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Mystery problem - need help solving it!
http://www.4g61t.org/forum/viewtopic.php?f=6&t=26176		 Page 1 of 3
Author:  snowdevl [ Mon Aug 25, 2008 6:35 am ]
Post subject:  Mystery problem - need help solving it!
Ok guys, i've had this problem ever since I put the motor in my car back in January, and haven't been able to solve it. I need some help.

When driving the car, i've got a bit of a miss. It is VERY intermittent, comes and goes. Feels exactly like timing being pulled (i assume thats whats happening). When I say intermittent, I mean I can plant it in 1st gear and the car will go perfectly, change into 2nd, plant it, and it feels like i'm towing a 2000kg trailor, change into 3rd and all of a sudden it goes perfectly again. Its random like that. Sometimes it will go fine for a whole day, and then the next morning when I get into the car it runs like arse. The problem seems worse when the car is cold, and seems to get better the longer I run it, but not always. I've almost been killed a couple of times when moving out into traffic when the cars cold, just doesn't wanna boogy at all.

Ok so first of all, i've got a check engine light. It comes on about a minute after starting the car, and stays on till I shut it off. I've pulled error codes using an LED, got code 13, Intake Air Temp sensor. This is in the AFM (known as a MAS in the US i think), so in theory I should be able to change the AFM and the check engine light should dissappear right? Wrong, i've tried two AFM's which are known to be good, problem unsolved. I am running an Evo '609' AFM btw, which i'm pretty sure is the same as a 2G DSM one, if that makes a difference. I checked the IAT wire with a multimeter a few months back and its fine too.

So I started thinking, maybe i've been reading the code backwards. Code 31 is the knock sensor, and a faulty sensor would explain why the car is pulling timing at inappropriate moments. Wrong, replaced the sensor, no difference.

I've tried a few other things too, spark plugs, leads, cam angle sensor, nothing made a difference. I actually found one of my rubber intercooler pipes had been BADLY squashed, replaced it and the problem went away (the check engine light stayed on, but the car stopped running like crap), and then it returned a few days later. I assume this was coincidence because the new pipe remains unsquashed.

Anyone got any bright ideas?

Thanks
Author:  Skrenos [ Mon Aug 25, 2008 8:47 am ]
Post subject: 
ECU?
Author:  TrevTec [ Mon Aug 25, 2008 10:31 am ]
Post subject: 
Sounds like a bad knock sensor to me
Author:  MR HYDE [ Mon Aug 25, 2008 10:59 am ]
Post subject: 
Are you usung a 1.6 ECU, or the 2.0 ECU
Author:  turbokid [ Mon Aug 25, 2008 11:05 am ]
Post subject: 
Quote:
ECU?
+1
Author:  snowdevl [ Mon Aug 25, 2008 3:02 pm ]
Post subject: 
Oh sorry, forgot to mention, i've tried 2 other ECU's, both single board 4G63T ECU's like mine, both working perfectly in the cars they belong to (VR-4 and 1.6L Cyborg). Still got the check engine light and mystery miss in my car.
Quote:
Sounds like a bad knock sensor to me
Thats what I thought too. In fact, when I pulled my old knock sensor out and saw how crappy it looked, I was 100% sure that a new sensor would sort it. I borrowed one out of a mate's VR-4, and to my horror, still got the dreaded CEL and mystery miss.



Ok I figure it might help if you guys knew a bit more about my car...

4G61T
4G67 head, VR-4 cams
Big 16G, Evo 3 exh-manifold
3" turbo back exhaust
VR-4 intercooler, 2.5" in/out with VR-4 piping
Evo '609' AFM
4G63 N/A intake manifold / TB / K&N
510cc Evo 3 injectors
Walbro 255lph fuel pump

Single board EPROM chipped VR-4 ECU, new caps 4000km ago
VR-4 RS ignition & fuel maps
Injector compensation
Injector deadtime adjustment
AFM compensation
Fuel cut removal
Octane reset on start-up
Launch control
Author:  turbokid [ Mon Aug 25, 2008 3:07 pm ]
Post subject: 
sounds like you have a ghost.

im not sure on the mitsu ecu's but one of my old cars needed the ecu reset after changing sensors that throw CEL's or the problem (and error code) would persist.
i'd still be looking into the AFM though if thats what the ecu is unhappy about.

was that evo AFM on the motor before?
what did you change at the same time the motor went in the car?
Author:  snowdevl [ Mon Aug 25, 2008 3:19 pm ]
Post subject: 
The ECU would've been reset every time I swapped it out to try the other ones.

Unfortunately everything I have listed above was done at the time of the swap, including the Evo AFM. I've tried another two Evo AFM's with no luck :(
Author:  colt200e [ Mon Aug 25, 2008 3:25 pm ]
Post subject: 
I also had the same problem..
I had a leaky gas tank, which lead to my 2 255 walbros crapping out on me for some reason..., I also had leaks around the injector seals.

Do you have an aftermarket fuel pressure regulator? maybe your maxing out the stock one?
(sorry if I missed it in your post),
if so which one? also, does it have a liquid filled guage?

Stock fuel lines?, might be toast.

Good luck,
Author:  snowdevl [ Mon Aug 25, 2008 3:32 pm ]
Post subject: 
Hmm, don't think my gas tank is leaking, the car actually gets pretty good mileage for what it is, and the Walbro shows no signs of giving up so far.

BUT, funny that you mention the injector seals. I actually noticed a little puddle pooling on the intake manifold by number 1 injector. I soaked it up with a cloth and had a sniff, it didn't have a smell so I assumed it was just water. I suppose it COULD be fuel though?

I'm running a stock 4G63T VR-4 regulator. I know of a few cars that run a much crazier setup than my car with the factory regulator no problems.

Did you also have a check engine light? If so, did it disappear after you sorted out your fuelling issues?
Author:  joggle [ Mon Aug 25, 2008 4:28 pm ]
Post subject: 
When swapping the ECU's did you have to use the same E-prom chip?
Author:  snowdevl [ Mon Aug 25, 2008 4:38 pm ]
Post subject: 
Nope, both the other ECU's have their own eprom chips for 510's, Evo AFM etc.

One of the guys, Patrick from the 4G61NZ forums, runs almost the exact same setup as me, 4G61T with all the mods i've listed above. Only differences are he runs a TD04 vs my TD05, and he runs a factory fuel pump vs my Walbro. His ECU is chipped exactly the same as mine. He also runs no knock sensor without any problems, no check engine light, and it runs hard and solid as it should. I thought, if his car runs fine without one, in theory, mine should too? So I unplugged it to see how it would run. No difference, still got the light, and maybe it was just my imagination, but the car seemed slower than it did with the sensor plugged in.
Author:  ColtMax [ Thu Aug 28, 2008 7:13 am ]
Post subject: 
You may want to recheck you t-belt timing.
Weird knocking problems can occurr with out of phase t-belt.

How much is you ignition base timing?
Author:  kezark31 [ Thu Aug 28, 2008 4:50 pm ]
Post subject: 
my 1.6 summit used to do that tried all that and the coil pack and ignitor. finaly check the plug wire with a ohm meter and they were toast!

easy to over look they looked brand new.......ohm meter told the real story, the were at like 8 should be .01-5 per foot
Author:  snowdevl [ Thu Aug 28, 2008 6:14 pm ]
Post subject: 
Quote:
my 1.6 summit used to do that tried all that and the coil pack and ignitor. finaly check the plug wire with a ohm meter and they were toast!

easy to over look they looked brand new.......ohm meter told the real story, the were at like 8 should be .01-5 per foot
Hmm, just went and checked mine. I'm not very electrical savvy so this doesn't really make a whole lot of sense to me haha. With my multimeter set on ohms at 20k, three leads measured between 8.50 and 9.50, one lead measured 12.53 or something. Obviously with the multimeter set at 200k it read between 0.85 and 0.95 on three leads and 1.25 one one lead. I really didn't know what to set it to so.. yeah :lol: Are these readings normal?
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