Topic: 2.5 rebuild

[RickBrins]

I'm hoping I have better luck with mine.

The block will be back this week, they had to bore 30 over. I was hoping 10 would be enough, but I guess the extra displacement won't hurt. Does anyone know what 30 over would increase the 2.5 to?

[jfrabat]

Just for reference, I would not expect performance gains from a 30 over...  But you can calculate the displacement with the formula:

πr^2 x stroke x # of cylinders = 3.1416 x radius(squared) x stroke x # of cylinder

Felipe

[RickBrins]

Thanks for the formula, I kinda ballparked some of the numbers earlier after figuring out the formula myself. 30 over is not really much different and no, I don't expect to notice any change from that. I have expect I will send the biggest difference just from the fresh build and tighter tollerences.

[paulsadog]

I am still waiting for the block to come back from the machine shop, so I don't know exactly what I will see different, but according to the posts on here that talk about them, they are good mods.

The injectors are Ford GT injectors, I found rebuilt ones on eBay, set of 4 around $65.

Performance Distributors makes the FirePower ignition.

Both mods have really good posts on the boards with excellent information.

Do you have a part number on those injectors?  I also have a 2.5l and have been doing some reading about upgrading from stock injectors. I spoke with a tech from Bosch and was told that they, Bosch, never made an injector for the 2.5l. That's not to say there isn't 1 that will fit its just Bosch never engineered 1. Here is 1 thread I was reading,

http://4bangerjp.com/forums/index.php/topic,3479.0.html

So what I get from looking into different injectors is that you may be able to get away with a 19lb injector but nothing higher for the 2.5l. In my little brain this makes sense because the PCM has been programed for a 17lb injector but I can believe the PCM has some flexibility to compensate for a somewhat flow rate.

Your thoughts?

[RickBrins]

The injector part number I used is Bosch 0280155700 I'm just getting the engine back in this week,  so I will have to let you know how they do.  They are the 4 hole 19# Injectorsand I am putting on a Standard Motor Products PR211T Fuel Pressure Regulator that bumps the pressure up slightly in the fuel rail.  If my research is correct the slight bump in pressure should help with the higher pressure Injectors.  Again,  I will see once I get it all in and running.

[grumpygy]

For some reason, my Jeep does not like the screaming demon coil.  I keep burning them...  I know I am the odd one out there, but I have gone through 3 of them already, so I kind of gave up on them.  Other than my case, i have not heard any complaints from other users, so it must be something with my Jeep.

Question cause this just hit me.  I'm running the screaming Demon No Problem.  But I have a late 94 build YJ.  Wonder if one of the Other changes that year was in the Distributor. Maybe the earlier ones takes a different Ohm coil than the late year. 

The reason I know is I has to change my axle bearings, the cross bearing.  They went with a larger size later in the year and I got the small ones not knowing any difference.

[jfrabat]

Question cause this just hit me.  I'm running the screaming Demon No Problem.  But I have a late 94 build YJ.  Wonder if one of the Other changes that year was in the Distributor. Maybe the earlier ones takes a different Ohm coil than the late year. 

The reason I know is I has to change my axle bearings, the cross bearing.  They went with a larger size later in the year and I got the small ones not knowing any difference.

As far as I know, there was no changes...  But I could be wrong!

[RickBrins]

Engine is in, nothing super noticeable yet,  but still only 50 miles on the break in.  However,  I am getting a lean code 51. Could that be the computer still trying to adjust to the new Injectors and pressure Regulator, on do I need to look at something else?

[RickBrins]

Engine is in, 50 miles into break in.  No real noticeable changes yet,  but I will give it some time.  I am getting a lean code 51 at highway speeds, could that be because the computer has not caught up with the new Injectors and pressure Regulator yet,  or do I need to look at something else?

[jfrabat]

Engine is in, 50 miles into break in.  No real noticeable changes yet,  but I will give it some time.  I am getting a lean code 51 at highway speeds, could that be because the computer has not caught up with the new Injectors and pressure Regulator yet,  or do I need to look at something else?

Don't think so.  I did the change, and did not get a lean code.  And if it were the case, you would be running rich, not lean, as the more pressure and larger injectors would result in more fuel if the time was set for the old injectors...  There might be something else going on.

[RickBrins]

I only get the code 51 when I drive at wide open throttle.

[jfrabat]

Check your TPS...  Mine was acting up and causing some issues some time ago...

[RickBrins]

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?

 

Don't think so.  I did the change, and did not get a lean code.  And if it were the case, you would be running rich, not lean, as the more pressure and larger injectors would result in more fuel if the time was set for the old injectors...  There might be something else going on.

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?

[Jeffy]

I only get the code 51 when I drive at wide open throttle.

That makes sense if you're using the OEM fuel regulator.  The Jeep wants 17.4# but when you're at WOT with 19# injectors at the lower pressure, you're only making 17.2#.  It's not a problem when not at WOT so it should be okay.  If you're going to go WOT then you'll want to convert the fuel system from 36# to 42#.  The only problem is bypassing the stock unit.  Member sharpxmen has done it with his engine.  It's somewhere in the Projects.

[RickBrins]

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.