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Choppy Power/ Cutting Etc

ShiftyTys

By ShiftyTys,
in Engines & Forced Induction

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ShiftyTys Rising Star

ShiftyTys

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yup.

how would going to a cooler plug help? When I swaped to iridium, the old plugs were coloured perfectly, not indicating detonation or other nasties (had light tan colour, no damage to tip or ceramic etc)

please advise...

ShiftyTys Rising Star

ShiftyTys

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irridium / platinum + boost = :P

i replace about 10 sets a week.

hmm. Fair enough. Lol

but it had ngk coppers in it before I change coilpacks n plugs. I only changed to iridium and splitfires BECAUSE of this problem. That's why I'm kinda thinking it's not an iridium problem, as it did it with the coppers.

So what else could it be?

ShiftyTys Rising Star

ShiftyTys

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hmm. Fair enough. Lol

but it had ngk coppers in it before I change coilpacks n plugs. I only changed to iridium and splitfires BECAUSE of this problem. That's why I'm kinda thinking it's not an iridium problem, as it did it with the coppers.

So what else could it be?

however correct me if I'm wrong, you've obviously got alot more know how than myself, I'm just confused cos it originaly had coppers when this problem started :P

ShiftyTys Rising Star

ShiftyTys

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were the coppers gapped properly?

umm. One would assume so. Honestly. I can't know for sure. They were put in when I needed a new coilpack a while back. The boys down at HPF/Amberly Auto did it. They usualy are pretty on the ball down there.

However who knows. What u recommend the gap be at? These iridiums are .8 and cos the coppers where the same heat range I assumed they where .8 too.

ShiftyTys Rising Star

ShiftyTys

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.8 is the standard...

does it ever clear up after a long drive?

at times I feel that it is worse when cold. Esspecialy those first realy yucky severe kinda ones at lower rpm. That's always heaps worse when cold. And eases off (doesn't stop though) after driving for a fair time. but as for the higher rpm one. That severity remains the same no matter how long I've been driving for. But as mentioned in first post, it may (rarely) not

even occur, it won't do it maybe every 3rd attempt. And when it DOESNT occur, I don't know if this is in my head, but the power feels a bit lacking.

ShiftyTys Rising Star

ShiftyTys

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could be your plugs fouling and clearing up on long drives...

bung o2 sensor making it too rich, especially on cold start perhaps?

old plugs showed no signs of fouling, as far as I could tell with regards to coloration and wear. Plus now the plugs are new (however possibly have the iridium + boost = :P dillema)

is there a way to isolate the o2 sensor as a possible culprit? Or in my case, actualy locate it!

Thanks for u help so late :) (if I dont reply any more it means my brain went into

a sleep deprived coma, to Wich I'll respond asap in the morn)

daisu Mentor

daisu

Posted
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Mate, based on your description, I had the exact same problem.

You tried to accelerate quickly and it bogs, hesitates and jerks. Difference with mine was it wouldn't push through unless you lifted off the throttle some.

I unplugged my O2 sensor and the symptoms would ease up/disappear but then, without the O2 sensor I got shit fuel economy. Tried a new O2 sensor but that didn't fix it.

I did heaps of things, cleaned the AFM, resoldered connections, new copper plugs, changed the gap to 0.7mm, swapped all of my coilpacks/loom/ignitor with known working items from a mates car.

The problem remained until one day I removed my front mount/pipes and replaced it with a large sidemount. My deduction is that there was an air leak on the inlet piping (which isn't surprising considering I had welded my own pipes and I didn't pressure test them).

Makes sense that the more boost you run the worse it gets. Get a PVC pipe end cap, screw a tyre valve into it, install it in place of your AFM and pressurise your inlet piping, this should identify any leaks pretty quickly.

ShiftyTys Rising Star

ShiftyTys

Posted
  • Author
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Mate, based on your description, I had the exact same problem.

You tried to accelerate quickly and it bogs, hesitates and jerks. Difference with mine was it wouldn't push through unless you lifted off the throttle some.

I unplugged my O2 sensor and the symptoms would ease up/disappear but then, without the O2 sensor I got shit fuel economy. Tried a new O2 sensor but that didn't fix it.

I did heaps of things, cleaned the AFM, resoldered connections, new copper plugs, changed the gap to 0.7mm, swapped all of my coilpacks/loom/ignitor with known working items from a mates car.

The problem remained until one day I removed my front mount/pipes and replaced it with a large sidemount. My deduction is that there was an air leak on the inlet piping (which isn't surprising considering I had welded my own pipes and I didn't pressure test them).

Makes sense that the more boost you run the worse it gets. Get a PVC pipe end cap, screw a tyre valve into it, install it in place of your AFM and pressurise your inlet piping, this should identify any leaks pretty quickly.

wow. Thanx for your reply. I'll DEFINATELy add pressure test system to my list of things to do. Thanx heaps.

I'll let u know how it goes!!

Thanx again. Tys

  • 1 year later...
ShiftyTys Rising Star

ShiftyTys

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Ok big delay.

thought id add some closure to this topic for anyone who wants to know what the poblem was.

turned out to be a stuffed AFM.

Boys at AVO sorted it out for me, they had a spare AFM to test. was flawless from word go.

Ended up removing AFM and going MAP sensor and ECU lol.

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