Pulsing revs at cold start (360)

Hi Mates,

Question. My 360 F1 sometimes (happened twice now) has a strange "hickup" upon cold start.

I get a "Check OK", start the car, engine starts, so far so good, then when I slowly drive out of the garage, the throttle response is with pulses, same goes for the engine revs.

First time it happened, it shut the engine of, did a restart and all was fine. Did 6 or 7 cold starts the following days and all was fine.

Today it happened a second time. Also on a colf start. No I just gently pushed the throttle, and within a few meters, say 35, the engine was fine.

Any ideas? common issue? Would like to get some feedback.

Thnx!

 

Had it aswell. Not every time. When the engine comes one time above 2500 rpm it just run smooth and the throttle just reacts normal.

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It could be extra air getting in unmetered (after the airflow meters) or gasses escaping out upsetting the mixture and the ecu's trying to compensate. Or it could even be bad/dirty air flow meters.

Without seeing the car its difficult to guess.

 

The coolant temp sensor might be on its way out. The ECUs rely on the CTS when running in cold start, open loop mode.

 

Thnx for the insights. Any ideas on how I can maybe check/analyze things?

 

I've had this happen on a few of my cars. It's usually a idle control valve or vacuum leak.

 

You can R/R with a new part or test the old part. I hate to throw parts at a problem, so I test the old parts first. Image Unavailable, Please Login

 

Just like 360trev mentions; Could be bad MAF’s or dirty ones.

I also remember reading this exact same problem in an old thread and in that case it turned out to be the self learning procedure of the ECU’s after having the battery switched off. One can read all about how to go about the self learning process on Aldus Voice eminent home page...

 

I have encountered the same ‘problem’. Each time I start my car it pulses for about 2 or 3 minutes then idles normally.
I don’t use the car very much so put it down to lack of use.
I haven’t disconnected the battery so it can’t be that.
How do I check/clean the MAFs? Is it a diy job?

 

How strange. My car does this too. I just let it idle for a few minutes. or restart it. In my experience, trying to find the cause in the absence of a stored code is a monumental task. There are too many possibilities. When I got my Mondiial many years ago, it had major vacuum leaks due to vacuum hoses that were hard as stone. As a result, the idle speed was all over the map, but it didn't surge like my 360.

 

mine has it to.i think the throttle positioning are calibrating themselves.

 

could be fuel system pressure bleed off from lack of use. If this is the case, start the car for just a quick second, shut if off and start again. Idle should be consistent.

 

I think I’ll just leave it. Doesn’t seem to do any harm and it clears pretty quickly. I never worry about cars unless I hear knocking or it doesn’t start. I’m an optimist.
Car is now tucked up for the winter so will get it checked next year when it goes in for exhaust upgrades.

 

Mine goes in for maintenance, next month, winterstop, will get back to you with what they come up. Thnx, glad Im not the only one expierincing this ;-)

 

I think I read a post by 360Trev somewhere that if you turn the key to position 2 without starting then press the throttle pedal to the floor this allows the system to reset itself.
Has anyone else seen this?

 

My '99 has done this since I got it 2 years ago. I simply turn the key, start it.....if it pulses, turn it off and restart it. The second start always works just fine. I believe it has something to do with fuel pressure. There were some previous posts about this concern.
IMHO Don't worry about it.

 

I would do ready stuff first.

1). Clean your MAFs with MAF cleaner.
2). Do an engine reset.

Dan


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mine does it to, and honestly i like the sound. Sort of one piston wake,s up the other one and further.(lol) and it does not any harm.

 

One time when I hadn’t driven in a few weeks and it was fairly cold it did a rough and slow idle for a couple seconds before it went back to normal, I imagined it was something like one bank starting quicker than the other, if that’s a thing.

 

This problem can be caused by dripping injectors from bad seals. Fuel drips into the combustion chamber, causing a very rich mixture on start and stumbling until the excess fuel is cleared. Symptom confirmed by second start always working fine because the excess fuel was cleaned out on the first start attempt. Possibly caused by the rubber injector seals degrading from contact with ethanol. Mine was cured by having the injectors cleaned and the seals replaced by Viton, which is impervious to ethanol. You will notice mine has a few extra cylinders, but the injectors are pretty much the same.


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Terry, when this occurred, were there any codes thrown that pointed towards dripping injectors?

 

Negative, no codes, no CEL, just the system initially having to deal with the extra-rich mixture. Dripping injectors do not seem to bother the Motronic 2.5, 2.7, and 5.2 Ferraris as much as 7.3 and 7.1.1, probably because of the more precise metering on the later Motronics and generally lower idle speeds.