Misfire and stuttering under load.

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Oldandslow
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Re: Misfire and stuttering under load.

Post 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.
1991 Legacy SS 5spd
cj91legss
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Re: Misfire and stuttering under load.

Post 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.
91 L-TW Wagon with a full Swap -RIP
92 SS Prefaced, GD dash swapped, 22T/205 Hybrid 20 psi - BEAST!
93 SS Bone Stock Gone!
94 TW Bone Stock Gone!
91 SS 4EAT Sold!
98 LGT 4EAT
98 LGT Wagon 4EAT
Oldandslow
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Re: Misfire and stuttering under load.

Post by Oldandslow »

Ohhh I did not know this. Where is the Ecu one located?
1991 Legacy SS 5spd
cj91legss
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Re: Misfire and stuttering under load.

Post 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?
91 L-TW Wagon with a full Swap -RIP
92 SS Prefaced, GD dash swapped, 22T/205 Hybrid 20 psi - BEAST!
93 SS Bone Stock Gone!
94 TW Bone Stock Gone!
91 SS 4EAT Sold!
98 LGT 4EAT
98 LGT Wagon 4EAT
Oldandslow
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Re: Misfire and stuttering under load.

Post 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.
1991 Legacy SS 5spd
cj91legss
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Re: Misfire and stuttering under load.

Post 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...

Sent from my SM-N920T using Tapatalk
91 L-TW Wagon with a full Swap -RIP
92 SS Prefaced, GD dash swapped, 22T/205 Hybrid 20 psi - BEAST!
93 SS Bone Stock Gone!
94 TW Bone Stock Gone!
91 SS 4EAT Sold!
98 LGT 4EAT
98 LGT Wagon 4EAT
Oldandslow
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Re: Misfire and stuttering under load.

Post 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.
1991 Legacy SS 5spd
cj91legss
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Re: Misfire and stuttering under load.

Post by cj91legss »

For what it's worth I bought an aem 320lph pump on ebay for 100 bucks.

Sent from my SM-N920T using Tapatalk
91 L-TW Wagon with a full Swap -RIP
92 SS Prefaced, GD dash swapped, 22T/205 Hybrid 20 psi - BEAST!
93 SS Bone Stock Gone!
94 TW Bone Stock Gone!
91 SS 4EAT Sold!
98 LGT 4EAT
98 LGT Wagon 4EAT
Oldandslow
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Re: Misfire and stuttering under load.

Post 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.
1991 Legacy SS 5spd
Oldandslow
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Re: Misfire and stuttering under load.

Post 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
1991 Legacy SS 5spd
cj91legss
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Re: Misfire and stuttering under load.

Post by cj91legss »

You can test if you have an idea which injector might be giving you problems.

Sent from my SM-N920T using Tapatalk
91 L-TW Wagon with a full Swap -RIP
92 SS Prefaced, GD dash swapped, 22T/205 Hybrid 20 psi - BEAST!
93 SS Bone Stock Gone!
94 TW Bone Stock Gone!
91 SS 4EAT Sold!
98 LGT 4EAT
98 LGT Wagon 4EAT
Oldandslow
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Re: Misfire and stuttering under load.

Post by Oldandslow »

How do I test? Couldn't find anything online.
1991 Legacy SS 5spd
cj91legss
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Re: Misfire and stuttering under load.

Post 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.

Sent from my SM-N920T using Tapatalk
91 L-TW Wagon with a full Swap -RIP
92 SS Prefaced, GD dash swapped, 22T/205 Hybrid 20 psi - BEAST!
93 SS Bone Stock Gone!
94 TW Bone Stock Gone!
91 SS 4EAT Sold!
98 LGT 4EAT
98 LGT Wagon 4EAT
Oldandslow
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Re: Misfire and stuttering under load.

Post by Oldandslow »

Oh I'm not sure which one it is, or if it's an injector at all.
1991 Legacy SS 5spd
beatersubi
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Re: Misfire and stuttering under load.

Post 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?
93 legacy wagon L, 22T swapped (TW imitator) now with five forward speeds. (Gone, but never forgotten)
johndrivesabox wrote: Rally, my kyboard is brok, his has nohing o do wih h liquor.
Originalcyn wrote:Apparently everyone hates Gabe.
Oldandslow
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Re: Misfire and stuttering under load.

Post by Oldandslow »

Already tried that unfortunately. Gapped them all to spec.
1991 Legacy SS 5spd
beatersubi
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Re: Misfire and stuttering under load.

Post by beatersubi »

Any changes?
93 legacy wagon L, 22T swapped (TW imitator) now with five forward speeds. (Gone, but never forgotten)
johndrivesabox wrote: Rally, my kyboard is brok, his has nohing o do wih h liquor.
Originalcyn wrote:Apparently everyone hates Gabe.
Oldandslow
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Re: Misfire and stuttering under load.

Post 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.
1991 Legacy SS 5spd
zeke
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Re: Misfire and stuttering under load.

Post 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?
91 ss Ej22t dohc td04 sti Slanty haltech elite 1500
beatersubi
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Re: Misfire and stuttering under load.

Post by beatersubi »

Welp... my hesitation/stutter is back. Does it much worse before its warmed up.
Have you found any resolution to your issue?
93 legacy wagon L, 22T swapped (TW imitator) now with five forward speeds. (Gone, but never forgotten)
johndrivesabox wrote: Rally, my kyboard is brok, his has nohing o do wih h liquor.
Originalcyn wrote:Apparently everyone hates Gabe.
Pntaste4evr99
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Re: Misfire and stuttering under load.

Post 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???
94 Winestone SS 5MT Rob 550 20g. (Pickle)
Original WA car with 460k miles and climbing
luceleaf
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Re: Misfire and stuttering under load.

Post 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.
beatersubi
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Re: Misfire and stuttering under load.

Post 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.
93 legacy wagon L, 22T swapped (TW imitator) now with five forward speeds. (Gone, but never forgotten)
johndrivesabox wrote: Rally, my kyboard is brok, his has nohing o do wih h liquor.
Originalcyn wrote:Apparently everyone hates Gabe.
Oldandslow
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Re: Misfire and stuttering under load.

Post 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.
1991 Legacy SS 5spd
Oldandslow
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Re: Misfire and stuttering under load.

Post 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...
1991 Legacy SS 5spd
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