Hello everyone!

Sorry if this has come up before, I know there are some (almost) similar cases as mine, but I haven't found any solutions so far.

I have a '11 Panda Van 1.2 8v (the 69hp version, code 169A4000). The car is driving fine, no other problems apart from the pulsating/hunting idle. It's not noticeable when no auxiliaries are switched on (or at least I'm not sensitive enough), but the lights and fans on (especially the lights), it gets much more prominent. It seems like that it has an even interval (~3 sec), it drops to ~500 rpm then back normal. It ticks over nicely, then drops again. It never stalled though. Now I know there might be some electrical load issues but what's odd is that this only started to happen AFTER I cleaned the throttle body. (Took it off, cleaned with carb cleaner, reassembled, also did an oil and filters change). Before that the idle was perfectly fine, I just noticed that gunk had built up on the butterfly valve so I thought why not.
I checked diagnostics (not MES though), no error codes at all. Took the airbox off, I can see the butterfly valve moving while idling. It starts to close, rev drops, then it opens, rev goes back to normal. It seems to me that the ECU doesn't know the correct position (or there is some sensor giving wrong info)?
I cleaned the breather hose (was dirty inside, but no blockage I think) also cleaned the small diameter breather hose going from the airbox to the lower part of the intake manifold (which is blocked by the way, so the hose is not doing anything apparently). They aren't split, also tried pulling them off while idling, blocking the airbox ends of the breathers, no difference. Cleaned the MAP sensor, no difference. Did an ECU reset, no difference. Battery also seems to be fine. I've been using the car for about 2000 kms since then, so it won't adapt probably. As this engine is drive-by-wire there is no idle control valve, at least I haven't found it.

So my question is, might be that it needs a throttle relearn procedure I'm not aware of? I've read that there might be but there are also contradicting info regarding this procedure. It would be strange if suddenly some other sensor went haywire at the same time when cleaning the TB. Also I don't think I broke the TB as it's working perfectly at any other point in time.

Things that were changed last year so should be good:
- spark plugs
- ignition coil and leads
- upper lambda probe

Might be TL;DR, anyways, thanks in advance!

Ivan

First off a little bug bear of mine.


when cleaning a carb you can't spray with brake/carb cleaner as per loads of YouTube video's. There's delicate electronics built into the side that can get damaged. You dampen the cloth and wipe away..

Now thats out of the way.


I dont think thats whats happened here.


have you a way to scan live data. Throttle angle should be quite a low percentage.


If solvent has got into the inlet manifold its likely to have found itself on the MAP sensor. Held on by one T25 screw. Left hand side of the Black plastic inlet manifold.



there is an idle control valve its under side and covered by a plastic shield.



will worry about that latter


Have a look at the MAP and I will have a think about electrical load.


If you have jump leads try with another car connected would eliminate battery and charging

Thanks for the reply!

koalar said:

have you a way to scan live data. Throttle angle should be quite a low percentage.

Click to expand...

Yes, I did a live scan a while ago. I've seen the throttle angle change in sync with the rpm drop. I've also seen this while watching the butterfly valve with the airbox removed.

koalar said:

there is an idle control valve its under side and covered by a plastic shield.

Click to expand...

When I removed the throttle body I couldn't see anything looking like an ICV. As far as I understand idle is controlled entirely by the butterfly valve on the 69hp version. Could not find any part number either for an ICV valve for this engine.

koalar said:

Have a look at the MAP and I will have a think about electrical load.

Click to expand...

Looked at MAP sensor and cleaned it already, made no difference.

koalar said:

If you have jump leads try with another car connected would eliminate battery and charging

Click to expand...

Will do, thanks!

When I removed the throttle body I couldn't see anything looking like an ICV. As far as I understand idle is controlled entirely by the butterfly valve on the 69hp version. Could not find any part number either for an ICV valve for this engine.


correct

09 Flyby wire had an ICV
11 flyby wire doesn't


not sure if it 100% by date

This problem with the RPM dropping down to 500 on idle is caused by increased pressure in the engine cooling system. First of all make sure the bleeding is done correctly. The very culprit usualy is the valve on the radiator's cap (expension vessel's cap), that valve is stuck and it does not open when the pressure gets to high and the valve is supposed to open. Replace that cap and the problem is solved.

Mike1alike said:

This problem with the RPM dropping down to 500 on idle is caused by increased pressure in the engine cooling system. First of all make sure the bleeding is done correctly. The very culprit usualy is the valve on the radiator's cap (expension vessel's cap), that valve is stuck and it does not open when the pressure gets to high and the valve is supposed to open. Replace that cap and the problem is solved.

Click to expand...

not sure I understand the pathway between coolant pressure and low idle ?

I know. A lot of people doesn't and that is why it does not get solved, lots of time.
But mind you, that valve is there on the cooling system with an exact purpose. It does not just sit there because the automobile manufacturer had nothing else to do with it and through it there, it's there to keep the pressure inside the cooling system on a certain working level.
Physically I don't know how exactly this idle low rev is produced, but I know for sure that high pressure inside cooling system does make this low rev idle. I had it on my Punto and that valve was stucked. Replaced it with a new cap and the problem was fixed.

I stand corrected and I think I've found the issue that was causing the rev to drop down to 500RPM on idle.
I think the high pressure in the cooling system was just somthing extra that added up to the real cause and by fixing the pressure problem I just managed to make the engine not rev down to 500RPM, but it was really not running free as it should.
I found out that the roller in the adjustable tightener of the accessories belt was being blocked by the deformed cover that were helding it in place. That put an extra load on the engine and caused the rev to drop down. By the looks of it, I think it took it a while to get in that state. For now I took it off and placed a washer instead, the washer is pressing the inside of the bearing of the roller and the roller moves free now.
I hope this helps anyone who is facing this issue. It is a tricky problem, a hidden one. Hidden under a deformed cover.

Would love to see some pics of the interior of the panda van. Always keeping my eye out for a van interior.

I don't own a Panda, mine is a Punto. They are equipped with similar or very much alike engines and the do share the same problems. That is why I'm reading here other topics too, beside Punto mk2.