Technical Bravo 1.4 90HP cold start issues, varying idle speed

[zoltanpapp82]

Hello,

I bought a 1.4 natural aspiration petrol engined Bravo, made in 2008, so an early version. Altough it is not a muscle car is very convinient to drive. I have no issues with it only the idling drives me crazy. I monitored some values with Fiat ECU Scan, so values are based on that:

First start every morning the idle speed starts at 750, throttle is about 6%, of course engine shakes quite well. And after 2..4 seconds the idle rises to ~1300 and stays there for a while than lowers to 750 as the engine is getting warmer. On cold start the expected idle speed is ~1300 but stays 750 for some seconds, I do not know why. When I step on the gas it rises immediately, so if I start the engine with gently stepping to the gas the symptom can be hided.

Is it normal? No fault code is present, no poor gas reaction, just tricky start after longer whiles.

The other is the idle speed "flatness". Throttle position varies continuously a couple tenth percent which makes idle speed variation like 20..30 RPM. I read somewhere that 30RPM variation is just normal, but I never seen such a symptom on my cars, neither on my MKII Panda (ok, it has a separate idle motor) nor on the 1.6 Astra. I can hear the variation which sounds worse (faster variation) when load is engaged, like high beam, air conditioning.

Is it normal? Mechanic says he cleaned the throttle valve with cleaner. Shall I disassemble and clean it thoroughly?

The car just had a new battery and new filters, spark plugs, engine oil, coolant...

Thank you,
Zoltan

 

[Cadabena]

My 2010 1.4 120hp TJet does exactly the same, I wouldn't worry about it. Seems to do no harm, I imagine the ECU picks up the engine isn't running at its best and does its rise to 1300rpm 2-4 seconds later as you say.

 

[zoltanpapp82]

Cadabena, thank you for the prompt response! Good news!

Then only the idle speed bugs me, why it is not constant...?

Thanks,
Zoltan

 

[zoltanpapp82]

Can anybody add some items to check? I read already many things. MAP sensor cleaning. Throttle body cleaning. Any other?

Thank you,
Zoltan

 

[zoltanpapp82]

Happy New Year to all!

Today afternoon I removed the throttle body to check for buildup. It was badly clogged: Video

Also I noticed that the mechanism has a small play, I do not know if it is normal... but due to the spring tension it should not be an issue.

Also the intake pressure sensor had some leftover material on it... maybe oil vapor, humidity, petrol mixture?

All cleaned, built back together and tried to run throtthle relearn procedure as written in https://www.fiatforum.com/newbie-central/292687-throttle-body-relearn.html

But after 25 minutest the engine was still around 85degC, ~2degC outside temperature, so it was unsuccessful - fan did not start. Fortunately it may not be required. Engine runs smooth, throttle position is not varying much - stays around 1.5%, was around 6% before the cleaning. Idle is between 729..752 variation not noticable in the sound. Prevously the fluctiation was even worse when some load is engaged. Now it slightly drops and reaches the above values.

Also on todays first start the engine speed picked up the ~1300RPM immediately, with no delay.

I'll post a follow up in some days.

 

[aschiuta]

Mechanic says he cleaned the throttle valve with cleaner. Shall I disassemble and clean it thoroughly?
Zoltan

It is time to change the mechanic !

 

[zoltanpapp82]

Having 6 cold starts since the cleaning. So far it is working fine: raised idle kicks in immediately, good hot idling and "load management".

 

[vele123]

Happy New Year to all!

Today afternoon I removed the throttle body to check for buildup. It was badly clogged: Video

Also I noticed that the mechanism has a small play, I do not know if it is normal... but due to the spring tension it should not be an issue.

Also the intake pressure sensor had some leftover material on it... maybe oil vapor, humidity, petrol mixture?

All cleaned, built back together and tried to run throtthle relearn procedure as written in https://www.fiatforum.com/newbie-central/292687-throttle-body-relearn.html

But after 25 minutest the engine was still around 85degC, ~2degC outside temperature, so it was unsuccessful - fan did not start. Fortunately it may not be required. Engine runs smooth, throttle position is not varying much - stays around 1.5%, was around 6% before the cleaning. Idle is between 729..752 variation not noticable in the sound. Prevously the fluctiation was even worse when some load is engaged. Now it slightly drops and reaches the above values.

Also on todays first start the engine speed picked up the ~1300RPM immediately, with no delay.

I'll post a follow up in some days.

Thanks for posting this. It did work for me. I cleaned the throttle body but without disassembling it. Just removed the air intake plastic and detached the vaccum lines. Cleaned the throttle body with WD40 with cloth carefully opening the flap and holding it open with another screw driver while carefully cleaning by hand and with a cloth on the screwdriver. I opened the flap and cleaned it in one take, to avoid messing the DC motor and sensors while moving it. DO NOT MOVE IT OFTEN. DO NOT MOVE IT IF THE BATERRY IS ON. Of course you need to disconnect the battery before cleaning. For the relearning I let the car without battery power for more than an hour. Then, for 90 seconds put the key on MAR ignitian (the first step of the key) then remove the key for 90 seconds. Place the key on MAR for 5 seconds and START. Do not hit the accelerator pedal on the first START. The car will start at 750 rpms and then in 2 seconds will pick up the 1300 choke, as it was cold. Let the car run for 5 minutes do not hit the pedal. Turn off. Let it cool for a while, like 15 minutes. Start again, keep it running for 2-3 minutes and give it a good rev like 7000 rpms for 2-3 times. Drive it as usual. Give it a good rev every once in a while so the DC motor opens the flap at MAXIMUM with the WD40 inside and bea able to burn any leftover impurities as fast as possible.

EDIT: I cleaned the vaccum lines that go in the air intake tube with WD40 too. Spray a little in the lines and in the little plastic male connector that goes in the engine. Let it dry. Do blow in them, but carefull the WD40 has even worse taste than petrol.

My varying idle speed before cleaning was approx. 500-600 to 750 alternating every one half second. The car would stall when breaking before a trafic light when I shift from 3rd to 2nd gear and hit the cluch. It is was finito. And as it was warm would refuse to start. Not very drivable. But this did the job
Thanks once again @zoltanpapp82