Impreza slow to build boost
Discussion
Just had the Impreza on Surrey Rolling Road. By and large things seem ok, but the car is very slow to build any boost. The curve (which I'll try and post up later) builds slowly and only reaches 0.8 bar at 5,000rpm. One it's there it holds 0.8 bar fairly well.
Charlie suggested a sticky wastegate or weak spring. Anyone got any ideas where I should start looking for such things?
One other thing, my rear drivers' side wheel is buckled. It's a standard Subaru alloy powder coated black (I think). Is it possible to have them repaired or do I need to replace it?
Cheers
Al
Charlie suggested a sticky wastegate or weak spring. Anyone got any ideas where I should start looking for such things?
One other thing, my rear drivers' side wheel is buckled. It's a standard Subaru alloy powder coated black (I think). Is it possible to have them repaired or do I need to replace it?
Cheers
Al
dnb said:
There's a control solenoid connected to the wastegate. These get sticky with oil over time and then don't work properly. They can be cleaned with carb cleaner with the car in test mode.
Ah ha, thanks. Is test mode the one where I connect the black and green connectors under the dash?Al....
Once you've cleaned out the boost control solenoid, take it out again and see if that makes a difference. If it doesn't then it's propbably ok, therefore as has been said it could be a sticking wastegate. In order to get to clean the waste gate the best you can do is to take the intercooler off, take the heat guard off around the turbo and move the waste gate manually to see if it feels like it's sticking. It should feel strongly springy. I have done this umpteen times now and it's dead easy to do, just a bit fiddly when getting to a couple of the bolts off the Turbo heat guard.
If it's making boost and holding it then it's probably unlikely to be the wastegate as i would assume it's working ok from that, so more likely a dirty boost control solenoid if anything or one of the Air hoses feeding or coming off the Turbo/intercooler is leaking. If could also be your uppipe leaking thereby not allowing the full exhaust gases to get to the Turbo. Is your MAF working properly, i don't know if the older Scoobs used a MAF.
After this you have to have a look at the map. If the map is running rich then it will boost more slowly and be a tad laggy too but will be pretty safe. Running a leaner map will spool the turbo up more quickly and get to full boost quickly but then you potentially risk detonation.
If's a fine line between performance and reliability.
Another option maybe to get someone with the appropriate cable and logging software on a laptop to log your car and check to see if the engine is working as the mapping has intended. Is it a Prodrive map or standard OEM, or other option/aftermarket ECU you have on your car. I have all the kit to log and map the car but if it's an ECUTEK map i couldn't even download it or overwrite it. The most i could do is take logs.
John F is the man for this. I may not have seen eye to eye with him over one or two issues in the past but there is no doubting his extremely comprehensive and in-depth knowledge on Scoobys!! He's your man for sure and he's a pretty good bloke really!!
Once you've cleaned out the boost control solenoid, take it out again and see if that makes a difference. If it doesn't then it's propbably ok, therefore as has been said it could be a sticking wastegate. In order to get to clean the waste gate the best you can do is to take the intercooler off, take the heat guard off around the turbo and move the waste gate manually to see if it feels like it's sticking. It should feel strongly springy. I have done this umpteen times now and it's dead easy to do, just a bit fiddly when getting to a couple of the bolts off the Turbo heat guard.
If it's making boost and holding it then it's probably unlikely to be the wastegate as i would assume it's working ok from that, so more likely a dirty boost control solenoid if anything or one of the Air hoses feeding or coming off the Turbo/intercooler is leaking. If could also be your uppipe leaking thereby not allowing the full exhaust gases to get to the Turbo. Is your MAF working properly, i don't know if the older Scoobs used a MAF.
After this you have to have a look at the map. If the map is running rich then it will boost more slowly and be a tad laggy too but will be pretty safe. Running a leaner map will spool the turbo up more quickly and get to full boost quickly but then you potentially risk detonation.
If's a fine line between performance and reliability.
Another option maybe to get someone with the appropriate cable and logging software on a laptop to log your car and check to see if the engine is working as the mapping has intended. Is it a Prodrive map or standard OEM, or other option/aftermarket ECU you have on your car. I have all the kit to log and map the car but if it's an ECUTEK map i couldn't even download it or overwrite it. The most i could do is take logs.
John F is the man for this. I may not have seen eye to eye with him over one or two issues in the past but there is no doubting his extremely comprehensive and in-depth knowledge on Scoobys!! He's your man for sure and he's a pretty good bloke really!!
Edited by ScoobieWRX on Sunday 17th February 13:13
A friend of mine had a similar problem, it turned out to be a jubilee clip on the hot side of the I/C that was only done up finger tight after an engine replacement.
Doesn't exactly inspire you with faith for the rest of the work carried out....
Check all boost pipes for splits and loose connections. It's a classic problem for 200SX's too. Tracking down a boost leak can be very painful (remember the car doesn't build boost when it's revving at a standstill) but it's worth it.
Doesn't exactly inspire you with faith for the rest of the work carried out....
Check all boost pipes for splits and loose connections. It's a classic problem for 200SX's too. Tracking down a boost leak can be very painful (remember the car doesn't build boost when it's revving at a standstill) but it's worth it.
That's a good point, the wastegate is clearly doing something as you can see it maintain 0.8 bar quite nicely once it gets there. Is there any reason it could stick low down the rev range but not higher up?
I've just been out in the car so I'm waiting for it to cool down before I try to clean the boost solenoid. Doesn't look promising though, I popped the hoses off before I went out and they seem to be perfectly clean.
I've just been out in the car so I'm waiting for it to cool down before I try to clean the boost solenoid. Doesn't look promising though, I popped the hoses off before I went out and they seem to be perfectly clean.
Thats pretty good for an old Scooby with just the STi exhaust. How many miles has it done??
The only thing with the MINES ECU is that there are very few tuners in the UK that can remap a mines. Outside of the UK you'll have to go to MINES in Japan direct. I think they remap by removing the EPROM from the ECU as it probably sits on a non-solder socket and use an EPROM programmer to flash the chip.
The only thing i would recommend for now is to change the air filter for a high-flow green flat panel or K&N Air filter. That may help things a little if it's breathing better, and change the whole exhaust for either a full decat decat system to include uppipe, or as a minimum if it hasn't been done already, change the uppipe for a decat uppipe. That will improve spoolup no end.
The other option for changing some of the engine electronic parameters is to run either a piggy back module system, or start using manual electronic boost controllers, AFR controller etc... or change the ECU altogether for something a bit more mainstream like Apexi PowerFC and commander, GEMS, MOTEC, SIMTEK ECU... but then you are starting to talk cost.
Cheapest options i reckon are the Air filter and uppipe and you will feel the difference, then stick it on the rolling road again and give Charlie some more of your dosh
The only thing with the MINES ECU is that there are very few tuners in the UK that can remap a mines. Outside of the UK you'll have to go to MINES in Japan direct. I think they remap by removing the EPROM from the ECU as it probably sits on a non-solder socket and use an EPROM programmer to flash the chip.
The only thing i would recommend for now is to change the air filter for a high-flow green flat panel or K&N Air filter. That may help things a little if it's breathing better, and change the whole exhaust for either a full decat decat system to include uppipe, or as a minimum if it hasn't been done already, change the uppipe for a decat uppipe. That will improve spoolup no end.
The other option for changing some of the engine electronic parameters is to run either a piggy back module system, or start using manual electronic boost controllers, AFR controller etc... or change the ECU altogether for something a bit more mainstream like Apexi PowerFC and commander, GEMS, MOTEC, SIMTEK ECU... but then you are starting to talk cost.
Cheapest options i reckon are the Air filter and uppipe and you will feel the difference, then stick it on the rolling road again and give Charlie some more of your dosh
Edited by ScoobieWRX on Sunday 17th February 15:40
After all that trouble I had with the MOT emissions I was wondering if one of the cats had collapsed, could that explain the problem?
The breathing certainly does need looking at in any case. Standard filter - albeit new - and still got the snorkus thing in there by the look of it.
The car is just shy of 100,000miles but had a rebuild about 5,000 miles ago. Sadly the previous owner was allergic to paperwork (never kept a thing) so I can't say who did it.
I didn't get around to cleaning the boost solenoid in the end. I've been playing with my remote control helli. I have the attention span of a concussed duckling..
The breathing certainly does need looking at in any case. Standard filter - albeit new - and still got the snorkus thing in there by the look of it.
The car is just shy of 100,000miles but had a rebuild about 5,000 miles ago. Sadly the previous owner was allergic to paperwork (never kept a thing) so I can't say who did it.
I didn't get around to cleaning the boost solenoid in the end. I've been playing with my remote control helli. I have the attention span of a concussed duckling..
Speaking of Ducklings i had a very tasty roasted one this evening. It must have been well concussed as it definately wasn't moving when i stuck it in the oven 
If you have a collapsed Cat then it would probably blow any debris out or further along the exhaust but if anything that would make things better with less of a restriction
If you have a decent performance exhaust with a 100 cell high flow cat (in the downpipe only) it should get through the MOT no probs with just one cat on the whole exhaust. Your previous emissions issues could be because the cats are buggered in your current STi Exhaust or maybe there are none
If you want to save some dosh just buy a performance downpipe, and decat the uppipe youself. I think old scoobs only had 2 cats, one in the uppipe and one in the downpipe. They have 3 on newage Scoobs like mine with one after the downpipe as well (although i only have 2 now )
If you get stuck with anything shout!!
If you have a collapsed Cat then it would probably blow any debris out or further along the exhaust but if anything that would make things better with less of a restriction
If you have a decent performance exhaust with a 100 cell high flow cat (in the downpipe only) it should get through the MOT no probs with just one cat on the whole exhaust. Your previous emissions issues could be because the cats are buggered in your current STi Exhaust or maybe there are none
If you want to save some dosh just buy a performance downpipe, and decat the uppipe youself. I think old scoobs only had 2 cats, one in the uppipe and one in the downpipe. They have 3 on newage Scoobs like mine with one after the downpipe as well (although i only have 2 now
) If you get stuck with anything shout!!
Old scoobs had 1 or 2 cats - one in the downpipe (always there from the factory) and one in the centre section (often not there in the case of STi, some WRX and PPP fitted cars).
No "classic" scoob ever had an up-pipe cat.
An old scoob can go through the MOT easily with just a standard centre section cat.
If it's a pre-1996 MINES ECU then I (or anyone else who was involved with ScoobyECUs) can most likely re-map it. They're the same technology as the Prodrive PPP of the time.
No "classic" scoob ever had an up-pipe cat.
An old scoob can go through the MOT easily with just a standard centre section cat.
If it's a pre-1996 MINES ECU then I (or anyone else who was involved with ScoobyECUs) can most likely re-map it. They're the same technology as the Prodrive PPP of the time.
The emissions problem thread is around here somewhere, will look tomorrow.
Basically the car failed miserably even though you could smell the cats working. I put some injection cleaner and a new tank of petrol and it improved massively. Nearly enough to pass the UK test. I didn't bother going back though as I convinced the guy to pass it under the 3.5% test for an import. Be interested to know what it's doing now. Seemed to be fuelling well on the rolling road.
For reference, the car still burns TONS of oil. It can get from max to below the dipstick in less than 300 miles. Any ideas why? It worries me far more than the slow boosting.
Basically the car failed miserably even though you could smell the cats working. I put some injection cleaner and a new tank of petrol and it improved massively. Nearly enough to pass the UK test. I didn't bother going back though as I convinced the guy to pass it under the 3.5% test for an import. Be interested to know what it's doing now. Seemed to be fuelling well on the rolling road.
For reference, the car still burns TONS of oil. It can get from max to below the dipstick in less than 300 miles. Any ideas why? It worries me far more than the slow boosting.
Last time I had a Scoob using oil (and not being dead or nearly dead!) the PCV valve under the thottlebody had stuck open so that the crank case was gently pressurised under boost. Oil was blown through the intake and burned. The rockers are also good candidates for leaks, but I think you'd have to leave the gaskets out for it to be as bad as you describe!
Is it not smoking when you drive or does it smoke a bit when on boost. It may be thrwoing up a lot of oil into the turbo. That's a lot of oil to get through though in 300 miles (1 litre), Maybe your oil rings are on their way out, but it should be smoking well as an indicator of knackered oil rings. Sounds like what DNB said and it's leeking somewhere, possibly only under working conditions/pressure rather than when engine is off.
On an old Scooby it may be the head gaskets gone as they use fibre gaskets instead of strong steel ones. When you park up next after a run out get a large sheet of cardborad and put that under the car. A quick check for oil leaks would be to take the plastic aero cover/tray underneath the engine off the car to see if that has any fresh oil in it. Leave it off and you will see the next day if there is any oil leaked onto the clean cardboard. If there isn't try sitting there for a bit with the engine running so it gets properly up to working temps and crank case pressure. If there is no oil leak then it will be the engine eating the oil. Could be a number of internal issues then but at least you will know.
On an old Scooby it may be the head gaskets gone as they use fibre gaskets instead of strong steel ones. When you park up next after a run out get a large sheet of cardborad and put that under the car. A quick check for oil leaks would be to take the plastic aero cover/tray underneath the engine off the car to see if that has any fresh oil in it. Leave it off and you will see the next day if there is any oil leaked onto the clean cardboard. If there isn't try sitting there for a bit with the engine running so it gets properly up to working temps and crank case pressure. If there is no oil leak then it will be the engine eating the oil. Could be a number of internal issues then but at least you will know.
Gassing Station | Japanese Chat | Top of Page | What's New | My Stuff