More mysteries from the Subaru.

Shift518 Automotive
1

In having two more issue that are leaving scratching my head.

At cold, after start up, with throttle input the car bogs for a split second before revving up, and I just barely blip the throttle it drops revs for a hair and goes back up. Once it sits for a few minutes or warms up, it goes just fine.

Believe me I cleaned the throttle body, MAF, and replaced the MAF because it sounded like a ringer for it. No luck.

The other problem is rather interesting.

The car has a cooling problem that’s not an overheating problem, but rather cooling.

The car gets to operating temp just fine, but if it goes past 4k RPM, the temperature drops, and the longer it stayes at higher rpm the more it will cool. It’s not a typical sensor either reading wrong, the blowing heat gets milder too.

I’m sure it’s something as simple as an air bubble or thermostat, but everything in the cooling system is new, and I can’t rationalize why it’s cooling instead of over heating at high revs. No leaks either nor is it speed related, I can be at a standstill and rev it to cool.

Heat tends to fluctuate on occasion too which makes me want to test the coolant for exhaust gases :ahh

2

Not sure about the throttle blip/idle drop one, but the heating/cooling issue- I’d check to see about a sticking t-stat- especially at the higher rpm’s- the t-stat could have a bad spring that just blows wide open, letting too much coolant pass through, dropping the temps too much, too quick. Just a guess, sir- but good luck!

3

Idle-air control is gunked up in regards to the first issue

4

sounds to me like if you fix the throttle response problem you gotta perfect track car :wink:

5

I have plenty of potential track cars, I need a daily :lol

6

put a thermostat in it.

7

I told you it was the tstat vlad. It’s like a $15 part.

8

Still warrantied, I just have to get around to switching it, to see if that’s the issue.

9

Pft, who needs a Subie when you have MW2.

10

Haha, i’m sorry but when it comes down to being under the car in the cold or running around yelling “BOOM HEADSHOT!!!” the latter typically wins.

11

vlad use a stock subie t-stat most aftermarket ones have issues due to the stages at when they open .we see it a lot at the shop , the cold bog could be a m.a.p sensor out of wack

12

Seems like that was exactly the problem.

Stocker is in, cooling system fixed.

Now to troubleshoot the idle.

I’ll be going after MAP or IAC next to see if one of them is making it act funny.

Right now it has changed to the point where it idles real low for most of the time (500rpm or so) with a rare occasional self controlled blip upto 900/1000rpm for a second or two just to go back down to low idle.

Also my damn knock sensor is dead and keeps throwing the light, which is throwing the timing on a roller coaster ride :ahh

13

sell it

14

knock sensors are easy on those ,driver side of block one bolt connector easy fix just dont overtighten it

15

Yep, right below the spider of an IM.

Looks like a Pita to reach without removing stuff, I’ll get to it. Been driving with the code going on and off for about a month now, no biggie.

I <3 the damn thing too much to sell it.

16

nah it aint to bad with a long extension wobble socket ,if my fat ass can hunker over it and do it without removin a ton of shit so can u i dont wanna hear exscuses

17

I’m starting to get a bad feeling my head gasket is going.

With the new thermostat the car ran great for a week or so (OE stat), but recently it would struggle to reach dead middle of the gauge like it did before, the heat would be luke warm fluctuating to boiling hot, and now it takes way too long to warm up or reach middle, or fails to reach OP Temp at all.

I’ll check the coolant level again, and go on a spirited drive to see if I got bubbled coming out the overflow tank showing another internal leak.

Car has been down on power and mileage recently too.

I’m glad I bought another car in the meantime.

18

a leaky hose w/p and so on will cause this also as its suckin air and air binding it .dont assume h/g for those reasons ,although it is a scooby sooooooo

ohhhhhh and i have one at the shop needing them also lolololollol

19

Lol if you search on craigslist for “needs head gasket” see how many Subarus come up.

Wp is all new, hoses should be good, and I remember filling it to the brink recently, so if it’s still full of coolant, it won’t look good.

20

Well just checked the coolant - full to the top.

Drove it hard, at higher RPM’s, checked the overflow bottle, no bubbling coming up.

Upon getting up to temp, the needle was ever so slightly fluctuating up and down, barely visible, as it was getting up to operating temp while driving.

I’m going to look into the basics again and double check the dealer Tstat, because most issues start happening soon after the replacing the old sticking one that caused the car to cool down as it would get going.