Car stalling while driving

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Littlevil
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Car stalling while driving

Post by Littlevil »

I recently purchased my first Subaru, a 1992 Legacy touring wagon with a 5spd swap. I've slowly been fixing all it's quirks (next up is the insanely sloppy shifter).

However while driving recently my car has been stalling while driving!! Basically what happens is I'll be in gear (3rd or 4th usually) at around 4k rpm and I'll put the clutch in, the rpms will then drop like crazy until the car stalls, and sometimes even when I hit the gas the revs will plummet again.

Unfortunately I haven't been able to replicate the problem on purpose, 90% of the time the car works perfectly. But every once in a while it'll do this.

If anyone has any ideas it would be greatly appreciated.

Littlevil
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Re: Car stalling while driving

Post by Littlevil »

I've been doing some research, and I was thinking that it might be the idle switch inside the TPS. Possibly as i'm coming off throttle the idle switch isn't making contact which then chokes out the engine. But while I was looking around I noticed one of the plug wires was cracked, so i'm going to start by replacing my plugs and wires and see if that helps. Do you guys use fancy iridium or platinum plugs or just copper?

mike-tracy
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Re: Car stalling while driving

Post by mike-tracy »

viewtopic.php?f=12&t=634&p=428907&hilit ... gk#p428907

I use NGK coppers, they work great in these cars
1992 Legacy SS 5mt, build in progress
Josh Colombo wrote:
Mon Jan 14, 2002 10:23 am
Wait....I'm confused now.

Littlevil
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Re: Car stalling while driving

Post by Littlevil »

Thanks mate!

Littlevil
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Re: Car stalling while driving

Post by Littlevil »

So I installed a new knock sensor after reading about a guy who had very similar problems to me (and I had a knock sensor cel) and the issue seemed to go away for a little while, but it still stalled when I shifted to neutral from 5th :'(. I think my next step is building an engine diagnostics unit so I can get some more info on the problem.

I wonder if it has anything to do with it being a manual swap? It also has the AC deleted so maybe there's artificial load on the motor.

wtdash
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Re: Car stalling while driving

Post by wtdash »

I'd read thru the 5-speed swap here: https://www.surrealmirage.com/subaru/swap/swap.html
To see what is required (i've since forgotten). May be some clues.
Turbo Subies:
'87 GL-10 Turbo 4WD Wagon (pre-Loyale) - SOLD
'90 BJ, EJ22T/DOHC and 5-speed swap - SOLD
'04 FXT, Forged internals, VF39, STI TMIC, Cobb AP- SOLD
'93 Legacy SS - 5-speed, SOLD :-(
'02 WRX GG-SOLD
'96 BD - turbo'd-SOLD

Littlevil
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Re: Car stalling while driving

Post by Littlevil »

Thanks wtdash, i'll give it a read through and see what I can find out.

Littlevil
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Re: Car stalling while driving

Post by Littlevil »

Well things have gotten alot worse. Car left me stranded on the highway today, I got it towed home and now I'm trying to figure out wtf is going on.
It will not start, earlier it would start for a second then die, but now it just turns over and doesn't even try.

First off I can't hear the fuel pump running when I switch on the key, and when I pop the fuel cap there's no pressure...

But I just pulled the codes and I got 22 (knock sensor), 31 (throttle sensor), and 49 (air flow sensor).

I got the knock sensor code a while back and I replaced the knock sensor so I think that's just a left over code.

It's tough, my intuition tells me it's a fuel pump problem, but why are there codes for throttle sensor and air flow sensor? Would those codes stop the engine from running? I did disconnect the air flow sensor yesterday while the battery was still connected so would that have thrown a code?

Something interesting though is that it left me stranded after doing the exact same issue as earlier, I put in the clutch and the motor dies.

At this point I don't think that it's the 5spd swap causing these problems lol

wtdash
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Re: Car stalling while driving

Post by wtdash »

"First off I can't hear the fuel pump running when I switch on the key, and when I pop the fuel cap there's no pressure..."
Time to install a DW fp (or similar). If you bought a used Subaru, you 'must' be able to wrench, correct? :D
But check the relay and wiring 1st (you'll want to google/search here for that info).
Not a tough job. Be prepared for 25+ years of accumulated dirt on top of the tank to clean off...like when I did this on '98 Forester:
Image
Turbo Subies:
'87 GL-10 Turbo 4WD Wagon (pre-Loyale) - SOLD
'90 BJ, EJ22T/DOHC and 5-speed swap - SOLD
'04 FXT, Forged internals, VF39, STI TMIC, Cobb AP- SOLD
'93 Legacy SS - 5-speed, SOLD :-(
'02 WRX GG-SOLD
'96 BD - turbo'd-SOLD

Littlevil
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Re: Car stalling while driving

Post by Littlevil »

Oh man that looks nasty, at least fuel pump is an easy job! But you're right, I need to make absolutely sure it's the pump and not the wiring.

rallyak
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Re: Car stalling while driving

Post by rallyak »

I had an air flow sensor go bad and would die when driving sometimes intel it completely went bad. I tested by unplugging the air flow sensor and it started and drove it home. It will run rich being unplugged but should start.
Charles

90' White/Gray Outback DD workhorse (670,xxx) miles
92' Onyx Metallic (430,xxx) Wife's DD
68' Barracuda formula S 340 4spd coupe (ongoing project)
66' Mustang 2+2 4spd wife's (ongoing project)

Legacy777
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Re: Car stalling while driving

Post by Legacy777 »

I will second the MAF sensor, especially since you got a code for it.

Plug in just the green diagnostic connectors. This will cycle the relays on and off, including the fuel pump relay. This will let you know whether the fuel pump is turning on or not. If you put a gauge on the fuel delivery line that will tell you whether you have the appropriate pressure or not.....however, I think it's the MAF since I had a similar issue.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm

Littlevil
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Re: Car stalling while driving

Post by Littlevil »

Thanks guys, I'll try unplugging the MAF and see if she runs! I do have a spare MAF thankfully so I can install it if that's the problem.

I unplugged the supply fuel line and cycled the relays before I ordered my walbro, so either way new fuel pump is on the way, so I sure hope the old one is bad.

Legacy777
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Re: Car stalling while driving

Post by Legacy777 »

Ok, well keep us updated on what you find out.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm

Littlevil
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Re: Car stalling while driving

Post by Littlevil »

So I installed the new fuel pump last night and the car runs fine when cold, but when hot the old problem still exists. I guess they are two seperate issues! I plan on testing the MAF today so hopefully that's my problem!

Littlevil
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Re: Car stalling while driving

Post by Littlevil »

Very weird thing here guys... When I unplug the MAF the car instantly dies. It will start for a sec then instantly die. Not sure what that means...

wtdash
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Re: Car stalling while driving

Post by wtdash »

I'd still get another MAF. Used is OK, although they do fail, it's not super common.

Unfortunately the turbos used the rare metal MAF. They were also used on the '90-'91 (?) 5-speed Legacy, if you're lucky to a have a pullnsave/used auto parts nearby. New may be $pendy and/or hard to find.

The plastic green label JECS/AUTecs MAFs aren't compatible (unless you install an EJ20G ECU + a bunch of other things :D )
Turbo Subies:
'87 GL-10 Turbo 4WD Wagon (pre-Loyale) - SOLD
'90 BJ, EJ22T/DOHC and 5-speed swap - SOLD
'04 FXT, Forged internals, VF39, STI TMIC, Cobb AP- SOLD
'93 Legacy SS - 5-speed, SOLD :-(
'02 WRX GG-SOLD
'96 BD - turbo'd-SOLD

Littlevil
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Re: Car stalling while driving

Post by Littlevil »

I have a spare MAF luckily! I just need to clean it up (btw just sensor kleen? I know you can't wipe them) and get a new gasket and i'll throw it on! Car is still driveable atm, I just have to heel-toe the shit out of her haha.

wtdash
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Re: Car stalling while driving

Post by wtdash »

Rumor is not to use carb cleaner or anything w/too strong/forceful a spray - to avoid damaging the element. So sensor kleen FTW.
Turbo Subies:
'87 GL-10 Turbo 4WD Wagon (pre-Loyale) - SOLD
'90 BJ, EJ22T/DOHC and 5-speed swap - SOLD
'04 FXT, Forged internals, VF39, STI TMIC, Cobb AP- SOLD
'93 Legacy SS - 5-speed, SOLD :-(
'02 WRX GG-SOLD
'96 BD - turbo'd-SOLD

Littlevil
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Re: Car stalling while driving

Post by Littlevil »

So I replaced the MAF sensor, and unfortunately it did not fix the problem, same exact thing happens. I suppose it's possible that the spare MAF was also bad (It's kinda dirty even after cleaning) but that seems pretty unlikely because it still runs great while cold then tries to die while hot.

This weekend i'm going to go through surreal mirages electronics section and make sure my ecu is properly attached, make sure the tcu and cruise control units are gone, and hopefully i'll find something there.

Legacy777
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Re: Car stalling while driving

Post by Legacy777 »

You mentioned it works fine when cold and then has issues when warmed up. Can you elaborate on this? Engine temperature related issues and poor performance tend to lead me down the path of the coolant temp sensor due to how the ECU calculated AFR. What is your MPG like? How long has this issue been happening? Any idea on the age of the coolant temp sensor? They are cheap to replace so you may want to try that if you don't have any other input.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm

PaulMcP80
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Re: Car stalling while driving

Post by PaulMcP80 »

Sounds like a coolant issue to me as well. I've brought my Legacy under high temperatures (I was looking at these houses in Greece for the holidays, in September) and it worked fine until I had a coolant leakage, which led to the issues you're describing.

Littlevil
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Re: Car stalling while driving

Post by Littlevil »

Unfortunately I don't know the MPG Josh because the speedo is dead, but it seems reasonable to me. The car's been down for awhile now since I've been doing the shift linkage and I snapped off the turbo coolant line (damn 30 y/o plastic!). But I'll see if I can calculate it.

This issue has been happening ever since I installed a thermostat, the previous owners were running it without one. Which ties in nicely to the coolant temp theory, because when it was running without a thermostat it was running quite cold. No clue on how old it is but I bought a new coolant temp sensor and I will install it when it gets here!

Legacy777
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Re: Car stalling while driving

Post by Legacy777 »

The thermostat you installed, was it a Subaru thermostat? If not, they can cause issues. I would recommend using a genuine Subaru thermostat. I believe Stant may make one that is identical in size/shape.

If you have a Subaru thermostat and having the same issues I would look at replacing the coolant temp sensor...they are about $20.

The other thing is the speedo not working. The ECU gets that data and can act weird if it doesn't get the speed sensor input.

Have you pulled the codes from the ECU? I'd suggest doing that to see what's in there. Clear the codes and then recheck.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm

Littlevil
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Re: Car stalling while driving

Post by Littlevil »

It was not a genuine Subaru thermostat but I read your earlier posts on thermostats when I replaced it and the one I purchased is the Stant which as far as I understand is an OEM replacement. It has the bleeder valve and everything.

Last night I pulled a coolant temp sensor out of a spare coolant channel I had laying around and installed it in my car. So we'll see on the commute today if it made a difference!

The speedo is an incredibly frustrating problem for me, It's super hard to find a new speedo cable! Even my Subaru dealer doesn't have one. But I thought there are two speed sensors in our cars, one for the ECU and one for the dash? If the ECU is getting that data it could definitely be the problem. Either way it's something I'll be working on fixing ASAP.

I've been periodically pulling codes and checking them, but I've been lazy about it and haven't been clearing the codes. I'll clear them today and check them this weekend.

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