- Location
- In a strange land
I will go 209.
Project Unicorn - a light duty trail rig
- Thread starter cal
- Start date
- Location
- Colorado
- Location
- Torrance, CA
I'm going to say "$1 Bob."
- Location
- Hammertown, USA
So when we last left off, I had the car running, and home, but had fuel pressure issues still and some pinging under low RPM load.
After replacing the fuel pump relay, I was getting super erratic fuel pressure readings. As it turns out, that was a combination of gauge problems, and the schrader in the NRT fuel rail being just a hair too deep in the fitting. If I pull the schrader out before hooked up a gauge each gauge gets a consistent reading, but I get very different readings on my HF and OTC gauges, which are different again from Chris Jenson's snap on gauge. I'm going to say the snap on is probably the most accurate, giving me 56 PSI. Inexplicably higher than the 49 PSI the new FPR should be giving me, but we're going to roll with it.
Chris Jensen from Christuned and our own Mark Nelson came by and wired the jeep up for diagnostics on Sunday. A digital fuel pressure gauge, a wide band o2 sensor, and OBD2 readings, all going into a data logger tied to Chris's laptop.
Not having ready access to a dyno on a Sunday, we used a local freeway on ramp to do hard WOT pulls, and then cruised to the next exit on light throttle to get more readings. Pretty fascinating stuff actually. I didn't take a lot of photos of Chris's work, but he built fuel and air maps to visualize what it is doing and made adjustments. This is the only map I photo'd, which was after the 1st adjustment.
I have no more photos of the process, but I'll talk about it.
At first the jeep at WOT was running so rich that it wouldn't register on the wideband o2. It took 3 tunes of trimming fuel before we could get good readings. With each adjustment the jeep got A LOT faster. About the 5th adjustment we started getting a good base, the low RPM pinging stopped but we started to get new pinging under WOT. I want to say we did 5 more ECU revisions, with each adding more pinging but did make us a lot faster, then Chris stepped us back a tune or two and added some more fuel under load, which stopped the pinging completely (but did take some power away). At the end of the day we ended up with near stock ignition timing and a lot less than stock fuel, but a bit more than Chris wanted to see.
He was able to tune the engine to running very well (and i'm super happy with it) but we did determine that maybe 11.4 is too much compression for a customer car. Russ and I are still talking about what to try next.
I'm sure I am forgetting things, but:
* Air/fuel map customized for my engine
* Timing adjusted to get the most bottom end and cut out pinging
* Aux fan set to come on at 180 so that it runs most of the time (my request)
* Idle bumped from 550 to 700 to smooth out idle vibration
* Threshold for misfire raised to limit the JTEC random misfire codes that haunt us
* Fast idle bumped from 1100 to 1300 (for future high idle switch addition)
Mark provided me with an SCT 9550 tuner which Chris loaded up with this tune, the factory tune, and a limp mode tune (-4 timing and add fuel) just in case I hurt the motor or get crappy gas while traveling.
Working with Chris was fascinating, and I learned a ton - mostly about how little I actually know. We discussed how he works with other customers, and his frustration that customers often want a magical tune but won't spend a couple hundred bucks on the equipment required to do data logging, and expect him to dial it in based on engine specs. Why spend $4000 on a motor if you won't spend $300 to see what it is doing and tune it? He doesn't understand, (I do, XJ guys are cheap).
After going through this process, I can tell you that there is no way you could do this just off of engine specs, and anyone who is selling a tune that way is doing you a disservice. If you have a custom motor and want to get the most out of it, i HIGHLY suggest you contact Chris for a list of what diagnostic gear to buy (you'll spend about $350) and get him some data logging, and talk about doing a tune (i can't say what his services will cost, you have to ask him).
After they left I took a cranking compression reading off of the engine, and went back over everything. I have a slight trans cooler leak that I'm going to have to pull the airbox and aux fan to find, and I clocked the exhaust away from the oil pan and have a slight exhaust leak to adjust now.
I am super happy with how the car drives now. Now that I have it in the final config I'm debating regearing to 4.56, and I certainly need to install a shift kit in the trans.
A couple of other things of note:
* Chris suggested I try a 180* thermostat. Village wisdom tells us that the ECU won't like that, but I've been told it won't be a problem and may help combat pinging if I get crappy fuel.
* My intake air temp was MUCH lower than Chris expected and sees with most other jeep engines. He attributed that to the aFe intake, and suggests that becomes something we recommend to people going forward.
After replacing the fuel pump relay, I was getting super erratic fuel pressure readings. As it turns out, that was a combination of gauge problems, and the schrader in the NRT fuel rail being just a hair too deep in the fitting. If I pull the schrader out before hooked up a gauge each gauge gets a consistent reading, but I get very different readings on my HF and OTC gauges, which are different again from Chris Jenson's snap on gauge. I'm going to say the snap on is probably the most accurate, giving me 56 PSI. Inexplicably higher than the 49 PSI the new FPR should be giving me, but we're going to roll with it.
Chris Jensen from Christuned and our own Mark Nelson came by and wired the jeep up for diagnostics on Sunday. A digital fuel pressure gauge, a wide band o2 sensor, and OBD2 readings, all going into a data logger tied to Chris's laptop.
Not having ready access to a dyno on a Sunday, we used a local freeway on ramp to do hard WOT pulls, and then cruised to the next exit on light throttle to get more readings. Pretty fascinating stuff actually. I didn't take a lot of photos of Chris's work, but he built fuel and air maps to visualize what it is doing and made adjustments. This is the only map I photo'd, which was after the 1st adjustment.
I have no more photos of the process, but I'll talk about it.
At first the jeep at WOT was running so rich that it wouldn't register on the wideband o2. It took 3 tunes of trimming fuel before we could get good readings. With each adjustment the jeep got A LOT faster. About the 5th adjustment we started getting a good base, the low RPM pinging stopped but we started to get new pinging under WOT. I want to say we did 5 more ECU revisions, with each adding more pinging but did make us a lot faster, then Chris stepped us back a tune or two and added some more fuel under load, which stopped the pinging completely (but did take some power away). At the end of the day we ended up with near stock ignition timing and a lot less than stock fuel, but a bit more than Chris wanted to see.
He was able to tune the engine to running very well (and i'm super happy with it) but we did determine that maybe 11.4 is too much compression for a customer car. Russ and I are still talking about what to try next.
I'm sure I am forgetting things, but:
* Air/fuel map customized for my engine
* Timing adjusted to get the most bottom end and cut out pinging
* Aux fan set to come on at 180 so that it runs most of the time (my request)
* Idle bumped from 550 to 700 to smooth out idle vibration
* Threshold for misfire raised to limit the JTEC random misfire codes that haunt us
* Fast idle bumped from 1100 to 1300 (for future high idle switch addition)
Mark provided me with an SCT 9550 tuner which Chris loaded up with this tune, the factory tune, and a limp mode tune (-4 timing and add fuel) just in case I hurt the motor or get crappy gas while traveling.
Working with Chris was fascinating, and I learned a ton - mostly about how little I actually know.
We discussed how he works with other customers, and his frustration that customers often want a magical tune but won't spend a couple hundred bucks on the equipment required to do data logging, and expect him to dial it in based on engine specs. Why spend $4000 on a motor if you won't spend $300 to see what it is doing and tune it? He doesn't understand, (I do, XJ guys are cheap).After going through this process, I can tell you that there is no way you could do this just off of engine specs, and anyone who is selling a tune that way is doing you a disservice. If you have a custom motor and want to get the most out of it, i HIGHLY suggest you contact Chris for a list of what diagnostic gear to buy (you'll spend about $350) and get him some data logging, and talk about doing a tune (i can't say what his services will cost, you have to ask him).
After they left I took a cranking compression reading off of the engine, and went back over everything. I have a slight trans cooler leak that I'm going to have to pull the airbox and aux fan to find, and I clocked the exhaust away from the oil pan and have a slight exhaust leak to adjust now.
I am super happy with how the car drives now. Now that I have it in the final config I'm debating regearing to 4.56, and I certainly need to install a shift kit in the trans.
A couple of other things of note:
* Chris suggested I try a 180* thermostat. Village wisdom tells us that the ECU won't like that, but I've been told it won't be a problem and may help combat pinging if I get crappy fuel.
* My intake air temp was MUCH lower than Chris expected and sees with most other jeep engines. He attributed that to the aFe intake, and suggests that becomes something we recommend to people going forward.
Last edited:
I cured a lot of ping on my Nissan SR20s bypassing the thermostat loop as it (like the Jeep 4.0) will recycle hot coolant even after the thermostat opens, writeup here (thermostat loop starts on page 4).
Not going to work for the Jeep, but that hot coolant ending up back in the motor isn't doing you favors for stopping ping.
Not going to work for the Jeep, but that hot coolant ending up back in the motor isn't doing you favors for stopping ping.
- Location
- Southern Maryland
you can afford 93 octane
- Location
- Hammertown, USA
93 octane doesn't exist on the west coast. 91 at $4.50 a gallon and climbing, or 100 at $8.99 a gallon.
donthelegend
NAXJA Forum User
- Location
- St. Louis, MO
Awesome build, thanks for sharing all the details with everyone, and congrats on getting it running/driving again!
Looks like you haven't swapped the built axle in yet? Curious to see the final details on it when you get it in.
Looks like you haven't swapped the built axle in yet? Curious to see the final details on it when you get it in.
- Location
- Hammertown, USA
That got derailed by both Dallas and I blowing our engines, a month apart. I'll get back it it in a month or two, when I get some more free time.
- Location
- Torrance, CA
- Location
- In a strange land
No good deed goes unpunished.
- Location
- Hammertown, USA
Well, since people seemed to have stopped guessing, Anak comes in closest to the cranking compression of 205 psi.
We actually expected it to be closer to 220-230, and are a bit surprised by it. 4643 was closer to 240.
We actually expected it to be closer to 220-230, and are a bit surprised by it. 4643 was closer to 240.
- Location
- Billings MT/Rapid City SD
- Location
- Hammertown, USA
91 is roughly $.025 a gallon more most of the time, around here. $7.50 more for a (30 gallon) tank of gas that conservatively will take me 450 miles (assuming 15 mpg, I'm getting 18 so far though). Roughly $0.016 more per mile in fuel costs.
Even if the increase in price to 91 is double what i calculated, I'm going to pay 3 cents a mile more?
- Location
- Billings MT/Rapid City SD
- Location
- Hammertown, USA
The magic of strokers. Use less throttle, burn less gas.
The hard part is not deciding to use more throttle. ALL. THE. TIME.
The hard part is not deciding to use more throttle. ALL. THE. TIME.
- Location
- Hammertown, USA
Changed the oil today, removing the break in oil.
Made the valvetrain a bit quieter (surprisingly so). I have to fix a small trans cooler leak and adjust the downpipe (I have a tiny exhaust leak). Will give me something to do tomorrow. I think I need to adjust the TVP cable as well as it shifts into 4th a bit sooner than it should and takes more gas than I'd like to downshift.
In general though I'm pretty happy. It has torque like driving a v8 truck, and i cruise mostly between 1700 and 2300 RPM's.
Made the valvetrain a bit quieter (surprisingly so). I have to fix a small trans cooler leak and adjust the downpipe (I have a tiny exhaust leak). Will give me something to do tomorrow. I think I need to adjust the TVP cable as well as it shifts into 4th a bit sooner than it should and takes more gas than I'd like to downshift.
In general though I'm pretty happy. It has torque like driving a v8 truck, and i cruise mostly between 1700 and 2300 RPM's.
- Location
- Fullerton, Ca
I ordered the AFE cold air kit to replace the K&N. Have you tried the 180 thermostat yet? I'm thinking of getting that and finally tuning mine before the tax return is all gone.
If you need the a/c done let me know, I think it's feeling like summer already.
If you need the a/c done let me know, I think it's feeling like summer already.
- Location
- Hammertown, USA
No. I wasn't going to post about it yet....
the shop I had change my oil (i brought my own oil and filter) did not appear to have used the oil I provided. What I drained from the pan looked like maybe 5w10, and it appears to have washed my bearings out. Within 20 miles I had lost all oil pressure.
I'm on business trip this week, next and the week after. I'll have a couple of days home here and there, when I get a chance I need to tear into it and figure out what happened.
I'm somewhat pissed about it, but it will give me a chance to correct a few things I wasn't happy with.
*sigh*
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