HELP!! Au xr8 series 1 Running rough, - Page 3

keshin · 30-08-2014, 03:38 PM

Took car for about 10km drive ran like I'm used to leads must be causing problems, have pulled them away from motor, when I pulled up I did another key on engine on test and found only 1 bank is running rich.

I tried to record it on laptop but had a problem will record it on way home and hopefully I can upload it and show you

keshin · 30-08-2014, 04:34 PM

Just quick update, havent forgot you guys just had a software problem on the laptop all fixed now, will record later when i take it for another drive,

Evgeni · 30-08-2014, 07:12 PM

Quote:

Originally Posted by baker1

Hi, pull the cap off the cam sensor again and grab the shaft and see if you can move it side to side. They wear the bushes out and the shaft walks away from the sensor and causes a misfire. also try unplugging the cam sensor and see if the miss goes away

Thanks Baker,
If this is a common problem, would be worth checking out. Increases in the air gap would definitely drop the output voltage.

Your brother doesn't have a scope/scanner by any chance does he? lol You could have a look at the waveform and see what is happening. With these types of sensors, they sometimes employ what's called a floating ground. You'll know if backprobing one wire only gives you half a picture.
Backprobe both wires of the sensor and run it through the one channel. Output is in AC voltage.

If all the leads are original or the same age, I would replace the lot. Your rich running can definitely be contributed now to at least a partially burn knowing the leads are shorting to ground.

Fuel pressure looks good. System not losing pressure, due to leaks etc.

keshin · 30-08-2014, 07:15 PM

He's my mates brother was only in town for couple of hours, he lives 4 hrs away so unfortunately that's not an option, will check camshaft sensor shortly.

Car is however driving better since moving the leads (only thing I have changed was messing with leads)

keshin · 31-08-2014, 04:21 PM

ok guys new video, i replaced leads, missfire/hesitation is gone, runs like i remember.
however! i still am pulling running rich codes,
first test only code was bank 1 running rich,
next test one bank running rich one bank running lean,

heres the video of it running live again, car had been for good 15km drive then leads swapped, the this video.

http://youtu.be/rRlcEuwcnVY?list=UUH...xL9K_sQE0uD1WA

keshin · 31-08-2014, 04:56 PM

just done test couple more times, one test had no errors, another had running rich on bank 1 , 3rd test said iac,

Evgeni · 31-08-2014, 07:19 PM

That vid looks good. The short terms being within 10% is normal and yours dont really go past 15%. Both banks are running slightly rich. What is encouraging is the short terms look like they are responding to the o2's, which means the computer is not intervening.

Without a reading on the cam sensor, I can't confidently say on a forum that you need to replace it. If you do end up getting a look at it,there is no specific voltage you are looking for, except a signal switches from high to low as the cam sync spins around. The signal will increase in voltage and frequency as the rpm increases. This may be a cause of the extra fuel being fed into the motor.

IAC codes can be a symptom of something else. The valve will be a 2 wire design. Unplugged the power feed will show battery voltage, the other wire will be the control wire. To test them you need to plug the sensor in and backprobe the control wire.
A testlight connected to battery positive on the control wire will close the pintle on the IAC and drop the rpm.
Conversely, a testlight on battery negative on the control wire will open the pintle fully on the IAC, raising rpm.
If you are able to lower and raise the rpm via bypassing the computer, the IAC is fine.

The computer will have a desired rpm and IAC count which is how it monitors this circuit. There are no other feedback loops that I can see. For example let say there is a vac leak. On a MAF engine this will drop rpm at idle as the extra air will be after the MAF. To counter this the computer may command the IAC to open more to raise the rpm.
From the video, it didn't look like the IAC was working overtime at all. Maybe just keep an eye on it. Just a theory, but thinking vac leaks often lead to a slightly rich condition.

keshin · 31-08-2014, 07:49 PM

Thanks heaps, i will check for vac leaks tomorrow,
I will also see about if i can find someone to look at the cam sensor
I will find my test light and do a test on the iac now and let you know

thanks heaps for all your help i will keep you posted,
as i never had the diag to plug in before these problems i have no idea if these codes where there before, so now that its running how im used to (if not better) it's time for me to find whats causing these codes as i am concerned that driving it could damage something (codes worry me lol unlike good old carby v8's)

keshin · 01-09-2014, 03:02 PM

Quick update, iac is working, revs increased and decreased when hooking neg or pos to control wire

Evgeni · 01-09-2014, 07:35 PM

Good and bad news at the same time. Maybe just run it for a bit and have a look at forscan after it has racked up a few km's.
What is strange is that there are no long term figures. They would represent the adaptive feature of the pcm. eg, the long terms would usually start registering -10 or there about based on your short terms. The computer would reference this at start up and give the engine 10% less with the expectation that this will bring the system back to stoichiometric.
Maybe as it adapts to a complete or close to complete burn the figures, which aren't too bad will fall into line over the next 100kms?

keshin · 01-09-2014, 10:05 PM

I will get the software running properly to record the screen and take another video on Wednesday as I will be doing about a 100km trip,

Wednesday night I will take a video of my friends xr8, his is the series 2 but his doesn't show the long term fuel trims either, maybe it's a limitation of the elm or the fact au's have that obd2/ weird "CAN" thing

gra · 02-09-2014, 12:29 AM

hello there was just wondering about the oil pressure problem where was the wire loose and would u have a pic of it just mine does the same thing series 1 xr8 tried the extra negative between altinator and battery / chassis but still same drops to 0 when at red lights but then picks up to about half way cheers

keshin · 02-09-2014, 01:43 AM

Mine only happened on braking, I have heard of the oil pickup coming detached (this was my immediate worry) my wire seemed to be lose on the actually oil sensor. But mine oil pressure only dropped on hard breaking. Silly question but have you checked your oil? Make sure you have oil, I don't know if the xr series ones have an alert for low oil.

Evgeni · 02-09-2014, 09:29 AM

I can access the long terms on a 6. Might have something to do with the communication between the elm or forscan with the computer. The V8 guys in the build sections are doing some really cool stuff with their tuning etc but I understand that they are using different software, so there is definitely a long term pid.

blue oval joe · 28-12-2020, 05:15 PM

hi there keshin,
i know it was a while ago now, but did you find a solution to the xr8's rough idle problem?
I'm having a similar issue with an au xls ute v8.
cheers.

keshin · 28-12-2020, 05:47 PM

Hey mate I’m pretty sure it turned out it was the spark plug leads, replaced them and I also did fuel filter (filter wasn’t the issue)

blue oval joe · 16-01-2021, 08:48 AM

Yep, new leads and plugs fixed the misfire and it running rich (carbon particles out of exhaust!). But it didn't fix the rough condition, turns out it was the harmonic balancer, it had rotated 30 degrees. Had one go in a 95 fairlane and it nearly shook my back teeth out! This one, the vibration was around 1000 and disappeared at 1500-2000, weird.
Thanks for your assistance, I hope this info helps someone else.
All the best.

Cheers, Joe.