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Re: Misfire and stuttering under load.

Posted: Sun Feb 19, 2017 4:43 am
by Oldandslow
Sorry didn't see your reply. I do not know of the age but the temp gauge seems to be working correctly, not sure if that means anything.

Re: Misfire and stuttering under load.

Posted: Sun Feb 19, 2017 4:55 pm
by cj91legss
There are 2 coolant temp sensors. 1 for the ecu and one for the gauge. The one for the ecu goes bad and it causes all sorts of problems.

Re: Misfire and stuttering under load.

Posted: Sun Feb 19, 2017 5:02 pm
by Oldandslow
Ohhh I did not know this. Where is the Ecu one located?

Re: Misfire and stuttering under load.

Posted: Sun Feb 19, 2017 5:04 pm
by cj91legss
Its under the intake manifold threaded into the coolant crossover tube. Both of them are side by side. The single wire sensor is for the gauge and the double wire sensor is the one you want to check out.

If that doesn't change your issue, I'd also suspect fuel pump?

Re: Misfire and stuttering under load.

Posted: Sun Feb 19, 2017 8:57 pm
by Oldandslow
Thanks, I found it. Ordered a new one since it was pretty cheap. I checked the fuel pressure before and I'm getting over 30psi at idle so I don't think its the pump.

Re: Misfire and stuttering under load.

Posted: Sun Feb 19, 2017 9:02 pm
by cj91legss
Oddly enough it still can be. Your symptoms are extremely similar to an issue I had and could not find the culprit, even with help from a several friends.

I could drive the car just fine but as soon as I tried to get on it hesitation bucking and popping from the intake. Went at it for a long time with swapping parts. Finally one day the pump just died. Swapped in another good pump and I had full boost and drive ability. It literally had everyone stumped.

I swapped maf, cam, crank, cats, throttle bodies, coils, ignitor, and any other stupid sensor I could think of...

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Re: Misfire and stuttering under load.

Posted: Sun Feb 19, 2017 9:17 pm
by Oldandslow
Wow that sounds like my exact issue. If this sensor doesn't fix it, i'll throw a new pump in and see what happens.

Re: Misfire and stuttering under load.

Posted: Sun Feb 19, 2017 9:18 pm
by cj91legss
For what it's worth I bought an aem 320lph pump on ebay for 100 bucks.

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Re: Misfire and stuttering under load.

Posted: Mon Feb 20, 2017 10:48 pm
by Oldandslow
Well the sensor didn't fix it. It was cheap so its no big deal. I found a walbro with install kit on ebay. If that doesn't fix it then I might have to give up lol.

Re: Misfire and stuttering under load.

Posted: Thu Feb 23, 2017 11:47 pm
by Oldandslow
Well I give up. Fuel pump didn't help at all, it was a good idea though. Other than a bad injector which I have no way to test, I'm out of ideas. I guess I'll just drive it like it is til it blows lol

Re: Misfire and stuttering under load.

Posted: Thu Feb 23, 2017 11:48 pm
by cj91legss
You can test if you have an idea which injector might be giving you problems.

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Re: Misfire and stuttering under load.

Posted: Sun Feb 26, 2017 1:59 am
by Oldandslow
How do I test? Couldn't find anything online.

Re: Misfire and stuttering under load.

Posted: Sun Feb 26, 2017 2:06 am
by cj91legss
If you can get an idea of which cylinder is giving you a problem, you can swap that injector to a different cylinder and see if the issue follows it.

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Re: Misfire and stuttering under load.

Posted: Sun Feb 26, 2017 7:24 am
by Oldandslow
Oh I'm not sure which one it is, or if it's an injector at all.

Re: Misfire and stuttering under load.

Posted: Tue Feb 28, 2017 5:00 am
by beatersubi
I've been experiencing a similar issue with bucking/missing but only under positive manifold pressure. I figured it was merely the original knock sensor, so I picked one up from RockAuto, but it didn't solve the issue. So I checked the plugs and it must have been a while since I last replaced them because the gap was out to .050"+. I tightened them up to .035" and it runs much better. I'm still going to get a new set of plugs, but its surprising how much better it runs with a tighter gap.
I see that you replaced the plugs in yours, but what did you set the gap to?

Re: Misfire and stuttering under load.

Posted: Wed Mar 01, 2017 1:59 am
by Oldandslow
Already tried that unfortunately. Gapped them all to spec.

Re: Misfire and stuttering under load.

Posted: Sun Mar 26, 2017 3:14 pm
by beatersubi
Any changes?

Re: Misfire and stuttering under load.

Posted: Mon Mar 27, 2017 10:09 pm
by Oldandslow
Haha nope. Some drives are worse than others but it still misfires until you get past like 3k rpm. Then it clears up, It hates being down low.

Re: Misfire and stuttering under load.

Posted: Tue Mar 28, 2017 4:03 am
by zeke
How is the condition of your intake piping I had a similar issue before I put a catch can set up and deleted my bpv. Do you have oil building up in your intake track at all?

Re: Misfire and stuttering under load.

Posted: Mon Jun 19, 2017 2:54 am
by beatersubi
Welp... my hesitation/stutter is back. Does it much worse before its warmed up.
Have you found any resolution to your issue?

Re: Misfire and stuttering under load.

Posted: Mon Jun 19, 2017 4:45 am
by Pntaste4evr99
I had a similar situation before I swapped to a coil in plug setup.....Don't know if that helps at all, also cleaned all the grounds in the engine compartment(intake and firewall) probably didn't do anything but maybe???

Re: Misfire and stuttering under load.

Posted: Tue Jun 20, 2017 3:32 am
by luceleaf
this is a shot in the dark but i had a similar issue with an intermittent misfire and it ended up being the ignition coil. there were hairline fractures that were causing a short circuit. it was raining one day i opened the hood and you could see the electricity arching. I upgraded to a MSD8239. Im non turbo so idk how similar your ignition system is.

Re: Misfire and stuttering under load.

Posted: Tue Jun 20, 2017 5:05 am
by beatersubi
luceleaf wrote:this is a shot in the dark but i had a similar issue with an intermittent misfire and it ended up being the ignition coil. there were hairline fractures that were causing a short circuit. it was raining one day i opened the hood and you could see the electricity arching. I upgraded to a MSD8239. Im non turbo so idk how similar your ignition system is.
That's an interesting observation. I've been thinking it was a fuel/ecu problem this whole time. I have a spare coilpack I can swap in and report on the effects. Thanks for the suggestion.

Re: Misfire and stuttering under load.

Posted: Sat Jun 24, 2017 1:57 am
by Oldandslow
Sorry it's been so long guys after the winter the car was put away and I haven't messed with it until this week. Getting the fuel injectors flow tested and cleaned will post an update. Also I already tried the ignition coil.

Re: Misfire and stuttering under load.

Posted: Sun Jun 25, 2017 2:32 am
by Oldandslow
Well injectors did not fix the problem... I'm officially stumped. Might just have to take it to a subaru dealer and see if they can diagnose it...