Sagaris engine problem - Can't seem to find the cause
Discussion
Hello,
to get straight to the point, when I put my foot down in any gear except first my engine starts stumbling and shuttering like it is drowning in too much fuel. It takes a few seconds before the engine finds his breath again and starts accelerating.
I have had the car looked at and what we can see is that there is a big difference between the data from the lambda sensors and trottle possition sensors on the two banks. But we cannot find the reason for this.
Also in the adaptives file of the ECU you can see that one bank fluctuates a lot more than the other bank.
Same thing with the throttle position sensors... the one at the front fluctuates all the time while th eother is stable. Same for the lambda readouts... one stable, another not.
I do not get any sensor errors and we have tried to change the lambda sensors but nothing worked. I am not sure if this is correct but for me a sensor works or it doesn't work.
I also had the mass checked out and put in some other extra cables but this is not the issue either.
Does anybody have an idea how I can best tackle this issue?
Thanks a lot.
Tom
to get straight to the point, when I put my foot down in any gear except first my engine starts stumbling and shuttering like it is drowning in too much fuel. It takes a few seconds before the engine finds his breath again and starts accelerating.
I have had the car looked at and what we can see is that there is a big difference between the data from the lambda sensors and trottle possition sensors on the two banks. But we cannot find the reason for this.
Also in the adaptives file of the ECU you can see that one bank fluctuates a lot more than the other bank.
Same thing with the throttle position sensors... the one at the front fluctuates all the time while th eother is stable. Same for the lambda readouts... one stable, another not.
I do not get any sensor errors and we have tried to change the lambda sensors but nothing worked. I am not sure if this is correct but for me a sensor works or it doesn't work.
I also had the mass checked out and put in some other extra cables but this is not the issue either.
Does anybody have an idea how I can best tackle this issue?
Thanks a lot.
Tom
Hi Tom,
you said you have erratic readings with the throttle potentiometers. Is only one 'out of bounds' or both ? If it's only one you could remove the plug from it, the engine/ECU runs fine with only one of them.
Or you could do the following (with both Pots connected):
Use my MBETool, turn on ignition and deactivate the immobilizer, dont' start the car,
Then open the Scope Window and enable only both Pots. Press down the accelerator slowly and look at the graph on the screen. Do both pots show the same values ? There should be a steady increase from 15% to the max.
Now you know if both throttle pots work. If not, replace them. It's very easy to do.
you said you have erratic readings with the throttle potentiometers. Is only one 'out of bounds' or both ? If it's only one you could remove the plug from it, the engine/ECU runs fine with only one of them.
Or you could do the following (with both Pots connected):
Use my MBETool, turn on ignition and deactivate the immobilizer, dont' start the car,
Then open the Scope Window and enable only both Pots. Press down the accelerator slowly and look at the graph on the screen. Do both pots show the same values ? There should be a steady increase from 15% to the max.
Now you know if both throttle pots work. If not, replace them. It's very easy to do.
Edited by EvoOlli on Wednesday 23 April 11:51
Could be the coil pack/HT Leads/Lambdas or the throttle pots or any combination of them!. The throttle pot (position) readings should move smoothly between about 15% at idle & 95% fully open, they should move together and stay within about 1-2% of each other. Lambda's should switch rapidly. The coil trace on the diagnostics should be smooth with no spikes running at idle.
Momentary hesitation under load as you accelerate usually points to HT leads and or coil pack starting to fail.
Does it do it at all temps? Mine struggles at cold temps but absolutely fine at high temps. I have heard that replacing rubbers on throttle bodies and getting throttle body spindles rebushed can help. http://www.tvrpower.co.uk/machining/
Andy
Andy
Does it do it at all temps? Mine struggles at cold temps but absolutely fine at high temps. I have heard that replacing rubbers on throttle bodies and getting throttle body spindles rebushed can help. http://www.tvrpower.co.uk/machining/
Andy
Andy
Hi,
It seems my issues are caused by the lambda sensors. We could see when we measured the exhaust gas that the CO2 levels were much to high. At some point the lambda sensors would work and CO2 levels would drop but only for a few minutes.
We had a look at the sensors and it seems they were very badly installed. We had to use a lot of heat to get them out but as they were positioned incorrectly in the factory we could not get any new ones in....
We also put in a etra mass cable from the lambdas to the engine block.
We hope to have the car back together later today to see if it fixed.
Thanks for all the suggestions.
Tom.
It seems my issues are caused by the lambda sensors. We could see when we measured the exhaust gas that the CO2 levels were much to high. At some point the lambda sensors would work and CO2 levels would drop but only for a few minutes.
We had a look at the sensors and it seems they were very badly installed. We had to use a lot of heat to get them out but as they were positioned incorrectly in the factory we could not get any new ones in....
We also put in a etra mass cable from the lambdas to the engine block.
We hope to have the car back together later today to see if it fixed.
Thanks for all the suggestions.
Tom.
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