Splutter/hesitation/misfire.
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This is a discussion on Splutter/hesitation/misfire. within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; I dont know much about cars but im learning so bear with me Ive read through the sticky ( http://www.clubwrx.net/forums/genera...3-if-you-have- ...

  1. #1
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    Splutter/hesitation/misfire.

    I dont know much about cars but im learning so bear with me

    Ive read through the sticky (http://www.clubwrx.net/forums/genera...3-if-you-have- misfire-code-please-read.html). I know misfires are hard to diagnose over the net but before I either eat my mechanic or explode into an EMP shockwave I need to try 1 last thing and post here.

    I was about to buy a 2001 bugeye WRX. STI block and turbo, prodrive downpipe, and software upgrade (I think) pushing roughly 250WHP. Car was running really well. Owner let a supposed "rally navigator" drive the car who blew the engine by redlining for 10 mins constantly in gymkhana. Owner then suggested we take it to a mechanic who would offer a 30,000km warranty on workmanship and he would still sell the car to me for the same price while he incurred all costs. Sounded good cause who gets a 30,000km warranty on a 9 year old car.

    After a ridiculous wait the car was completed. Popped on dyno and had what I could best call hesitations. Tuner couldnt tune the car. We also noticed a bad "lifter" ticking sound. Mech was on holiday. I took the car and drove around while only boosted on .5. While the mech was away I took to another mech to see if he could find the problem as I was concerned the car may break. He picked up an error code which turned out to be the O2/lamba sensor. We replaced this. No mores errors and no obvious problems. He swapped NAF. We drove the car for 2 hours with his laptop plugged in trying different acceleration methods to get readouts on air/fuel (I think thats what he was looking at but I know he said it shouldnt go below 11 or 10 something.....). Worst "misfires/hesitations" when I drove flat out from start to end 3rd. Zero misfires happened when I slowly pushed the accelerator through the revs and only reaching 100% at 6kish through each gear. Apparently the reading also couldnt show if it was going below 10 whatever as there was something on my car stopping the reading at 11?

    I drove the car 1 more day and engine died. Mech opened engine and it dropped a valve. Destroyed 2 and 4, valves and pistons. Damaged heads really badly.

    Mech warranty kicks in and he rebuilds. Puts big port heads on + 2.5ltr gaskets. Drops engine in. Ive been running it for the last 1000kms with oil changes at every 250km. Tonight he did an oil change and applied a map to take the car for a run to see how its going. Guess what? Hesitations are still there. He drops to .5 boost and sends me off saying I need to book the car in so he can problem solve. He thinks coil packs. Ive heard the other mech says its not possible cause I would have "misfires" constantly whereas mine come in mainly under boost and only when my foot is flat. Other mech also said its not so much a misfire, its more a hesitation in his opinion. Someone also mentioned its possibly fuel regulator and that the car may be flooding.

    Coil packs sound like a possibility? Im obviously going to get this twit to do a swap out but im really doubting he knows what hes doing.

    Any info would be great as im just beyond frustrated. Ive "had" the car for 4 months and not once been able to put my foot down and just enjoy the power.
    Last edited by wancieho; 11-24-2010 at 02:26 PM.

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  3. #2
    Registered User EvoEatr's Avatar
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    Quote Originally Posted by wancieho View Post
    I dont know much about cars but im learning so bear with me

    Ive read through the sticky (http://www.clubwrx.net/forums/genera...3-if-you-have- misfire-code-please-read.html). I know misfires are hard to diagnose over the net but before I either eat my mechanic or explode into an EMP shockwave I need to try 1 last thing and post here.

    I was about to buy a 2001 bugeye WRX. STI block and turbo, prodrive downpipe, and software upgrade (I think) pushing roughly 250WHP. Car was running really well. Owner let a supposed "rally navigator" drive the car who blew the engine by redlining for 10 mins constantly in gymkhana. Owner then suggested we take it to a mechanic who would offer a 30,000km warranty on workmanship and he would still sell the car to me for the same price while he incurred all costs. Sounded good cause who gets a 30,000km warranty on a 9 year old car.

    After a ridiculous wait the car was completed. Popped on dyno and had what I could best call hesitations. Tuner couldnt tune the car. We also noticed a bad "lifter" ticking sound. Mech was on holiday. I took the car and drove around while only boosted on .5. While the mech was away I took to another mech to see if he could find the problem as I was concerned the car may break. He picked up an error code which turned out to be the O2/lamba sensor. We replaced this. No mores errors and no obvious problems. He swapped NAF. We drove the car for 2 hours with his laptop plugged in trying different acceleration methods to get readouts on air/fuel (I think thats what he was looking at but I know he said it shouldnt go below 11 or 10 something.....). Worst "misfires/hesitations" when I drove flat out from start to end 3rd. Zero misfires happened when I slowly pushed the accelerator through the revs and only reaching 100% at 6kish through each gear. Apparently the reading also couldnt show if it was going below 10 whatever as there was something on my car stopping the reading at 11?

    I drove the car 1 more day and engine died. Mech opened engine and it dropped a valve. Destroyed 2 and 4, valves and pistons. Damaged heads really badly.

    Mech warranty kicks in and he rebuilds. Puts big port heads on + 2.5ltr gaskets. Drops engine in. Ive been running it for the last 1000kms with oil changes at every 250km. Tonight he did an oil change and applied a map to take the car for a run to see how its going. Guess what? Hesitations are still there. He drops to .5 boost and sends me off saying I need to book the car in so he can problem solve. He thinks coil packs. Ive heard the other mech says its not possible cause I would have "misfires" constantly whereas mine come in mainly under boost and only when my foot is flat. Other mech also said its not so much a misfire, its more a hesitation in his opinion. Someone also mentioned its possibly fuel regulator and that the car may be flooding.

    Coil packs sound like a possibility? Im obviously going to get this twit to do a swap out but im really doubting he knows what hes doing.

    Any info would be great as im just beyond frustrated. Ive "had" the car for 4 months and not once been able to put my foot down and just enjoy the power.

    So your mechanic rebuilt the new heads? I am thinking one of three things here...perhaps a tight valve, an ignition problem, or something gone array with the tune...Does the vehicle misfire at all with it running at idle? Is the check engine light currently on? I dont mean to bad mouth anyone but does this "mechanic" know what he is doing? I would kind of wonder what went arrary for a vehicle to drop 2 valves and damage a piston just like that...that kind of stuff usually doesnt happen to a rebuilt engine if it is installed properly...

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