Hello;
I have a 1994 Alfa romeo Q4, the car has stock chip, but I am using another fuel pressure regulator that is adjustable and rising rate.
I installed a wideband meter on the car and the car was running too rich, so I kept lowering fuel pressure to adjust my mixture at WOT under boost.
I raised boost "stock chip with stock timing and stock Intercooler" to 1.3bar and Air fuel ratio mixture were still in the 10.5:1 range, when suddenly the engine BLEW, it started to blow oil out of the BOV, and smoking very badly.
After disassembling the engine which has been done for 3 times now, and everytime I find the same problem, I found that the 3rd piston melted, and Aluminum pieces stuck to the cylinder wall, and this is the 3rd time it happens and from the same place, which is from the intake side not the exhaust side.
I had the injectors cleaned and measured the flow rate, I have swapped injectors incase the injector was the reason, but still the same problem.
please advise me what am I missing here, I know 1.3bar is alot of boost for stock turbo, stock chip, stock Intercooler, but I know a couple of friends running that boost on their cars with no problems, I also have a Fiat Ritmo with a Lancia delta integrale 2.0 16v turbo engine and am running 1.2bar and never had this problem.
kind regards
Nabil
Alfa 155 Q4 2.0 16v turbo engine problems
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nabilhpe
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Guy Croft
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Although i can pretty well work out most engine problems I actually have no idea what that engine is, so please post tech description (4 cyl, V6, turbocharged as standard or modified, any mods at all you've done beyond what you have described etc) and photos and I will be able to help then for sure.
GC
GC
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SteveNZ
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sumplug
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Rich Ellingham
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It has detonated due to being too hot in the cylinders, this is identiacal to a 16v turbo unit where the fuel pressure was lowered to lean the mixture back from a rich state. this is very bad on the std intercooler as the fuel was compensating for the cooler's lack of cooling capacity, as soon as the fuel was reduced the inlet temperature becomes too high, and melts the piston and produces detonation damage on the cylinder head and wall. Its normal to see the damage on the inlet side of the chamber.
You cannot run that boost with such an intercooler, you are putting the turbo out of its intended efficiency range and introducing too much heat into the inlet. You need a bigger intercooler and turbo to reduce the inlet temperatures, of turn down the boost. Adjusting the fuelling on by fuel pressure alone on turbo car is the wrong way to do it, a mappable fuel/ignition system is what you need for this.
Rich
You cannot run that boost with such an intercooler, you are putting the turbo out of its intended efficiency range and introducing too much heat into the inlet. You need a bigger intercooler and turbo to reduce the inlet temperatures, of turn down the boost. Adjusting the fuelling on by fuel pressure alone on turbo car is the wrong way to do it, a mappable fuel/ignition system is what you need for this.
Rich
book 38
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Fahrell
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I partially agree with the above post from Rich...
Yes, you need to maintain the mixture slightly rich to help cool the cilinder.
and the original spark timing is way too advanced for this new boost pressure. causing knock/predetonation for example. And in some cases you will not notice.
a few years ago I used to run with 1.3 bar in my engine before changing to ethanol (which is way better than petrol in withstanding compression and cooling effect) but I use a piggyback controller who retard my motronic original timing advance and pulses extra injectors... used this configuration for a year with no trouble at all... even with the original intercooler (and my country is hot!)
today I use ethanol and peaks of 1.5 bar, and still the original intercooler, but with the extra fuel and the piggyback controller retarding my timing advance, still no trouble...
Yes, you need to maintain the mixture slightly rich to help cool the cilinder.
and the original spark timing is way too advanced for this new boost pressure. causing knock/predetonation for example. And in some cases you will not notice.
a few years ago I used to run with 1.3 bar in my engine before changing to ethanol (which is way better than petrol in withstanding compression and cooling effect) but I use a piggyback controller who retard my motronic original timing advance and pulses extra injectors... used this configuration for a year with no trouble at all... even with the original intercooler (and my country is hot!)
today I use ethanol and peaks of 1.5 bar, and still the original intercooler, but with the extra fuel and the piggyback controller retarding my timing advance, still no trouble...
Andr’‚© Farkatt
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SteveNZ
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nabilhpe
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yes thank you, the Alfa 155 Q4 has a Fiat/Lancia 2L 16VT engine as steve said.
I have attached some pictures of the old piston that was damaged before, and of the new piston that got damaged last sunday.
when the first piston got damaged, I was using the same engine but on another car, with a different wiring harness and ECU.
Do you think the different Intake manifolds that Fiat/Lancia and Alfa use has something to do with this? I mean why piston #3? I am using the Intake manifold that is used on stock Lancia Delta HF HPE.
My last question would be, what is the efficiency range of the stock T3 60trim trubo? what kind of boost can the stock turbo pistons withstand? considering 8v and 16v pistons, and the stock intercooler is that bad or it becomes bad coz we raise boost level? what is a safe boost limit to run using stock intercooler? I guess I should consider water/methanol injection system.
kind regards
Nabil
I have attached some pictures of the old piston that was damaged before, and of the new piston that got damaged last sunday.
when the first piston got damaged, I was using the same engine but on another car, with a different wiring harness and ECU.
Do you think the different Intake manifolds that Fiat/Lancia and Alfa use has something to do with this? I mean why piston #3? I am using the Intake manifold that is used on stock Lancia Delta HF HPE.
My last question would be, what is the efficiency range of the stock T3 60trim trubo? what kind of boost can the stock turbo pistons withstand? considering 8v and 16v pistons, and the stock intercooler is that bad or it becomes bad coz we raise boost level? what is a safe boost limit to run using stock intercooler? I guess I should consider water/methanol injection system.
kind regards
Nabil
- Attachments
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- P1010046 small.JPG (46.75 KiB) Viewed 13218 times
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- P1010045 small.JPG (74.1 KiB) Viewed 13218 times
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- Old engine piston Damage
- P1010043 small.JPG (69.22 KiB) Viewed 13220 times
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- New engine piston Damage
- P1010040 small.JPG (68.95 KiB) Viewed 13219 times
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Fahrell
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If the mixture is right (slightly rich for turbo) and spark timing correct, the pistons, any with reasonable quality, will withstand "any" boost pressure you have... what kills pistons is wrong setup or equipament failure (including fuel pressure/flow/bubbles, misfires, knock, lubrication problems etc...)nabilhpe wrote: what kind of boost can the stock turbo pistons withstand? considering 8v and 16v pistons, and the stock intercooler is that bad or it becomes bad coz we raise boost level? what is a safe boost limit to run using stock intercooler? I guess I should consider water/methanol injection system.
kind regards
Nabil
the stock Intercooler is ok, but as you increase boost pressure (and thus the air temperature and flow) it becomes restrictive and inneficcient, but still works.
If you solve whatever problem is happening in your cilinder, with the right setup for your engine, I suggest that you have to start to think in a frontal, high flow, frontal IC when you use more than 1,4 bar
water/methanol injection system is radical... use it only when you solve all your problems and still need it.
thank you
Andr’‚© Farkatt
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sumplug
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Surely if you increase boost pressure, you are forcing more air into the chambers and so increasing the CR which then takes the pistons out of their desired working enviroment leading to failure. Higher boost equals more heat and the tendency for piston to "Pickup" and fail. But why number 3 piston on this engine only?
Andy.
Andy.
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Guy Croft
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Thanks for the photos and some good background there. Some good info and replies from members - thanks. It is distressing to hear of your engine problems and at least you've got the courage to talk about it, but I'll tell you you¢ž¢re making the most basic installation and build mistakes.
To begin with:
Repeated detonation on the same cylinder could be due to:
1. Knock sensor not picking up the signal from that cylinder as well as the others
2. Particularly high exhaust temperature conditions in that cylinder and port (can be as a result of back pressure, see later)
3. Injector atomisation poor on that cylinder
Either way it¢ž¢s immaterial which cylinder it is. This just happens to be the one that exhibits this damaging phenomenon first. Run the engine long enough and all the cylinders will end up the same or worse. Put simply ¢‚¬Å“ your mission is to stop the detonation on that cylinder and the rest of the engine will be fine too.
I don¢ž¢t know how you ‹Å“raised the boost¢ž¢ but I suspect you have ‹Å“fooled¢ž¢ the wastegate by putting a bleed valve in the manifold pressure hose to the unit. This bleeds off air from the system and effectively ‹Å“tells¢ž¢ the wastegate that boost is lower than it actually is. The wastegate valve thus stays closed (or more closed than it would be) and more gas is allowed to feed to the turbine.
I cannot say I agree with the practice. You are causing high pressure air to vent from the inlet manifold - upsetting the fuel pressure regulator and the whole calibration map. And it is commonly said that a production turbocharger can be made to develop 20% more boost than it is set up to deliver (by wastegate control). I read this everywhere and I think ¢‚¬Å“ as a former Chief Engineer with Napier Turbochargers - oh really? What you get first if you do that is a big increase in exhaust back pressure for a start. This, ignoring everything else ¢‚¬Å“ can overheat the cylinder head on the exhaust side (well known to cause burned ex valves and cracked seats) and give a big increase in exhaust residuals in the chamber ¢‚¬Å“ reducing power, leaning out the charge, taking the cylinder temperature into the detonation zone.
Moreover, what you¢ž¢re doing by raising the boost by this means is taking the whole turbocharger operating regime away from the optimum operating envelopes. Apart from making the engine thermal efficiency terrible, that¢ž¢s liable, in the extreme (and 30% more boost on a production turbo is extreme) - to cause all sorts of turbo temperature and flow related problems. Where are your turbine and compressor operating in the map? You¢ž¢ve no idea without holding the maps in your hand and reading turbo speed probe under load up and down rev band ¢‚¬Å“ which you can¢ž¢t do.
You can¢ž¢t do engines like that. We don¢ž¢t need to go into it any further here - Don¢ž¢t do it. Either gasflow the head and get more power for same boost or get a bigger capacity turbo from a specialist supplier. It¢ž¢s better to run a big turbo below max boost than overstrain a small one by upping the boost.
More boost means higher charge temperature in proportion with increase in pressure ratio, it must be assumed that the intercooler is NOT going to be big enough. You may not know that over 50 deg C inlet temperature is very borderline for detonation and I would not tolerate over 45 Deg C. Don¢ž¢t forget the heat transfer from the inlet port to the incoming air is significant add-on. And as far as fuelling is concerned the engine will go chronically lean if you raise the boost at all - and if I read you right you're actually lowering the fuel pressure. You cannot do this because it will totally mess up the injector delivery behaviour. An injector needs a certain pressure in the rail and altering the fuelling requires electronic recalibration of the pulse width - assuming the injector is big enough.
Furthermore:
1. If you raise the boost you must retard the ignition.
2. You must not reduce the fuel pressure to set the mixture.
(These parameters require mappable ecu)
3. If you increase the max boost you must decrease the CR.
4. The fuel octane may be too low for the increased boost.
5. The plugs will need to be race grade at 1.3 bar boost (19 psi).
For a start you need to rebuild the engine and set it up for lower CR, I suggest 7.5/1. If you don¢ž¢t fancy head mods, go for 17 psi boost ¢‚¬Å“ production pistons are plenty strong enough for that. Personally I don¢ž¢t hold with increasing boost to get more power without optimising the head. It¢ž¢s a stupid thing to do and always done for cost reasons. The OE injectors will probably cope. Return the fuel rail pressure to OE setting. Get yourself in touch with a calibration expert and get a mappable ecu. I also recommend bigger intercooler or at least water spray cooling to it.
Follow this carefully or you¢ž¢re going to keep blowing engines.
GC
To begin with:
Repeated detonation on the same cylinder could be due to:
1. Knock sensor not picking up the signal from that cylinder as well as the others
2. Particularly high exhaust temperature conditions in that cylinder and port (can be as a result of back pressure, see later)
3. Injector atomisation poor on that cylinder
Either way it¢ž¢s immaterial which cylinder it is. This just happens to be the one that exhibits this damaging phenomenon first. Run the engine long enough and all the cylinders will end up the same or worse. Put simply ¢‚¬Å“ your mission is to stop the detonation on that cylinder and the rest of the engine will be fine too.
I don¢ž¢t know how you ‹Å“raised the boost¢ž¢ but I suspect you have ‹Å“fooled¢ž¢ the wastegate by putting a bleed valve in the manifold pressure hose to the unit. This bleeds off air from the system and effectively ‹Å“tells¢ž¢ the wastegate that boost is lower than it actually is. The wastegate valve thus stays closed (or more closed than it would be) and more gas is allowed to feed to the turbine.
I cannot say I agree with the practice. You are causing high pressure air to vent from the inlet manifold - upsetting the fuel pressure regulator and the whole calibration map. And it is commonly said that a production turbocharger can be made to develop 20% more boost than it is set up to deliver (by wastegate control). I read this everywhere and I think ¢‚¬Å“ as a former Chief Engineer with Napier Turbochargers - oh really? What you get first if you do that is a big increase in exhaust back pressure for a start. This, ignoring everything else ¢‚¬Å“ can overheat the cylinder head on the exhaust side (well known to cause burned ex valves and cracked seats) and give a big increase in exhaust residuals in the chamber ¢‚¬Å“ reducing power, leaning out the charge, taking the cylinder temperature into the detonation zone.
Moreover, what you¢ž¢re doing by raising the boost by this means is taking the whole turbocharger operating regime away from the optimum operating envelopes. Apart from making the engine thermal efficiency terrible, that¢ž¢s liable, in the extreme (and 30% more boost on a production turbo is extreme) - to cause all sorts of turbo temperature and flow related problems. Where are your turbine and compressor operating in the map? You¢ž¢ve no idea without holding the maps in your hand and reading turbo speed probe under load up and down rev band ¢‚¬Å“ which you can¢ž¢t do.
You can¢ž¢t do engines like that. We don¢ž¢t need to go into it any further here - Don¢ž¢t do it. Either gasflow the head and get more power for same boost or get a bigger capacity turbo from a specialist supplier. It¢ž¢s better to run a big turbo below max boost than overstrain a small one by upping the boost.
More boost means higher charge temperature in proportion with increase in pressure ratio, it must be assumed that the intercooler is NOT going to be big enough. You may not know that over 50 deg C inlet temperature is very borderline for detonation and I would not tolerate over 45 Deg C. Don¢ž¢t forget the heat transfer from the inlet port to the incoming air is significant add-on. And as far as fuelling is concerned the engine will go chronically lean if you raise the boost at all - and if I read you right you're actually lowering the fuel pressure. You cannot do this because it will totally mess up the injector delivery behaviour. An injector needs a certain pressure in the rail and altering the fuelling requires electronic recalibration of the pulse width - assuming the injector is big enough.
Furthermore:
1. If you raise the boost you must retard the ignition.
2. You must not reduce the fuel pressure to set the mixture.
(These parameters require mappable ecu)
3. If you increase the max boost you must decrease the CR.
4. The fuel octane may be too low for the increased boost.
5. The plugs will need to be race grade at 1.3 bar boost (19 psi).
For a start you need to rebuild the engine and set it up for lower CR, I suggest 7.5/1. If you don¢ž¢t fancy head mods, go for 17 psi boost ¢‚¬Å“ production pistons are plenty strong enough for that. Personally I don¢ž¢t hold with increasing boost to get more power without optimising the head. It¢ž¢s a stupid thing to do and always done for cost reasons. The OE injectors will probably cope. Return the fuel rail pressure to OE setting. Get yourself in touch with a calibration expert and get a mappable ecu. I also recommend bigger intercooler or at least water spray cooling to it.
Follow this carefully or you¢ž¢re going to keep blowing engines.
GC
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nabilhpe
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Update 29th Dec 2006:
I forgot to mention earlier that this car doesn¢ž¢t run the stock turbocharger, in fact it runs a turbo from the Lancia Integrale with the .60A/R stamped on it as well as T3 60, and it has a .63A/R Turbine housing.
Yes Guy, the boost got raised by fooling the wastegate, you said something about "3. Injector atomisation poor on that cylinder" why just on that cylinder and how to solve that? We changed injectors and the problem got repeated.
The damaged piston got changed as well as bearings, the other 3 pistons look brand new, I have some photos on my phone and will try to upload them when I find my cable.
The boost got reduced to 1 bar, water sprayers are added to cool the Intercooler as well as a fan, a chip file to run 1 bar boost is first thing to order after new year, and the wiring harness will be precisely tested especially the 3rd injector wires - any hints on how to do that other than continuity and resistance?
About fuel pressure as I mentioned earlier regarding lowering it to lean out the mixture, I have to mention that the fuel pressure regulator on this car goes to about 4.2 bar fuel pressure under boost and not to just 3 bar, the fuel ran on this car is 98 Ron unleaded "TOTAL", and this car has a Spesso 1.9mm head gasket.
Happy New Year
Nabil
I forgot to mention earlier that this car doesn¢ž¢t run the stock turbocharger, in fact it runs a turbo from the Lancia Integrale with the .60A/R stamped on it as well as T3 60, and it has a .63A/R Turbine housing.
Yes Guy, the boost got raised by fooling the wastegate, you said something about "3. Injector atomisation poor on that cylinder" why just on that cylinder and how to solve that? We changed injectors and the problem got repeated.
The damaged piston got changed as well as bearings, the other 3 pistons look brand new, I have some photos on my phone and will try to upload them when I find my cable.
The boost got reduced to 1 bar, water sprayers are added to cool the Intercooler as well as a fan, a chip file to run 1 bar boost is first thing to order after new year, and the wiring harness will be precisely tested especially the 3rd injector wires - any hints on how to do that other than continuity and resistance?
About fuel pressure as I mentioned earlier regarding lowering it to lean out the mixture, I have to mention that the fuel pressure regulator on this car goes to about 4.2 bar fuel pressure under boost and not to just 3 bar, the fuel ran on this car is 98 Ron unleaded "TOTAL", and this car has a Spesso 1.9mm head gasket.
Happy New Year
Nabil
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Rich Ellingham
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As a note to your fuel pressure as you may know already, the pressure in the rail has to increase with boost pressure.
What happens is the final fuel pressure remains the same as the injectors see it. If the std fuel pressure is say 3 bar, then at 1 bar boost there would be 3 bar pushing fuel out and 1 bar of charge air pushing it back in = 2 bar net.
Thus to maintain fuel pressure the fuel system pressure must increase directly proportional to boost pressure. Altering the spring on an adjustable regulator changes this base pressure across the whole rpm range.
The Tipo 16v phase 1 has a manifold referenced adjustable base pressure regulator, the later cars like the Fiat coupe 16v turbo have a manifold referenced fixed base pressure regulator. Neither of these are the ‹Å“nonsense¢ž¢ that is a 'rising rate' regulator (i.e. One that changes fuel pressure at a non-proportional rate to manifold pressure).
Rich
What happens is the final fuel pressure remains the same as the injectors see it. If the std fuel pressure is say 3 bar, then at 1 bar boost there would be 3 bar pushing fuel out and 1 bar of charge air pushing it back in = 2 bar net.
Thus to maintain fuel pressure the fuel system pressure must increase directly proportional to boost pressure. Altering the spring on an adjustable regulator changes this base pressure across the whole rpm range.
The Tipo 16v phase 1 has a manifold referenced adjustable base pressure regulator, the later cars like the Fiat coupe 16v turbo have a manifold referenced fixed base pressure regulator. Neither of these are the ‹Å“nonsense¢ž¢ that is a 'rising rate' regulator (i.e. One that changes fuel pressure at a non-proportional rate to manifold pressure).
Rich
book 38
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Guy Croft
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turbo from the Lancia Integrale with the .60A/R stamped on it as well as T3 60, and it has a .63A/R Turbine housing.
Sorry but I have no idea what this change will do. If you want to get more boost without consulting a turbo expert like Turbo Techincs in the UK then please raise the boost on the stock turbo, don't change the turbo too..!
As for cylinder 3 you can probably put it down to coincidence. But - I hope you have re-honed and fully detergent cleaned that cylinder with the detonation problem - in my book that would need a whole engine strip.
Apart from that you are moving in the right direction.
GC
Sorry but I have no idea what this change will do. If you want to get more boost without consulting a turbo expert like Turbo Techincs in the UK then please raise the boost on the stock turbo, don't change the turbo too..!
As for cylinder 3 you can probably put it down to coincidence. But - I hope you have re-honed and fully detergent cleaned that cylinder with the detonation problem - in my book that would need a whole engine strip.
Apart from that you are moving in the right direction.
GC
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nabilhpe
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Rich, thank you for the clarification, sometimes we know that things just happen, but we dont know how:-) thanks for clirifying this matter.
On a side note, the Alfa have the same FPR as the one that equips the TIPO 16v, adjustable its weber with the 7/2.5 numbers stamped on it.
I already have a cartech adjustable FPR that I have aside, not using it.
Guy, that turbo was installed on the on the car since the day it was bought about 2 years ago, when he bought the car it had nothing but the shell and interior, oh and the gearbox, other than that it had nothing concerning the engine or turbo, so everything had to be bought 2nd hand, and I guess I should contact turbo experts, and that I will do after new year.
P.S. I have to note that the Alfa 155 is for a friend of mine, he just passed by with the ECU, I copied the chip on that car and compared it with another 155 turbo chip and what a surprise I got, I am not a chip guru, but I have the Galep programmer and when I compare files using the REMAP3000 software "I know its a bad S/W but I am just a hobbiest who likes to look what is different between one file and another" so anyway the curves between the 2 files are way apart, it might be the chip that was already on the car is from a 2.0 16v N/A ECU, and my friend just told me that if he disconnect the coolant temp. sensor wire, nothing does happen, so that chip is messed up big time and damaging his engines.
thank you.
On a side note, the Alfa have the same FPR as the one that equips the TIPO 16v, adjustable its weber with the 7/2.5 numbers stamped on it.
I already have a cartech adjustable FPR that I have aside, not using it.
Guy, that turbo was installed on the on the car since the day it was bought about 2 years ago, when he bought the car it had nothing but the shell and interior, oh and the gearbox, other than that it had nothing concerning the engine or turbo, so everything had to be bought 2nd hand, and I guess I should contact turbo experts, and that I will do after new year.
P.S. I have to note that the Alfa 155 is for a friend of mine, he just passed by with the ECU, I copied the chip on that car and compared it with another 155 turbo chip and what a surprise I got, I am not a chip guru, but I have the Galep programmer and when I compare files using the REMAP3000 software "I know its a bad S/W but I am just a hobbiest who likes to look what is different between one file and another" so anyway the curves between the 2 files are way apart, it might be the chip that was already on the car is from a 2.0 16v N/A ECU, and my friend just told me that if he disconnect the coolant temp. sensor wire, nothing does happen, so that chip is messed up big time and damaging his engines.
thank you.
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