View Full Version : My Legacy 1990 turbo 2.0 (manual) starts to jerk when I push
New Subaru Fan
01-06-2010, 12:29 AM
.... her too hard
Hi Guys,
When I accelerate very fast she starts to jerk really hard :smt081
In the beginning we thought it could be because of the older turbo design but the guy I met yesterday told me his Legacy GT (same as mine) accelerated smoothly and he even didn't know what I was talking about.
So now I'm thinking there might be a fuel issue (pump, filter, injectors or something like that).
I really need to address this issue as I don't want to ruin the engine after we replaced HGs etc.
Has anybody ever had this sort of problems or has anyone an idea?
Cheers
Robbks
01-06-2010, 12:40 AM
Q) how much boost are you running?
the early coilpacks on those motors can get old and will break-down at 16-17PSI
Start with easy things like new spark plugs (gapped to 0.8mm) and no need to spend big $$, just standard copper plugs are fine, but the gap is critical.
Check the entire intake tract and vacuum hoses for leaks, air leaks are a major cause of poor running of these engines (especially twin turbo ones like mine)
new fuel and air filters is easy to do an quick to rule them out.
you probably should invest in an upgraded fuel pump anyway, bosch or walbro
then see how it runs
it could be a dirty AFM, clean it by spraying it with Electrical Contact Cleaner (No Residue variety)
it could even be a leaky injector seal, causing too much fuel into the engine
mike-tracy
01-06-2010, 02:39 AM
Hi Guys,
When I accelerate very fast she starts to jerk really hard :smt081
In the beginning we thought it could be because of the older turbo design but the guy I met yesterday told me his Legacy GT (same as mine) accelerated smoothly and he even didn't know what I was talking about.
So now I'm thinking there might be a fuel issue (pump, filter, injectors or something like that).
I really need to address this issue as I don't want to ruin the engine after we replaced HGs etc.
Has anybody ever had this sort of problems or has anyone an idea?
Cheers
Is this happening only when the motor or transmission is cold? I have experienced this on all my manual transmission Subarus. What fixed it was this:
http://www.smart-service.com/store-tran ... e-kit.html (http://www.smart-service.com/store-tranquil-sleeve-kit.html)
Of course you'll need to pull the transmission.
New Subaru Fan
01-06-2010, 06:19 PM
Q) how much boost are you running?
the early coilpacks on those motors can get old and will break-down at 16-17PSI
Start with easy things like new spark plugs (gapped to 0.8mm) and no need to spend big $$, just standard copper plugs are fine, but the gap is critical.
Check the entire intake tract and vacuum hoses for leaks, air leaks are a major cause of poor running of these engines (especially twin turbo ones like mine)
new fuel and air filters is easy to do an quick to rule them out.
you probably should invest in an upgraded fuel pump anyway, bosch or walbro
then see how it runs
it could be a dirty AFM, clean it by spraying it with Electrical Contact Cleaner (No Residue variety)
it could even be a leaky injector seal, causing too much fuel into the engine
Thanks for this great reply - I'll get into this.
I can't tell you how much boost I'm running at the moment but I'll try to find out.
New Subaru Fan
01-06-2010, 06:22 PM
[quote="New Subaru Fan":3b1zr5pa]Hi Guys,
When I accelerate very fast she starts to jerk really hard :smt081
In the beginning we thought it could be because of the older turbo design but the guy I met yesterday told me his Legacy GT (same as mine) accelerated smoothly and he even didn't know what I was talking about.
So now I'm thinking there might be a fuel issue (pump, filter, injectors or something like that).
I really need to address this issue as I don't want to ruin the engine after we replaced HGs etc.
Has anybody ever had this sort of problems or has anyone an idea?
Cheers
Is this happening only when the motor or transmission is cold? I have experienced this on all my manual transmission Subarus. What fixed it was this:
http://www.smart-service.com/store-tran ... e-kit.html (http://www.smart-service.com/store-tranquil-sleeve-kit.html)
Of course you'll need to pull the transmission.[/quote:3b1zr5pa]
No it is not only happening when the engine is cold. And I don't think it's clutch related. When the car jerks I can hear that the engine kind of stops working.
Thanks
Robbks
01-07-2010, 12:02 AM
OK, reading your other thread.
get that thermostat back in ASAP.
your water temp sensor (in the water crossover pipe under the inlet manifold) could also be stuffed which gives the ECU incorrect water temp readings and is causing abnormal fuelling until the motor warms up properly (longer than usual with not t-stat)
they're only a $25 part from Subaru and relatively easy to swap out
New Subaru Fan
01-07-2010, 01:46 AM
OK, reading your other thread.
get that thermostat back in ASAP.
your water temp sensor (in the water crossover pipe under the inlet manifold) could also be stuffed which gives the ECU incorrect water temp readings and is causing abnormal fuelling until the motor warms up properly (longer than usual with not t-stat)
they're only a $25 part from Subaru and relatively easy to swap out
Oh thanks.
I've already recognized how important t-stat is and put it back a couple of days ago. This jerking problem exists for a couple of months.
By the way I can recall one interesting thing: as we disconnecting the fuel lines before taking out the engine there was no 'fountain' of the fuel some described. I just wonder whether it is normal in these 1990 Legacy?
Robbks
01-07-2010, 05:21 PM
all depends on how long the car had been sitting before letting the lines off.
the fuel presure will slowly dissipate from the lines over about 1/2 an hour (in my car at least, i have a fuel pressure gauge on my rails)
New Subaru Fan
01-07-2010, 06:58 PM
all depends on how long the car had been sitting before letting the lines off.
the fuel presure will slowly dissipate from the lines over about 1/2 an hour (in my car at least, i have a fuel pressure gauge on my rails)
Oh true. Ok then it shouldn't be meaningful in my case.
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