Topic: 2.5 rebuild

[Jeffy]

I put a 41# fuel pressure regulator on it, I believe the range is 41-50#.  It is off a chrysler 6 cylender or something.

We had to re-use the exhaust donut on the Banks header because I could not find a new one, it is possible that the issue is an exhaust leak.  Anyone know where I can get A Banks donut gasket? Auto zone, Pep Boys, anything.

Did you check the pressure at the rail to varify?

[RickBrins]

I will be doing that tomorrow, if I read properly,  I want around 44#?

[RickBrins]

The fuel pressure read between. 42# and 46#, I even watched the guage as I drove at highway speeds to make sure the pump and pressure were keeping up at high flow,  so it seems that the lean condition is coming from something else. I did a spray test around the intake manifold,  and checked all vacuum lines.  I will be putting a new exhaust (donut)  gasket on as soon as ups delivers it,  and after that I'm hooking up a wide band o2.  I'm trying to avoid a new o2 sensor until the break in oil is changed, I'm told that the additives are tough on them.

It runs smooth and strong low end, a little weak at the normal range that the 4 banger struggles. I was hoping for just a bit more,  but maybe when I get the code 51 figured out things will be better.

[sharpxmen]

The code is. . .  51: Oxygen sensor stuck at lean position. .  So is that maybe telling me that I am running rich so the O2 sensor is stuck full lean trying to lean it to the proper ratio? . Also,  the Highway power seems lower than before, is that still due to the break on period,  maybe a result of the improper fuel mixture,  or the computer still trying to settle in?

 
The Computer was powered down for a couple of weeks,  so it probably wasn't set for any configuration.

What fuel pressure Regulator did you use?  Did you make any other changes,  and did you notice more power, better MPG, or both?

 what's your fuel pressure at idle with and without the vac line attached to the pressure regulator, if you have 50psi without the vac line (if that's what you meant by 41-50 as in 41 idle 50 wot) then it's way too much compared to 39 stock., there's no reason to go that high and could explain the code
if that's not it is the O2 sensor new? if not I would give that a shot and see if it fixes it.

[RickBrins]

Update..... About 250 miles on the engine it developed a bad miss in number 4. It turned out to be a plugged or bad injector,  so the stock Injectors are back in.  I was still getting a lean code. Hooked up a wide band o2 sensor and under most conditions all was normal,  but once at highway speeds for a few minutes it would go very lean and throw a code (51) and stay lean no mater what speed/power changes were made.  After a few minutes things would go back to normal. Removed and replaced the new o2 sensor and test drive generated no codes.  It was late,  so wide band drive will be today.  (the battery died in the wide band computer yesterday and had to be charged)  I expect better readings.  Also hope to have better power if the lean condition is fixed.

[sharpxmen]

Update..... About 250 miles on the engine it developed a bad miss in number 4. It turned out to be a plugged or bad injector,  so the stock Injectors are back in.  I was still getting a lean code. Hooked up a wide band o2 sensor and under most conditions all was normal,  but once at highway speeds for a few minutes it would go very lean and throw a code (51) and stay lean no mater what speed/power changes were made.  After a few minutes things would go back to normal. Removed and replaced the new o2 sensor and test drive generated no codes.  It was late,  so wide band drive will be today.  (the battery died in the wide band computer yesterday and had to be charged)  I expect better readings.  Also hope to have better power if the lean condition is fixed.

at wot the o2 sensor won't fix the lean state since it's open loop (the o2 reading has no influence on the mixture)

[RickBrins]

New o2 sensor did solve the check engine light.  When the old (new) o2 sensor would get stuck in lean mode the wide band o2 sensor would show that the engine was running lean in all throttle ranges for 5 or 10 minutes before returning to normal. . New o2 sensor solved the issue.

[kashola]

Glad you got your issue sorted out.  Just wondering how well it runs with the bigger injectors and FPR.  I tried the yellow Ford injectors on my Jeep with stock FPR and the old girl did not like it.

[RickBrins]

One of the injectors had a problem from the start and was not working, so the original injectors are back in, and I never was able to determine if the 19# injectors were a good idea or not. Having a fresh build has helped enough for what I need, although I was hoping for a little bit better mpg.

[sharpxmen]

they atomize better, minor improvements otherwise (flow is almost identical at the operating pressure for YJ)

[kashola]

From what I've read, the yellow tops flow more than has been reported by some.  I believe this to be at least part of the issue with mine.  With the higher pressure you're running, it may be causing some of your mileage issues due to more fuel volume in open loop.  What are you getting?  I have since switched to a different set of later style injectors and they seem to be a little better.

[RickBrins]

I went back to all stock, injectors and regulator. I still have the high energy ignition, but no change in mpg, still the same as before the rebuild... 15 mpg.

[sharpxmen]

From what I've read, the yellow tops flow more than has been reported by some.  I believe this to be at least part of the issue with mine.  With the higher pressure you're running, it may be causing some of your mileage issues due to more fuel volume in open loop.  What are you getting?  I have since switched to a different set of later style injectors and they seem to be a little better.

they flow slightly less (but just, not a concern)