General Fiat grande punto 1.4 16v starjet variable manifold

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General Fiat grande punto 1.4 16v starjet variable manifold

Bill Tsouk

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Hello guy's.

I am new in community and i think my fiat G. P has issue with manifold. When the car is cold and start the engine i have a little play on rpms for example from 1400 to 1300 and also i hear a noise like pull air from some cracked tube... After little time when the rpm falls to normal rpm (850 rpm) the noise stoped and the engine not jerk..... I had replace all coils my sparks is new i had check all inlet from front for any air leak but i cant find something. Also my fuel trims seems ok ( long fuel trim +3%). In running conditions like a trip a havent some issue its all ok only on the morning. Can you help me???
Thank you.
 
Hello guy's.

I am new in community and i think my fiat G. P has issue with manifold. When the car is cold and start the engine i have a little play on rpms for example from 1400 to 1300 and also i hear a noise like pull air from some cracked tube... After little time when the rpm falls to normal rpm (850 rpm) the noise stoped and the engine not jerk..... I had replace all coils my sparks is new i had check all inlet from front for any air leak but i cant find something. Also my fuel trims seems ok ( long fuel trim +3%). In running conditions like a trip a havent some issue its all ok only on the morning. Can you help me???
Thank you.

Hi. ?
Are you SURE this isnt a 'normal' feature of that class of motor?

You mention fuel trims..

How is all the fuelling in both open and closed loop.

What have you used so far?

OBD scanner?
Oscilloscope?

Charlie
 
Dear sir thank you for your answer.

For the fuel trims i use an obd scanner.
Also i dont know if this noise is normal i will try to record a video this noise and i upload to hear this noise
For the open loop coditions i can not see the fuel trims because this car has narrowband oxygen sensor
 
Guys hello again i found a video on YouTube with my problem when the car is cold it seems a little bit jerking until the revs goes down...... I had change all spark plugs my coil pack is new i clean the throttle body but i can not understand the problem..... Maybe wants ecu update???
Link from video:
[ame]https://youtu.be/U_eoTCv_n3I[/ame]
I wiil waiting for your answers
Thank you
 
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Petrol engines need their mixture to be enriched to compensate for bad pulverization and re-condensation on cold internal walls. This usually results in an RPM increase and possibly some jerking.
So it seems that your car behaves as expected, but the noise it generates...

BTW, what do you mean exactly by "cold" ? Engine's first start of the day or minus outside temp ?

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)
 
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Thank you for your answer.

With cold i mean the first start of the day with outside temp
Maybe around to 3 or 5 degrees....
So you believe this behavior is normal for this type engine???
 
How many miles since LPG installed?

Positive Long fuel trim on this engine is not normal from my experience.
There must be a leak somewhere. Check the PCV hose for a start. It's a classic fail.
 
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I had do around to 100.000 kilometers with lpg i check the fuel trims and with petrol is around +3 - 5 always positive. With lpg is +5- 8 again always positive. And i observe when the fuel trim is around +8 the cold start is more smoothly than when the trims is around +3. Very strange.... The pcv tube is a small silidrical black box????
 
I had do around to 100.000 kilometers with lpg i check the fuel trims and with petrol is around +3 - 5 always positive. With lpg is +5- 8 again always positive. And i observe when the fuel trim is around +8 the cold start is more smoothly than when the trims is around +3. Very strange.... The pcv tube is a small silidrical black box????

Higher RPM's are fine for engine starts.
The fuel trims could mean the lpg filters need replacing, or just a reprogramming of the lpg system.

They aren't high enough to think about a vacuum leak.
You still might want to take off the air filter housing and check there are no cracked vacuum hoses .
Jerking could also be a result of cracked/loose/hard engine mounts.
 
Ι check the pcv hose and its not cracked.... Also i buy a spray and i spray some spots on manifold with engine running on idle and nothing change so i think i haven't a vacuum leak or i can find it..... The solenoid vavle vvt can be the problem about this cold start or no?? I haven't trouble code but i had read a post from someone which tell about this valve
 
Drive for a day only with petrol and switch off the LPG system. Check next morning fuel trims before you switch on the engine.

Adjusting the LPG map on starjet engine is tricky and most of the installers know sh*t about this engine.
 
Yes my friend the most from lpg installers don't know so good this engine. The first time i had a lot of problems about the map of the lpg but i explaine on him about variable manifold etc and he make new adjustments on the road and know if close off the lpg for a day the fuel trims is on +3 and if i work the car with lpg the fuel trim is +6 i had watched this parameters already.. But the strange is tha the cold start seems more smoothly when i work the car with lpg and the fuel trim goes on +6
 
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