leak point.
If not found then next test will be after engine cools off over night or 6 hours.
When engine is cold loosen and remove fan belt from crank pulley
Have a can of starter fluid(ether) handy.
Start engine, it can run fine with no water pump for 2 minutes, Battery Light will stay on
With no fan blowing air over engine finding a leak will be easier
Spray ether around lower intake while listening for RPM change, also upper intake and the air tube from MAF to intake

Spark plug gap, 0.054 is for stock engine, you are pulling in more air and so more fuel, may want to bump that up to 0.059
Wider gap gives better low RPM performance but less coil recovery time above 4,000rpm, so gap is relative to drivers needs, the 0.054 is average use stock

Bigger cams can cause engine to lope, and with MAF sensors this can cause issues but as manufacturer said it is not likely, and a lope is different than rough running.


Is idle better cold than warm?

 

[cp2295]

My 410 comp can makes my engine lope and it idles slightly rough. I'm pretty sure the delta cam has similar specs so I wouldn't be too concerned unless shes really loping then it would most likely be a vacuum leak or a leaky injector making it too rich


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