348 engine start trouble

FYI, when you replace the sensors you don't replace the shims as they were, you have to measure the depth and add as needed. The housing changes over time.

 

I believe the distance should be between 0.9mm and 0.35mm (but the units of measurement aren't shown in the WSM)

Just standing on the (broad) shoulders of those before me

 

I had more than 1 mm distance on the left sensor, now around 0.7 mm.
I better get a sensor in stock...

 

You are in the french Alps?
Maybe You saw one of my fellow citicens there, he has has also been biking in france the last weeks. You cant miss him, he´s wearing a yellow shirt.

 

You can set the sensor gaps anywhere between 0.35 an 0.9 mm (better not too close to the limits) but, whatever gap you decide to have on one, you have to bring the other one to that gap as close as possible (thus the very thin shims).

 

Can you post a picture of your vacuum gauges. The vacuum in the intakes is pulsing rather strongly so the gauges normally have adjustable buffers to keep the needles steady. Below is my vintage vacuum gauge set (before and after balancing of my 348) where you can see small taps at bottoms of the pictures with which you can reduce the opening to the gauges and eliminate the pulsing.

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Looks like your kit is from the same manufacturer as mine (bought ~25 years ago, Taiwan made), still unchanged. Yes, the grey things appear to be valves to control the pulsing. These seem to be the newer version as compared to what is on my kit. Looking at the clearer picture I found on Ebay, I can see that the cap on the grey thing is screwed-on, probably to control the opening. Have a look at it, perhaps the one on the jumping needle line is not adjusted correctly. You also try to unscrew the cap and see if some part is missing inside.

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The procedure for balancing the 2.5 should be the one described on page C36 of the WSM (the procedure for 2.7 is on pages C81 to C89 which were added to the WSM later, i.e. considered to be "the missing pages"). Extracts relevant to instructions on page C36:

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Just noticed the instruction in the above extract on the CO adjustment by the screws (pots) on the MAF sensors. There have been discussions here on whether the CO screws are effective only during the open loop or all the time. The instruction in the extract appears to suggest that the CO screws are effective all the time since, prior to the described CO adjustment, the WSM (on page C35) states that the engine should first be warmed-up to 80C by which time the engine will be well into the closed loop.

Or is this, perhaps, another one of the Ferrari WSM "imperfections"?

 

I don't have the later C81 to C89 pages anyone have those?

 

Talking about balancing of the banks, I have completed my IAC valve controller (for the 2.7 engines). The controller keeps the two IAC-s steadily at exactly the same openings (as selected by the pot) enabling bank vacuum balancing at the specified 850 rpm. Tested it today only for the idle control (works very well), will do the vacuum re-balancing later in the week.

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The missing pages....

 

Thank you!

 

"injectors are new" where did you get injectors Marc or where they rebuilt?

 

Bonjour Marc,

What FuelPressure Sensors did you use?
Sperformance sells them €500 a piece
I am looking at Volvo V90 parts (under 100.)