gtb ,engine bucks when i put my foot down? help please
20 January 2011, 12:25 AM
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gtb ,engine bucks when i put my foot down? help please
96 p subaru legacy gtb twin turbo
if you apply gentel pressure to the throttle to no more than half way down the car will pick up speed and keep going , however if i put my footdown the engine bucks and nothing untill you relise the ecelerator,
the cat is removed and the cat light is on
there is/was a smell of petrol
engine idles mint no issues
starts first time everytime
the only thing that happened different was very low on fuel but didnt run out, thats all
i had just sold it and 2 minutes later had to take it back maybe she didnt like it but dam the timing was off lol
please help if your in manchester i can come to you to look if your a mechanic just tell me what you want
many thanks markyp
if you apply gentel pressure to the throttle to no more than half way down the car will pick up speed and keep going , however if i put my footdown the engine bucks and nothing untill you relise the ecelerator,
the cat is removed and the cat light is on
there is/was a smell of petrol
engine idles mint no issues
starts first time everytime
the only thing that happened different was very low on fuel but didnt run out, thats all
i had just sold it and 2 minutes later had to take it back maybe she didnt like it but dam the timing was off lol
please help if your in manchester i can come to you to look if your a mechanic just tell me what you want
many thanks markyp
20 January 2011, 08:17 AM
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The only CAT light they have is the temperature light. Even if you cut the wires to the sensor the light wont come on. Are you sure its not the CEL light?
Would be worth checking the codes (connet the black connectors under the dash) but my guess would be broken down coilpack(s).
Would be worth checking the codes (connet the black connectors under the dash) but my guess would be broken down coilpack(s).
20 January 2011, 08:32 AM
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thanks pal
i thourght it was a cat light as its removed its red and looks like a rarther straight steaming turd lol soz best way i could think to explain that
again thanks for your reply pal
again thanks for your reply pal
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20 January 2011, 11:52 AM
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Well thats your problem, JDM's NEED super/v power (highest ron possible), chances are what you are seeing is det (not good, causes big end and piston failure), and will cause the issues you are seeing due to the ecu not able to correct any further.
Switch to said fuel above and it may save your engine!
Tony
Switch to said fuel above and it may save your engine!
Tony
20 January 2011, 01:42 PM
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(Taken via a link on this thread: https://www.scoobynet.com/general-te...e-symbols.html)
...and I don't think they change much for any of the classics.
You should see the check engine light appear when the engine is not running and the ignition is on. If you do not see it, you may have a faulty bulb. Gonna make it difficult to diagnose the problem without that being sorted!
The ECU will adapt for 95 RON but it will keep trying to push the ignition advance into det and pulling it back as part of the active knock control. This won't destroy the engine overnight but it adds to the wear. For engine longevity it is better to run on higher octane fuel if possible.
The legacy twin turbos are a bit of a diagnostic nightmare all of their own, though. You'll probably find people more experienced with these cars over at uklegacy.com.
20 January 2011, 02:33 PM
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The ignition alone is more than enough to cope with 95 RON fuel. The issue is more that while the car corrects the IAM (which is really an octane estimator) until the car is reasonably knock free, the fine learning map will continue to try to advance the ignition until knock occurs, then pull back, within the ECUs knock correction authority. Note this is essentially how *all* modern knock control systems work, so no big surprises, but it is better to use the right octane in the first place and not have this happen - it will reduce the wear on the engine.
The belief that the knock control is limited on classic ECUs is really a myth.
20 January 2011, 03:13 PM
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mechanic
have we got a man i can go and see in manchester on here that i can pm that would be a great help just for someone with a bit of expertise haveing a quick check
again many thanks for your time its appriciated
the reply with the pic of the engine light helps cat on fire i went to the original topic and the guy says that that light comes on when he unplugs his cat and he gets a smell of petrol , but it goes when he plugs it back in,
are carnt do anything till i take the clocks out and sort the check engine bulb out so i hope that isnt to much of a big job
cheers mark
again many thanks for your time its appriciated
the reply with the pic of the engine light helps cat on fire i went to the original topic and the guy says that that light comes on when he unplugs his cat and he gets a smell of petrol , but it goes when he plugs it back in,
are carnt do anything till i take the clocks out and sort the check engine bulb out so i hope that isnt to much of a big job
cheers mark
20 January 2011, 07:06 PM
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Mark, you have a couple of options depending where you are in manchester, Adge on here has a place over towards Urmston, there is a place in Buxton and a place up in lancs (a couple actually).
You could also have a chat with Andrew Carr (look on the lads website, www.ladsoc.co.uk) who is a mapper.
Sprint, I have to disagree with you, 97 ron is the minimum I would run any pre 99 JDM on, MY99 onwards need 100-102 ron for which they were mapped (you just have to look at the ammount of P1 engine rebuilds, ok much more agressive map but alot of the failures were not maf related).
There is also a vast ammount of early WRX's run on 95 ron fuel that have needed engine rebuilds due to det (standard and modded cars), as you may well know, light prolonged det is just as bad as short heavy det, the ecu just isnt capable of doing a good job, and no, knock correction sucks on classics, its much better on new age JDM's, especially from MY03 cars, and is not the IAM only x8 on classics, I know its x16 on new age, and the OP's car is also decatted, that wont help on 95 ron
OP, you need to fill with the highest octane fuel available to you, also look at getting anything that will monitor your engine, a ks3 is a good start (www.phormula.co.uk).
Tony
You could also have a chat with Andrew Carr (look on the lads website, www.ladsoc.co.uk) who is a mapper.
Sprint, I have to disagree with you, 97 ron is the minimum I would run any pre 99 JDM on, MY99 onwards need 100-102 ron for which they were mapped (you just have to look at the ammount of P1 engine rebuilds, ok much more agressive map but alot of the failures were not maf related).
There is also a vast ammount of early WRX's run on 95 ron fuel that have needed engine rebuilds due to det (standard and modded cars), as you may well know, light prolonged det is just as bad as short heavy det, the ecu just isnt capable of doing a good job, and no, knock correction sucks on classics, its much better on new age JDM's, especially from MY03 cars, and is not the IAM only x8 on classics, I know its x16 on new age, and the OP's car is also decatted, that wont help on 95 ron
OP, you need to fill with the highest octane fuel available to you, also look at getting anything that will monitor your engine, a ks3 is a good start (www.phormula.co.uk).
Tony
20 January 2011, 11:09 PM
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Mark, "det" is short for "detonation". Petrol engines are designed to burn fuel through combustion, which is a smooth burning process, but if the conditions inside the cylinder are wrong (e.g. too hot, too much ignition advance, etc) then part of the charge can explode rather than burn. This is pinking, or knocking, or det, and can cause engine damage. The greater proportion of the charge that explodes, the more damage potential there is. Higher octane fuel is less prone to det than lower octane, and the car has to actively retard the ignition (and take other measures) to protect the engine when low octane fuel is used.
I'm afraid I can't help you with recommending a mechanic, as I am at the other end of the country, although I would give +1 to Andrew Carr. I would recommend getting the check engine light working as a priority and use the read memory connectors to read the codes from the ECU (assuming there are some!). If code 66 appears, then you definitely need to get over to uklegacy.com.
I don't know what you are disagreeing with here. I also recommended higher octane fuel upthread, to be more specific, I would go for Shell V-Power or Tesco Momentum 99, and I clearly stated that using lower octane fuels would result in increased engine wear. Whilst I cannot rule it out, I would certainly not assume or state that the present issues Mark is suffering are to do with fuel, without some kind of supporting evidence. The assertion that classics are more susceptible is pretty much without foundation that I can see.
Pretty much all turbo cars have issues with knock, and of course the hatch has had serious problems, far more serious than any other impreza that I'm aware of. The quality of det protection afforded by the ECU are defined by a number of things:
1. the underlying sensitivity of the knock sensor and detection circuit
2. the effectiveness of the control algorithm
3. the map parameters used by the algorithm
As for 1., the classic sensor and hardware is very sensitive and well designed, something I have confirmed by data logging, although it is possible for individual cars to have problems, such as degraded sensor or "noisy" engine bay after mods, this is true of any car. As for 2., the algorithm for knock correction has not really changed much, simply because Subaru have had a good algorithm from day one. There have been changes, but they are really minor tweaks rather than major changes, and probably achieve more in terms of extra power than extra protection. 3. of course, varies considerably from car to car, and is the real variable; but this is not a simple question of "newage good, classic bad". The P1 map was not ideal for UK fuel, neither was the 2008 hatch. In fact, the early cars typically have more conservative map parameters than later cars, which is part of the reason they take longer to learn - they are generally more reluctant to advance the ignition than the later cars, which can actually make them safer.
Part of the issue I think you might be missing here is there is only one way to actively control knock, and that is by advancing the ignition until the car begins to knock, and then pulling it back. This is exactly what happens in both classics and the newage cars, so if you are running low octane fuel, the consequences are going to be similar. You're going to get mild knock, because it is the only way the engine learns. So whether classic or newage, the engine "finds" the right ignition level by allowing mild det. Mild det will shorten the life of the engine, so the general advice should be consistent to all Subarus - best to use the right fuel; the wrong fuel will shorten the life of the engine, but the ECU will correct for it, providing some relative protection, unless there is a underlying issue with the map.
Plenty of rebuilds on both classic and newage - no question that there are more classics, as these cars are older and have done more mileage. This doesn't stand alone as good evidence of poor knock control.
Without quantification, this statement is pretty meaningless. One is likely to cause increased wear, and over a long time kill the big end bearings, the other will either do nothing or perhaps break a ring land or even bend a rod, but it depends much on exactly how much det and how lucky you are. How important these are to you depends a lot on what you use the car for. Some people might be happy to replace their engine every 60,000 miles or so as hard driven P1s seem to suffer, others may prefer not to.
Again, absolutely contrary to my experience, which of the three things I have listed above do you believe the classics fall short of, and on what evidence? Or do you think my list of three is missing something? From reverse engineering and data logging subarus, I have seen no strong evidence to support this claim. Not saying it is wrong, but again, being an engineer I prefer hard evidence to speculation and hearsay.
This is something I do know, and I would say this is flat wrong, which does not bode well for your other claims. Which ECUs do you think have an IAM of x8? Every impreza ECU I have ever studied with an integer IAM, from 1992 onwards, are 16-step. (Some later ones have a floating point IAM, although that doesn't make them more accurate, it is the tolerance at the end of the binary search for octane rating that defines the accuracy; and that accuracy is slightly meaningless anyway, since the ratio between the limits of ECU authority are not going to be terribly linear vs. octane)
I'm afraid I can't help you with recommending a mechanic, as I am at the other end of the country, although I would give +1 to Andrew Carr. I would recommend getting the check engine light working as a priority and use the read memory connectors to read the codes from the ECU (assuming there are some!). If code 66 appears, then you definitely need to get over to uklegacy.com.
Sprint, I have to disagree with you, 97 ron is the minimum I would run any pre 99 JDM on, MY99 onwards need 100-102 ron for which they were mapped (you just have to look at the ammount of P1 engine rebuilds, ok much more agressive map but alot of the failures were not maf related).
Pretty much all turbo cars have issues with knock, and of course the hatch has had serious problems, far more serious than any other impreza that I'm aware of. The quality of det protection afforded by the ECU are defined by a number of things:
1. the underlying sensitivity of the knock sensor and detection circuit
2. the effectiveness of the control algorithm
3. the map parameters used by the algorithm
As for 1., the classic sensor and hardware is very sensitive and well designed, something I have confirmed by data logging, although it is possible for individual cars to have problems, such as degraded sensor or "noisy" engine bay after mods, this is true of any car. As for 2., the algorithm for knock correction has not really changed much, simply because Subaru have had a good algorithm from day one. There have been changes, but they are really minor tweaks rather than major changes, and probably achieve more in terms of extra power than extra protection. 3. of course, varies considerably from car to car, and is the real variable; but this is not a simple question of "newage good, classic bad". The P1 map was not ideal for UK fuel, neither was the 2008 hatch. In fact, the early cars typically have more conservative map parameters than later cars, which is part of the reason they take longer to learn - they are generally more reluctant to advance the ignition than the later cars, which can actually make them safer.
Part of the issue I think you might be missing here is there is only one way to actively control knock, and that is by advancing the ignition until the car begins to knock, and then pulling it back. This is exactly what happens in both classics and the newage cars, so if you are running low octane fuel, the consequences are going to be similar. You're going to get mild knock, because it is the only way the engine learns. So whether classic or newage, the engine "finds" the right ignition level by allowing mild det. Mild det will shorten the life of the engine, so the general advice should be consistent to all Subarus - best to use the right fuel; the wrong fuel will shorten the life of the engine, but the ECU will correct for it, providing some relative protection, unless there is a underlying issue with the map.
This is something I do know, and I would say this is flat wrong, which does not bode well for your other claims. Which ECUs do you think have an IAM of x8? Every impreza ECU I have ever studied with an integer IAM, from 1992 onwards, are 16-step. (Some later ones have a floating point IAM, although that doesn't make them more accurate, it is the tolerance at the end of the binary search for octane rating that defines the accuracy; and that accuracy is slightly meaningless anyway, since the ratio between the limits of ECU authority are not going to be terribly linear vs. octane)
21 January 2011, 02:40 PM
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3 places for you to take your car to that are not too expensive.
http://www.adgespeed.co.uk/
CAMS (Speak to Brian)
Tel:- 01254 689994
Mobile Tel :- 07931211871
UNIT 11 BROOK MILL COMPLEX
BRANCH ROAD
LOWER DARWEN
BB3 0PR
2 MINUTES OF JUNCTION 4 NEAR EWOOD PARK
Autotecnica
Place page
Unit 29
Harpur Hill Business Park, Buxton, Derbyshire SK17 9JL
01298 27391
Tony
http://www.adgespeed.co.uk/
CAMS (Speak to Brian)
Tel:- 01254 689994
Mobile Tel :- 07931211871
UNIT 11 BROOK MILL COMPLEX
BRANCH ROAD
LOWER DARWEN
BB3 0PR
2 MINUTES OF JUNCTION 4 NEAR EWOOD PARK
Autotecnica
Place page
Unit 29
Harpur Hill Business Park, Buxton, Derbyshire SK17 9JL
01298 27391
Tony
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