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Thread: Need some help from my tuning friends! Turbocharging an 08 Jeep Rubicon

  1. #1
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    Need some help from my tuning friends! Turbocharging an 08 Jeep Rubicon

    Hello all! I can use a little help here if you guys don't mind. I am new to tuning dodge but for the record I have tuned a few lsx cars about 5 years ago though I seem to be a bit rusty and getting my butt kicked by my Jeep. Like I mentioned in the title I have an 08 jeep wrangler that I have built a turbo setup on. The turbo is small, a t3/t4 garret with a .48 exhaust housing as my goal was a turbo that spooled quickly. As you can see from the logs I got what I wanted. My plan of attack building and tuning this turbo setup was to first build the setup and get it running and cruise it around with the stock MAP sensor and injectors to test the mechanics. Once the mechanical check is done I intend to instal the 2 bar map and last instal the 42lb injectors once I get the 2 bar tuning lined out. The problem is I am currently stuck on the first step and having issues. Driving the jeep around yields a nasty misfire at cruise. Between 1k to 2k the jeep bucks intermittently and runs rough but above 3k it runs great. I am currently running stock VE but have moved it up and down over 10-15% and still had no luck. As far as timing, i pulled 10 degrees out above 100kpa and in the upper range of part throttle, roughly 60 kpa and up. I also enriched the WOT PE fuel and decreased delays. I pretty much set it up so the engine would not go into limp mode or melt down if it senses positive pressure. While trying to troubleshoot the issue I put the factory tune up back in the jeep and it was still misfiring. I did a compression test and everything looked good and I changed the spark plugs out to NGK 4306. IAT's are scorching hot as I have no intercooler on it currently, it seems like it will need on badly. Any thoughts? I am currently at a loss here. Thanks for your help!

    jeep turbo.jpg
    sutton 08 jeep- spark, fuel, and dtc initial Aug 18th 2015 314 pm.hpt
    jeep tune 8-19-15 #5.hpl

  2. #2
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    spark plug.jpg

    Plug I just pulled, has about 15 miles on it with the tune you see above. Its on the lean side for sure. I might have some crappy gas by the looks of the strap,thoughts?
    Last edited by sut123; 08-19-2015 at 09:42 PM.

  3. #3
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    Well, I finally pulled my head out and decided to monitor individual cylinder misfires and noticed that all the misfires are coming from cylinder 2, 4, and 6 (drivers side) with the primary share going to cylinder #2. Jeep runs like ass when cylinder 2 isn't hitting. The above spark plug came out of cylinder 4. Here are a couple logs.

    misfire log 8-19 1007pm#1.hpl

    misfire log 8-19 1013pm#2.hpl

  4. #4
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    Are you giving it the beans with a 1 bar MAP sensor? Anything over atmospheric pressure it's going to run like crap since it can't sense and compensate for boost pressure in a 1 bar map. Hurry and get a MAP sensor on there that will read boost. A Neon SRT-4 map sensor is 2.25 bar, and the Caliber SRT-4 is a 3 bar sensor.

    Get one of those installed, resale the PCM for it, and things should start running much better. Not perfect, by any means, but at least better.

  5. #5
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    BoostJunky, thank you for the reply! As of now my goal has been to simply cruise it around at quarter throttle to get mechanical issues figured out. I have got into PE a couple times trying to accelerate into traffic due to it breaking up at part throttle adnd I knew Power Enrichment would take it to safer timing and fuels. I know your right, I need to stop with the one bar and move on before i melt it down. I am going to go ahead and toss the 2 bar map into it and get it to recognize the positive pressure. As far as I can tell all that I need to change is the Map senor linear to 46.38 and Map offset to 4.8. A 2 bar OS isn't required, correct? Thanks again for your help. If you were close Id buy you a beer!
    Last edited by sut123; 08-20-2015 at 03:18 PM.

  6. #6
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    Hey Sut - add pressure ratio to your logs as PID, I just tried to overlay everything to your tune (which is all by pressure ratio in the VE and timing tables) and realized you don't have it.

    I know the MAP sensor is causing some issues but looks like there is some other issues going on, fueling looks wacky, huge swings will make an injector not fire or fire very little for a split second and can cause a misfire/stumble.

    You using factory injectors on this tune, no 42lbrs yet?

  7. #7
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    Quick update. I took BoostJunkys advice and installed the 2 bar map and made some VE adjustments and the jeep woke right up. Most of the misfires went away and I was able to cruise it down the road for roughly 5 miles at 60 mph and the jeep did OK. There is still some part throttle tuning I need to clean up in order for it to run cleaner. The biggest battle Im having is I get into boost while part throttle while in closed loop so it will take some work to get that right. My Beta 2.25 charts or wideband input is not functioning so that creates an even bigger challenge. Anyways, I felt comfortable with the mechanical side of things and installed the new 42lb injectors. I am still a little confused as to what parameters need to be changed and to what. However, I did find a spreadsheet on here that calculates your fuel mass. I'm changing from the stock 22lb injectors to some ford 42 lb injectors I had on the shelf. I will add the number below and if you guys don't mind having a look at them for me I would greatly appreciate it. Is there anything else I am missing? The three tables I plan to change are InjPW vs. Fuel Mas, Fuel Mass vs. InjPW, and Startup InjPW Scalar. Thanks again for your help!!!

    Stock Values

    ms Fuel Mass(g) LBS/HR
    0.00 0.00000 0.0
    0.52 0.00059 9.0
    0.62 0.00144 18.4
    0.72 0.00189 20.8
    0.82 0.00230 22.3
    0.92 0.00269 23.2
    1.02 0.00308 24.0
    1.12 0.00338 24.0
    1.22 0.00370 24.1
    1.32 0.00402 24.2
    1.42 0.00436 24.4
    1.92 0.00592 24.5
    7.42 0.02367 25.3
    324.42 1.02398 25.1

    42lb injectors

    ms Fuel Mass(g) LBS/HR
    0.00 0.00000 0.0
    0.52 0.00113 17.2
    0.62 0.00275 35.2
    0.72 0.00361 39.8
    0.82 0.00439 42.5
    0.92 0.00514 44.3
    1.02 0.00588 45.8
    1.12 0.00645 45.7
    1.22 0.00706 46.0
    1.32 0.00767 46.1
    1.42 0.00832 46.5
    1.92 0.01130 46.7
    7.42 0.04519 48.3
    324.42 1.95487 47.8

  8. #8
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    Hey Sut - add pressure ratio to your logs as PID, I just tried to overlay everything to your tune (which is all by pressure ratio in the VE and timing tables) and realized you don't have it.

    I know the MAP sensor is causing some issues but looks like there is some other issues going on, fueling looks wacky, huge swings will make an injector not fire or fire very little for a split second and can cause a misfire/stumble.

    You using factory injectors on this tune, no 42lbrs yet?[/QUOTE]

    Thank you for the reply! I will add the pressure ratio in my future logs. I just installed the 42lbrs and the 2 bar map and getting ready to have a stab at getting them set up. As you mentioned above, I think the fueling was off by a decent amount. I have never tuned anything that has gone into boost so quickly and didn't take that into consideration when setting up my original VE table. i feel that on my last drive, after the 2 bar and VE increases, I was able to the O2 switching a lot faster and cleaner and it drove a ton better. Not perfect, but better. I just wish I could tie my wideband into it a histrogram! The Last log file I had where is drove decent and before I added the injectors:

    misfire log 8-20 1112 am-added bar map.hpl[QUOTE=06300CSRT8;395107]
    Last edited by sut123; 08-20-2015 at 03:53 PM.

  9. #9
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    I'm making some progress today fellas! Injectors are in,scaled, and tested! Jeep ran decent, still rich according to the ole wideband. WOT fuels are way rich and causing a bog. I am getting ready to hit the road at work on cruising fuel and timing and if I get lucky work on some WOT fueling. 06300CSRT8, here is the last log with PID you requested. I hope it was what you were looking for. If not please let me know and I will get it fixed up. Thanks again fellas!

    42lb injectors installed and 2 bar map- rich, need PE and VE work 8-20 2015 417 pm.hpl

  10. #10
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    Yes that worked, you are EXTREMELY lean right now, your fuel trims are maxxed out positive +32% in all your cruising rpms. Your scaling looks to be far off. What is your wideband reading while you are cruising?

  11. #11
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    06300CSRT8, thanks again for your input. I agree, at low kpa numbers are extremely lean. When I get closer to 100 kpa it gets pretty rich and falls over. Its a struggle on my end because I want to use a histogram with a wideband but I cant! Im running around with a pen and paper trying to record data. Anyways, I drove around for a little bit this morning. I shut off closed loop and power enrichment to gain uncorrected data by eliminating fuel trims. I wrote down some of the afr's I was seeing on the wideband compared to the datalogs KPA values. Here is what I found:

    Idle in gear- 850 rpm, 38 kpa, =18 afr
    idle rolling- 900 rpm, 41 kpa, =16afr

    driving 1500rpm- 44kpa = 15.3 afr

    driving 2000rpm- 68kpa = 13.3 afr
    driving 2000rpm- 100kpa 9.9 afr

    driving 2500rpm- 48 kpa = 14.9 afr

    driving 3000rpm- 50kpa = 15.1 afr

    sutton 08 jeep- VE tunning with LTFT disabled 8 21 2015 11am.hpt
    open loop log 1120am 8 21 2015.hpl

    As far as the MAP sens is concerned, I used a factory 2005 dodge neon srt4 turbo car Map sensor. Is this the sensor you claim is 2.5 bar? If so then my linear values are off, correct?
    Last edited by sut123; 08-21-2015 at 01:48 PM.

  12. #12
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    I made an interesting discovery today. The jeep would have intermittent issue with misfire primarily on cylinder 2 and it seemed like it was getting better then it would randomly come back and mess up my tuning process. The issue is with Inj pulse width going to zero on random cylinders when trying to accelerate and randomly at idle. It happens on random cylinders according to past logs. I will post up a log file but from your experience is this generally a computer of injector issue? This is a new one to me! Ive never had an injector just go to zero like this one has, weird.

    failed fuel injector.png

    pulse width cylinder 2 failure 8 21 2015.hpl
    Last edited by sut123; 08-21-2015 at 10:19 PM.