This was the stock engine, the 318 from the 99 Ram in my sig. I chose to upgrade that engine for sentimental reasons, until I blew it up it was a good block. I spent six months designing the upgrade, consulting various vendors, largely Hughes Engines. I had the block bored 0.030" over, and decked to a 9.98:1 compression ratio. I installed a cam with 0.555 lift (with a 1.6 ratio, but I run a 1.65). I also run a set of 26 pound-hour fuel injectors. The other gem is a set of Iron Ram cylinder heads with oversized valves. I took her to a dyno to get her tuned. Since I installed the engine, periodically I have trouble coming from speed to an idle and keeping her from stalling. I've learned the heel-toe to keep the engine alive. I keep throwing the trouble code P0172.

BTW, I thought I would get more out of this build. Where did I go wrong? One guy told me aluminum heads would net me another 40 horsepower....

 

P0172 is the o2 sensor telling the computer the engine is running rich. Too rich will cause a lot of loss in power. Do you have a tuner for your built engine? A good custom tune for your engine, compression, cam etc. is what you need. I know you said you brought it to a dyno but you might think about getting ahold of hemifever on here about writing you a tune. A lot of times dyno shops will keep built engines on the rich side to prevent running lean. They may have left it too rich giving you some issues. Do you know what your heads flow? For best results out of a built engine the cam should be chosen to get the most flow out of your heads. Also keep in mind your engine is still has to lug around a 6000 lb truck.

When you dynod your engine did you get the numbers? Just curious.

 

Maybe, for just the few bucks it would cost, you should try the spark plug non-fouler trick. Might work...

 

When the computer is reset or battery disconnected it will take a few cycles for the IAC valve to learn the idle, though I don't think that's what you are experiencing. Time for a custom tune. Talk to hemifever or flyinryan

 

P0172 is the primary o2 sensor throwing that code. Its important that it reads correctly so he definitely would NOT want to do a non fouler trick in that one. The non fouler is pretty much just for the rear or secondary, o2 sensor in the case that the Catylitic converter is removed.

 

P0172 1/1 Fuel Sys Rich

One of two things, You need a custom tune to account for the larger injectors, or, you need smaller injectors. I would opt for the custom tune. Get fuel ratios where they should be, and you will likely get more power out of the engine.

Dyno runs are generally made at wide open throttle, hence, the PCM will be running in open loop. O2 sensor makes no corrections in open loop.

 

I knew the code was from the primary but I was just thinking (again, it's only $5-10) to try it, to see if it makes the PCM happy. More or less for grins, or as a temporary stop-gap.

 

Only from old habits, the first thing I think of when someone says there custom built 5.2 or 5.9 magnum isnt as impressive as they thought it was going to be, automatically, I think.....fuel sync

 

Thanks for the replies! I'm trying to answer all of them.

Yes, the man spent two days trying to tune her. I was showing 204 horsepower, 239 foot/pounds of torque. He seemed to be a swell dude, for two days work he only charged me the dyno session, plus what that his tech charged him.

 

That's what I'm thinking. The guy on the dyno never asked my compression ratio, never asked for bore or stroke. Now, he did spend two days on her, but SO DID I!!! sitting around, waiting... Do you know how hard it is for someone with ADHD to just sit around and wait?!?