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OmgPete

Power loss, rough idle PLEASE HELP!

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Ok so this is starting to annoy me a bit and im not sure where to go next.

First things first, the car im having issues with is an S13 Redtop SR20DET, S15BB T28, Walbro 460lph pump, standard injectors, standard AFM, standard ecu.

So I entered a drift day last month and towards the end of my 2nd session it started to feel powerless in mid/higher revs, now that i think of it it was probably just after a bit of an over rev in 2nd gear. At the time i thought maybe it had something to do with oil pressure as i noticed id blown my front main seal when i got back to the pits. The issue started off as, the car would start fine like normal and everything seemed normal until id get to 3500-4000 rpm and it would feel like itd start missing and will just keep sounding rough and feeling powerless no matter how far i keep pushing it which i figured rules out the knock sensor as most people say that they go into closed loop mode at 5000rpm and it would also sound like itd miss every once in a while, while it was idling, but the idle didnt seem too bad.

From there i have

 

Replaced front main seal

Replaced spark plugs, although id already put new ones in before the track day

Tested coil packs which came up ok with a multi meter

Tested igniter with multi meter and seemed ok

Cleaned AFM

Checked earths and they all seem ok

Checked cooler piping for leaks/loose clamps

Ended up getting good coilpacks off a mate

 

Then things started to go downhill the other night when i put a bottle of Wynns injector cleaner in my fuel tank. Took it for a drive around the blocked after i did and the miss seemed to get worse and then my car was feeling like it was just about ready to die and i had to limp it home.

Tonight i made up a little contraption to clean my fuel injectors one by one using an old fuel rail and squirting carby cleaner through them while opening and closing them by giving them power from the battery. I then put them back in the car and couldnt get it to start. took my plugs out and one looked dry but had carbon on it and the other 3 were wet and smelt like fuel. cleaned them all and still couldnt get it to start. checked the plugs again and all 3 were wet but the one that was dry before seemed to be less wet than the rest but it may have just been my imagination. Put in another new set of plugs and only just got the car to start but my idle was rough as hell and continued even when i gave it some throttle and now its also blowing a shit load of white smoke out the exhaust when i rev it. Started thinking maybe it was a turbo seal, but i checked my hot side intercooler pipe and theres no oil in there anywhere so im guessing it may not be that?

Sorry for the huge write up, but if anyone has had the same kind of issue before or can help in any way, it would be greatly appreciated. Thanks.

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Sounds like the fuel pump and or filter to me? I would check the fuel related fuses also. I'm having very similar issues and abiut to change my fuel pump plus filter. Does it feel similar to when you're losing gas?? Mine started to stall intermittently aswell and took awhile to prime and start up again.

Edited by nsta

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I forgot to add, i did change my pod filter and fuel filter also with no luck.

Ill suss out the fuel pump tho. I was also thinking maybe it could be a bad batch of fuel but dono.

It kinda feels like it starts to run on 3 cylinders kinda thing, like itll keep picking up speed but very slowly and sounds rough

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Yep I also had a bad batch of fuel and was fouling my plugs and running rich. I would check your fuel pump!

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Or possibly fuel pressure regulator

When it's idling roughly try crimping the rubber return line to the tank and see if it improves idle, I've had one go and it gave similar symptoms to what you've described

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02 sensor ? Seen similar issues numerous times and this was the problem.

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I just started her up and it started beautifully tonight. Idle seemed to be back to normal, but it started blowing smoke out of the exhaust again so im beginning to think maybe it did blow the turbo oil seal. Anyone ever had a lack of power when it starts to build boost which was caused by a turbo seal?

I havent got a fuel pressure tester at the moment so i cant really test the pressure from the fuel pump but i did crimp the return line on the fuel rail and that made it start to bog down on idle which is a good thing right?

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Also, it was blowing smoke when i started it up (whiteish but could have been blueish lol) but when i took it for a squirt around the block and came back it had stopped blowing smoke

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Also, it was blowing smoke when i started it up (whiteish but could have been blueish lol) but when i took it for a squirt around the block and came back it had stopped blowing smoke

 

i believe this is not good, could be your head gasket, check your radiator, hopefully its not a milky texture when coolant and oil mix

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Also, it was blowing smoke when i started it up (whiteish but could have been blueish lol) but when i took it for a squirt around the block and came back it had stopped blowing smoke

 

i believe this is not good, could be your head gasket, check your radiator, hopefully its not a milky texture when coolant and oil mix

 

Definitely not headgasket, well 99% sure anyway. I checked the radiator the other day and it was still 100% full and nice and green. Nothing milky under the oil fill cap either

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Unplugged the o2 sensor the other day and went for a drive and it still had the same issue.

Tested fuel pressure today and it was at 41psi on idle and removing the vaccuum line bumped it up to 51psi so im guessing fuel wouldnt be the issue here either? The needle on the pressure tester kind of hopped around a bit, nothing major, like less than 0.5psi up and down, is that normal? Ive never used a fuel pressure tester before

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Doesn't the o2 sensor only come into play with closed loop operation on light throttle cruise?

Also have you checked the flow capability, just because the fuel pump has pressure with a closed system doesn't mean it can keep that pressure up with a flow. Fuel pressure needs to be tested under engine load

Edited by S15 sxytime

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Ibe got no idea to be honest.

Can that be done by revving or do i need to actually put it under load by going for a drive? Revving it would pop up to about 50ish but wouldnt hold it

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Also, its back to how it was before i cleaned my injectors so easy start and no smoke whatsoever

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Fuel pressure needs to be checked under load , either on a dyno or on the road with an accurate gauge. Pressure and volume are two different things.

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If you already changed the plugs and gapped them to 0.7 and it's still going it then as I mentioned before change your pump it's obviously lazy..

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