Topic: Fuel Pressure Regulator/MAP sensor

[road2damascus]

94 Jeep Wrangler S 2.5L, 5 spd, 30 9.5 15 BFG A/T KO

Mods: Bored out throttle body, Throttle body spacer, intake manifold bored out, Performance distributors rotor, cap and wires, E3 plugs, air restriction mod, Magnaflow cat, walker quiet flow muffler

So I just wanted to post my experience with installing a new MAP sensor and FPR 

First, my engine ran well at idle to 2500 RPM and a dog at anything above 2500. It was LOUD as well. Like a fart can Honda tuner muffler sound.

I tried cleaning the MAP and vacuum lines and it did nothing. So I replaced the MAP with a $30 Airtex/Wells 5S2397 from Rock Auto. I unhooked the battery for a half hour. I then took it for a drive. Noticeably different. Ran better and was much quieter. The wife even said, "I didn't hear you at the stop sign". The stop sign is over a block away! It even got better the more I drove it (computer relearning). I still did not have the WOT or smooth even throttle response.

I then ordered a Standard PR24 Fuel Pressure Regulator from Rockauto for $40 that was meant for a Chrysler 3.3L engine. It had great results. The power is evenly dispersed through out the rpm range and feels more powerful in the higher RPM'S. ***stock injectors***

I once installed the ford 19lb injectors but did not see a difference so I uninstalled them. I ruined part of one of the injectors, black plastic piece by the injector end broke off. I will have to find this piece and new o-rings before I re install them. I figure that I will now see the difference with the 19lb injectors along with these mods.

Future mods: Turbo, I have a TDO4 13t Volvo turbo charger with a 8psi waste-gate sitting on the shelf. Once I get a welder or someone that will weld for me, that doesn't cost $95/hr, I will start making the exhaust pieces, flanges, and mounting. Once I have money I will get the Split Second unit and other expensive stuff to this project. I have turbo experience and am looking forward to putting the 2.5 on roids. I had a donor wrangler with 4.0l and sold it. I like my 2.5 

[VA_YJ]

How do you like the walker quiet flow muffler?  I have a Banks cat-back and it's rather loud.  I can't hear anyway, but it bothers my spousal unit.  I'm looking for something that flows well without being excessively loud.

I am running the Ford Design III 19 lb. injectors with the stock YJ FPR.  As Sharpxman and others have pointed out, the 19 lb injectors result in slightly less flow than the stock injectors unless you bump up the fuel pressure.  Of course, the 4 hole injector atomizes fuel better.  I'm interested in the Chrysler 3.3 FPR.  What are preset pressures (with and without vacuum)?  Is it a direct bolt-on?  You have to match the fuel pressure to the injectors that you're using to get the desired results.

Thanks!

[sharpxmen]

I then ordered a Standard PR24 Fuel Pressure Regulator from Rockauto for $40 that was meant for a Chrysler 3.3L engine. It had great results. The power is evenly dispersed through out the rpm range and feels more powerful in the higher RPM'S. ***stock injectors***

well, you might have some other issues as that FPR is factory set at 50psi, your stock pressure is 39, so completely unsuitable without other significant mods (and i'm not talking CAI or anything to that nature, you'd need a pretty aggressive cam for that to work). If it works well with this FPR then i would maybe look at the fuel filter and possibly the fuel pump, and for sure monitor the fuel pressure while driving under load at wot, should stay at 50psi with this FPR, if it doesn't then you have flow capacity issues. What's your mpg?

[road2damascus]

VA YJ: The Walker quiet flow muffler is my third muffler. First was generic, second was Magnaflow, and third was Walker quiet flow. The Walker is quieter than the Magnaflow but I have no idea if there was any power increase or decrease. As far as the FPR I just put it on as it was on a list here on 4banger and thought it would be a improvement. It was a direct bolt on. Very easy. Unscrew gas cap, put rag under fuel pressure regulator connector.

Sharp: I would still like one of your FPR's. The Fuel Filter is one week old. Old filter was a NAPA Gold. New one is generic Auto Zone. It did not make a difference in performance after I put it on. I do not have a fuel pressure tester which is next on my list. As for MPG's with the pr24, I have not gone through a full tank of Gas yet so I can't calculate. It was getting 17.5 (last measured tank), 16.8 (tank before) both with a very light foot.  

[sharpxmen]

Sharp: I would still like one of your FPR's. The Fuel Filter is one week old. Old filter was a NAPA Gold. New one is generic Auto Zone. It did not make a difference in performance after I put it on. I do not have a fuel pressure tester which is next on my list. As for MPG's with the pr24, I have not gone through a full tank of Gas yet so I can't calculate. It was getting 17.5 (last measured tank), 16.8 (tank before) both with a very light foot. 

the light foot won't present that much of a difference since would be closed loop, however your fuel trims might be always on "-" which would still affect the mpg, not sure if there is enough room to relearn, it might, never tried that much fuel pressure on stock engine (i did with the supercharger on but i was getting black smoke before boost so that was a fail). Adjustable FPRs will be available in about 3 weeks.

[road2damascus]

I just drove the Jeep. With the new FPR I have been HEAVY on the accelerator mostly because I found power I never had and its fun  I am at 5/8ths (half way between half and 3/4) of a tank. I have 109 miles on the tank so far so it does not look like I am losing MPG. No black smoke or any change in exhaust.

[road2damascus]

Sharp, if I go to a larger injector than the ford 19's for the turbo, will I need to adjust fuel pressure accordingly? You can count me buying one of your FPR's in 3 weeks.

[sharpxmen]

Sharp, if I go to a larger injector than the ford 19's for the turbo, will I need to adjust fuel pressure accordingly?

not necessarily, depends where you end up with the AFR. Of course would be nearly impossible to be right on the money so the FPR is one way to adjust the AFR once you have a defined injector flow and boost, the other way is to alter the MAP output (which you'd would probably have to do as well) - best case scenario you do all 3: injectors, FPR and a programmable MAP. You could also use an FMU, but my knowledge with them is limited.

19# injectors won't be enough for any boost that would make a difference in the power output.

[road2damascus]

My last tank of fuel was 18.1 mpg. This was with the new FPR and MAP and running it in the higher RPM ranges more than usual.