Alto and the AirCon

[rks]

Originally Posted by Knight Rider

Okay, even I had the same problem, The Dealer told me that it was a manufacturing defect and the entire clutch assembly was changed, The problem started showing up again.

However after upgrading to K&N and headers, I do not face this issue anymore

My Santro developed a clutch shudder at around 35000 kms. The shuddering only happened after driving in start/stop traffic in city. After driving a bit on the highway or on clear roads, the shudder vanished. After I switched to 5" alloy wheels (from 4" stock steel rims), the pickup of the car increased noticeably and the clutch shudder has more or less vanished. After a while it resurfaced but again vanished when I found and fixed a slow puncture in my front right tyre (which also caused the mileage to drop substantially, by about 1 km/lit). I am running stock-size 155/70 R13 tubeless tyres.

I am convinced it is a fuel injection problem which could possibly also be solved by reprogramming the ECU. After the latest service (with the slow puncture still on) the problem reduced because the fuel injectors were cleaned. I also suggest using premium fuel (I use Speed).

[mclaren1885]

Rks, how can your clutch shudder disappear with change in rims? Unless you are indicating the loss in weight. While you clearly mentioned that it could be a fuel injection problem. Somehow I dont see these two topics relating each other.

Vidyut, I am sure you have read about DFCO on the other thread? Could the jerk be because of fuel being injected after the cut-off duration and hence the judder? I remember priyank putting up some such post from a honda forum. Actually found the link. http://www.team-bhp.com/forum/440366-post97.html (How to get 15+kmpl from a baleno ? Read on !!!!)

What RPM does this judder appear at? If its while accelerating it could also be because of a dirty fuel filter or fuel pump.

[rks]

Originally Posted by mclaren1885

Rks, how can your clutch shudder disappear with change in rims? Unless you are indicating the loss in weight. While you clearly mentioned that it could be a fuel injection problem. Somehow I dont see these two topics relating each other.

There is a slight, but noticeable increase in pickup after changing to lighter, wider alloys. This seems to have solved the problem. Knight Rider's problem also seems to have gotten solved after he changed to K&N filter, which would again have increased the pickup. My guess is that the ECU is not able to stabilize its output under the old setup; it is asking for more power. I have no idea why this happens, though.

If you google "clutch shudder" ecu you will get plenty of hits and maybe the solution to the problem. Many people seem to get clutch shudder in the mornings, when the engine is cold. Again the lack of power seems to cause the problem.

[esteem_lover]

Originally Posted by rks

After I switched to 5" alloy wheels (from 4" stock steel rims), the pickup of the car increased noticeably

I am running stock-size 155/70 R13 tubeless tyres.

Your wheel size is 5" or 13" ? be specific.
what was the weight of your 4" steel rims & what is the weight of your present 5" alloy rims ? would be interesting to see how much weight you have shed for that noticeable pickup.

[rks]

Originally Posted by esteem_lover

Your wheel size is 5" or 13" ? be specific.
what was the weight of your 4" steel rims & what is the weight of your present 5" alloy rims ? would be interesting to see how much weight you have shed for that noticeable pickup.

Sorry, I meant 5J alloys, as opposed to 4J stock steel rims; both are 13" rims. I believe the increase in pickup happens due to two reasons; lighter alloys plus increased contact patch due to wider rims (with same stock-size tyres). The increased pickup is noticeable; I can now drive at ~5 kmph (on level road with AC on) in second gear, whereas the car used to stall at less than 10 kmph earlier. Similarly for third gear I can now go down to ~20 kmph whereas earlier the car stalled at 25-30 kmph.

[mclaren1885]

I wouldn't attribute it to the lack of power somehow. Infact, I have the same issue on my baleno. My clutch is almost fried up, need to check the fuel filter and fuel pump too. Atleast my car doesn't suffer from lack of power, infact it has too much. Or the jerk could be completely fuel related. Because this judder happens most often when tank is less than quarter or you get bad fuel.

[esteem_lover]

Have you checked your plug chords etc. ?

[vid6639]

Originally Posted by mclaren1885

Vidyut, I am sure you have read about DFCO on the other thread? Could the jerk be because of fuel being injected after the cut-off duration and hence the judder? I remember priyank putting up some such post from a honda forum. Actually found the link. http://www.team-bhp.com/forum/440366-post97.html (How to get 15+kmpl from a baleno ? Read on !!!!)

What RPM does this judder appear at? If its while accelerating it could also be because of a dirty fuel filter or fuel pump.

Yup I read the DFCO and also thought it could be because of that. The cut off when you back off the throttle is very sharp which jerks the car.

Also when you back off then again accelerate there is a jerk especially when you do it really fast in stop go traffic.

The jerk when the cutoff appears is a forward jerk so it could be because the fuel is getting injected after cutoff.

So what's the difference between DFCO and IAC valve. their functions seems similar.

[mclaren1885]

Originally Posted by vid6639

So what's the difference between DFCO and IAC valve. their functions seems similar.

No their functions are different. While the DFCO cuts off fuel at no throttle conditions and injects fuel at a particular RPM (say at idle or just near to idle) after the cut-off time, the IAC valve helps is maintaining a constant idle (say 750 in case of idle and 1000 incase of idle in gear). The basic function of the IAC valve is to prevent the car from going off at no throttle position.

However a deeper dig into this jerking problem threw up another possibility. Ignition problem, due to spark plug wire arcing to the engine ground or a faulty spark plug setting. This diagnosis only gets worse. My baleno too jerks a bit too much in 1st and 2nd gears only. Sounded more like a fuel pump problem, though will check for the ignition timing thing and revert back.

[vid6639]

Originally Posted by mclaren1885

No their functions are different. While the DFCO cuts off fuel at no throttle conditions and injects fuel at a particular RPM (say at idle or just near to idle) after the cut-off time, the IAC valve helps is maintaining a constant idle (say 750 in case of idle and 1000 incase of idle in gear). The basic function of the IAC valve is to prevent the car from going off at no throttle position.

Okay so the jerking in my case is not near idle or at idle. it's more higher, I dont know the rpm as theres no tacho.

So the IAC valve maintains the idle whereas the DFCO cuts the fuel at no throttle. So once you back off the gas pedal the DFCO kicks in by cutting the fuel but the IAC valve makes sure that this fuel cut off does not stall the engine and again sparks which I guess is causing the jerk?

Is that right?

[rks]

In my case the clutch shudder used to start only while driving in heavy stop/go traffic and when releasing the clutch and accelerating in first/reverse gears (I do not recollect any shuddering in second gear). The shuddering used to be quite heavy at times; once the clutch release was complete, it stopped. Now I have done almost 50 K on the OEM clutch and there is no problem at all after switching to 5J alloys at 44K.

[rks]

I searched the web and found an interesting thread on clutch shudder problem in Subaru:

Car Talk Bulletin Boards: What's up with Subaru?

Quoting the first post (on page 2 of the thread, by GKlein):

I've posted our 2 replacement clutches on warranty before.

Our Forester warranty expired half a year ago and we were beginning to experience the clutch shudder problem again. We pointed this out to our dealer during a routine service and they reprogrammed the ECU (computer) at no cost. The clutch shudder disappeared!

All I can think of is that the engine somehow now runs smoother as a result of the adjustments to timing, mixture, etc.

We'll wait to see how long this lasts.

Of course this is only one of many possible reasons for clutch shudder and may not work in other situations.

[mail4ajo]

Updates on this issue...
Popular service center agreed for a ECU swap to see if the problem exists. They are continously saying there is no problem with the car. But I know it exists. My brother and friends and many others on the forum knows.

Its raining in Chennai now and the problems seems to be occuring less frequently. Usually very frequent when the cars gets heated up.

Will get the new ECU on monday. Last chance to see if this can be rectified. Will live with it if it still persists. Have spend so much time and effort on it. Any other updates, Vid, Technocrat, akroy etc?

[vid6639]

Yup same finding the problem is lesser on cooler days and early in the morning but when it's really hot and the engine also is hot it is much more.

Have not got time to get the ECU swapped.

[Technocrat]

Like I said before, after putting the K&N replacement filter the jerks have subsided a lot.