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aido

Is Backfire On The Mk1 & Mk2 Tt's Normal?

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Hey guys, just a quick question for the Mk1 & Mk2 owners, the other day I was out with Waddy and we were having a play with the Aristo, anyway, if you let your foot off the throttle around the 4k rpm mark, where the second turbo is starting to spool, and then let it go down to around the 3k rpm mark, you get a gunshot type sound where the car is backfiring...

I've been having a look around the net tonight and not sure if this is a good thing or a bad thing?

The car itself likes a burble every now and then, and occasionally I've heard it backfire when out on the roads if I let off the throttle under the right conditions.

Is this normal on cars with the 2JZ-GTE when they've been modded slightly, or does it sound like the cats are on their way?

The car flew through the last emissions test at the start of the year, and it's been sat for a few months doing nothing so it's not like it's really done much milage since the last MOT so in theory they should still be ok?

The car pulls like hell as it goes up through the rev range, and I noticed last night coming home when I floored it that you could see a load of ***** fly out, guessing it was fuel when I floored it as I've seen Mitsubishi 3000GT's do that when you've got WOT? Seeing as it pulls so well I'm assuming the cat hasn't broken up..

Waddy put this down to the car just dumping the unburnt fuel that has been put in as the car is expecting the turbo to kick in, but we're letting off - after seeing some stuff on the net I just wanted to clarify and make sure it's not doing any harm!

I can't see if the thing is shooting flames when it does it, it did pop the other day and the car behind me suddenly dropped back a bit quick so *** only knows what's happening there!

Thanks in advance!

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I'll get the cats checked out then Mat, thanks mate, any other ideas please?

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I get popping and burbling all the time with the MR2....seems to be very common when running uprated boost with a derestricted exhaust.

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Fingers crossed then fella, thinking about it my mates MR2 did this when it had another exhaust fitted!

Hopefully it will just be that as I do have the bleed valve on the boost and also the exhaust done :D

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My Soarer did this @ the ring last time...........was told I'd blown a cat

Hope that helps

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Oh bugger :lol:

Sounds like a good excuse to get it decatted then if it does turn out to be knackered :o

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Mine has never backfired Aido, but do get a looovely power-down note when I lift my foot at 4K revs like you, no backfire.

Mine has been decated and free-flowed

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Luckily it's only one cat that's gone. If you remove both cats make sure you've got a boost guage to keep an eye on the boost creeping up with both cats removed and have a restrictor ring put on too of about 2 1/4" IIRC :). It definitely does sound like the cats are gone, as mine doesn't backfire like that either.

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Sounds like you may have pre cat air leak,it will suck in air on over run and ignight any unburnt fuel in the cat causing a back fire.Check the exhaust to see if it has been damaged it may have been clobberd and moved on a joint busting a seal.When a free flow exhaust is fitted they are some times too big and will suck air back up the pipe on overrun.Have seen this happen a few times.

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Hi,

As gsw said if theres a slight leak on the exhaust if its blowing a little this can cause this.

If you do decat the exhaust,if the car does use a little oil then it will show up alot more after its been decatted.

For Ref no backfire on my car all the time ive own it.

Chips..

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Thanks again for all the comments guys, I've got the car booked in with a Supra guy to do the timing belt so I'm going to ask him to give everything the once over while he's at it!

Had a bit of a to do with an M3 tonight, the Aristo as is couldn't keep up in corners, but in a straight line there was basically nothing in it!

My mate took me out for a spin in the M3 afterwards, *** they're crazy, handling is amazing, he did a drift around the Whittington Moor roundabout in Ches for those that know it, I was ****ting myself!

All in all a good nights fun on the way home from the gym :lol:

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Luckily it's only one cat that's gone. If you remove both cats make sure you've got a boost guage to keep an eye on the boost creeping up with both cats removed and have a restrictor ring put on too of about 2 1/4" IIRC :). It definitely does sound like the cats are gone, as mine doesn't backfire like that either.

You don't get boost creep on MKII Aristo's Skeet, even with a full de-cat. You have to install a boost controller to increase boost...

Gaz.

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Hmm I always thought the wastegate was too small to regulate boost when decatted as the JDM Turbo's rely on exhaust backpressure to control boost...or is this only on the Mk1's and Supra's?

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Have been doing a load more driving and the car is fine when in auto mode, it's only when I'm playing in Manual mode that it pops and even then it's not that often - guessing that's good news?

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Hi,

As gsw said if theres a slight leak on the exhaust if its blowing a little this can cause this.

Chips..

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My Soarer did this @ the ring last time...........was told I'd blown a cat

Hope that helps

I remember that :D

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