Mondial DigiPlex MED 801A Testing

Hi - another update and question - we replaced all 8 fuel injectors and now the car is starting up really nicely when cold but it is immediately idling at 2,100-2,200 RPM. It comes down a little as it warms up but not really below 2,000. Then if we turn it off after a minute or two, it won't restart. Have not driven it, still trying to figure out if we can trust getting it out of the driveway. We could try to play with the fuel mixture screw or the idle screw. Any ideas on where to go with the high idle or why it only starts cold? We are still running a wire directly from the battery to the coil (through a relay) but I don't think that could be related....

 

High idle = If it's a stock US version Mondial 8, it will have a cold air idle valve that intentionally raises the cold start idle (until the thermoswitch on the coolant expansion tank closes). What version Mondial 8 do you have? If US version, is your cold start air valve system still present, or modified, or disabled?

No warm restart = have you checked for spark presence? If it has spark, but won't warm restart, measure the supply fuel pressure after engine running (or fuel pump running) = it shouold not fall to zero quickly.

 

Thanks Steve. Mondial 8 US version. Where is the cold start air valve system? How long would it normally take for that thermoswitch to close? That's a good idea to re-check spark on warm re-start, will take a look. Thanks.

 

The cold start air valve is item 35 here:

https://www.ferrariparts.co.uk/diagram/ferrari/mondial-8-usa/012-fuel-injection-system-fuel-distributors-lines

It is controlled by Electrovalve 52 (which is controlled by the thermoswitch in the coolant expansion tank).

I'm not sure about the time, but a couple/few minutes. The cold air system shuts off when the coolant reaches a temperature of 122 deg F (which closes the thermoswitch which changes the state of the Electrovalve which changes the state of the cold start air valve from open to closed) -- see page 35 in your 215/81 OM. You need to read your 215/81 OM - especially Section 3.

IIRC, you should have a yellow cold-running light in your dash that would show the state of the thermoswitch in the coolant expansion tank:

coolant cold = thermoswitch open = yellow light in dash "on" (and cold start air valve open)

coolant warm = thermoswitch closed = yellow light in dash "off" (and cold start air valve closed)

 

Thanks Steve. I think that dash light might not be working but read the manual and it seems to be acting in line with recommendation per the OM (except for dash light indication). (none of the engine heat dials in the dash seem to be working although oil and gas seem to be working thankfully, we're also getting lights on for cylinder 1-4 "slow down" and Cylinder 5-8 "slow down but have been ignoring those since they seem to be running fine...)

Today we need to test the system pressure/control pressure. I am pretty sure the hot start is a fuel pressure issue and I bet it's the accumulator... We'll see. I suppose it could be the fuel pump too. Been reading old fchat on that procedure. Will report back.

 

I need to correct myself about the yellow cold running light. Your OM seems to not include that feature even though the US version 308i-2V (which has the exact same engine/injection system as yours) does.

 

Hi - yet another update on this odyssey... We finally were able to measure the fuel pressure and we got some weird results (all while running fuel pump, not engine).
- Control pressure cold = 2 Bar (this seems good)
- System pressure cold = 1.5 Bar
- Turn off pump, control pressure drops immediately to zero
- Turn off pump, system pressure holds at 1.5 Bar

I had thought we had a fuel accumulator issue but I would think the system pressure wouldn't hold if that was the case. I also don't know why the system pressure is so low. We had the fuel distributor tested by CIS when they rebuilt the WUR and it was good, and the prior owner also put in a new fuel pump. My recollection was before we sent out the WUR to CIS, we had 5 Bar system pressure but also 5 Bar control pressure. So somehow we fixed one and now the other is bad. But thinking the low system pressure and the control pressure dropping are actually two different issues. Recall that we are having issues where the car won't warm re-start and also that it is stalling when stopped after driving.

 

That seems impossible if you have everything connected correctly -- the control pressure should never (really can never) be greater than the regulated supply pressure.

 

Ah thanks. We had pressure gauge on reversed. 5 bars system and 2 bars control when we fixed it. As soon as fuel pump is turned off when testing system pressure, the pressure drops to zero. From other threads that seems clearly busted fuel accumulator so we’ll go to that.

 

Well we pulled the line off the fuel accumulator after running the fuel pump for a bit and it was bone dry. So the diaphragm would seem to be fine. Any idea what else could explain the rapid fuel pressure loss under both system pressure and control pressure testing?

 

Two other possibilities:
1. Bad fuel pump check valve or missing fuel pump check valve which is not uncommon on your year as there is an early CIS fuel pump for your car with a built-in check valve (that became unobtanium for a while) and a later CIS fuel pump with an external check valve -- please post a picture of your fuel pump and its plumbing on the output. Also, if you do a search using "Bosch 69523" you'll get many prior threads about this issue.
2. Bad o-ring in fuel pressure regulator section of the fuel distributor (but only go here after ensuring #1 isn't the problem).

 

Interesting. Here’s a pic. The fuel pump was supposedly replaced by prior owner earlier this year but I don’t know what he used.
View attachment 4212852

 

Hopefully this one worked.
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Your check valve is missing -- you have the later CIS pump. The early Bosch 69523 pump looks like this (note the much longer output "nose":

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What you have is the later style Bosch 69532 pump (but without the screw-in check valve that uses a banjo fitting as shown in this picture):

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Wow ok thanks Steve. I’ll do some research from prior threads.

 

Isn’t the thing screwed into the nose the external check valve?
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I’m going to step out on a limb.
And say,,
Jafon,
I see a check valve, and there is usually, a screen in there, to protect the check valve from debris. if it’s new? Flush the system ( into a suitable container)
Or,, remember to Stop, Drop and Roll
( smile)
Do this, before connecting it to your CIS unit.

 

No, the "brass" piece in your system is just a hollow threaded coupling 109797 (https://www.ferrariparts.co.uk/part/ferrari/109797) -- the screw-in check valve requires a banjo fitting on the hose that connects to it. Have you even looked at the SPC figures of the fuel pump and hose routing for your model 308i-2V with early style fuel pump and the fuel pump for the later US version 328 with the later style fuel pump (308QV are a bit of a mixed bag that changed over time and version -- some with early and some with late)? You have homework -- not me . I will fault some of the respectable F part suppliers who (wrongly) sell the later CIS pump as being for the early cars, and it is a bit unfortunate that that threaded coupling from the early cars also fits the later style CIS fuel pump. I am recalling that either Bosch fuel pump may now be unobtanium, and that Rifledriver mentioned using an Evil Energy brand fuel pump, but whatever you do = you need a check valve on the output port of whatever CIS fuel pump you use. In your case, you could add the later style check valve, Bosch 1587010532, and then change the hose between the fuel pump and Accumulator:
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Thanks Steve. Got a good diagram of the change from GT Car Parts. Thought I’d share. Parts are in the mail…..
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Engine seems to be starting up cold and warm finally! Turning back to our original electrical problem, I've read a number of old posts around the ignition barrel problem and how to replace the barrel, but we have run into an issue that I haven't found any postings on and wondering if there is advice. We can't access the ignition to get it out because we can't get the plastic cover on top of the steering wheel off. The steering wheel doesn't really drop down even when the adjustment is loosened and the plastic piece won't come off without that. Curious if any ideas of how we get this thing off so we can actually get the ignition out and replaced. Including a picture of the plastic piece I'm talking about. (the colored wires are where the prior owner hacked into the ignition line to create the push button starter)
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Have you loosened nut #13 here?:

https://www.ferrariparts.co.uk/diagram/ferrari/mondial-8/032-steering-column

That splined joint needs to "slide" when the steering wheel is tilted.

 

Wow that nut #13 did not want to move. Will try more this weekend.

 

Yes, it does seem strange that they would provide hand-operated lever #47 for the User to adjust the steering wheel tilt, but nut #13 still needs a tool to be loosened; however, I believe your nut #13 is just wrongly overtightened, and the design intent was that nut #13 would be tightened just enough to remove any rotational play in the splined joint, but still allow it to slide for the tilt adjustment.

 

Hi - frustrating new problem, I took off the AAV and ran the fuel pump and ignition for a while (like 10+ minutes) to test the AAV open and closing. Realized I was leaking fuel that was dropping down the engine body. It’s not coming from the new check valve work. I found the drip all the way at the throttle and then dripping down through the throttle spring, almost seems to be coming through the plenum. (Pic below). I’m not sure how this is possible. I thought maybe the cold start injector was going crazy but I took that off and ran pump quickly and nothing came out of that, plus no voltage at that pin without cranking (as it should be). Does the AAV tubing act as some kind of vacuum seal that I messed up when I took it off? I can’t understand what else could be happening. The fuel injectors are all brand new, I assume they’re not leaking although maybe we need to go test. But not even sure how that would cause this.
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The fuel injectors do not control their fuel flow when the fuel pump is running -- the position of the Plunger inside the fuel distributor does. The Plunger could be stuck in a deflected position (either the Plunger itself in its bore or if the airflow metering flap mechanism is stuck deflected and is holding the Plunger deflected), or the Plunger's rest position (or the airflow flap's rest position) could be mis-adjusted.