Technical is butterfly supposed to open

[puntodad19]

Haynes book of lies, not my words, wiring diagrams need to be exact, rather than *typical*.... Cabin filter for the lads Punto not mentioned at all in the soft back Haynes manual we have. If it is in there then the info is increadably well hidden. A Haynes manual is better than nothing, but, incorrect exploded view of gearbox parts, reaming needed not mentioned, lack of specific data on modern sensors, vehicle specific sensors, no proper test procedures and expected values, incorrect capacities, unclear and insufficient detail in some pictures....lacking in info one would expect to find in a manual, a manual one has paid good money for.....and that just about to common car manual, never mind the more expensive specialist manuals.....

Not detailed enough, missing pertinent info that is needed, expected to be contained within the manual, the reason for buying the manual in the first place, but, better than nothing.

Parts exploded views can be extremely informative, bikers visit the likes of cmsnl.com.

Ygere is now a parts section on here for fiats, just need mail order suppliers info now ....

Research the fiat diagnostics stuff on here ......get a scope or Delphi like equipment......

19 wires or so in a door loom......86 in an engine loom.....I think you understand where this paragraph is heading....

Diagnostic kit and ECU's can get really confused when two electrical wires than where designed never to be connected in service, become of connected from time to time, due to rain.....
. .....so searching for that *fault* dictated going back to first principles, the principles you know of and are comfortable using.......but scopes are great.

Electronics dont like *seeing* "unexpected things/signals/voltages etc. Etc. Etc....

So, Haynes manuals, worth the cost ?

School report would say" can do better"......have they got better these days ?

 

[GrandePunto PL]

Here is simple data log for you (1,4 8V).

1. General view (engine rpm is scaled down 100x, to fit everything on the graph).
Basically, the butterfly follows the gas pedal (almost like it was mechanical linkage).
There is some ECU intervention, but only a few degrees here or there. Until it's emergency.

2. Cold start. Butterfly opens about 7 degrees at idle (1200 rpm). Then it drops when hot to about 3 degrees (next graph) and rpm to 700.
Three or seven is a small gap (one can mistake it for "closed" flap). As was stated before: idle air comes from the small breather hose also.

3. As for more electronic/program stuff, the ECU is trying to "help" the driver in certain driving conditions, it bumps up the RPMs. For example if you coast slowly on neutral gear, it can increase idle from 700 (engine hot) to 1000 rpm. To create more vacuum for brake servo.
In case of real emergency braking, when ABS kicks in, it (ABS) commands the ECU via CAN to bump the engine speed much more (2000-3000-ish RPM at least), if you don't stall it (you press brake and clutch simultaneously). Such effects (intentional functions, car is altering something) are normal in modern cars. Sometimes it is hard to tell if it's a bug or a feature.

At the other hand if the engine RPMs are dropping, you have a classic mechanical problem (>90% sure), like timing, or valve lash (8V engines) etc.
Old-school stuff still Rules. Random example: you can still use vacuum gauge to diagnose some problems. It's almost forgotten technique.
Now most folks (lames) want to fix cars using OBD fault codes only (like erasing a code is a "repair")... Don't fall into this kind of trap.

 

[GrandePunto PL]

4. Note that there are serious data lags in the system. Some data, fast changes may be lost. That's normal. Data frame can be 10x longer than single ignition event in the cylinder (so you stand no chance to "diagnose" it) and other fast activities (like snapping the throttle or releasing during gear change)...

That's why the only proper way to diagnose a car is an Oscilloscope! Period. Not OBD (it is NOT "oracle"), not parts swapping.
Here is an old guy doing it flawlessly: https://www.youtube.com/c/AutomotiveTestSolutions/videos !
As far as I know, oscilloscopes (diagnoscopes, whatever) existed in the 70's, so it's nothing "new" (except pressure transducers etc.).
Same for exhaust gas analysis, very useful (this is a number two tool after scope, ODB2 is a third in the pecking order, remember).

Again. Idle air comes from two sources. You can block one and engine is still running (it didn't even budge).


There you go. Now you know the very basics of how the throttle, idle RPM (and PCV system) works here.

Plus, study this PDF (Fiat_Grande_Punto_Service_Manuale), 126 MB one. It's Italian language, but it doesn't matter.
Pictures are enough to grasp what's going on: http://download.fiatforum.bg/Books/Grande_Punto/ !
Introduction to model (important document, especially for old mechanics, familiar with older FIRE family engine units, so they do it "old way" and get P0016 error after the timing belt job - so watch out, this "simple" car is a trap).

 

[qaz83885]

hi puntodad19​

thats very interesting and also disappointing too as i have use hayns a lot. thanks for the info as i was just about to buy one, do you know of a good manual for the doblo,. or event for the punto as its got the same engine

 

[qaz83885]

anyone know what a Ygere is?
thanks

 

[GrandePunto PL]

Official "eLearn" manual for Doblo...
https://aftersales.fiat.com/elearns...ish&sectionName=Procedure&validityName=1.4 8v