If I recall correctly, Nick did a plug n play with the injectors. The HP increase came from the change in injector configuration, ultimately changing the spray pattern.

 

hes gone! i talk to him when i had my muffler replaced, and we were gonna build my bull bar and then BAM he dissappeared working crazy hours and i think a baby was on the way

 

What about high flow cats like magnaflows?

 

Thats what i thought too. I dont remember that he did any tuning. I wonder what just doing that with a 4.7 would do???

How does one tell if the o2 sensors are bad?

I dont think that the cats have too bad of an issue with geting plugged, but i dont know how one figures that out.

 

You can ohm test the sensors, just refer to your Chilton's. The only way to check a cat is to cut the hoe out. Honestly, I would run one can of BG44K through your fuel system every 15K miles. It will help clean your O2 sensors and your cats.

 

Well, higher flow -- on intake or exhaust -- is only going to help if the engine is currently restricted. Same thing with bigger/better injectors -- will only help if the engine is capable of flowing additional air in order to use any additional fuel. Only way to make the engine itself flow more air -- again, assuming no intake/exhaust restrictions -- is to install a different camshaft (or turbo/super charge). Don't really want to get in that deep (cam change).

Unless the stock cats are getting plugged up, I don't think replacing them would be any help, especially considering the rest of the stock exhaust system. I took a look underneath and yes, the stock y-pipe is really bad, and no, there is no room to run true dual exhaust (what appears to be the fuel tank is in the way under the drivers side. So, I've ordered a Magnaflow Y-pipe (2.0/2.0 - 2.5) and will have a muffler shop install that sometime in the not too distant future. I think this will add a few HP. That should open up the exhaust somewhat (and there seem to be total of three -- yes, three! -- muffler devices under there (a muffler and a resonator, plus what looks like a 'pre-muffler' resonator). Hmmm....

Also pulled a spark plug, the truck has what appears to be the stock NGK copper plugs which have definitely seen better days (at 74.5K miles), so ordered a set of Pulsar Platinums (got a bit of a deal), according to some dyno figures posted by Pulsar they may add a few HP.

I also got a deal on a Airaid cold air kit, ordered that, and again according to some dyno figures posted (this time by K & N) this should add a few HP (especially in conjunction with a better y-pipe configuration). Overall, with the three changes, I'm hoping to see maybe 8 more HP. 10 tops. Every little bit helps. I'll also be installing a wideband O2 gauge to see how the air/fuel ratio looks before and after these changes.

I looked at a Hypertech programmer, but their dyno figures showed only about 8 HP gain below 3500 RPM, and didn't think $340 was a fair price to pay for 8 HP (although, in retrospect that's close to what I'll be paying for the three mods above). Now the dyno sheet did show that it really wakes the little 3.7 up from 4000 - 6000 RPM, by some 25 HP or more, but I'm not going to be operating in that range. Might revisit this item later.

I get these goodies installed I'll report back (probably be month or so).

 

Other than throwing a code, I ran some diagnostic software on a Corvette I used to own (years ago; this was in OBD I days) and it showed what I can only describe as a slow cycle on the O2 sensors. I put in new ones and the cycle rate just about doubled... the only thing I can theorize is that the quicker cycle (sample) rate will allow quicker response by the ECM. Don't really know how that would translate to dyno numbers or performance... but the ECM is definitely relying on the O2 sensors to tell it what is going on with the fuel/air ratio, which is critical to performance.

 

I had the local Valvoline quickie-lube shop do a fuel system treatment wherein they inject some stuff directly into the fuel rail or intake (or something like that... they don't put it in the fuel). $60 or $70 bucks, wasn't cheap.

Didn't make any change at all that I could tell... still have a touch of rough idle, no increase in fuel mileage.

 

Installed the new Pulsar BE1P spark plugs yesterday, will monitor fuel mileage for any improvement. The stock plugs, at 74K miles, came out with a gap of 0.060" (setting is 0.042"). Still seem to have the occasional hiccup at idle (I'm now betting on the injectors).

Have an appointment with local muffler shop tomorrow morning to get the Magnaflow Y pipe installed.

Have not received the cold air intake yet, but did note some interesting numbers today -- on an OBD2 reader, the IAT (inlet air temp) was 144 degrees while sitting in driveway after several minutes of idling, dropped only to 122 degrees after a few miles on a 45 MPH highway. Outside air temp about 80 degrees. Interesting... considering the design of the factory airbox, I would have thought it would not have been so warm. I'll check those temps again when I get the cold air kit installed (shipping is slow on that item). I'd think there are several horsepower available if that temp can get down to ambient or close to it.

 

I am a 4.7 guy but I am really interested in this mod..I think that factory y pipe is junk as well and although the Magnaflow pipe is universal all of the reviews seemed to be from Dodge guys, mainly Dakota owners, talking about how restrictive their stock y pipe was and how this really does provide a power gain. I wish someone had a dyno sheet of the mod though!