Stock SRT-4 AFR's too high!

[peelerboy]

I've got a genuinely stock 2004 SRT-4, except for a drop-in K&N air filter. When I installed the canned "93 Octane" tune with my DSP, my WOT AFR's went from the factory readings of 11.50's to a range of 12.80's to 13.20's. I first tried to fatten up the fuel percentage which seemed to help a little, but I was still consistently in the mid to high 12's for my WOT AFR's. I then started trying pulling boost back and while that definitely helped bring my AFR's down to high 11's/low 12's, I'm now making a lot less boost and hence, power. (according to my seat dyno)

And now I'm periodically hearing a twinkle of what I believe is spark knock. I logged numerous pulls at different speeds. I have yet to register any long term knock at all, but often have short term knock occurring during my pulls. The highest number was a 4.0 short term, and it is typically around 2.5 to 3.0 when shifting into the next gear. (from 3rd to 4th, for example)

I always run 93 octane gas and have tried a few different brands to see if one gas had substandard quality as compared to another. Didn't make any difference. Any suggestions as to what I should be looking for?

Thanks in advance!
Dale

[mikel]

all the stock vacuum lines in place?

[peelerboy]

all the stock vacuum lines in place?

I'm at least quite certain they are. I recently bought this car from it's 60 year old original owner who took it to the dealership for EVERYTHING. (including oil changes) He was a major advocate for keeping the car as original spec as possible. All my local SRT-4 friends were astonished at the car's condition and unmolested state.

When I put the original backup tune in, the AFR's go right back to mid 11's. That's where I have it currently for fear of doing any damage with the canned tune and elevated AFR's.

[mikel]

sounds like you may need a fuel pump rewire or upgrade...

[peelerboy]

sounds like you may need a fuel pump rewire or upgrade...

Are you thinking that my current (stock/original) fuel system can't keep up with the demands of higher boost?

[mikel]

correct, not uncommon on these cars.

[peelerboy]

And when you say "upgrade", are you referring specifically to a better pump?...or what? Because I see all sorts of things on the market between different pumps, return line kits, etc. Where would you suggest I start?

[peelerboy]

I suppose I just have to guess then?

[mikel]

Id suggest you start here...

http://www.srtforums.com/forums/f384/

Thanks