Engine/Transmission (1994 - 1998) Lean fuel mixture?

[SRehberg]

I installed a ATS 3 piece exhaust manifold on my '96 (stock) about 3-4mos. ago. Tonight I looked under the hood carefully, and noticed the no. 2 exhaust runner and part way into the no. 1 runner, the metal has a blue look to it. It's hard to tell if no. 5 & 6 have the same color, as it was under the cowl and evening was coming on. Is this normal for the ATS manifold as it ages or do I have a fuel issue that I need to address? The truck runs great with no apparent issues. The old cast iron manifold never showed a problem, but it was sure shrinking.



One other item. I just purchased a '96 CCab with 45K on it, and it has the 4. 10 rear gears. I wasn't use to the higher revs, as my other '96 has 3. 54 gears. Does the mileage suffer much? I know the sound level is definetly increased. I pull a 5th wheel, so I hope the lower gears will be good for that.

 

[y-knot]

Well we know it isn't a "lean fuel problem". Diesels draw in the max amount of air on every intake stroke, regardless of how hard you press the go pedal. They ,unlike gas engines which are compelled to maintain a very tight AIR/FUEL ratio, have no ratio's to follow. At an idle. some diesels can achieve a air/fuel ratio of 200-1, and higher. But the same diesel engine running down the highway may only be at 50-1. The only limiting factor is fuel, how much are you giving it, since the air intake is un-restrickted, it is always drawing in as much as it can. This is one of the wonderfull things about a diesel, and why they don't gobble down fuel when sitting in traffic. They have that high ratio, the poor fellow in the v-8 or v10, is still consuming at the same rate as always, around 14-1. On a diesel a suspected hot spot would be from to much fuel . Maybe a faulty injector. m I have only seen one ATS manifold installed on a truck, and while it was not "blue", it sure was rusty.

 

[SRehberg]

Thanks for the reply. It makes sense that to much fuel could cause the problem, so I guess I should pull that injector and have it looked at. I'm surprised it has given up this early (50K) but anything mechanical can go at anytime. No smoke unless you put your foot in it, then only light, but with just one loading it, maybe it wouldn't show.