Down on boost?
Discussion
Have been reading some of the recent posts on boost with interest.
According to my boost gauge I seem to be maxing at around 0.5 bar, and not long ago when I had the car repaired I was told it was peaking around that mark. Is standard boost (GTO3) meant to be 0.7 bar? If it is then I think I might be losing out on some fun here..
I've been over all the vacuum and boost pipes and made sure everything is tight and I don't think there are any leaks. The wastegate actuators were a bit rusty but I've made sure they're moving freely (that was fun on the front turbo!). And I've checked to see if there is power going to the boost control valve - there is.
Any ideas what could cause this? Could it just be the control valve is faulty and the cars running in "safe mode" or something? Would be a better fix than a problem with the turbos, or even worse the ECU. I've got the correct ECU map and the car does run very nicely, idles correctly, etc. so I don't think there's an ECU fault.
Apart from a BOV it's a standard car - they didn't wind the boost back at the factory after a few diffs got lunched did they?
Any ideas appreciated.
Cheers
Andy
According to my boost gauge I seem to be maxing at around 0.5 bar, and not long ago when I had the car repaired I was told it was peaking around that mark. Is standard boost (GTO3) meant to be 0.7 bar? If it is then I think I might be losing out on some fun here..
I've been over all the vacuum and boost pipes and made sure everything is tight and I don't think there are any leaks. The wastegate actuators were a bit rusty but I've made sure they're moving freely (that was fun on the front turbo!). And I've checked to see if there is power going to the boost control valve - there is.
Any ideas what could cause this? Could it just be the control valve is faulty and the cars running in "safe mode" or something? Would be a better fix than a problem with the turbos, or even worse the ECU. I've got the correct ECU map and the car does run very nicely, idles correctly, etc. so I don't think there's an ECU fault.
Apart from a BOV it's a standard car - they didn't wind the boost back at the factory after a few diffs got lunched did they?
Any ideas appreciated.
Cheers
Andy
Thanks guys. It does run very well and it's not really a big issue.. maybe I'm just having one of those "it doesn't feel as fast as it used to" moments and it's time to think about upgrades
I've tried booting it and keeping an eye on the gauge - tricky manoeuvre - and even in high gears it's not quite reaching 0.5 bar on the gauge. I can well believe they're notoriously inaccurate..
..but I did have the car run down the road with a laptop attached to it a while back and that's when I was told it was peaking at just over .5bar. I assumed this was an accurate boost reading, but don't know for sure how it was tested.
If it is running a bit low then that might be why my diff is one piece - though to be fair, I'm a bit of a wimp behind the wheel.
Thx for your input - it sounds like there might be no one "standard" taht applies to all cars.
I've tried booting it and keeping an eye on the gauge - tricky manoeuvre - and even in high gears it's not quite reaching 0.5 bar on the gauge. I can well believe they're notoriously inaccurate..
..but I did have the car run down the road with a laptop attached to it a while back and that's when I was told it was peaking at just over .5bar. I assumed this was an accurate boost reading, but don't know for sure how it was tested.
If it is running a bit low then that might be why my diff is one piece - though to be fair, I'm a bit of a wimp behind the wheel.
Thx for your input - it sounds like there might be no one "standard" taht applies to all cars.
It might be worth just checking that both actuators are operating correctly, we've seen a high attrition rate with the OEM actuators. Test each one seperately to see that they're opening and closing smoothly, and that the crack open pressures are similar, (around .4 bar).
We usually fit new 0.7 bar units.
Mike
We usually fit new 0.7 bar units.
Mike
and just to throw a spanner in the works the gauge on my 2002 2.5L GTO used to peak at 1.2 and settle at 0.9 but its just had the turbos out, apart, cleaned up and refitted. it now peaks at 1.4 and settles at 1
thats way too much apparently so dont use that as target! F##K me it flys though lol (previous exploding engine advice noted
)
thats way too much apparently so dont use that as target! F##K me it flys though lol (previous exploding engine advice noted
) Edited by jimbooo on Monday 6th April 19:36
I'm learning what bits do as I go along here..
Just ran the car up the road with the boost control solenoid disconnected and it was noticeably down on power. Gauge was reading about .2 or.3
I'm sure the gauge is way inaccurate, but at least with the solenoid connected it was reading .4 to .5, so am I safe to assume that part at least is doing its job?
My other major triumph today was plugging the dealer software into the car and resetting the adaptive maps.
The software says I'm reading about -0.5 bar manifold pressure at idle. I read somewhere that -0.7 is normal.. anyone know if this is the case?
It would be great if I could make the dyno meet tomorrow to pick all your brains and find out for sure if I've got a problem, but don't think I can make it this time
Just ran the car up the road with the boost control solenoid disconnected and it was noticeably down on power. Gauge was reading about .2 or.3
I'm sure the gauge is way inaccurate, but at least with the solenoid connected it was reading .4 to .5, so am I safe to assume that part at least is doing its job?
My other major triumph today was plugging the dealer software into the car and resetting the adaptive maps.
The software says I'm reading about -0.5 bar manifold pressure at idle. I read somewhere that -0.7 is normal.. anyone know if this is the case?
It would be great if I could make the dyno meet tomorrow to pick all your brains and find out for sure if I've got a problem, but don't think I can make it this time
FWIW the boost gauges fitted in the U.S. cars seem to be pretty accurate--at least not far off the boost measured with add-on sensors.
Another thing to check, however, is the integrity of the wastegate actuators. Again on U.S. cars, it has been observed that the diaphragms in those actuators can fail so that you effectively have a vacuum leak that you cannot see directly. This leak will definitely affect boost control but you won't be able to find it unless you have access to a smoke machine diagnostic tool.
Another thing to check, however, is the integrity of the wastegate actuators. Again on U.S. cars, it has been observed that the diaphragms in those actuators can fail so that you effectively have a vacuum leak that you cannot see directly. This leak will definitely affect boost control but you won't be able to find it unless you have access to a smoke machine diagnostic tool.
Very interesting, thanks. I've been over all the obvious places more than once checking for leaks, tightening, and retightening..
The wastegate actuators are very rusty and sorry looking, at least from the outside. I've already had a go at making sure they're not siezed or anything like that (fun on the front turbo in a very small garage!).
How much of a job do you think it would be to renew these, assuming all the vacuum pipes, etc are still OK? Do the turbos need to come off?
The wastegate actuators are very rusty and sorry looking, at least from the outside. I've already had a go at making sure they're not siezed or anything like that (fun on the front turbo in a very small garage!).
How much of a job do you think it would be to renew these, assuming all the vacuum pipes, etc are still OK? Do the turbos need to come off?
Changing actuators isn't too difficult, and can be done with the car up on jackstands. But before you buy new ones and change them out, here are a few things to try.
First, check the action of the actuators to make sure that they're working smoothly and closing all the way. I hook the vacuum line running from the boost solenoid to the actuators to a low pressure (<10 psi) source of compressed air. When I apply the compressed air, the actuators should both open. Release the air, and they should close. Check to see if both are working in sync by having a friend watch one while you watch the other.
Second, check the preload on the wastegate actuator rod to make sure that the wastegate is closed firmly when the actuator is retracted. I do this by disconnecting the wastegate actuator rod from the wastegate - carefully remove the E-clip holding the rod on the wastegate. This clip is tiny, and, given the chance, likes to spring off and hide on your garage floor, where it quietly laughs while you spend the next hour frantically searching for it. Remove the actuator rod from the wastegate, hold the wastegate arm in the fully closed position, and try to put the actuator rod back into place. If the preload is correct, you should have to pull the actuator rod out about 1/8 inch before the hole in the rod lines up with the pin on the wastegate arm.
First, check the action of the actuators to make sure that they're working smoothly and closing all the way. I hook the vacuum line running from the boost solenoid to the actuators to a low pressure (<10 psi) source of compressed air. When I apply the compressed air, the actuators should both open. Release the air, and they should close. Check to see if both are working in sync by having a friend watch one while you watch the other.
Second, check the preload on the wastegate actuator rod to make sure that the wastegate is closed firmly when the actuator is retracted. I do this by disconnecting the wastegate actuator rod from the wastegate - carefully remove the E-clip holding the rod on the wastegate. This clip is tiny, and, given the chance, likes to spring off and hide on your garage floor, where it quietly laughs while you spend the next hour frantically searching for it. Remove the actuator rod from the wastegate, hold the wastegate arm in the fully closed position, and try to put the actuator rod back into place. If the preload is correct, you should have to pull the actuator rod out about 1/8 inch before the hole in the rod lines up with the pin on the wastegate arm.
Thanks Jim - I'll try to test the actuators out as you suggest (except the part where the clip goes walkabout on the garage floor.. if I can help it!).
Looking at some of the recent discussion here, and some of the results from the dyno meet, it does seem like there are quite a few standard cars that have lower than standard boost. If faulty (or at least "sub-optimal") actuators is a common problem then this could definitely be the case on my car, which is 6 years old now.
If I have no joy testing them out or a bad result.. anyone know the best place to source replacements, how much, etc.?
I'm already starting to have a wet dream about proper boost levels just in time for the Summer!
Looking at some of the recent discussion here, and some of the results from the dyno meet, it does seem like there are quite a few standard cars that have lower than standard boost. If faulty (or at least "sub-optimal") actuators is a common problem then this could definitely be the case on my car, which is 6 years old now.
If I have no joy testing them out or a bad result.. anyone know the best place to source replacements, how much, etc.?
I'm already starting to have a wet dream about proper boost levels just in time for the Summer!
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