What could be causes my engine to lose power?
Discussion
Hello, I have a 1996 Daihatsu Sportrak with an 1.6 EFI petrol engine; hardly the most powerful car in the world. But right now it's even slower.
One day a while ago I had been offroading, all went well including quite a long drive home. A couple of days later I started her up and the engine was struggling not to stall while idling. Along with this it was very sluggish on the road, hills requiring one gear lower than normal the all ready poor low end torque and throttle response was even worse. A garage I took it to adjusted the idle so it doesn't stall now, it may also have made a difference to the power, but it's still much slower!
I've checked everything I knew:
Items changed last year: fuel, air & oil filters, oil, spark plugs, coolant, thermostat. I've checked the air filter again and it seems fine.
All plugs are receiving a spark, although I'm not experienced enough to comment on its 'quality'.
I've had a look for lose vacuum hoses, I think these are OK, unless I've missed one.
This problem certainly developed overnight. The engine stills sounds the same as it did before.
I'd really appreciate any help whatsoever in identifying possible causes. Thanks in advance
One day a while ago I had been offroading, all went well including quite a long drive home. A couple of days later I started her up and the engine was struggling not to stall while idling. Along with this it was very sluggish on the road, hills requiring one gear lower than normal the all ready poor low end torque and throttle response was even worse. A garage I took it to adjusted the idle so it doesn't stall now, it may also have made a difference to the power, but it's still much slower!
I've checked everything I knew:
Items changed last year: fuel, air & oil filters, oil, spark plugs, coolant, thermostat. I've checked the air filter again and it seems fine.
All plugs are receiving a spark, although I'm not experienced enough to comment on its 'quality'.
I've had a look for lose vacuum hoses, I think these are OK, unless I've missed one.
This problem certainly developed overnight. The engine stills sounds the same as it did before.
I'd really appreciate any help whatsoever in identifying possible causes. Thanks in advance
Was it wet when you went off-roading, i.e. lots of big splashy puddles etc? Or to the other extreme, very dry with lots of dust?
Because excess water or dust may have buggered up a sensor somewhere (MAF / air sensor, crank or cam sensor, temp sensor etc...) or if not the sensor, got into the electrical plug for one of them.
If so, this may be causing the ECU to not receive the correct data from one of them, and so it has gone into what's called 'limp mode' where it only gives the engine enough to run on, but without full power available.
Your first port of call should be to get an OBDII fault code reader on the ECU and see if there are any fault codes there.
Because excess water or dust may have buggered up a sensor somewhere (MAF / air sensor, crank or cam sensor, temp sensor etc...) or if not the sensor, got into the electrical plug for one of them.
If so, this may be causing the ECU to not receive the correct data from one of them, and so it has gone into what's called 'limp mode' where it only gives the engine enough to run on, but without full power available.
Your first port of call should be to get an OBDII fault code reader on the ECU and see if there are any fault codes there.
Wouldn't have thought cam or crank sensor as the engine is still running. Possible on the MAF if there is one. This would explain the idle issue as well. However more likely to be a MAP sensor on this (?) so low idle would be inconsistent with missing vac hoses. What do the plugs look like - are they a light brown, or black and sooty?
Blocked exhaust sounds like a good bet.
Blocked exhaust sounds like a good bet.
This is the first time I've posted on PistonHeads and I must say everyone's response is fantastic. Thanks.
Something I didn't mention is there's no check engine light, but I'll see if I can get some fault readings anyway.
There wasn't excessive water or dust but as with off roading there was a bit of both. The engine was nowhere near being at all submerged put it that way. The car was fine for an hour and a half drive at the end of the day before the problem occurred.
If it was a problem with the fuel supply, I would expect it to affect the top end of power demand most, but the problem is, if anything, more significant at lower revs. I'd like to think the same can be said for for air flow, induction and exhaust.
I'll whip the plugs out again and have a look, it does burn more than its fair share of oil so they'r never spotless, but I've run it much longer than this without changing before.
Something I didn't mention is there's no check engine light, but I'll see if I can get some fault readings anyway.
There wasn't excessive water or dust but as with off roading there was a bit of both. The engine was nowhere near being at all submerged put it that way. The car was fine for an hour and a half drive at the end of the day before the problem occurred.
If it was a problem with the fuel supply, I would expect it to affect the top end of power demand most, but the problem is, if anything, more significant at lower revs. I'd like to think the same can be said for for air flow, induction and exhaust.
I'll whip the plugs out again and have a look, it does burn more than its fair share of oil so they'r never spotless, but I've run it much longer than this without changing before.
OK I've just done the following test, I'm not sure if it's what you meant or not but it's something:
Connect two pins on the test connector under the bonnet and read the code displayed in the form of flashing dash lights. The response was 'Normal'. There are 5 pins on the test connector so I assume there is some more thorough analysis that can be done with more equipment, is that what you meant?
The 'diagnosis items' listed in the workshop manual that I could have read from the method I used are:
Normal
Pressure sensor
Ignition Signal
Water temperature sensor
Oxegen sensor signal
Throttle position sensor
Intake air temperature sensor
Vehicle speed sensor
Starter signal
Switch signal
So I would like to think it's safe to assume it's none of the above...
which begins to point towards something more serious.
Thanks again for any help!
Connect two pins on the test connector under the bonnet and read the code displayed in the form of flashing dash lights. The response was 'Normal'. There are 5 pins on the test connector so I assume there is some more thorough analysis that can be done with more equipment, is that what you meant?
The 'diagnosis items' listed in the workshop manual that I could have read from the method I used are:
Normal
Pressure sensor
Ignition Signal
Water temperature sensor
Oxegen sensor signal
Throttle position sensor
Intake air temperature sensor
Vehicle speed sensor
Starter signal
Switch signal
So I would like to think it's safe to assume it's none of the above...
which begins to point towards something more serious.
Thanks again for any help!
Often the MAF sensor becomes faulty or dirty and sends an incorrect value to the ECU, the ECU does not know it is receiving bad information so doesn't put the CEL on.
If you unplug the MAF whilst the engine is running and this makes an improvement then it is likely the MAF is your problem.
More often than not simply cleaning the MAF sensor with a squirt of contact cleaner will do the trick. The CEL will probably illuminate after unplugging the MAF but should go out again after cleaning is done.
If you unplug the MAF whilst the engine is running and this makes an improvement then it is likely the MAF is your problem.
More often than not simply cleaning the MAF sensor with a squirt of contact cleaner will do the trick. The CEL will probably illuminate after unplugging the MAF but should go out again after cleaning is done.
Ozzie Osmond said:
Ray Luxury-Yacht said:
regardless of whether you have a CEL or not - I say again, the first port of call is to scan the ECU. Otherwise, you are just running blind at the problem...
^^^^ ThisGet a proper diagnosis before you start chucking money around.
One thing I would check again is vacuum lines, one of them might have just popped off. Sometimes they are hidden under inlet manifolds and the like. You might notice a whistling noise but not always. You could also check the wiring to the lambda sensor which may have been snagged on something.
A vehicle as old as this only has a basic OBD facility and the OP has already run through the check list so paying out for a scan will not necesarily show up the fault.
I would go over the obvious again before spending any cash, checking for dirt, moisture, chafed wires, split pipes, blocked fuel lines, torn airfilter etc.
Good luck!
I would go over the obvious again before spending any cash, checking for dirt, moisture, chafed wires, split pipes, blocked fuel lines, torn airfilter etc.
Good luck!
Thanks. I think that is likely to be the case - only simple diagnostic facilities. But there are another 3 pins on that connector I didn't touch. Even so, £75 is no small amount, I'd rather eliminate what I can from inspection before paying for a scan, if it will be of any further help.
Tomorrow I'll have another look at the air filter, and the fuel filter also, check the exhaust, would it be worth disconnecting the cat and running it up the lane quickly? Can anyone tell me if I should still be looking at exhaust and induction despite the symptoms not being any worse at high revs?
Thank you all
Tomorrow I'll have another look at the air filter, and the fuel filter also, check the exhaust, would it be worth disconnecting the cat and running it up the lane quickly? Can anyone tell me if I should still be looking at exhaust and induction despite the symptoms not being any worse at high revs?
Thank you all
I suspect MAF sensor.
Check for fuel leaks around injectors, I had a broken seal which led to the engine running very rich to compensate, leading to loss of power and eventually flooding.
Everyone else has covered what I would otherwise have said.
This forum is quite an impressive beard, I must say
Check for fuel leaks around injectors, I had a broken seal which led to the engine running very rich to compensate, leading to loss of power and eventually flooding.
Everyone else has covered what I would otherwise have said.
This forum is quite an impressive beard, I must say
I think there's a MAP rather than MAF, but I suppose they're there for the same reason, so could cause the same symptoms. The engine struggles and slowly dies if this is unplugged. There's also something with two vacuum hoses attached to it, both coming from around the throttle. I can't find any reference to this online or in the manual, so don't know what it does. Unplugging it doesn't seem to make much difference.
Thanks
Thanks
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