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Old 27th November 2012, 06:52   #16
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Default re: Random power drop in Hyundai Elantra CRDi

rocky080,

I think it could be a dirty/ blocked fuel filter OR the crank sensor on it's way out. If EGR had been a cause, it would have set codes. These must be the first indications of the crank sensor going. At 78000 kms on the ODO, I'd change that. It could land you on the road-side. Also, as some have suggested, if you want to reset the ECU properly (100% sure), you need to keep the battery disconnected for 15 mins & dab the brakes a few times, to remove any residual power left in the ECU's internal capacitors.
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Old 27th November 2012, 10:40   #17
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Default re: Random power drop in Hyundai Elantra CRDi

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Originally Posted by SS-Traveller View Post
Not choked - there may be a diesel particulate sensor, which cuts fuel at higher rpm because the ECU thinks the car is polluting more than normal. IIRC the sensor is present in BS3/Euro-III vehicles, not in Euro-II ones.

Probably does - which is why the problem probably goes away after a high-speed high-rpm run.
LOL - ask the HyundaiASS and TATA-A$$ guys - they all do it! Won't flood the engine if the hose is applied for just a few seconds. Yes, the engine does start, and pours out a very black solution! Keep your distance from it, don't get it on your clothes, or the best dry-cleaners won't be able to do much later on!
But doing this procedure will only clean the Mufflers(Back box) right? I thought the catalytic converter was more near the headers(How do i clean this).

Quote:
Originally Posted by mustysekhon View Post
Check for turbo failure as well.
Turbo failure is out of the question as when the car is running fine it easily can do almost double century speeds.

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Originally Posted by mayankk View Post
For how long did you disconnect the battery?
15 minutes, and a couple of dabs on brakes seems ideal. I've occasionally not got a reset with quick jobs.
I disconnected the cable for more than 15 mins but had no idea i had to dab the brakes a couple of times.

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rocky080,

I think it could be a dirty/ blocked fuel filter OR the crank sensor on it's way out. If EGR had been a cause, it would have set codes. These must be the first indications of the crank sensor going. At 78000 kms on the ODO, I'd change that. It could land you on the road-side. Also, as some have suggested, if you want to reset the ECU properly (100% sure), you need to keep the battery disconnected for 15 mins & dab the brakes a few times, to remove any residual power left in the ECU's internal capacitors.
Fuel filter is brand new, it was changed very recently. I had this issue before the replacement a couple of times and after the replacement once thus far. I will get the sensor checked as well. But if the crank position sensor were to malfunction wouldn't this still throw up an error code, as incorrect info from this sensor can cause serious misfiring of the engine due to fueling issue(car jerking).

Dabbing the brakes a couple of times is new to me, will follow from now on when i reset the ECU. It had always reset before on disconnecting the cable for more than 15 mins.
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Old 27th November 2012, 10:54   #18
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Default re: Random power drop in Hyundai Elantra CRDi

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I thought the catalytic converter was more near the headers(How do i clean this).

But if the crank position sensor were to malfunction wouldn't this still throw up an error code, as incorrect info from this sensor can cause serious misfiring of the engine due to fueling issue(car jerking).
The cat con is after the turbo. You can only clean it indirectly if you get a de-carb done (preferably by a Hyundai A.S.S.). You should get one done if you have'nt already.

The heat of the engine (over long term) tends to melt the wires of the crank sensor. If you don't want to replace it, atleat get it removed & have a good visual examination. If the rubber insulation on the sensor/ wire is even slightly worn, replace immediately.

Also, since your car has been recently serviced, maybe some sensor wire or other electrical wire (even the battery terminals) might be loose. Get that checked too.
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Old 27th November 2012, 11:46   #19
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Default re: Random power drop in Hyundai Elantra CRDi

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The cat con is after the turbo. You can only clean it indirectly if you get a de-carb done (preferably by a Hyundai A.S.S.). You should get one done if you have'nt already.

The heat of the engine (over long term) tends to melt the wires of the crank sensor. If you don't want to replace it, atleat get it removed & have a good visual examination. If the rubber insulation on the sensor/ wire is even slightly worn, replace immediately.

Also, since your car has been recently serviced, maybe some sensor wire or other electrical wire (even the battery terminals) might be loose. Get that checked too.
I just checked with my SA about the De-carb of exhaust system and he says that he can only get the cylinders and other associated parts de-carbonised and not the exhaust system as such, he says if catalytic converter is blocked it will have to be replaced and no way of repairing/cleaning it. Also, about the sensor he says, if this was an issue the car would have starting trouble which i do not have. I am totally stumped.

Regards,
Rocky
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Old 27th November 2012, 11:53   #20
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Default re: Random power drop in Hyundai Elantra CRDi

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Originally Posted by rocky080 View Post
But doing this procedure will only clean the Mufflers(Back box) right? I thought the catalytic converter was more near the headers(How do i clean this).
True. Need to remove the exhaust system from the manifold (easy with the car up on a lift). Cleaning is still with high pressure water flush.
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Old 27th November 2012, 16:16   #21
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Default Re: Random power drop in Hyundai Elantra CRDi

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Originally Posted by rocky080 View Post
My SA thinks it might be any issue with the fuel temp sensor based on my feedback any thoughts on this?
Whats a Fuel temp (temperature?) sensor, or did you mean just the normal temperature sensor?

Usually when the temperature sensors go bad and engine is overheated, it will cut the AC off, and one can feel the engine heat on the legs through the Accelerator/Brake/Clutch paddle holes.

I also do not think its the fuel pump problem, lack of fuel flow will result in jerks, when accelerator is pressed, but will not limit the engine revving.

Its got to be electronics (sensor, or ECU related) that's playing tricks, but in this case too there should have been some error codes.
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Old 27th November 2012, 19:41   #22
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Default Re: Random power drop in Hyundai Elantra CRDi

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Originally Posted by mayankjha1806 View Post
Whats a Fuel temp (temperature?) sensor, or did you mean just the normal temperature sensor?

Usually when the temperature sensors go bad and engine is overheated, it will cut the AC off, and one can feel the engine heat on the legs through the Accelerator/Brake/Clutch paddle holes.

I also do not think its the fuel pump problem, lack of fuel flow will result in jerks, when accelerator is pressed, but will not limit the engine revving.

Its got to be electronics (sensor, or ECU related) that's playing tricks, but in this case too there should have been some error codes.
I was talking about the Fuel temperature sensor and not the cooling system temperature. I guess turbo diesels have this sensor.

Hopefully i am able to track this issue down soon before i do some real damage to the engine. Thanks for all the suggestion guys, will try getting the exhaust system cleaned and then check each sensor one by one. Any other suggestion/advice in the meanwhile is most welcome.

Regards,
Rocky
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Old 28th November 2012, 10:38   #23
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Default Re: Random power drop in Hyundai Elantra CRDi

Quote:
Originally Posted by rocky080 View Post
Any other suggestion/advice in the meanwhile is most welcome.
Are you still running you car with petes box?
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Old 28th November 2012, 10:52   #24
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Default Re: Random power drop in Hyundai Elantra CRDi

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Are you still running you car with petes box?
No, I only run it for track days now.
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Old 28th November 2012, 19:32   #25
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Default Re: Random power drop in Hyundai Elantra CRDi

I have used NaOH in the past, for cleaning out my Bullet's silencers & the old Maruti 800 exhaust system (whole silencer assembly) on more than one occasion. Had read up this technique on some online forum quite many years back, however, I am not sure if this would be suitable for modern day exhaust systems with their many sensors & electronic components.
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Old 28th November 2012, 19:44   #26
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Default Re: Random power drop in Hyundai Elantra CRDi

Quote:
Originally Posted by rocky080 View Post
Hey guys,

Off late i have been having a very weird problem with my Elantra of random power loss.

This is what happened on my last trip. I left home at 6.30 AM and traveled about 35 KM and stopped for breakfast for about 30 mins, then when i started again everything was fine for another 5kms, then there was a sudden drop in the cars acceleration and then i noticed that the car would just not go above 2700 rpm no matter how hard i press down on the accelerator in any gear. So i stopped over and shifted to neutral but then again same thing the car would just not go above 2700 rpm. There was no engine check light or anything. i even checked the temp it was just below half mark(its usual position). I called my SA in the service station and he told me remove the battery cable and re-connect it and try again. i did that but still no luck. So he told me to bring it to the service station when i was free and that it was safe to continue as the temp was normal and engine check light was not on. I went on with my trip with the rpm not going above 2700. The car was still able to do some decent three digit speeds even in this condition. Then i reached my destination which was another 105 kms away and turned the car off for about 1 hour or so then started it again and everything in the car was back to normal and i drove back the entire 140kms without any problem. I went to the service station and tried to get it checked but there were no error codes recorded and the car is running fine now. My SA advised me to get the car in again when the issue occurs without switching off the car.

This is the 4th time i am facing this issue in the last 5 months and i have not been able to track the issue. Any help in this regard is highly appreciated.

Below are the details of the car.

CAR: Hyundai Elantra CRDI
Model year: 2006
ODO: 78000
OIL: Fully synthetic Shell Helix engine oil being used
Regularly serviced at Hyundai Authorised service station.



MODS: Did not find any thread with this specific power loss issue for CRDI Elantra. Please merge with other thread if it already exists.

Regards,
Rocky


Is this happening only when you run the car about 30 40 kms or it happens on short trips also ?

I am asking this because the problem should be with the ventilation of your fuel tank. The fuel filling cap has a small vent hole which can get clogged with usage. If this happens then your car will run for a few kms without any issue. After some running the suction pressure starts to build up. If this pressure is not released then the fuel pump is unable to pump the fuel to the high pressure pump. When you stop for half an hour or one hour in between the pressure is again reduced back to normal and your vehicle will run normally untill the pressure builds up again.

So I advise you to first see the vent cap. Just observe when you open the fuel cap after long run you hear whoosh kind of sound. This indicates that the vent cap is clogged.

You can also keep the fuel cap a bit loose and try running your vehicle.

You have also mentioned that you are getting carbon impression on your wall. This indicates that your exhaust system is getting choked. You have to get the CAT along with other mufflers cleaned. But I dont think this is the cause of your problem as if this would have a issue you should have felt the power loss at all times.

So I think the fuel tank cap should solve your issue of temperory power loss
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Old 28th November 2012, 19:56   #27
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Default Re: Random power drop in Hyundai Elantra CRDi

Quote:
Originally Posted by CRDIsamir View Post
Is this happening only when you run the car about 30 40 kms or it happens on short trips also ?

I am asking this because the problem should be with the ventilation of your fuel tank. The fuel filling cap has a small vent hole which can get clogged with usage. If this happens then your car will run for a few kms without any issue. After some running the suction pressure starts to build up. If this pressure is not released then the fuel pump is unable to pump the fuel to the high pressure pump. When you stop for half an hour or one hour in between the pressure is again reduced back to normal and your vehicle will run normally untill the pressure builds up again.

So I think the fuel tank cap should solve your issue of temperory power loss
This has happened on short trips(5kms) as well, the scenario i gave was of the most recent one.
If the fuel tank vent hole is the issue wouldn't the car jerk and stall due to fuel starvation rather than limiting the rpm to 2700.

Regards,
Rocky
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Old 28th November 2012, 20:01   #28
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Default Re: Random power drop in Hyundai Elantra CRDi

Quote:
Originally Posted by rocky080 View Post
This has happened on short trips(5kms) as well, the scenario i gave was of the most recent one.
If the fuel tank vent hole is the issue wouldn't the car jerk and stall due to fuel starvation rather than limiting the rpm to 2700.

Regards,
Rocky
You are quite right. But there is no harm in trying to keep the fuel tank cap a bit loose and going for a drive.

The other probable cause is injectors giving excess back leakage due to which the pump is unable to maintain the required rail pressure.

But I still insist you on trying with the fuel tank cap.

Regards

Samir
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Old 28th November 2012, 20:11   #29
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Default Re: Random power drop in Hyundai Elantra CRDi

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Originally Posted by CRDIsamir View Post
You are quite right. But there is no harm in trying to keep the fuel tank cap a bit loose and going for a drive.

The other probable cause is injectors giving excess back leakage due to which the pump is unable to maintain the required rail pressure.

But I still insist you on trying with the fuel tank cap.

Regards

Samir
Thanks will get this checked. My first priority is the exhaust which i will get done over this weekend, then the sensors as i some how feel this is what is leading the ECU to restrict the rpm to precisely 2700. It feels like someone has installed a speed governor on my car.

Regards,
Rocky
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Old 28th November 2012, 20:17   #30
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Default Re: Random power drop in Hyundai Elantra CRDi

Just go through my earlier posts regarding the CAT CON which may be useful to you.

Heres the link

http://www.team-bhp.com/forum/techni...ml#post2926460
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