Topic: Computer changes for a high performance cam any ideas???

[lilftballpunk]

I called delta today in search of a more high performance cam. They said the most common is their 248 grind. I told him I wanted better and more performance. He said I would have to do adjustments with the computer parameters and fuel relation. I'm not to expierienced with this sort of thing anyone out there with some knowledge of what I can and should do?? It's the 2.5L engine (odviously) out of a 2001.

[aka-justin]

My guess would be an after market computer system ECU like this http://whiteracing.com/ecms.html

Seems a bit overkill for a 4 banger, a 6 cyclinder would be a lot easier to hot rod.

My 2 cents and only for what it's worth.

[sharpxmen]

about 4 things you can do w/o going into an aftermarket ECU

for open loop (wide open throttle)
1 - fuel injectors and/or
2 - adjust fuel pressure (a bit of a challenge on yours since the Fuel Pressure Regulator is in the tank)

for closed loop:
3 - use a programmable O2 sensor (disadvantage is that you'll get the AFR modified over the whole range)
4 - use a signal modifier to adjust the O2 sensor output based on MAP and rpm

with these you can adjust your AFR curve for max power (but will hurt your mpg if you modify the O2 output)

EDIT: on your year of vehicle if you have a second O2 sensor after the catalytic converter (I think you do) i am not sure if it will trigger a CEL or not

[chrisfranklin]

about 4 things you can do w/o going into an aftermarket ECU

for open loop (wide open throttle)
1 - fuel injectors and/or
2 - adjust fuel pressure (a bit of a challenge on yours since the Fuel Pressure Regulator is in the tank)

for closed loop:
3 - use a programmable O2 sensor (disadvantage is that you'll get the AFR modified over the whole range)
4 - use a signal modifier to adjust the O2 sensor output based on MAP and rpm

with these you can adjust your AFR curve for max power (but will hurt your mpg if you modify the O2 output)

EDIT: on your year of vehicle if you have a second O2 sensor after the catalytic converter (I think you do) i am not sure if it will trigger a CEL or not

That's interesting on the programmable or signal modified O2 Sensor, Sharp.  I might look at messing around with that at some point because I don't drive this Jeep in open-loop as much as I'd like.   

[sharpxmen]

the only issue with the programmable output wideband is that you change the AFR over the whole range. The signal modifier is better in this case, with the wideband you kill 2 birds with 1 stone since you'll be able to monitor the AFR precisely but the signal modifier has more flexibility when it comes to tweaking AFR at specific operating range.

All this though should be done once you made some other mods, preferably porting the head and intake manifold as well as installing a perf cam.

[dwtaylorpdx]

It seems to me that I've watched several of these piggyback
systems in our forums get lots of talk then it gets painful.
the MOPAr computer has some very hard limits... Usually taking
more than one add-on to fool it, then the results seem to be irregular.

At some it seems a full stand alone system is simply easier and really cheaper.
There are several that are in the 1200-1400 dollar range.

Dave

[sharpxmen]

It seems to me that I've watched several of these piggyback
systems in our forums get lots of talk then it gets painful.
the MOPAr computer has some very hard limits... Usually taking
more than one add-on to fool it, then the results seem to be irregular.

At some it seems a full stand alone system is simply easier and really cheaper.
There are several that are in the 1200-1400 dollar range.

Dave

even with a standalone you still need a wideband o2 to tune it so that's another $200, make that a total of $1500 average based on your estimation and you still have to tune it

the other alternative is $200 for an adjustable FPR (or $90 if you buy it here), $150 for a piggyback (if you care about the mpg) and another $200 for a wideband - total $300 on a low to $550 for high so not even close to $1500, you drop another $1k on a standalone + you're at square zero still needing full rewiring and full tune (not just adjustments)

[dwtaylorpdx]

My point is that it will work when your done, I'm on several forums both Jeep and BMW
and I see people talking about the piggyback tuning bits and I'm just wondering about
the real success rate. It was really more of a "can anybody confirm" statement 

I fiddled with a couple and neither would give me the AFR across the power band that I wanted.
My stock unit

I count it like this:
150 for a Adjustable Regulator
150 for injectors
300 for Piggyback #1
300 For #2 (Cause you need a O2 fiddler or MAF or ...
300 for a dyno tune for #1
300 for tuning #2
1200 to rebuild the motor when they push it too far... (DIY not a pro rebuild)

Reinstall the stock ECU when it wont work...... Priceless.... :) ROFL...

So whats the thoughts?

Dave

[sharpxmen]

My point is that it will work when your done, I'm on several forums both Jeep and BMW
and I see people talking about the piggyback tuning bits and I'm just wondering about
the real success rate. It was really more of a "can anybody confirm" statement 

I fiddled with a couple and neither would give me the AFR across the power band that I wanted.
My stock unit

I count it like this:
150 for a Adjustable Regulator
150 for injectors
300 for Piggyback #1
300 For #2 (Cause you need a O2 fiddler or MAF or ...
300 for a dyno tune for #1
300 for tuning #2
1200 to rebuild the motor when they push it too far... (DIY not a pro rebuild)

Reinstall the stock ECU when it wont work...... Priceless.... :) ROFL...

So whats the thoughts?

Dave

you're talking turbo or supercharged, the topic was for a normally aspirated engine and you only need #2 in that case. It is $200 list but i've seen it cheaper. And in that case you don't need injectors (unless they're shot but that would be the same with the a/m ecu)

if you monitor the stock Jeep ECU you'll notice that when you accelerate for example on a ramp to keep the speed will go into open loop but at some point will settle into closed loop and get to the 14.7 AFR which won't give you best power - all you do with the O2 modifier is to adjust the range and make the AFR lower  but only for specific rpm and MAP sensor readings so you can still cruise for best mpg but get a bit more power before (close to) going in open loop.

My take on what you said is: if you pay $300 for a tune there is no way you'll get anywhere with a blank ECU, there's really no magic with one, still has to be tuned.

I am not sure how the OBDII computer works with the 2 x O2 sensors but i'd be interested to find out - my understanding is that the second one is to measure cat efficiency but i have no idea if altering the first one would affect the readings on the second or if the second O2 would alter the AFR in any way so i can't speak for that.

one vs the other (and i probably said this before): you alter the fuel delivery slightly to get better power vs. you start from 0 figuring out timing, rpm, MAP, IAT, CTS, TPS readings and injector duty cycle and it's not an easy task

and there are also emissions, you can always go back to stock with a flick of a switch vs. try to tune the new ecu for emissions testing

btw, are you running an aftermarket ECU on your Jeep? how did you get more power after installing the Hesco cam, i'd like to hear about it and would probably be in topic for this thread too.

[dwtaylorpdx]

Well, I even meant on a NA engine, the problems are smaller but still there.
The builder who did my engine timed the cam just up to the point the computer laid over.

The stock computer on the normally aspirated engine seems to tolerate a point or
so of compression and decent lift on the cam, it did not like the full house advance
on the cam so my engine builder adjusted the cam timing till it was happy. In the current
economy I have not been able to swing any more electronic improvements. Interesting thing is my 94
sounds like its not acting like the one you fiddled with, My engine has no fuel curve, it has
like steps. The AFR never seems to move on a curve, always in specific steps, eventually
dropping into a static 14.7 unless you hold the throttle WO.

My engine has the hesco cam, 4.0 TB (Stock bore), Tri-Y headers (Thorley) and Hyperutectic
pistons with a moly coating on the skirts. (Stock part number for 95&95 2.5 according to  the book.)
I think these were the pistons that were installed if you had the "clatter problem" from the 90's 2.5 engines.

From what I can tell o0n friends cars withteh 2nd O2 it does not really measure anything,
its binary, IN spec or out of spec to identify a bad cat.

There are a couple standalone ECU's I've worked with that really
we were able to get tuned fine on the road. SDS is one, It has no
laptop and is very simple, one guy driving one adjusting and its a
30 or 40 minute deal to make it go... Took about 8 hours to install.
I think they get about 1500 for one these days... Downside is fairly
rough idle control as they really sell it for racing not street use.

Good topic though... HOpefully the bonus godss will be good to me this year!

Dave

[sharpxmen]

it is mostly steps, the only time i noticed that is goes back in closed loop rather slowly (read a bit slower) is when you increase throttle suddenly and keep it there (but not WOT) - once it gets to speed i noticed the AFR migrating towards stoichiometric rather than switching suddenly to closed loop

I was doing some reading on the stock and a/m cams

seems that the stock ones are all 270 duration and .424 lift for both i6 and i4
lobe separation angle and duration are also the same at 112 deg (up to '95, in '96 it changed but i think only the 4.0)
overlap is also the same at 46deg

but the cam centerline angles are different
2.5L
intake 114
exhaust 110

4.0L
intake 120
exhaust 104

that's a 2 deg offset on the i4 and 8 deg on the i6 from factory

for example the hesco RVOB6 (i think it's the same cut with RVOB4)
duration 264
lift 470
overlap 44
lobe separation angle 110
centerline intake/exhaust 110/110

mopar
dur 248
lift 440
O/L 32
LSA 108
C/L In/Ex 108/108

most aggresive one i've seen is a Crower 44312 (this is for I6)
duration In/Ex 292/298
lift In/Ex 499/512
O/L 75  (wonder what the idle is at)
LSA 110
C/L In/Ex 106/114

[dwtaylorpdx]

The overlap is VERY important thats for sure, Too much and it will never pass smog...

Dave