Carina E 4afe Engine Problem

May 16, 2007

hi folks,

Noticed so many threads with engine problems here, maybe you could help troubleshoot my problem.

The car is a -93 carina e, 1.6 lean burn.

After the engine warms up, the idle start to fluctuate between 500-900 rpm. There is also a slight loss of responsivness.

I don't think this is an injector issue, disconnecting electrical cables from injectors made the engine very rough, so (I think) its running always on 4 cylinders. Also measured injector resistance and its consistent 14,8 ohms.

Forcing the EFI system to run on 'backup' mode by disconnecting the engine temperature sensor cures the problem, but obviously fuel economy suffers. Have had all sensors checked, they are working in spec.

Don't think its the Idle valve in the throttle body, because engine idles perfectly around 700 just before full warmup. Tried new sparkplugs, no help. Any ideas what could cause this?

May 20, 2007

never assume...clean out the ICV and the throttle body

May 24, 2007

i had similar symptoms recently, that was one the ht leads. I definitelydoesnt sound like the injector or 02 sensor (have had fun with those too...)

October 29, 2008

i had similar symptoms recently, that was one the ht leads. I definitelydoesnt sound like the injector or 02 sensor (have had fun with those too...)

Hi,

I am new here.

I have Toyota Corolla 1993 1.6 GLi Auto. Having problem with the petrol consumption . It gives me very low mileage (mix city and motorway). I normally buy £35 petrol 32.83 Litre..it gives me about 170 mile Max. Last time on £10 petrol 9.02 litre it gaves me 45 mile. So bad. I am learning and I have done diagonestic and there is no error code. Recently serviced and also changed the Lambda sensor...but no change. I have cheched coolant sensor by multimeter ..it works fine (learnt from you tube). Please hELP!!!!!!!

December 7, 2008

hi folks,
Noticed so many threads with engine problems here, maybe you could help troubleshoot my problem.
The car is a -93 carina e, 1.6 lean burn.
After the engine warms up, the idle start to fluctuate between 500-900 rpm. There is also a slight loss of responsivness.
I don't think this is an injector issue, disconnecting electrical cables from injectors made the engine very rough, so (I think) its running always on 4 cylinders. Also measured injector resistance and its consistent 14,8 ohms.
Forcing the EFI system to run on 'backup' mode by disconnecting the engine temperature sensor cures the problem, but obviously fuel economy suffers. Have had all sensors checked, they are working in spec.
Don't think its the Idle valve in the throttle body, because engine idles perfectly around 700 just before full warmup. Tried new sparkplugs, no help. Any ideas what could cause this?

I have a similar probblem the iddle sounds like yours most of the time. In the beggining i only had rough idle problems but now some times will misfire when started after a few hours for about 4 seconds. I some times get oxygen sensor warning but clears after restart. I have performed many sensor test among which:

1) I have measured the oxygen sensor signal with an osciloscope and it takes about 3 seconds for rich-lean oscillation when idling (a bit long). Also the falling edge of the signal that indicates the time it takes for going from rich to lean (i.e that the injectors are commanded by ECU to give less fuel therefore lean burn) it is too slow about 1 second.

2) I have checked the sensor in other conditions and seems responsive. e.g for fast step and release of the gass the sensor gives sharp steps up and down (150ms or so rise and fall). If it was ta sluggish sensor this would not have been possible.

3)When driving If the gass pedal is released with a gear engaged the sensor gives a constant rich mixture does not oscillate. This to me indicates that due to the high revs the piston of a faulty injector(s) sucks in fuel that is left unburnt (low air at released gass pedal).

4) Also after some driving the sensor no longer gives an oscillating signal. In my opinion this is due to the engine going to an emergency mode (I suspect). It gets stuck to rich when driving and gets stuck to lean if left to idle for a minute or so. this I suspect would . By the way there is no engine warning signal when this happens, only after long journeys 40m and more i get a O2 sensor fault. So don't be sure everything is ok!

I have had to change exhaust downpipe gaskets a couple of times in 4 years, Catalyst 6 mnths ago and now the silenser is getting noisy. I suspect an overly rich mixture for a long time damaged my exhaust system. The ceramic insulator of spark plug of the suspected cylinder is a quite brown at its base (The outside part of the spark plug i mean the white stuff). Also the ignition wire of that spark plug is a bit brown compared to others.

When leaving the car off overnight and removing tha spark plugs the cylinder in question smells of petrol. This may mean the presurised fuel is slowly released by the leaking injector into the cylinder. This to me indicates leaking injector

The crankcase is leaking oil on the side of the suspected injector.

Injectors are strange things they can get clogged or stck open or both resistance is a good way to check but i have read of cases where resistance falls when hot. so measure after a good warm-up.

If any body has any ideas please help

December 17, 2008

Now I have checked my Injectors and they look fine everything inside specifications Flow, resistance, leaks!

I think the lambda sensor is faulty. It could posibly be that it is in the limits of operation and it causes too lean a mixture that drops the idle speed.

I think maybe the average value of oscillation of the sensor might have gone up that would falsly indicate a rich mixture therefore forcing the actual mixture to go lean. It is an expensive test to do but I think I will eventualy change my lean burn sensor.