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Location:
Sydney
Registered:
October 2003
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Engine turns over but backfires
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Sat, 01 May 2004 10:22
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Well after much reading and learning, I finally got all the wiring done on my 3sgte. Turned the key today and she kicked over, but then backfired and stopped!! From what I can tell I think its a backfire anyway - a semi-loud click/bang that seems to be coming out the exhaust manafold. You hear it more from the engine bay then the exhaust though....
Any ideas where I can start looking? I've done a brief search but they all seem to apply for cars that just backfire occasionally - not so much it wont even start!
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Location:
toowoomba qld
Registered:
March 2004
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Re: Engine turns over but backfires
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Sat, 01 May 2004 10:37
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I'd say it's just backfiring the same thing happened with a mates gemini when we put a new motor in it he just got it tuned and it wen't well from there good luck on finding what the problem is but thats what i think it is
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Location:
Sydney
Registered:
October 2003
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Re: Engine turns over but backfires
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Sat, 01 May 2004 10:57
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I'm to embarressed to say what the problem was, but its all good now 
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Location:
toowoomba qld
Registered:
March 2004
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Re: Engine turns over but backfires
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Sat, 01 May 2004 10:59
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what was it?  glad to hear you solved it
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Engine turns over but backfires
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Sat, 01 May 2004 10:59
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LOL, thats a lotta help mick 
i was going to suggest checking ignitions leads first, then check spark timing, then check ignitor connections (if dual coils), then check cam timing, and finally, check valve lash.....
first one then huh done it many times
Cya, Stewart
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Location:
Sydney
Registered:
October 2003
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Re: Engine turns over but backfires
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Sat, 01 May 2004 11:03
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yep first time ive done more then a general service. so i thought a conversion wouldn't be a bad place to start.
(just remember to connect the idle bleed valve up - works better that way)
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Location:
Sydney
Registered:
October 2003
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Location:
toowoomba qld
Registered:
March 2004
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Re: Engine turns over but backfires
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Mon, 03 May 2004 12:01
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weird  maybe condensation in under the distributor cap? it defently sounds like its backfiring by the way you've described the sound (my opinion) that can cause it to do that, maybe there a airleaks at the inlet manifold gasket or the inlet manifold it self? or the problems in the fuel supply but its got me beat good luck on solving it
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: Engine turns over but backfires
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Mon, 03 May 2004 12:09
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how is the ignition timing rob?
i dont remember you talking about this one on sunday, but i have had a similar problem with a couple of my engine swaps, and it turned out to be ignition timing.
Did you check it when you put the motor in? Remembering of course you have to earth out the connector with no keys in, and then start the car with the connector earthed...
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Location:
Brisbane
Registered:
February 2003
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Re: Engine turns over but backfires
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Mon, 03 May 2004 12:16
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plug order right on the dizzi/ignition? (does 3SGTE have dizzi or coil pack?)
my RA40 turbo made very empressive backfire and exhaust pops & bangs when i did this 
..was the first time i got my poor little cat to do the jump into air with feet extended and start running before returning to ground thing - the bangs helped clear the accumulated leaves from rear of car.
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Location:
Newcastle, Hunter Valley
Registered:
January 2004
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Re: Engine turns over but backfires
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Mon, 03 May 2004 12:28
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my 3t was doing that, it turned out to be bad leads.
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Location:
On your mum!
Registered:
May 2002
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Re: Engine turns over but backfires
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Mon, 03 May 2004 12:57
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Incorrect timing (waay retarded), incorrect ignition lead set up (1 and 4 swapped with 2 and 3), pinched fuel line (lean), disconnected/faulty map sensor and or signal line, no fuel... just keep chasing and good luck.
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Location:
Sydney
Registered:
October 2003
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Re: Engine turns over but backfires
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Mon, 03 May 2004 23:09
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Whats weird is that I'm sure it was running fine on sat night. The only thing I changed was added about 20cm to the leads on the igniter and then screwed it into the firewall. Should these cables be shielded?
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Location:
Brisbane
Registered:
February 2003
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Re: Engine turns over but backfires
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Tue, 04 May 2004 08:40
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nah - only sensitive stuff like O2 sensor and knock sensors. some crank angle sensors also like sheiding (hall effect maybe). but all that would do is make idle go pear-shaped and erratic engine behavior thru-out rev range.
maybe undo what you did and see if problem still there?
i'd say you bumped something during the move or plugged it in the wrong way. i think i managed to seriously change timing on the 18R when removing an oil filter - is easy to do, specially if working into night with crap lights.
it won't hurt to pop the spark plugs out and see which pots are firing
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Location:
Sydney
Registered:
October 2003
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Re: Engine turns over but backfires
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Tue, 04 May 2004 10:10
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Ok, done some testing....
To define the sound alittle more, you would sware that there was a hold in the exhaust around the manifold or drop pipe. Its got that lawnmower sharpness to it. However extensive testing shows no sign of leakage (engine was cold and I ran my hand around every gasket, pipe, etc)
All plugs are firing. I ran the engine on 1cyl at a time to confirm this (not in the mood to be shocked today) When running on cylinder 2,3 (not at same time) the engine runs rough, but doesn't make nasty sound. When running on 1,4 it does make the nasty sound. Yes they were all in the right positions on the dizzy. Haven't pulled the plugs out yet...
chuckster: I dont see how I could have bumped it out of timing...there is a cover over the timing belt and the dizzy is screwed in.
I think the fuel pressure is good (can hear is rushing around) - how do you test this?
New development
When increasing revs (prob up to 2000 but dont have tacho hooked up yet) the revs suddenly start fluctuating all by themselves. Like go up to 3000 then drop to 2000, go up to 3000, drop to 2000. And it just keeps repeating this all by itself.
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: Engine turns over but backfires
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Wed, 05 May 2004 09:03
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damn dude this sounds like a mission and a half. I hope you get it all sorted ASAP. i hate being without a car.
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Location:
Sydney
Registered:
October 2003
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Re: Engine turns over but backfires
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Wed, 05 May 2004 11:03
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Any other ideas? I'm going to check the timing on friday night (not really sure how - but I'm sure I'll work that out before then, cant be to hard)
Karl which connector were you talking about earthing out?
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Location:
Sydney
Registered:
October 2003
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Re: Engine turns over but backfires
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Fri, 07 May 2004 12:55
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Well, you know how I said it sounded like a hole in the exhaust? Well there was a hole. So thats that fixed. Wasn't sure wether to make a new thread or follow on here...
The problem with the erratic idle is still persisting. It runs ok upto about 1200rpm, where it then starts rising and falling all by itself. After you get above about 3000rpm everything returns to normal.
My thoughts at this stage is that the AFM might be sticking or something...any idea's?
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Location:
Brisbane
Registered:
February 2003
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Re: Engine turns over but backfires
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Sat, 08 May 2004 02:15
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check wiring/behaviour of the TPS and maybe the AFM - erratic idle and/or jumping revs when pedal held steady might be poor signal being sent to ECU.
Someone else here (Mac using ST162 driver?) recently had similar problem which proved to be dodgy TPS.
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Location:
On your mum!
Registered:
May 2002
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Re: Engine turns over but backfires
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Sat, 08 May 2004 11:46
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Or too much, or too little base ignition timing may now be the problem. Are you timing it at the correct mark?
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Location:
Sydney
Registered:
October 2003
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Re: Engine turns over but backfires
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Sat, 08 May 2004 12:01
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I actually haven't open the timing cover at all. Might do that tomorrow.
Had another look at it today - hooked up the 'turbo pressure vsv' that wasn't connected, although it didn't seem to change anything. Whats it susposed to do??
Have a more detailed description of what it does --
When the revs reach 1300, there is a sound like a tiny BOV, the air flow meter opens more to indicate there is more air going into the engine. And then the revs drop to 900. They then climb back upto 1300 and repeat.
Have checked both AFM and TPS - all are working fine within set ranges. As far as I can tell there are no boost leaks, and the wastegate actuator doesn't move.
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Location:
Brisbane
Registered:
February 2003
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Re: Engine turns over but backfires
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Sat, 08 May 2004 12:49
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is the fast idle (aux air) thingo leaking/working OK?
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Location:
Sydney
Registered:
October 2003
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Re: Engine turns over but backfires
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Mon, 10 May 2004 07:47
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Well I've reached the end of my patentience today. Does anyone know of a good mechanic (around the sydney-blacktown) area that could fix up the rest of the wiring / other problems? I'm just sick to death of it, and dont have the time anymore.
Current problems are -
- gauges on dash are not behaving correctly
- enging is 'hunting' when accelerator pushed
- auto transmission needs to be wired into the new computer
- large hole in the exhaust under dump pipe
Doesn't seem like much, but who knows what else might go wrong. Let me know if you know someone who would be able to tackle finishing this project off - even if you feel capable I'd be willing to pay as long as it works
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Location:
On your mum!
Registered:
May 2002
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Re: Engine turns over but backfires
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Mon, 10 May 2004 09:04
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Perhaps rocco's performance?
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