[sparkguy]

Originally Posted by 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.

I can vouch for it. I cleaned throttle body yesterday and problem of engine stop at low RPM vanished like anything.

Thanks theMAG and everyone for suggestions

[Jeroen]

Originally Posted by namit

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.

Couple of note; Engine Check Lights and codes showing up are two different things. Not all codes trigger an Engine Check Light. Also, depending on your ECU, but for many parameters monitored it will store the fault. So even for intermediate problems checking the codes is always a good idea. It take a lot of the guessing, trial and error and opinions aways. It is the easiest ways to get facts.

The reason your mechanic doesn't want to change out TPS by itself, might have some merits in it. The sensor and the Throttle body need to be positioned if not calibrated very precisely for optimum performance. Many manufacturers don't sell the sensors separately for that reason. (E.g. Jaguar). It doesn't mean it can't be done, but it's probably good to understand what the real reason is.

So finding a mechanic that will do it, doesn't necessarily mean you've found a better mechanic. Maybe you just found one that doesn't quite understand how tricky this can be.

Jeroen

[Samfromindia]

I am posting this on behalf of my friend who owns a Chevrolet SRV.

RPM of the car is fluctuating at idle as shown in this video:

https://youtu.be/KJnpFFLDbXY

The car idles at 1500 RPM which sometimes shoots up to 3000.

Throttle body of the car is replaced for 9K but he is still getting the same issue. He have tested 20 ecm (second hand), changed new Throttle body without any luck.

Any help regarding this will be appreciated !

[scorpian]

Have you checked for any leaks? If you have already replaced the throttle body i believe with the same part number and have also checked with so many ecm then i would start looking at some air/vacuum leak. If the throttle body has an IAC valve, you could try disconnecting the coupler that goes in to it and see if the rpm shows some improvement.
A can of wd40 sprayed usually helps me find any leaks in the intake etc by observing the rpm fluctuating up and down.

Please do update this thread so that we can narrow down further.

[Jeroen]

Scorpion advise is spot on. In my experience fluctuating idle RPM rarely require the throttle body replaced. On many cars it tends to be a problem with the idle air valve, or whatever the manufacturer calls it. Pull the electrical plug of that valve, if the RPM become steady you have found the culprit.

Also, air leaks (and a faulty idle air valve is essentially an an air leak) can cause this effect. Spraying WD40 across all parts on the inlet air assembly (filter housing, hoses, fitting etc).

Another ofter used technique is just gentle tugging and pushing of all the different components in the inlet air assembly with the engine running. If the RPM changes you are pushing/pulling close to the leak!

Good luck

Jeroen

[kkg]

I once got my Chevrolet Sparks' TBcleaned. I insisted my FNG to do it manually rather than with sprays. He reluctantly did it and immediately afterwards, the RPM started fluctuating. He tried everything but could not rectify it and lastly contacted his fellow mechanic friend at Chevy service center.

Next day he took the car to Chevy and got the ECM scanned and reset, and problem vanished forever.