Difficulty Starting Engine and Uneven Idling

[Plim72]

  On 11/11/2010 at 11:40 PM, Siewss said:

Hi, my car's on e-throttle, and that's one of the main reason cited for going the non-repair route. I was told it's senstive and cleaning the valve may have dire consequences.

 

Is resetting the throttle a mechanical adjustment? The AD mech actually reset the ECU, which obviously is the incorrect solution.

 

I'll call them up today regarding throttle reset - thanks for the tip.

 

 

throttle reset? something new to me too. i thought all along irregardless of cable or e-thottle, they are all controlled by ECU or some say PCM. i never have a ethrottle car before so maybe there is another ecu just for it?

 

from what i am able to see by logging into my car ecu, there is a complex table with multiple I/O just for idling..there are too many factors that can affect it..injector duty cycle, engine temp, ambient temp, crank sensor, MAF/MAP, O2 sensor, icv etc..

But generally, as the engine temp gets warmed up, it will switches over to closed loop. That is where your problem lies...feedback and demand are contantly changing or out of limits, making the ecu confused, and thus idling unstable. If AD can log into the car ecu, it would be so much easier...

 

Mazda6 MPS is one smooth operator..one of my shortlist at that time..

 

better do correction here.. bait for flaming..cable ICV control by ecu, throttle plate by human haha

 

Edited November 12, 2010 by Plim72

[Yeobh]

The problem is when the engine is hot, so it is either the fuel system as KB27 mentioned suffer heat soak or the ignition coil is about to fail. The other problem can be due to fracture carbon fibre in one of the spark plug cable , or wrong spark plug being used.

 

Never hear of resetting throttle, hope this is new info and not BS

[Siewss]

  On 11/12/2010 at 12:17 AM, Kb27 said:

I didn't follow all your posts, but you seemed to have a problem with starting engine after a heat soak.

That would point to a fuel problem. Perhaps a fuel line is run too close to the hot exhaust or something.

 

http://autos.yahoo.com/maintain/repairqa/t.../ques093_4.html

 

Good tip. I'll check with the AD if they actually had that checked.

 

Anyway, I've arranged to send the car in next week to for the throttlebody and ICV cleaning.

 

[Siewss]

  On 11/12/2010 at 8:24 AM, Plim72 said:

throttle reset? something new to me too. i thought all along irregardless of cable or e-thottle, they are all controlled by ECU or some say PCM. i never have a ethrottle car before so maybe there is another ecu just for it?

 

from what i am able to see by logging into my car ecu, there is a complex table with multiple I/O just for idling..there are too many factors that can affect it..injector duty cycle, engine temp, ambient temp, crank sensor, MAF/MAP, O2 sensor, icv etc..

But generally, as the engine temp gets warmed up, it will switches over to closed loop. That is where your problem lies...feedback and demand are contantly changing or out of limits, making the ecu confused, and thus idling unstable. If AD can log into the car ecu, it would be so much easier...

 

Mazda6 MPS is one smooth operator..one of my shortlist at that time..

 

better do correction here.. bait for flaming..cable ICV control by ecu, throttle plate by human haha

 

I learn something new everyday. I googled for answer related to starting difficulty and rough idling and there seemed no end to the possibilities....Looks like the problem will have to be identified through process elimination.

 

[Siewss]

  On 11/12/2010 at 11:02 AM, Yeobh said:

The problem is when the engine is hot, so it is either the fuel system as KB27 mentioned suffer heat soak or the ignition coil is about to fail. The other problem can be due to fracture carbon fibre in one of the spark plug cable , or wrong spark plug being used.

 

Never hear of resetting throttle, hope this is new info and not BS

 

Ignition coil, hmmm... one brother offered to spray my coils because it seemed to have solved his problem. I'll need to be able to fix the time with him.

 

I checked with the AD WS about resetting throttle - they told me they did, and that's through the ECU. It sure didn't solve the problem.

 

[Pisces69]

  On 11/11/2010 at 11:27 PM, Siewss said:

On the contrary, the e-auto choke (controlled by ECU right?) works well. Cold start is less of an issue that warm start. Usually early in the morning, the engine will rev straight to 2krpm once fired up, and drops to ~ 1krpm after a tens of seconds. But my engine tends to remain very hot even after a long while after turning off, so if I try to start 2 hours after I last turn off, I'll encounter the long cranking problem. However, I've noticed that even cold start these past 2 days is starting to take longer than usual

 

I'm fine with the idea changing parts rather than repair, but that's provided the parts are available. But I also expect that in the unfavorable position of part unavailability, there should be a better alternative than wait for parts.

 

 

Hard to start when hot usually were on carb cars where there was petrol vopourised in carb due to heat n need to 'prime' carb b4 it wud hv enough fuel to start. Now injector engines i seldom hear this problem.

 

Maybe u can check yr sparking. Maybe low spark due to damaged plug cables, plug too small or big gap or wrong plugs even. Or yr battery old n low current during starting. Might also b sensors which giving wrong readings so yr air/fuel mix is wrong or timing setting wrong.

 

Looks like u need to check 1 by 1 to trouble-shoot problem. If u hv a good mech wil b easier cos he has all necessary tools n equip n wil b easier to check.

[Pisces69]

  On 11/11/2010 at 11:31 PM, Siewss said:

Yes. Reliable WS + honest mechanics are few and far between. So if you have found one, you've discovered a gem.

 

Ya i treasure my mech. But i dont let him know cos then i spoil him n he become ya ya wh me.

 

I just dread e day he retires cos he already >50 years old.

 

[Sky61]

a few things - ignition coil pack, ignition coil harness, spark plugs, spray contact cleaner on air flow meter(if ur car is using it), clean idling valve, 02 sensor replacement

[Minikong]

  On 11/12/2010 at 11:02 AM, Yeobh said:

The problem is when the engine is hot, so it is either the fuel system as KB27 mentioned suffer heat soak or the ignition coil is about to fail. The other problem can be due to fracture carbon fibre in one of the spark plug cable , or wrong spark plug being used.

 

Never hear of resetting throttle, hope this is new info and not BS

 

 

i just reset the throttle, and it give me 1 damn nice sweet start up, after i park my car for like 6 hourr...

let me see these few day and see how it go haha

[Plim72]

i have dust off one of my auto books and happened to flip to a page regarding ethrottle. i then realised e-throttle or ETC as they are called is either pedal follower or torque based, for mazda6...what that means is that they have no ICV to speak of. all the finer controls required during idling is done by alternating the thottle plate only. Therefore all the talk about ICV getting clogged is not valid in this case..

 

on a side note, ETC is hell of a control system on its own..most importantly, imagine that they have to safeguard the events of throttle plate getting stuck and stays wide open even through user is already off the thottle!!

[Plim72]

  On 11/14/2010 at 5:49 AM, Plim72 said:

i have dust off one of my auto books and happened to flip to a page regarding ethrottle. i then realised e-throttle or ETC as they are called is either pedal follower or torque based, for mazda6...what that means is that they have no ICV to speak of. all the finer controls required during idling is done by alternating the thottle plate only. Therefore all the talk about ICV getting clogged is not valid in this case..

 

on a side note, ETC is hell of a control system on its own..most importantly, imagine that they have to safeguard the events of throttle plate getting stuck and stays wide open even through user is already off the thottle!!

 

Ignore my nonsense about no icv. I am too far forward looking for my own good haha

[Siewss]

  On 11/13/2010 at 1:31 PM, Pisces69 said:

Hard to start when hot usually were on carb cars where there was petrol vopourised in carb due to heat n need to 'prime' carb b4 it wud hv enough fuel to start. Now injector engines i seldom hear this problem.

 

Maybe u can check yr sparking. Maybe low spark due to damaged plug cables, plug too small or big gap or wrong plugs even. Or yr battery old n low current during starting. Might also b sensors which giving wrong readings so yr air/fuel mix is wrong or timing setting wrong.

 

Looks like u need to check 1 by 1 to trouble-shoot problem. If u hv a good mech wil b easier cos he has all necessary tools n equip n wil b easier to check.

 

The AD service consultant said they have checked everything that needs to be checked - just nothing found. But I really don't think it's my spark. I just go back from KL last night - other than starting difficulty and rough idling, the car cruises beautifully. Sensor could be a possibility - just thought it'll show up as CEL....

 

[Siewss]

  On 11/13/2010 at 1:36 PM, Pisces69 said:

Ya i treasure my mech. But i dont let him know cos then i spoil him n he become ya ya wh me.

 

I just dread e day he retires cos he already >50 years old.

 

Before he finally hangs up his overall, ask him to recommend you to another trustworthy mech.

 

[Siewss]

  On 11/13/2010 at 1:57 PM, Sky61 said:

a few things - ignition coil pack, ignition coil harness, spark plugs, spray contact cleaner on air flow meter(if ur car is using it), clean idling valve, 02 sensor replacement

 

You know what, these are some of the possible causes highlighted when I googled. I think I'll compile a list and go back to the AD WS and check with the service consultant what's been checked and tick them off the list.

 

[Siewss]

  On 11/13/2010 at 2:49 PM, Minikong said:

i just reset the throttle, and it give me 1 damn nice sweet start up, after i park my car for like 6 hourr...

let me see these few day and see how it go haha

 

How is it so far? Hope it's a once-and-for-all solution.

 

Did you do the reset through ECU?

 

[Siewss]

  On 11/14/2010 at 6:26 AM, Plim72 said:

Ignore my nonsense about no icv. I am too far forward looking for my own good haha

 

Actually what you've just told me is very similar to the service consultant's explanation. He mentioned that the butterfly valve is controlled by a motor that's actuated by electrical impulses too small to be measured.

 

That's the reason why he recommended changing the whole throttle body.

 

 

 

[Pisces69]

  On 11/16/2010 at 3:15 PM, Siewss said:

Before he finally hangs up his overall, ask him to recommend you to another trustworthy mech.

 

 

I dont think its so simple. He might say god but e mech see me might want to me?

 

 

Lets see what happens when he decides to retire. Maybe by tat time i not driving anymore.

[Minikong]

  On 11/16/2010 at 3:21 PM, Siewss said:

How is it so far? Hope it's a once-and-for-all solution.

 

Did you do the reset through ECU?

 

 

yes but the problem is back again, then i change my ignition coil, then the problem is much better, and i jsut changed to jcw racing spark plug today, the car is now much smoother, but the start up is fine for now, but like under powercause will drop to 500 rpm then back again. but everyrhing is very fine