General car start failure, ralenti failure

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General car start failure, ralenti failure

emeone

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Hello, I greet you from Spain

Excuse my english

I've had this problem in my car for months, the FIAT mechanics don't know what it is.
Has anyone here had this bug?

when starting the car the RPM oscillates and the engine vibrates

Thanks a lot

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Does this happen also when engine is warm?
Vacuum leak or breather issue?
Is the tube going on left side of the engine cover to the back and towards throttle body ok. They had problems cracking atleast on some 2017 models.


Does the car still have warranty?
 
Hi.
-The car only does it when it is cold.
-Forgive me, I don't quite understand what you mean.
-Yes, or so I think, I have taken it 5 times to the FIAT workshop and they do not find the fault
-Yes, the car is under warranty, the FIAT workshop is checking it for the fifth time and I have filed a claim with FIAT Spain, I am waiting for you to answer me
 
Might be a breather or vacuum issue combined with some electronic changeover? Possibly fuel pressure but does not behave right for that unless it is turned off for some reason on cold start.

Fiat garage should be able to read live data what is happening on the engine, including the manifold pressure, fuel injection and spark advance. Fuel pressure is usually measured with attached gauge unless Tipo has sensor for it.

Vacuum is lost -> mixture is wrong and almost stalls.
Too much vacuum -> no air to run the engine.

Oil on breather might make it act slow on cold starts, but clear soon?
Can't really say.
 
For such a new car, it should be the battery or poor connection to it. Starter doesn't get power? No faults code would be stored for that. Cold weather makes a poor battery loose its power.
 
If it starts but it vibrates and the engine RPM oscillates, it sounds like you have a dodgy ignition - probably a coil pack.

When the car is doing this, try removing the HT lead (or the coil itself, if it's a sit-on-top one) from one of the spark plugs. So that you don't get electrocuted.. :D wear some rubber gloves while you do this and make sure you don't earth yourself accidentally on the car, or through your footwear.

If the car dies, then that coil/HT was keeping the car running, so replace the coil/HT. Repeat the test with the next spark plug. You might find that removing one of the coil/HTs does not cause the car to die... so you'll know that the problem is on that cylinder.

If you have coils on the plugs, then it's probably the coil but check the spark plug too. If you find one sooty plug, then that's probably the suspect cylinder too. You can move the individual coil (or the plug) to another cylinder and see if the problem moves with it.

You won't always get an error code with a dodgy coil (which is why the garage might not know how to fix it) since if it's not working, it can't send back an out of parameter signal to the ECU.

Ralf S.
 
On a modern car you should never remove HT leads when car is running. Doing so will damage the electronics!
 
But it'd be a very stupid thing to do anyway. Maybe one could do that in the 80's.
 
I am no mechanic, but it seems odd that a main dealer with a Fiat diagnostic check cannot pin point what the problem is.


When I had a similar problem with my 23 year old Volvo 940, I borrowed a home made diagnostic fault code reader and it told me the problem was with the Mass Air Flow Meter. Now, I am not saying that is the problem here, but if a 23 year old Volvo with a very basic fault code reader can identify what is wrong, why not with a much more up to date Tipo?
 
But it'd be a very stupid thing to do anyway. Maybe one could do that in the 80's.

1980s? I never had a car THAT new.... :eek:

If the OP doesn't want to disconnect an HT lead while the engine is running, he can disconnect the HT lead and connect it to a spare spark plug (**don't remove a plug from the engine), which he can lay on top of the cylinder head, so that it's earthed. Then start the engine.

That way the coil (if it's not knackered) has somewhere to send it's charge and if it's dark, he'll be able to see whether the spark plug actually has a spark or not.

Modern electronics don't just die if there is a malfunction somewhere.. otherwise people would need new ECU's every time they had a faulty spark plug, or HT, or coil pack.

Removing the HT while the engine is running is *maybe* not the best idea ever... since there is some risk of an electric shock .. but a) if you do get a shock, at least you'll know that you have an HT lead problem, and b) if you disconnect the HT from a running engine, you will immediately hear/feel if the engine revs change or fluctuate. If you take reasonable precautions, it's worked fine for at least since the 1980's, as you pointed out. :D


Ralf S.
 
It is not a good idea to run an engine with an ht lead disconnected but not grounded.

Ford fiestas with the zetec/sigma engine do suffer engine ecu failure caused by plug/ht lead/coil pack faults.
 
Which way does your engine oscilates?
Does the rev go down to 500 RPM or does it go up?
 
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