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Thread: Small cam 2014 cherokee srt8 not responding to ve changes

  1. #1
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    Small cam 2014 cherokee srt8 not responding to ve changes

    working on a small cammed srt8, turned ANN off as i couldnt make it idle with it on, now it idles but afr swing a lot, they can go into the 12's as it may go very lean, same thing happens when driving around part throttle i dont get a stable error but sometimes is really rich and sometimes its lean in the same part of the table. The wot portion simply does not respond to any change i make to the ve table it simply ends up being 10.9 afrs no matter how much i take out of that part in the ve table.

    i have tuned a couple of cammed GM but this is my first JEEP, here is the tune it came with (not stock), the changes i made and a datalog driving around with the changes.

    Tune idle.hpt
    tune0.hpt
    drivearound2.hpl

    is there something im not doing and should have done?
    Last edited by mJolnir; 04-27-2019 at 12:25 PM.

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    I bet the swings have to do with the cam still being moved around a lot from the factory VVT tables. Two choices, one completely disable it for a test, itll just run the cam maximum advanced which isnt a bad thing. Take a new log and see if the swings in fueling stop happening. If so, then go back and make your desired angle normal table on the exhaust side be pretty much 134 degrees for everything up to about 4800rpms FOR ALL YOUR TABLES, I see you did it to the normal table but the ECU will move to Catalyst heating and scavenging at different times. This will keep it nice and steady and max advance. I dont ever usually part throttle a car past that rpm, so from there you would set similar values to the WOT table on the exhaust side, as well.

    Cant comment on the WOT part, whats your wideband setup? Looks like it might be cat overtemp, go into your Fuel->Temp Control and max out your thresholds (all 4) and zero out the FA Enrich Max table.

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    Quote Originally Posted by 06300CSRT8 View Post
    I bet the swings have to do with the cam still being moved around a lot from the factory VVT tables. Two choices, one completely disable it for a test, itll just run the cam maximum advanced which isnt a bad thing. Take a new log and see if the swings in fueling stop happening. If so, then go back and make your desired angle normal table on the exhaust side be pretty much 134 degrees for everything up to about 4800rpms FOR ALL YOUR TABLES, I see you did it to the normal table but the ECU will move to Catalyst heating and scavenging at different times. This will keep it nice and steady and max advance. I dont ever usually part throttle a car past that rpm, so from there you would set similar values to the WOT table on the exhaust side, as well.

    Cant comment on the WOT part, whats your wideband setup? Looks like it might be cat overtemp, go into your Fuel->Temp Control and max out your thresholds (all 4) and zero out the FA Enrich Max table.
    Wideband is a AEM 30-0334 obd2 unit, the sensor is located after where the CAT would have been.

    The cams i simply parked them at 134 exhaust, all the tables except scavenging and max airflow which i will change now.

    Will also test with baro learn off as i have read that sometimes causes issues when tuning.

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    Back from some more testing, put all the tables in the vvt tab to 134*, tuned the baro learn off, bumped my idle rpm up. then tried tuning ANN on, it would idle but when i stopped at the light it would go very lean and almost die. Then turned ANN back off, and turned vvt off, afr at idle would still swing from 12.0 afr to 18 and back the same as when vvt was on.

    Any other ideas on what could be causing this?

    drivearound5 annoff.hpl
    Tune idle3.hpt
    latest log and tune

    EDIT:
    i see tat desired cam angle and actual cam angle are different by a few degrees is this normal?
    Last edited by mJolnir; 05-03-2019 at 02:40 PM.

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    Advanced Tuner Blue Bee's Avatar
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    I see this issue when pushrod length is not correct. Remember in park cam sits full advanced anyway and don't move even when revving, so really the VVT stuff isn't messing with you. I haven't looked at your logs but you should log (if not already) TB voltage and adjust accordingly at idle voltage and small range table, also what is idle RPM setpoints? Add some spark to each side of the idle torque spark proportional to "catch" it quicker-if needs be. Speaking of cam error, does this have the comp limiter in it, or is one even needed? If you know the range and cam error is always more than a few degrees you have a valvetrain problem for sure, I've even seen botched installs where the a cam bearing is being chewed and won't allow cam to move freely and get angle error and DTC's.

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    Quote Originally Posted by Blue Bee View Post
    I haven't looked at your logs but you should log (if not already) TB voltage and adjust accordingly at idle voltage and small range table...
    I've been trying to figure this out. Is there an idle target airflow = rpm in the PCM and then you just trick it into opening more by telling the PCM that it the TB is actually flowing less at that voltage?

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    Quote Originally Posted by Blue Bee View Post
    I see this issue when pushrod length is not correct. Remember in park cam sits full advanced anyway and don't move even when revving, so really the VVT stuff isn't messing with you. I haven't looked at your logs but you should log (if not already) TB voltage and adjust accordingly at idle voltage and small range table, also what is idle RPM setpoints? Add some spark to each side of the idle torque spark proportional to "catch" it quicker-if needs be. Speaking of cam error, does this have the comp limiter in it, or is one even needed? If you know the range and cam error is always more than a few degrees you have a valvetrain problem for sure, I've even seen botched installs where the a cam bearing is being chewed and won't allow cam to move freely and get angle error and DTC's.
    It does have a phaser limiter, the car started giving me "crankshaft sensor/cam corelation" code, and lately is givig me a camshaft position sensor code, im starting to think maybe cam timing is a tooth off

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    Quote Originally Posted by mJolnir View Post
    It does have a phaser limiter, the car started giving me "crankshaft sensor/cam corelation" code, and lately is givig me a camshaft position sensor code, im starting to think maybe cam timing is a tooth off
    That's a good possibility. But to be sure, those codes also are the symptoms of just a bad cam sensor. Easy to swap, cheapish part, prob worth trying before pulling the motor apart.

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    Quote Originally Posted by mJolnir View Post
    It does have a phaser limiter, the car started giving me "crankshaft sensor/cam corelation" code, and lately is givig me a camshaft position sensor code, im starting to think maybe cam timing is a tooth off
    I doubt it's off a tooth unless it runs real bad all the time. I'd scope the cam and crank sensors and watch pattern, if they look good then I'd suspect it's throwing those codes because of angle error and moving fast enough when commanded. Which leads back to a possible cam bearing problem.

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    Quote Originally Posted by Blue Bee View Post
    I doubt it's off a tooth unless it runs real bad all the time. I'd scope the cam and crank sensors and watch pattern, if they look good then I'd suspect it's throwing those codes because of angle error and moving fast enough when commanded. Which leads back to a possible cam bearing problem.
    He could just disable all of the VVT and see if DTCs come back. Disabled it would run full advance and sit at 134 the entire time.

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    Quote Originally Posted by 06300CSRT8 View Post
    He could just disable all of the VVT and see if DTCs come back. Disabled it would run full advance and sit at 134 the entire time.
    Well they won't with cam not being commanded around. So then if it's chewing a cam bearing you have just masked a problem...for now.

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    Quote Originally Posted by Blue Bee View Post
    Well they won't with cam not being commanded around. So then if it's chewing a cam bearing you have just masked a problem...for now.
    Not sure what youre missing about that, how can you prove its a slow moving cam and not sensors or some other issue? Stop moving the cam. Proves your suggestion if codes don't come back.

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    Quote Originally Posted by 06300CSRT8 View Post
    Not sure what youre missing about that, how can you prove its a slow moving cam and not sensors or some other issue? Stop moving the cam. Proves your suggestion if codes don't come back.
    Because if you are not moving the cam how is it going to throw slow response codes? It will only throw those based on cam angle error and not following commanded in a timely fashion. So if cam is "parked" at full advance-no VVT, it's not going to throw a slow response code. It's not commanding a "response" with VVT off. SO from there is why I suggested scoping cam sensor, watch the pattern and you can find known good patterns online to quickly determine if the sensor is good instead of just replacing parts. Has cam/crank relearn been done on this since cam job?

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    Quote Originally Posted by Blue Bee View Post
    Because if you are not moving the cam how is it going to throw slow response codes? It will only throw those based on cam angle error and not following commanded in a timely fashion. So if cam is "parked" at full advance-no VVT, it's not going to throw a slow response code. It's not commanding a "response" with VVT off. SO from there is why I suggested scoping cam sensor, watch the pattern and you can find known good patterns online to quickly determine if the sensor is good instead of just replacing parts. Has cam/crank relearn been done on this since cam job?
    Dude youre missing it, process of elimination. Right now he has no clue if its your cam bearing claim or my claim it could be bad sensors. I recommend parking the cam to decide if the sensors are bad or not. Itll throw correlation codes, even with the cam parked, if the sensors are going bad. That's easier than dishing out $90 in sensors and spending an hour replacing or heading to a dealer or garage with the right tool to monitor the sensors. Just park the cams fully advanced. No codes, then that rules out my recommendation and leaves yours.
    Last edited by 06300CSRT8; 05-10-2019 at 11:52 AM.

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    Quote Originally Posted by 06300CSRT8 View Post
    Dude youre missing it, process of elimination. Right now he has no clue if its your cam bearing claim or my claim it could be bad sensors. I recommend parking the cam to decide if the sensors are bad or not. Itll throw correlation codes, even with the cam parked, if the sensors are going bad. That's easier than dishing out $90 in sensors and spending an hour replacing or heading to a dealer or garage with the right tool to monitor the sensors. Just park the cams fully advanced. No codes, then that rules out my recommendation and leaves yours.
    I agree with you man, that's also why I asked if the car had a cam/crank relearn done since the work. Usually a correlation codes pops quicker with the cam moving, and doesn't at all mean a sensor is failing. I'm just going off the dozens I've dealt with and fixed though. Sensor failure will usually throw circuit or performance codes-as the PCM does know what the signal should look like- then may throw a correlation code, but what tips you off on actual sensor failure is circuit or signal performance DTC's.

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    Advanced Tuner Blue Bee's Avatar
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    Quote Originally Posted by 06300CSRT8 View Post
    ...
    OP does really need to post the exact DTC's he got, after looking back through he states a correlation and "cam position sensor" code...so was it a position code...or a sensor code...? The DTC itself is going to tell more of the story.

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    Quote Originally Posted by Blue Bee View Post
    I agree with you man, that's also why I asked if the car had a cam/crank relearn done since the work. Usually a correlation codes pops quicker with the cam moving, and doesn't at all mean a sensor is failing. I'm just going off the dozens I've dealt with and fixed though. Sensor failure will usually throw circuit or performance codes-as the PCM does know what the signal should look like- then may throw a correlation code, but what tips you off on actual sensor failure is circuit or signal performance DTC's.
    How do one do a cam/crank relearn on these engines? This might help with my other questions on the "Need a bit of advice on ANN - 392 with a mild - big CAM" thread.

    Thanks, Mouritz

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    Hey guys, we swapped sensors from another srt8, still codes, so what we found is that on the phaser limiter install the guy took all the bolts out and the spring came out flying, so we bought a new phaser, and went by mmx instructions, after that took it to the dyno and it put down 428whp, took it to the track and went a disappointing 13.5 feeling really lazy out of the hole.
    After that i checked for codes and got slow phase response code.

    here is the log from that pass, camshaft is no longer parked at 134, found on the dyno that it put more horsepower down to advance it to 128 after 4500rpm
    tracktest2.hpl
    Tune 89oct.hpt

    as you can see, idle afr its still swinging a lot
    Last edited by mJolnir; 05-13-2019 at 01:38 PM.