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SOLVED - Help! Car's had a heart attack

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Kimmo
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SOLVED - Help! Car's had a heart attack

Post by Kimmo »

So I'm a couple of minutes from home the other day, when the Exa almost dies on the freeway... one minute she's running fine, the next I've got a cylinder if I'm lucky.

On go the hazards and it takes me ten minutes to limp home. After a day or two I went to start it and it fired and ran for a couple of seconds, but didn't respond to the throttle at all so I'm pretty sure it's not an air leak (I couldn't find anything)... after that it would only kick over once or twice off the starter and that's it. Kinda seems like maybe a fuel system thing?

Not sure if the ignition's at fault; the lead off the coil shows a nice regular spark, but it looks a bit pissy and yellow...

Any ideas?
Last edited by Kimmo on Sun Dec 29, 2013 1:20 pm, edited 1 time in total.
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tassuperkart
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Post by tassuperkart »

Coil or PTU?
Take out dissie, connect up, disconnect coil and turn by hand. Are injectors all firing? Rule out a rooted CAS.

Oracle
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Kimmo
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Post by Kimmo »

tassuperkart wrote:Coil or PTU?
Take out dissie, connect up, disconnect coil and turn by hand. Are injectors all firing? Rule out a rooted CAS.

Oracle
Sorry mate, I'm pretty rusty. PTU?

So if I remove the dizzy and hook it up and turn it, the injectors are supposed to fire, huh? I suppose I should hear them?

I'll give it a shot.
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Kimmo
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Post by Kimmo »

Wait a sec, how do I ensure the dizzy's properly indexed when I re-insert it?

Edit: NM, I gave it a shot and it can only go back on two ways, easy. I'll try the test now...
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Damo
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Post by Damo »

Kimmo wrote:Wait a sec, how do I ensure the dizzy's properly indexed when I re-insert it?

Edit: NM, I gave it a shot and it can only go back on two ways, easy. I'll try the test now...
Only one way Kimmo, off center drive. :wink:


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Kimmo
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Post by Kimmo »

So I heard all four injectors ticking away, I guess that's good news.

Just to be extra sure I wasn't out of juice (it was running low) I stuck another 5l in, but no difference.

A couple of times it ran okay for a few seconds, responding to the throttle even, but then died. After that it'd just momentarily kick over like before.

It's probably completely unrelated, but just in case - quite a while back I noticed my tacho didn't work for the first few seconds after firing it up... when it does go for a bit, the engine isn't running long enough to show up on the tacho, IIRC.
Damo wrote:Only one way Kimmo, off center drive. :wink:
Even better :)
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Post by Damo »

It sounds like it could be a few things. First off, do a diagnostics check on the ecu (running if possible), that will rule out cactus AFM, coolant temp ect ect.

Unplug the AFM to see if the engine cranking/starting probs change dramatically. Also, unplug the ECU coolant temp sensor and bridge the harness to check for a change, while you are there, measure the resistance of the temp sensor itself.

Outside of that, I would be leaning to post AFM air leak.


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Post by tassuperkart »

Sorry m8, PTU = Power Transistor Unit.
Little can thingy on the coil aka coil trigger.

Its most likely an ignition related issue with yours and Id first try changing the coil, then a ptu.
Just do one thing at a time to isolate the issue.
Dont forget to do your usual voltage checks with a multimeter. make sure your getting enough jiggawatts etc.

Ptu's are made of pretty stern stuff and tend to work for a long time.
Coils are prone to failure in comparison.

Oracle
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Kimmo
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Post by Kimmo »

I'm getting a code 23 and a 31, idle switch and aircon.

Doesn't seem to be anything wrong with the switch (it's missing the cover so I can see), but I haven't tested it yet. I removed the A/C, but pretty sure I left the switch on the HVAC controls; I knew it was involved in the diagnostic. Dunno if that means I should be getting a 31 though. I'm guessing those two errors are NBD.

...Aha! It runs pretty much the same without the AFM plugged in.

Hope it's not completely fucked; if I haven't sold or given away my spare, it's across town at my mum's. Having a squiz inside it now...

The resistor track looks just about worn through in a spot corresponding to idle, but I don't think that's it; the track isn't cut by the spot, and I was accelerating to 80 fairly hard when it died...

Image

On my sweet old analog multimeter (the digital one won't give me a good reading) I get 42, 40, 20, 14, 7, 4, 2.5, and 2Ω for that series of discrete resistors below the track, from left to right. Across the lot and the track, I get 120Ω, for some reason (not including the extra resistor, bottom right, 1.5Ω). But when I put the probes on the extreme ends of the track itself, the reading is inconsistent, showing anywhere from ~350Ω to 200Ω or below... and if I try to swipe the left probe along the track, all hell breaks loose with resistance going high for the most part rather than gradually coming down, only momentarily dropping as the probe passed each circuit line running under the track (terminating in a dot above it).

I had the bright idea of tweaking the wiper so it was effectively a bit shorter, moving it off the worn path onto fresh track, but that was no good because somehow it seems as if the entire track is suddenly fucked, while the other resistors on the board remain fine - I can't get a decent signal outside the worn path either. I tried cleaning it up with a felt bit in the dremel to no avail.

I have NFI how this could make such a sudden difference - one day it's running fine, then apparently not. Apparently isolate the cause, but it's not the sort of thing that's just broken - it's something that pretty much had to have degraded over time (wouldn't it?), meaning although it sure seems like a fault, I'm thinking it's not the one responsible.
Last edited by Kimmo on Sun Dec 29, 2013 12:48 pm, edited 3 times in total.
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Kimmo
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Post by Kimmo »

tassuperkart wrote:Dont forget to do your usual voltage checks with a multimeter
Unfortunately I don't have any spare car bits around anymore, so I can't try swapping stuff out too easily...

What are those usual checks? Rusty, remember ;)
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Kimmo
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Post by Kimmo »

Bah, I'm a dickhead.

All this fucking around because I didn't notice that I didn't notice the intake pipe was off the turbo (my AFM is on an elbow and sits near the clutch lever)... was pretty sure I checked for leaks, but come to think of it, that was just after I rolled off the freeway to find a park under momentum and I was a bit frazzled...

Sorry fellers, nothing to see here, apologies for wasting your time. I should've known it was NBD - every time I've had a problem since I got a recoed donk (increasingly tired running gear aside), it's turned out to be something simple and stupid and my fault.

One of the reasons I love this car :)

Happy holidays :D
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Post by Damo »

I'll put $100 down right now that you won't miss something like that again in the next couple of years. :D

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Timmzy
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AFM

Post by Timmzy »

Kimmo,

Don't apologise - I've learned some interesting stuff about aging AFM's from your post. I was going to suggest an AFM issue, as I have been frigging around with a standard correctly operating E15ET. Unplugging certain sensors to see what it does.

At some point these AFM's will wear out. What happens then? :)

Also - about 80% of the problems I look at with my cars - not just N12's - are this type of "tube come off" or forgetting to plug something in or do something up. I think unless you are doing this type of trouble shooting thing every day, you cannot expect to be rad at it!

Keep posting :)

Says me who hasn't' posted in years...

Darren.
Race it.
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tassuperkart
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Post by tassuperkart »

hah.. Your still lurking tho Darren, same as Damo.
Thats as good as posting I reckon!!!!

oracle
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baz
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Post by baz »

el oh el
My old exa I created from granny spec to a neat little BRIGHT car: http://forum.n12turbo.com/viewtopic.php?t=3903

Current Car: 2004 Vz SS Ute
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