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Registered:
March 2003
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 engine splutter at higher boost problem
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Sat, 01 March 2003 04:16
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Hi,
I have dont a couple of minor mods recently and now my engine
splutters at higher boost pressures of 15psi.
I wired in the 4.7v zener diode mod ... part no (Zener 1W 4V7
1N4732/BZX85C4V7) it is 1 or 1.3 watt part. Is this the right
component?
I wired the zener from signal BLUE/BLACK (L-B 3) to ground BROWN (BR
1) with the band facing the signal wire.
I next turned up the boost on my turbosmart pneamatic boost
controller to 15psi.
Now when you drive the car it splutters and coughs once it gets to
15psi ... up until usually 14 psi it is ok. Its not like what fuel
cut used to be like but it aint good.
I just wanted to make sure that the fuel cut mod I did was done
correctly.
So what does everyone think .. mabey the air fuel ratios are messed
up now at higher boost (leaning out) and I should wait until I get
aftermarket engine management before I run higher boost or that fuel
ratios should still be reasonable seeing its only a few extra psi and
my fuel cut mod is not working properly.
Any advise appreciated.
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Location:
MACKAY
Registered:
May 2002
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Re: engine splutter at higher boost problem
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Sat, 01 March 2003 11:18
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What sort of plugs are you using , If they are iridium or platinum , Chuck them in the bin and put in a set of Denso or NGK-R's .
Trevor
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Location:
Canberra
Registered:
May 2002
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Re: engine splutter at higher boost problem
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Sat, 01 March 2003 12:43
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or if you've already got steel plugs, try closing the gap down to 0.8-0.9mm.
This splutter, is it just a hesitation, or is there backfiring/popping out the exhaust?
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Registered:
March 2003
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Re: engine splutter at higher boost problem
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Sun, 02 March 2003 02:43
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Yeah it doesnt hesitate ... its not like boost/fuel cut ... the best I can describe it is as a splutter and loss of acceleration/power. It doesnt backfire or even pop really. Its sorta does seem like the spark is breaking up. Ill try susing the plugs, gap em down etc and see how that goes.
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Location:
Wollongong
Registered:
May 2002
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Re: engine splutter at higher boost problem
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Sun, 02 March 2003 10:26
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I had similar problems with my 1J at higher boost. New plugs fixed everything 
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Location:
Sydney
Registered:
May 2002
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Re: engine splutter at higher boost problem
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Sun, 02 March 2003 10:54
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Does the car feel like it's surging?
As the mods have progressed on my 1J, I've dropped the gap down contuously to avoid the problem - now down to 0.7mm and it still happens at high boost (1.2 bar) / high load (>75% TPS). It's a limitation of the coils/ignition system in my case and requires some expensive ignition upgrades.
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Location:
Canberra
Registered:
May 2002
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Re: engine splutter at higher boost problem
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Sun, 02 March 2003 11:21
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manny: What brand & heat range plugs do you use? I would have thought that the 1J ignition system was more than capable on almost all 'street' turbo setups.
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Registered:
March 2003
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 Re: engine splutter at higher boost problem
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Mon, 03 March 2003 03:58
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Yeah, I fixed the problem ... I just pulled all the plugs out,
cleaned the head where the plug sits of oil, dirt etc, cleaned the
silicon boots for the plugs, and the stems of the coils then reduced
to gap on the plugs to just over 0.8mm and problem gone.
The plugs Im running are pretty new. The are NGK R Laser Platinum BCPR6EP-11 3350 units about $20.00 AUD each.
Now it runs hard and smooth all the way to red line with 15psi .
Plugs showed no sign of overly lean mixtures and fuel cut mod appears
to be working fine. Its all good.
By the way the car is a 90 model JZA70 Supra and the engine the 1JZ-GTE with the stock twins.
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Location:
Canberra
Registered:
May 2002
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Re: engine splutter at higher boost problem
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Mon, 03 March 2003 08:05
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nice one! sounds like a sweet car. glad its working now as it should.
Cheers
Phil
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