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Old 24th September 2011, 21:17   #16
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Default SX4 Fluctuating RPM and varying voltage

I browsed through threads on idling problems, yet this is a different experience to me, not reported before. I want to share my complete experience, so might be slightly lengthy one. excuse me for that.

I have replaced my stock air filter with K&N (no forced air induction). And a 4 channel AMP for ICE also connected. Car was given a 4th servicing at 30,000 a month before. At the time of servicing at Pratham motors, I requested for a minor dent repair on a fender/paint job. The car took 3 days to be in shape (including servicing) - and I'm too happy to take delivery at 8 PM at night with rains on full swing.
And then I have surprises in a pandora's box. The car failed to start as the battery was fully discharged. I yelled and the service engineer suggested that body workshop guys had probably switched on the headlights and hence the discharge. One of the mechanics came out with a sawp battery, and connected with my battery terminals at 90 degrees. (what a fool, doesn't realise that acid can pour out) and then cranked. Car started. I advised that they should recharge my battery and moved on with their swap battery (amaron). to my surprise, the car immediately cranked which I have never experienced with my exide (stock). After leaving the service center, I hit the main road, shifted to neutral only to see problems with idling. The car wanted to idle at 300 RPM and stalled. I always had to keep my foot on accelerator to keep it alive. I realised ECU reset is required. After reaching home, I finally did ECU reset and everything was fine (could not do so due to start and stop traffic in heavy rains).
Next day I swapped for my recharged battery and reset the ECU (battery removed for 5 mins). Battery was at 12.8 volts. The cranking experience was lousy (takes 2 secs to fire up engine compared to amaron's 1 secondish feel).
This is where the problem started.

The car wants to idle at as low RPM it can technically and gradually stabilise at around 700 RPM everytime I hit neutral/clutch/idle. Even after long driving. If I switch on A/C, the RPM keeps on bouncing, though the good thing with A/C on is that it will atleast not stall the engine.

When the car gets down to 500 RPMs, the headlights brightness and (when raining) the wiper blades speed also drops. So I suspect the alternator is not doing fine below 500 RPM. Is that fine ?
From what I gathered from other threads, I suspect one of these to be at fault:
1. Faulty O2 sensor
2. Alternator
3. Heavy load due to 4-ch AMP (I tried removing AMP fuse, not visible benefits though)
4. Bad battery
5. Throttle body (clean ?)
6. Injectors (clean ?)

#5 and #6 IMHO should have been taken care in 4th servicing.

Please advice guys. Its a nightmare getting stalled randomly.
And also dropped voltages at low RPM is scaring me.
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Old 24th September 2011, 21:24   #17
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Default Re: SX4 Fluctuating RPM and varying voltage

The car was running fine with Amron battery after the ECU reset. Now your old battery is in place, you are experiencing problem. I suggest you take the car to a separate battery showroom (preferably exide showroom) and get it checked!! Most probably a problem with the battery

Best of luck!!
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Old 24th September 2011, 21:28   #18
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Default Re: SX4 Fluctuating RPM and varying voltage

While I have experienced better cranking with Amaron, but 1-day was too short to observe the idling issues with the swap (hence keeping battery as an option). I want to replace the battery as last option (one day I have to, but also want to rule out fault with other components). And stock battery at 12.8 volts looks good to me. On the lighter side, I'm curious if all this could also be attributed due to my past style of redlining in first gear all the way till 6000 RPM. (K&N made it easier) - for coming out in start-stop traffic and overcoming absence of VVT.

Last edited by devsoftech : 24th September 2011 at 21:36.
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Old 24th September 2011, 21:43   #19
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Default Re: SX4 Fluctuating RPM and varying voltage

question is did the car had that error before giving for servicing
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Old 24th September 2011, 21:58   #20
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Default Re: SX4 Fluctuating RPM and varying voltage

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Originally Posted by SirAlec View Post
question is did the car had that error before giving for servicing
Absolutely no errors. A very valid point I overlooked, thanks for bringing this up. Except those mild RPM fluctuations when A/C is working (switches the coupling mechanism)
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Old 24th September 2011, 22:05   #21
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Default Re: SX4 Fluctuating RPM and varying voltage

Quote:
Originally Posted by devsoftech View Post
From what I gathered from other threads, I suspect one of these to be at fault:
1. Faulty O2 sensor
2. Alternator
3. Heavy load due to 4-ch AMP (I tried removing AMP fuse, not visible benefits though)
4. Bad battery
5. Throttle body (clean ?)
6. Injectors (clean ?)

#5 and #6 IMHO should have been taken care in 4th servicing.

Please advice guys. Its a nightmare getting stalled randomly.
And also dropped voltages at low RPM is scaring me.
Get the throttle body cleaned for fixing the idling issue. The idling rpm is usually governed by a stepper motor to control the butterfly valve. (This is true for Fiat, not sure about SX4). The K&N filter also might have played a role here. The minute filter oil droplets along with the fine dust particles might have clogged the throttle body. This happened to me when I renewed the K&N filter and the oil quantity was a bit high.
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Old 24th September 2011, 22:09   #22
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Default Re: SX4 Fluctuating RPM and varying voltage

i would have suspected the alternator, but since you already mentioned that Battery might be once of the suspects, i suggest to check that first, Perhaps, one of the cells is dead and might be causing a mild short circuit.

The other possibility is that alternator is the problem. The alternator has a component called the rectifier which rectifies and controls the voltage so it never goes beyond the correct level. This also might have gone. Eitherway, a good battery center should be able to tell the problem.

Even if the battery is the problem, i still suggest to check the alternator, as that might be the main cause of the battery failure in the first place.
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Old 24th September 2011, 22:28   #23
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Default Re: SX4 Fluctuating RPM and varying voltage

  1. Check battery earthing (ground) connections, and tighten if required.
  2. Check alternator output voltage, as well as max output current.
  3. Bench-charge the battery to full specific gravity (around 1.255 to 1.260) before running the car with it - if the battery will not achieve this after overnight bench charge, time to get a new battery.
Suggest you do the above before suspecting issues with the oxygen sensor / throttle body / IACV / injectors.
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Old 25th September 2011, 14:09   #24
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Default Re: SX4 Fluctuating RPM and varying voltage

Fastest diagnosis is to get the battery checked at a battery dealer. As stated by others, one of the battery cells may be bad, resulting in low current when on load.

The ECU can act up if sufficient voltage/current is not available, so first check the battery and then every thing else. If it is OK (I doubt it as replacement battery stopped the symptoms), check the alternator for proper voltage at idling. Then and only then check the other components.

In my Alto K10 I had bad FE and drop in performance, due to clogging of the air filter with water after washing - it was not evident on casual inspection as the filter looked very clean. You can check if that is so, by taking the filter out and observing the behaviour.
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Old 25th September 2011, 16:05   #25
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Default Re: SX4 Fluctuating RPM and varying voltage

Had a similar problem , similar circumstances.
http://www.team-bhp.com/forum/techni...e-problem.html (Sx4 Idle Problem)
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Old 25th September 2011, 16:13   #26
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Default Re: Sx4 Idle Problem

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Originally Posted by Born2Slow View Post
Got my car back yesterday. Its idling fine now. No clue what the problem was.Still running the old battery, as of now saved 4k,but not sure for how long.
An update. Had to change the batteries soon after as the old batteries were very week. But interesting thing was even with the old batteries running out a couple of times the idle problem never returned.
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Old 25th September 2011, 17:55   #27
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Default Re: SX4 Fluctuating RPM and varying voltage

I did go through the above thread before starting this one, but that thread didn't have similar infrastructure (K&N) and fluctuating voltage issues. Mods amay please feel free to merge with your topic. Being a new topic, I did help me gather some pointers specific to my configuration. BTW, Any one based out of bangalore, can they suggest me a good place to verify alternator/battery health. Otherwise all I know is a MASS. Plan to complete this battery/alternator verification by next week. Just curious if the stock battery is covered under 3 yrs extended warranty/30,000 kms. And If I have to go for a battery replacement which one I should go for (To support my 90/100W headlights and 4 ch AMP) ?
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Old 25th September 2011, 18:54   #28
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Default Re: SX4 Fluctuating RPM and varying voltage

My car is also fitted with K&N, 130/100 headlights and 4 channel amplifier.The problem was about 4 moths back. The MASS guys did a good job, after that I have covered 2000 kms with no problem, but had to change the batteries as I was having starting troubles. (no idle problem though)
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Old 27th September 2011, 23:39   #29
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Default Re: Sx4 Idle Problem

SX4 has an electronic throttle body that needs to be calibrated in case the battery is disconnected for some time and after reconnecting the vehicle is started without calibration.

If not done then there can be instances of erratic idling.

Calibration Procedure accodring to a Dealer WM.

Disconnect Negative Terminal for some time
Reconnect the terminal.
Switch on the ignition, do not crank the engine. Leave it for a minute. You can hear a motor work intermittently within the engine room (upon keen observation) i guess it is the throttle actuator.
Crank the engine and voila its done.
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Old 28th September 2011, 12:09   #30
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Default Re: Sx4 Idle Problem

The Sx4 breathes better with a Cotton filter instead of the original paper filter. Just make sure that you wash it down and dry according to specification it before re-installation every 5000 kms for the best performance.
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