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2jzgte hesitating under boost


jza800

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I am having hesitating issue under boost from 3 gear and up.. if i go full trottle in 1st or 2nd gear, i have no hesitating at all.. i have a wideband aem gauge in the car, and i can see when the engine hesitating i have a afr range on 13.5 to 13.8, and then goes down to 10.8 when it stop hesitating.. i have notice that i have to be in the 3500 rpm range before it starts to hesitating, it is feeling like a spark blow out or something.. i run on Denso IK22 Iridium Power Spark Plugs.. can it be a worn out spark plug that are the problem?? the plugs have about 6000 km on them..

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I would check the coil pack connectors and wires and coil packs mate. But I would also change the plugs as they have done double the amount of miles I would put on a set of plugs but that's just me.

 

The connectors is good, as i have put new coil pack clips on all 6.. havent checked the coil pack it self, but will do..

 

do you now how many miles on Denso IK22 Iridium Power Spark Plugs

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What's the spec of the car?

 

fmic intercooler - stock engine but run ttc mode at the moment - aftermarked fuel pressure regulator on the return on the stock fuelrail- 1st cat still there, but the 2nd cat removed with a decat exhaust system and hks dragger,

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The lean-looking AFRs will probably be an artifact of the misfire rather than a cause. The AEM gauges tend to not read AFRs richer than 10.8 so you might be overfuelling way beyond that and the misfire is the over-rich mix not igniting. Once you get into the 9:1AFRs that can happen.

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fmic intercooler - stock engine but run ttc mode at the moment - aftermarked fuel pressure regulator on the return on the stock fuelrail- 1st cat still there, but the 2nd cat removed with a decat exhaust system and hks dragger,

 

What aftermarket reg are you using and why is it in TTC mode?

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Why have you got a stock car with a fuel pressure reg?

 

Iridium plugs will last a lot longer than 4000 miles for sure. 13.8 on boost is pretty lean

 

it was on the car when i got it.. so dont now why...

 

yes i now that is lean, but as i comes with the misfire/hesitating, i think that is why, because it goes straght to 10.8 after, and it pulls like normal..

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The lean-looking AFRs will probably be an artifact of the misfire rather than a cause. The AEM gauges tend to not read AFRs richer than 10.8 so you might be overfuelling way beyond that and the misfire is the over-rich mix not igniting. Once you get into the 9:1AFRs that can happen.

 

hmm, why dosent i do it in 1st and 2nd then?? as there is no problem at all under wot..

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Have you checked for fault codes?

 

hmm, why dosent i do it in 1st and 2nd then?? as there is no problem at all under wot..

 

The higher the gear, the higher the boost pressure will be, as the engine is under more load. Misfire at higher boost levels tends to be ignition related ie. plugs, coils, coil pack clips or wiring. What boost pressure are you running?

 

You could try a grade cooler spark plug (Denso 24 or NGK 8) to see if that cures the misfire, just a cheap set of copper plugs gapped up would do, see here: http://www.mkivsupra.net/vbb/showthread.php?41927-FAQ-Spark-plugs

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yes i have no fault codes, other than the code 42..

 

i run stock boost range, 0.7 to 0.9 depending off the weather, i now the engine have run fine, before i took it out off the car because of lots off paint job..

 

i took the plugs out off my old engine, where they did run fine, with no problem at all, so they have been out off the engine about half a year, where i did all the paint job on engine and car.. before i put it all back on the engine, i change the connector on all the coils, and all coil packs looked all fine as they came out off my old engine to, so dont think it can be a wirring or coil or plug problem, but offcourse i cant say 100%..

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i have now unplugs the 2 relaeys to the ecu, so will let them off to tomorrow, so i hope the ecu can be reset after ttc mod.. so will take the car for a long drive Saturday and see if that change everthing.. if not i will trie with new plugs, as they are old as somebody mentioned.. and hope for a miracle :D

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Put a stock regulator on it, put it back to stock sequential and diagnose from there. TTC is utter madness, God knows why people do it, or say they like it. It just undos all that Toyota did to make the car special and able to produce a flat wide torque curve. it also has potentially serious fuelling implications. Just because a wide band reads lean does NOT mean the conditions in the cylinders themselves are all lean...

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i have taken you advise, i have removed the aftermarked fuel pressure reguator, it seems to be one the those ebay regulator

 

http://www.ebay.co.uk/itm/UNIVERSAL-FUEL-PRESSURE-REGULATOR-KIT-Gauge-Hose-SILVER-SUBARU-/170954284206?pt=LH_DefaultDomain_3&hash=item27cdab5cae

 

so have taken it off and put the hose return on the return on the engine again.. so hope that would help..

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New reg kits should come with a rail adapter, lets hope that yours didnt have the stock reg guts removed and used as an adapter for the aftermarket unit.

 

the aftermarkedet was put/fittede on the return pipe on the engine/from the stock regulator on the fuelrail, and the return hose was on the regulator.. and with a vacumhose on the top to the intake..

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