MY99 WOT Hesitation
15 March 2004, 02:07 PM
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MY99 WOT Hesitation
Sorry to drag this up again - I've used search and tried to narrow down what the problem may be, but it seems a new possibility is put forward with every thread I read!
My problem is this:
MY99 UK Turbo, ITG Filter, ScoobySport backbox - otherwise standard. Low mileage, well maintained etc.
Idles fine - solid 800rpm when warm. Boost gauge shows 0.85-0.9 bar under WOT. Does around 230 miles to a full tank. Power output is 236BHP @ 6k rpm. Runs on Optimax.
The problem I'm having is that under WOT the car seems to kangaroo slightly. This occurs whether hot or cold. This occurs in every gear. Very noticable in 1st (pulling away from lights etc) and still noticable in 5th! ( foot to the floor on the motorway - until I hit 70MPH of course
)
From reading other threads it seems it may be ANY of these problems:
Oily Wastegate Solenoid, split or loose intercooler piping, a faulty MAF sensor, a faulty lamba (o2) sensor, a feature of the ECU (i.e. emissions regulation - but I think this only affects 2nd gear under certain conditions?).
Some suggested fixes are to put the ECU in to test mode and spray brake cleaner in to the pipes that connect to the wastgate solenoid, feel for splits in the intercooler piping and replace if any found, disconnect MAF while engine is idling and see if it stalls to determine MAF fault, blip the throttle before acceleration to bypass emission regulation 'feature'...
I would appreciate any tech tips that might be able to help me narrow down what this problem might be based on the symptoms.
Cheers,
Jay
My problem is this:
MY99 UK Turbo, ITG Filter, ScoobySport backbox - otherwise standard. Low mileage, well maintained etc.
Idles fine - solid 800rpm when warm. Boost gauge shows 0.85-0.9 bar under WOT. Does around 230 miles to a full tank. Power output is 236BHP @ 6k rpm. Runs on Optimax.
The problem I'm having is that under WOT the car seems to kangaroo slightly. This occurs whether hot or cold. This occurs in every gear. Very noticable in 1st (pulling away from lights etc) and still noticable in 5th! ( foot to the floor on the motorway - until I hit 70MPH of course
)From reading other threads it seems it may be ANY of these problems:
Oily Wastegate Solenoid, split or loose intercooler piping, a faulty MAF sensor, a faulty lamba (o2) sensor, a feature of the ECU (i.e. emissions regulation - but I think this only affects 2nd gear under certain conditions?).
Some suggested fixes are to put the ECU in to test mode and spray brake cleaner in to the pipes that connect to the wastgate solenoid, feel for splits in the intercooler piping and replace if any found, disconnect MAF while engine is idling and see if it stalls to determine MAF fault, blip the throttle before acceleration to bypass emission regulation 'feature'...
I would appreciate any tech tips that might be able to help me narrow down what this problem might be based on the symptoms.
Cheers,
Jay
15 March 2004, 04:54 PM
#2
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could be a plug breaking down, on a mapping session my car would just judder fractionally on WOT, in Mr Rawles opinion a plug, which i duely changed & i have never had this prob since
16 March 2004, 10:32 AM
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Oily wastegate solenoid.
Quite possible. What level is your engine oil at on the dip stick? Cleaning is fairly straightforward, as you've already said...
Split or loose intercooler piping.
Your boost gauge would tell you if that were the cae, but as it says 0.85-0.9bar, I don't think it's that.
A faulty MAF sensor.
Quite possibly. You have a 5 year old car, probably using the original MAF. That in itself is risky, but you also have an ITG filter, which is known to pose a threat to MAF sensors. You've already indicated one method for testing. The other is to reset the ECU and see if that makes any difference to the idle and full throttle acceleration. If it doesn't, the MAF's probably OK. If resetting makes everything worse, then it stands a good chance your MAF's on it's way.
Faulty lambda sensor.
Doubt it, as you're getting reasonable MPG and your idle's OK.
A feature of the ECU.
You should have the AE801 ECU, which doesn't suffer from that characteristic in the same way the later AE802 ECU (MY00) does. And the 2nd gear problem is as you say, only in 2nd gear. But I think that's specific to the AE802 as well.
Spark plugs.
Quite possibly. Do you know when they were changed last?
HT leads.
Had you considered those...?! Unlikely though.
Quite possible. What level is your engine oil at on the dip stick? Cleaning is fairly straightforward, as you've already said...
Split or loose intercooler piping.
Your boost gauge would tell you if that were the cae, but as it says 0.85-0.9bar, I don't think it's that.
A faulty MAF sensor.
Quite possibly. You have a 5 year old car, probably using the original MAF. That in itself is risky, but you also have an ITG filter, which is known to pose a threat to MAF sensors. You've already indicated one method for testing. The other is to reset the ECU and see if that makes any difference to the idle and full throttle acceleration. If it doesn't, the MAF's probably OK. If resetting makes everything worse, then it stands a good chance your MAF's on it's way.
Faulty lambda sensor.
Doubt it, as you're getting reasonable MPG and your idle's OK.
A feature of the ECU.
You should have the AE801 ECU, which doesn't suffer from that characteristic in the same way the later AE802 ECU (MY00) does. And the 2nd gear problem is as you say, only in 2nd gear. But I think that's specific to the AE802 as well.
Spark plugs.
Quite possibly. Do you know when they were changed last?
HT leads.
Had you considered those...?! Unlikely though.
16 March 2004, 09:18 PM
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Judge - many thanks mate. Its people like you with answers like that who make SN a great site. Seems as though I can pretty much rule out the intercooler piping, ECU emissions feature and lamda sensor. 
I guess the best order to attempt fixes would be:
1) Try new spark plugs
2) Clean oily wastegate solenoid (As I'm a newb under the bonnet - a real close up pic of the pipe i need to spray down (once detached) would be great if someone could take one. I've seen the pic on another thread (driver strut tower one) but am still feeling a bit unsure. Knowing my luck I'll spray the brake cleaner in the wrong place and cause a fire lol.)
3) Reset ECU to check the MAF
4) HT leads - not sure what these are but I'll google them in a minute
I guess the best order to attempt fixes would be:
1) Try new spark plugs
2) Clean oily wastegate solenoid (As I'm a newb under the bonnet - a real close up pic of the pipe i need to spray down (once detached) would be great if someone could take one. I've seen the pic on another thread (driver strut tower one) but am still feeling a bit unsure. Knowing my luck I'll spray the brake cleaner in the wrong place and cause a fire lol.)
3) Reset ECU to check the MAF
4) HT leads - not sure what these are but I'll google them in a minute
16 March 2004, 09:23 PM
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hmmm.. just thinking back to my drive home today... the kangarooing was happening even with the throttle gently depressed. not sure if that helps with the diagnosis at all...
17 March 2004, 08:12 AM
#7
If kangeroo occurs on light throttle it could be the Lambda providing a duff signal and causing the ECU to screw up the AFR/Stoich levels
You can drive with this disconnected, as the ECU will use the fuel map rather then using the reading from the Lambda to determine AFR. The ECU also takes a long time to record an error (I never saw one with it disconnected for 2 days).
With it disconnected you will defo have smoother cold start/running (normally the Lambda is not upto temperature and confuses the ECU until warm). This may also help with you knagerooing...
Good Luck....
An ECU reset / Diagnostic drive should pick up a dodgey Lambda (Code 32, I think).
connect black-to-black, green-to-green under the dash/steering column.
Igntion on fully (don't start).
Throttle to the floor for approx 2 secs
Throttle half way for about 2 secs
Throttle closed
Start car, go for casual drive.
After a short time the Check Engine light will flash. If it is a constant on off then it thinks all is dandy. If it is a combination of flashes then this is the error code i.e 3 flashes follwed by 2 flashes is code 32 Lambda.
You can drive with this disconnected, as the ECU will use the fuel map rather then using the reading from the Lambda to determine AFR. The ECU also takes a long time to record an error (I never saw one with it disconnected for 2 days).
With it disconnected you will defo have smoother cold start/running (normally the Lambda is not upto temperature and confuses the ECU until warm). This may also help with you knagerooing...
Good Luck....
An ECU reset / Diagnostic drive should pick up a dodgey Lambda (Code 32, I think).
connect black-to-black, green-to-green under the dash/steering column.
Igntion on fully (don't start).
Throttle to the floor for approx 2 secs
Throttle half way for about 2 secs
Throttle closed
Start car, go for casual drive.
After a short time the Check Engine light will flash. If it is a constant on off then it thinks all is dandy. If it is a combination of flashes then this is the error code i.e 3 flashes follwed by 2 flashes is code 32 Lambda.
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17 March 2004, 09:46 AM
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Originally Posted by Scott.T
If kangeroo occurs on light throttle it could be the Lambda providing a duff signal and causing the ECU to screw up the AFR/Stoich levels
You can drive with this disconnected, as the ECU will use the fuel map rather then using the reading from the Lambda to determine AFR. The ECU also takes a long time to record an error (I never saw one with it disconnected for 2 days).
With it disconnected you will defo have smoother cold start/running (normally the Lambda is not upto temperature and confuses the ECU until warm). This may also help with you knagerooing...
Good Luck....
An ECU reset / Diagnostic drive should pick up a dodgey Lambda (Code 32, I think).
connect black-to-black, green-to-green under the dash/steering column.
Igntion on fully (don't start).
Throttle to the floor for approx 2 secs
Throttle half way for about 2 secs
Throttle closed
Start car, go for casual drive.
After a short time the Check Engine light will flash. If it is a constant on off then it thinks all is dandy. If it is a combination of flashes then this is the error code i.e 3 flashes follwed by 2 flashes is code 32 Lambda.
You can drive with this disconnected, as the ECU will use the fuel map rather then using the reading from the Lambda to determine AFR. The ECU also takes a long time to record an error (I never saw one with it disconnected for 2 days).
With it disconnected you will defo have smoother cold start/running (normally the Lambda is not upto temperature and confuses the ECU until warm). This may also help with you knagerooing...
Good Luck....
An ECU reset / Diagnostic drive should pick up a dodgey Lambda (Code 32, I think).
connect black-to-black, green-to-green under the dash/steering column.
Igntion on fully (don't start).
Throttle to the floor for approx 2 secs
Throttle half way for about 2 secs
Throttle closed
Start car, go for casual drive.
After a short time the Check Engine light will flash. If it is a constant on off then it thinks all is dandy. If it is a combination of flashes then this is the error code i.e 3 flashes follwed by 2 flashes is code 32 Lambda.
black to black can be used for an ECU reset
green to green can be used for the 'test' mode where the solenoids click etc (useful for cleaning)
black-black & green-green at the same time plus a drive until the CEL light comes on can identify faults?
Maybe I should try the 'diagnostic drive' before any other checks/fixes?
17 March 2004, 09:46 AM
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Personally, my order would be...
1. Replace ITG panel filter with STi/K&N/Green/JR.
2. With warm engine idling, perform the "disconnect MAF test".
3. Reset the ECU, which should help rule out lambda as well as MAF (as Scott.T suggested).
4. Clean wastegate solenoid.
Incidentally, if you've never reset the ECU before, something to be aware of. If there are no problems, the CEL will flash almost instantaneously, informing you it's reset. However, if there's a problem with say the lambda sensor, it may take up to 10 minutes to reset, and even then may or may not indicate a problem with the lambda. Again, as Scott.T said, disconnecting the lambda doesn't cause a CEL, so your lambda could well be knackered, but the reset ECU could convince you otherwise.
I'm afraid I can't find another picture of the wastegate solenoid. Don't worry though, it should be fairly straightforward, once you've got your head under the bonnet.
BTW, HT lead are the leads that carry the power to your spark plugs.
1. Replace ITG panel filter with STi/K&N/Green/JR.
2. With warm engine idling, perform the "disconnect MAF test".
3. Reset the ECU, which should help rule out lambda as well as MAF (as Scott.T suggested).
4. Clean wastegate solenoid.
Incidentally, if you've never reset the ECU before, something to be aware of. If there are no problems, the CEL will flash almost instantaneously, informing you it's reset. However, if there's a problem with say the lambda sensor, it may take up to 10 minutes to reset, and even then may or may not indicate a problem with the lambda. Again, as Scott.T said, disconnecting the lambda doesn't cause a CEL, so your lambda could well be knackered, but the reset ECU could convince you otherwise.
I'm afraid I can't find another picture of the wastegate solenoid. Don't worry though, it should be fairly straightforward, once you've got your head under the bonnet.
BTW, HT lead are the leads that carry the power to your spark plugs.
17 March 2004, 09:52 AM
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ECU reset info...
Blacks only is "read mode".
Greens only is "test mode".
Blacks and greens is "reset".
Blacks only is "read mode".
Greens only is "test mode".
Blacks and greens is "reset".
17 March 2004, 10:17 AM
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Many thanks for taking the time to help me with this Scott & Judge.
I think I'll try the ECU reset as defined here first so I can rule out lambda and MAF in one shot.
One further question I have though, that site suggests I drive sensibly during the ECU reset process whereas elsewhere I have read its best to get 4 of your fattest mates and some sandbags in the boot and put your foot down!
Maybe I should drive sensibly for the actual diagnotic then do it again using the 'fat mates' method to improve performance? Or is that complete nonsense?
I think I'll try the ECU reset as defined here first so I can rule out lambda and MAF in one shot.
One further question I have though, that site suggests I drive sensibly during the ECU reset process whereas elsewhere I have read its best to get 4 of your fattest mates and some sandbags in the boot and put your foot down!
Maybe I should drive sensibly for the actual diagnotic then do it again using the 'fat mates' method to improve performance? Or is that complete nonsense?
17 March 2004, 10:30 AM
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Your ECU is very capable of "coarse" and "fine" ignition learning, after the reset has taken place, so probably best to stick to the advice from the site...
17 March 2004, 08:06 PM
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***update***
After filling her up with a full tank of Optimax I carried out the ECU reset. No error codes showed up - just the constant on/off CEL.
What's surprising is that the car actually feels a lot more responsive now and the kangarooing problem seems to have gone away...
I think I'll still put the standard air filter back in and replace the MAF though.
After filling her up with a full tank of Optimax I carried out the ECU reset. No error codes showed up - just the constant on/off CEL.
What's surprising is that the car actually feels a lot more responsive now and the kangarooing problem seems to have gone away...
I think I'll still put the standard air filter back in and replace the MAF though.
18 March 2004, 09:19 AM
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Might not be your MAF then after all. Have you also tried the warm idle MAF disconnect test?
Incidentally, how long did it take to flash the CEL when you reset?
Incidentally, how long did it take to flash the CEL when you reset?
18 March 2004, 02:04 PM
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Judge, didn't try the warm idle MAf disconnect test. Think I still should?
The flashing CEL light came on about 10 seconds after I started the engine. I'd just got home from work and engine was still warm so not sure if that makes a difference. I still took it for a sensible 5 minute drive with the CEL flashing.
The flashing CEL light came on about 10 seconds after I started the engine. I'd just got home from work and engine was still warm so not sure if that makes a difference. I still took it for a sensible 5 minute drive with the CEL flashing.
18 March 2004, 02:18 PM
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If it reset that quickly, I'd say it's very happy with the sensors. I'd still do the other MAF test though, just to rule it out if nothing else...
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