[namit]

Hi,

My Aveo is giving missing problems - at times engine stops when on idle as the RPM needle drops to .250 and at times it functions normaly.

At times this is with A/c and at times without A/c.

Service centre guys have checked everything from fuel pump and throttle body cleaning also.

Now they are saying that they need to change the Throttle body, which is 9000/- bucks.

Firstly need inputs on what could be the possibilities of this issue and if do you think changing the throttle body will yield results.

Cheers.

[v&v]

Does the check engine light glow or any error code May be even TPS is faulty (Throttle position sensor)?

Also do check for
Fuel filter : When was it last changed. Check for clogging.
and
Coils & Spark plug : Some time this too can be a suspect too.

[namit]

Originally Posted by v&v

Does the check engine light glow or any error code May be even TPS is faulty (Throttle position sensor)?

Also do check for
Fuel filter : When was it last changed. Check for clogging.
and
Coils & Spark plug : Some time this too can be a suspect too.

NO engine light and the fuel filter has been checked.
Spark plugs checked but which coil you referring to ?

I agree, TPS can be faulty but these service centre guys told that its better to change the entire throttle body.

[lancer_rit]

Originally Posted by namit

NO engine light and the fuel filter has been checked.
Spark plugs checked but which coil you referring to ?

I agree, TPS can be faulty but these service centre guys told that its better to change the entire throttle body.

Why ? I think it may be to do with the TPS. First Change the TPS, and then drive it around, and afterwards you can take a call ?
If there is any accidental scrapped Aveo in the workshop, you could ask them to replace the TPS from that car and check it out.

[v&v]

Originally Posted by namit

NO engine light and the fuel filter has been checked.
Spark plugs checked but which coil you referring to ?

I agree, TPS can be faulty but these service centre guys told that its better to change the entire throttle body.

Coil i was referring to ignition coil. I think TPS should be available separately and usually cost 20 to 25% of TB. Even an O2 sensor too can trigger these symptoms mentioned.

[namit]

Originally Posted by lancer_rit

Why ? I think it may be to do with the TPS. First Change the TPS, and then drive it around, and afterwards you can take a call ?
If there is any accidental scrapped Aveo in the workshop, you could ask them to replace the TPS from that car and check it out.

Actually, TPS is available separately but the Chevy Authorised service centre guys are saying that its recommended to change the entire throttle body as fitting the sensor in the throttle body doesnt always fit properly, resulting in issues again.

Even i am surprised that these Authorised guys are saying so bcoz if Chevy is providing TPS as an additional part so these guys should be able to fix it in the TB.

And this is Autovikas, which is supposed to be the best Chevy service outlet.

Dont know what to do ...........

[lancer_rit]

Originally Posted by namit

Actually, TPS is available separately but the Chevy Authorised service centre guys are saying that its recommended to change the entire throttle body as fitting the sensor in the throttle body doesnt always fit properly, resulting in issues again.

Even i am surprised that these Authorised guys are saying so bcoz if Chevy is providing TPS as an additional part so these guys should be able to fix it in the TB.

And this is Autovikas, which is supposed to be the best Chevy service outlet.

Dont know what to do ...........

Well, I haven't seen the engine bay for Aveo. But for Lancer, the TPS is a separate unit which is connected to the TB by tubes IIRC (will check again). Maybe, you should take a look in your engine bay and/or consult a mechanic. Also, check with another Chevy workshop, maybe ? I know that for Lancer, TPS can be (and has been changed) independently.

[namit]

Thanks V&V and Lancer_rit ......

actually they have TPS as a separate component but reluctant to change it and insiting on TB change as they say that puting the TPS is a difficuilt task and for best results i should go for TB change.

[vigsom]

Originally Posted by namit

Thanks V&V and Lancer_rit ......

actually they have TPS as a separate component but reluctant to change it and insiting on TB change as they say that puting the TPS is a difficuilt task and for best results i should go for TB change.

nothing is difficult ; they just want to take the easy route.

Please consult a reliable and honest independent in Delhi - even an adjustment in your existing tps should do the trick.

are you able to hear some hissing noise somewhere near the throttle body?If yes,there is a small hose which must have come loose/cut - just check that once

[dhanushs]

btw, doesn't it show up on an OBD if a TPS is faulty? I would suggest you do that 1st and then go for the replacement.

[IndigoXLGrandDi]

@namit,

Get the Alternator Belt checked for Wear and Tear.

The same problem was present in our Indigo XL Grand Dicor.

The Idle Rpm used to fall to 450-500 rpm occasionally irrespective of Engine Temperature. Even when the vehicle is at speed of 60-80kph.
Also when the rpm falls to 500 rpm, 1) Only one horn blows 2) The Headlight goes dim.

The Alternator Belt has been replaced.
But I have not got the car back since the injectors are being refitted. The Injectors have to be removed to replace the Timing Belt. Thats another story.

But in your case, I would recommend to get the Alternator Belt checked.

[theMAG]

Before changing a throttle body, a very good idea is to get it cleaned manually- and specifically not by sprays. You'd be surprised at the amount of grime that comes out when the TB is cleaned manually - and makes a tangible difference to the performance afterwards.

[ritedhawan]

I agree about the above opinion. Get the throttle body cleaned manually, it should make a lot of difference--it made a lot of difference in my car, even though the problem still remains, but surely mitigated. In my GM car, I used to face this persistant issue , but after getting the throttle body manually cleaned the problem got restricted in my car to the extent of being prevalent only in cold-start. Moreover, had the TPS gone bad , the yellow light should glow.

[namit]

Good to see so many helpfull answers.

Now, my analysis :-
- throttle body was already cleaned prior to opening this thread, but in vain
- Finally got the throttle body changed but now the problem of RPM dropping is persistent only in the first start of the day and that too the car does not switch off, rather stabilizes itself and the car stays ON

Just to share another observation - i have this probelm of my Santro jerking intermittently when driving as if its running only on 3 cylinders (as if 1 spark plug faulty), but this problem was not diagnosed by the Scanner until this problem occurred and immediately i took my car to test on scanner - this turned out to loose injector wiring.

Hence i believe that only when the problem is there, scanning it then will show the errors otherwise NOT.

Back to AVEO issue - i believe the TPS to be fine as that would have shown in the scan but that was clean.

Now what should i do with this pattern of RPM dipping and then stabilizing only in the first start of the day (consistently).

Cheers.

[ritedhawan]

namit: the problem of RPM dropping is persistent only in the first start of the day and that too the car does not switch off, rather stabilizes itself and the car stays ON

Exactly the same thing in my GM car, as I talked about in my last post, that even after cleaning the throttle body manually, the problem has not been completly rectified, but mitigated. For first 3 min , I 2 get this RPM dropping issue, but since the car engine doesn't stop so as to re-crank it. I am willing to look the other way since the issue remains for 3 min. maximum and more importantly the issue vanishes once the engine reaches its optimum temperature. But, surely I would like to know from fellow T-Bhpians: whats seems to be the real cause?