HELP!! Au xr8 series 1 Running rough,

[Evgeni]

np - interesting problem. Good for trying to work out what it is as well. Changing parts gets expensive!

[keshin]

Originally Posted by Evgeni

np - interesting problem. Good for trying to work out what it is as well. Changing parts gets expensive!

thats exactly it cant afford to replace parts that dont need replacing, i have taken the video and i was wrong, the o2 sensor does drop, not all the way but you will better understand it than me just waiting for it to upload.

[macman]

Originally Posted by keshin

anyone know what this hole is, its open not blocked

What the ?!?!

There's supposed to be a sensor in that hole. I don't know what that sensor in that hole does (or what it's called) but it can't be good being completely missing.

And surely air being drawn through that hole isn't being filtered, let alone metered by the MAF. Surely that could be causing problems!

[keshin]

Originally Posted by macman

What the ?!?!

There's supposed to be a sensor in that hole, it has a similar plug to that of the IAC valve so look if there's a loose plug hanging around the area. I don't know what that sensor in that hole does, but it can't be good being missing.

And surely air being drawn through that hole isn't being filtered, let alone metered by the MAF. Surely that could be causing problems!

you legend, found it straight away, honestly dont think its ever been there tho lol will run again now

[keshin]

i will run another test on it now and see what error codes come up, the sensor that goes there was the air temp sender
i believe if it was in there it was blown out in the backfire, but i really dont remember it

Evgeni would you like me to redo the a video now that it is put back in?

[Evgeni]

If it is all running good then no need for a vid - happy to help you try and interpret the readings where you need, so just put it up when you feel you need to.

I dont like being a negative person, but just wondering why a temp sender would only affect one bank? I never say never until I see it happen, so just wait and see how it runs with it in. My gut tells me that this may have been blown out when you had a backfire. If it is the case, the problem may be elsewhere.

Unmetered air will lead to a low rpm in a MAF engine.

[keshin]

yeah i agree man sorry, i didn't mean to imply it fixed it, it is still running rough just didn't notice the sensor,

i have made a 5 min video this time for you. i am definetly still running rich (had to open shed it was bad) i also redid the test and now only pull up the two error codes

p0172- HO2s sensor mixture constantly lean
p0175- system too rich bank 2

https://www.youtube.com/watch?v=flLh...ature=youtu.be
hopefully this looks somewhat better

[Evgeni]

Hope your not too high after that ...lol
Guess things are looking alot more normal now. Both banks running rich. Those codes should clear, as it is certainly not lean. Both o2's now fixed rich.

Maybe an issue with fuel, high pressure, rupture diaphragm on the pressure regulator, leaking injectors?
EGR valve open at idle?

Injectors would reference the cam signal, so if there is a spare cam sensor you could test with. Just trying to remove other variables.

[keshin]

ok im trying to understand this one, feel dumb now

first up i dont have access to a spare cam sensor

as for the regulator arent they on the exit side of the fuel rail (maybe its clogged and causing high pressure)

as for the egr valve. im not actually sure of what that is or where to look for it lol

[Evgeni]

Not overly familiar with the location of everything on the v8's but just did some searching and it turns out the au didn't have an egr. Can someone confirm? It's basically for emissions. Recirculates exhaust gas at cruise for emission and economy. Usually electronically control and will lead to a rough idle if open at idle.

The regulator should be vacuum controlled. sometimes a quick test is to pull the vac line off and let the car run. Sooner or later fuel will spit out of the regulator through the vac line connector due to a ruptured diaphragm.

[keshin]

Thanks man i will test it now lol time to get high again haha

[keshin]

okay well i ran it for about 2-3 mins and didnt get any fuel out.

[Evgeni]

Least that one off the list. I think you can narrow things down to the cam sensor and a fuel problem. These can and are likely to be related.

I think that is the limit of forscan - you'll need other equipment to test fuel pressure. Suppose you could pull the injectors out and leave them on a sheet of paper to see if they leak.

Also, strange that Long term trims weren't showing. Not sure why that is. Hope it gives you some direction though.

[keshin]

thanks mate im sure ill have more questions arise for you. I will look into the pressure regulator and a pressure guage tomorrow.

Will keep ya's updated Thank you

[keshin]

Hey Evgeni I was watching the live data again today an I noticed when I give the car a quick snap on the throttle the fuel system goes into open loop the reverts back to closed loop. Is this normal?

[Evgeni]

Generally speaking no, it is not normal. But I dont know the parameters for every EFI management system. The computer will ignore the o2's at WOT, but does the system need to go into open loop for this.

What is clear is that the computer has stopped taking fuel away at the 20% mark. We know it can do more as it got up to 40% before the sensor was plugged in. What is the chances of a condition that needed exactly 20% less fuel? Too much of a coincidence.

Is this still with those old plugs? I'm wondering if the car has detected a rich condition, from an incomplete burn and the computer is taking fuel away to protect the cats after a misfire event.
We know the o2 sensors are ok. Wouldn't be a bad idea to get a gas analyser on the exhaust and have a look at the CO levels. This would confirm the rich condition. I know you can smell fuel, but this can be a high hydro carbon content due to a bad burn or miss as reported before.

[keshin]

To start with I took the car for a test drive today (needed more fuel) from take off I have a fair amount of hesitation almost like it wants to backfire but doesn't, this is evident through most of the throttling and gears, if I hold the throttle in one spot (maintaining speed) it feels normal (maybe a slight hiccup here and there)

If I WOT it still has power but again splutters etc.

I have new spark plugs in there all pre gapped and checked at 1.3mm
I will note I replaced the cat converters 6 months ago with hiflow just to rule out a bad cat.

I'll get a spark plug and do a test on each lead to make sure all are firing

Also just a thought, would it help if I got a laptop and did a live data recording while driving? I could also record the revs and upload them as a video ?

Sorry forgot to mention I didn't snap the throttle all the way on just a really quick rev.

[Evgeni]

Just be careful using forscan while driving. I did this and the car cut out on me a couple of times; good fun in the middle of Sydney!!
I reckon the ignition would be ok - you would feel a miss on the engine. If anything, the hesitations would indicate a lead is tracking. At WOT, the system is meant to go rich, so spluttering would not fit this picture. Could back up the tracking lead theory. You can spray a little water on the leads in the dark and see if you can see any tracking. Don't go overboard with the water though.

I guess it would be good to see what is going on if you took the car for a spin - understand it is a bit of set up work getting a video and uploading etc, so happy if you want to just describe it as well, as I can't guarantee any fixes either.

What would be handy is a scope reading on the cam sensor - which forscan can't do. It says it does, but I couldn't get it to register - signal is probably too fast. See if you can get it to do it - I tried it on a 6.
The signal is meant to be an AC sine wave. There should be a metal piece or pieces that would pass closer to the magnet on the sensor when the synchoniser spins around. When metal passes through a magnetic field, it raises voltage. As it moves away it drops the voltage. The computer uses these highs and lows and references this with the crank signal to determine what stroke each cylinder is on - fires the injectors accordingly.

If the cmp signal is low as in your scan, someone programming the computer may have decided that this is not enough to shut the system down. Take some fuel away to protect the exhaust and revert to a group firing strategy to keep the car going. Just a theory, but just trying to explain what I think might be happening.
Unfortunately, scopes are expensive. :(

If you are going to go out for a drive, make sure that tps signal is moving with your foot so to speak and doesn't move without you moving as well.

[keshin]

lol you wouldn't believe it but i was just fiddling with the leads and found something interesting

I connected the timing light to each lead at the coil pack and only some lit up,
then i did the same to each lead at the spark plug end, again only some lit up,
interesting enough i bumped cylinder 4's lead and the heat sheild on it had a little spark going to the block.

I am about to test each lead again then i will spray the water and see what happens,
After that ill put up my results,

feeling kinda dumb that i missed this but as we know, costs alot just to replace parts, just can't believe i didn't think to try the timing light first. Guess the best thing is once we get to the exact issue this will make a great rundown of things to look at for people in the future haha

[Evgeni]

I make a million mistakes as well, before I get to the bottom of anything! I haven't used my timing light in over 10 years...lol
If you have an amp clamp - a coil drawing over 8 amp would be a good indicator of a short. With higher currents, this breaks down the lead and the windings of the coil quicker. i.e a bad lead with eventually fry the coil.
Also MSD coils (not sure what you have) have a multiple firing event at idle - probably make a timing light go crazy. Guess that's why they call it multi strike ..lol

[keshin]

NEW DEVELOPMENT

i just thought to connect the timing light to each lead while running, results as follows

AT COIL END (NEXT TO PLUG)
1. flashed
2. flashed
3. flashed
4. flashed
5. no flash (unplugging lead caused spark between lead and coil)
6. no flash (unplugging lead caused spark between lead and coil)
7. no flash (unplugging lead caused spark between lead and coil)
8. no flash (unplugging lead caused spark between lead and coil)

AT SPARK PLUG END (NEXT TO PLUG)
1. Flashed
2. Flashed
3. Flashed
4. Flashed
5. Flashed
6. No flash
7. No Flash
8. no flash

WATER TEST
1. no sparks
2. no sparks
3. no sparks
4. no sparks
5. no sparks
6. no sparks
7. no sparks
8. no sparks

HEAT SHIELD TEST
1. no metal casing
2. no metal casing
3. no sparks
4. sparked
5. no sparks
6. no sparks
7. no sparks
8. no sparks

[keshin]

moved heat shield further up the spark plug lead, still sparks up further (seems any where it is on the lead it sparks)

also the lead is not cut etc where the heat shield is

EDIT: I have just tested each lead one by one by unplugging from car spark plug placing another plug in and leaning on the engine.
Every lead fired the plug

[keshin]

Tested TPS with key on car off.......Live Data showed it got to 4.48v foot to floor

[Evgeni]

You can conclude that from at least cyl 4 down, the leads are tracking. Once something goes to ground, the whole of the circuit will be ground voltage/zero volts - as opposed to just where the spark is shorting on the rocker for example.

Guess the leads are shorting out on cyl 5 to 8 which is why it is not lighting even at the coil end - and explains why you still have spark when the lead is removed. It's not igniting the fuel, which is the source of the rich condition.

You've definitely solved at least part of the problem. What's a new set of leads cost? $100?

[keshin]

Originally Posted by Evgeni

You can conclude that from at least cyl 4 down, the leads are tracking. Once something goes to ground, the whole of the circuit will be ground voltage/zero volts - as opposed to just where the spark is shorting on the rocker for example.
Guess the leads are shorting out on cyl 5 to 8 which is why it is not lighting even at the coil end - and explains why you still have spark when the lead is removed.
You've definitely solved at least part of the problem. What's a new set of leads cost? $100?

repco want 280 ish i think it was lol ebay cheaper, although i edited the post so see what you reckon now lol sorry i should try and post all at once

[Evgeni]

Saw the edit. The plug is firing because you've had to move a lead away from the engine. It will probably fire up your timing light as well.
Anything metal and not insulated is a ground source and electricity is like water. It will seek the least resistance or the easiest path to ground. Any white marks where the lead is draped over the rocker? This would be a clue as to where the spark is going. Once you move the lead away, there is more of an air gap to a ground source.

Just be careful - as long as a ground source is closer to the spark than your body, you will be safe. That's 40000v and it will hurt. When the insulation of the lead has broken down, leaning on the engine is a bit of a gamble.

[keshin]

lol oh yeah lead 4 gave me a good boot earlier when i unplugged it from the spark plug while the engine was running

[keshin]

pulled all leads away from metal and ran it again. no difference there where a couple of marks but where just dirt, sprayed water again and no sparks only spark still is from lead 4

my friends brother is a trade mechanic and he is coming with a fuel pressure guage (fingers crossed) tomorrow, so hopefully he see's something im missing lol

[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

[keshin]

mechanic just did fuel pressure test.......
idel- 35-36 psi
revs- increase by about 5 psi,

no leakage when car turned off in 10 minutes

mechanic says yes spark plug lead 4th cylinder is definitely stuffed due to the heatshield spark and believes there is probably another one on passenger side that's no good