348 Hot Start Issue: I Have Tried Everything!

You haven’t been mimicked the hot start problem . Only proved the injectors work and don’t leak .
I am new to 348 s but had a long conversation with a highly regarded U.K. Ferrari Indy who was around when the 348 was born .
He told me the car I purchased from him , he’d serviced it the past 10 yrs , looked after it and at some stage retro fitted aftermarket the fuel pressure regulators ( its a 94 ) bcz of a known hot start issue that creeps into the OEM regulators .Also fuel starvation at the top of the rev range is another issue they end getting as they age .

Sort of pointing at them in a proud kinda way saying “ it won’t cause any of those issues “
“ those issues “ being head straching hot starting amongst others .
View attachment 3796103
Image Unavailable, Please Login

 

Although it should not be relevant in the case "pre and after re-learn" starting, perhaps you should try starting, after re-learn, by first priming the fuel system.

Otherwise, one thing that affects the mixture at cold starts is the resistance of the CO screws on the MAFs. What resistances are you currently having?

NOTE: Turning the CO screw Clockwise (Higher Ohms) will make the mixture Richer.

 

I've tried priming by clicking the key to on 3 or 4 times before starting, no change. I haven't measured the MAFs, but no idea how that would matter pre and post learn cycle. Anyway, I'm at peace with it at this point, roughly every 5 years I mess around with it. There's a thread in here of other 2.7 owners with the same problem so I think it's just a quirk of the system.

Op may have something similar going on, the fact it starts when floored is what's interesting. Maybe TPS issue or temp sensor causing idle air control to be off when hot? How does it idle hot? What rpm? Maybe before starting hot, click to run and cycle the tps once or twice before starting and see if that helps.

 

Yes sir! Excellent advice. I have them on order if I'm going to go to the labor and trouble and time and coolant mess to pull them out and test them I'm just going to replace them with new as they are 33 years old! But it will be interesting to remove and test the old ones and then I can test the new ones alongside and compare. Car runs great cold,warm or hot and idles well and steady.
Today I hope to perform the fuel pressure test which will be interesting and I might delve into the mass air flow maybe give them a good cleaning and check those resistance values but like you said probably doesn't have much to do with starting.
Very interesting about the Indy mechanics comments about the original fuel pressure regulators.

 

You cannot prime the fuel system by turning the key to "on" (whether once or many times) because the fuel pumps do not run at ignition "on". The fuel pumps will only start running when you start cranking the engine.

It is possible that the ECU, for the first start after its reset, does not refer immediately to the ohm value of the CO pots (uses its default tables) but adopts this value during the process of re-learning. If so adopted ohm value of the CO pot is too low, it will cause somewhat leaner mixture at subsequent cold starts which could potentially be your problem.

NOTE: the CO pot resistance does not alter the MAF signal (the pot is not connected to any part of the MAF circuitry); this resistance value is used by the ECU to trim the fuel mixture.

 

I have a 2.7 456GT that for the last 6 months has been having the same hot start issues intermittently. 27k miles on the car too

Currently have all 12 injectors out to Mrinjector for service and have replaced both coolant sensors. Beyond that, I have gone thru most of what else is on the list above to check. Hoping once it's back together this may be cured.

Also have a COP ignition I added, but had been running a few thousand miles on it already when problems started.

 

Could be...but the 2nd time it starts flawlessly. I would have thought failing FPR or something if it didn't always start perfectly after an ECU reset. I have video of when I did the major after it had been sitting for 3 years and it fired almost immediately. I was shocked as I figured it'd need time to fill the new filters, prime the rail etc. but it fired right up and idled.

If the MAF value was off you'd think it would always be difficult to start once it did the learn, unless there's also a routine in the ecu to ignore the trim value if it fails to start or something....

 

Regarding priming the fuel system I think the previous poster was saying that he would bump the key a couple of times to rotate the engine to try to Prime the fuel if I'm not mistaken I reread his post.
Anyway I appreciate all the advice and help and people sticking with me on this thread but unfortunately things have gone from bad to worse but I am making progress. Now the car is still doing the same hot start issue but it is now backfiring profusely. But it will still start if you put the pedal to the floor so that got me thinking okay it has to be flooded....right... I pulled all eight plugs and they were dry as a desert! So now I'm thinking that there is nothing wrong with the fuel system and that is ignition timing related sooooo I started looking around in the engine bay and I can't believe no one has suggested it and I completely forgot about them. These are the little gizmos under the plastic cover next to each coil. Ferrari calls them the Power Module aka Ignition Control Module aka a Trigger. Unbelievably if you Google in general terms what the symptoms of a bad ignition control module you will see almost every one of my symptoms difficult start hot start issues backfiring rough idle etc etc etc! Please do not confuse these with the large boxes behind each seat which is the Ignition/Supply Control System AKA Engine Control Module. Anyway there's certainly cheap enough under 50 bucks I've got them ordered they'll be here Friday I'm just going to replace them on principal but I have very, very high hopes. Part # 0227100200
The reason being my outboard boat engine gave me the same problems this summer and it turned out to be what is called an ignition control module AKA trigger which controls timing of spark. I will absolutely report back my findings but I'm not going to mess with the fuel system anymore I now believe the problem is timing.

 

Yes, it is possible that the ignition "Power Modules" are somewhat playing up when hot. These modules do not control the ignition timing, only switch the ignition coils on and off (electronic switches, equivalent to old school contact points). The ignition timing is controlled by the engine ECUs (the large boxes behind the seats).

I have not experienced electronic ignition switching modules playing up when hot (only experienced their sudden complete failure) but I did have a couple of cases on my other cars where the engine would start misfiring and die when its ignition coil heated-up. It would not restart immediately but after some half an hour when the ignition coil cooled down a bit. Pouring cold water over the coil also helped.

So give it a try with new ignition modules but be prepared to also replace the ignition coils. Luckily, the coils are used by many other cars and are not very expensive. Here are the cross references for both, ignition coils and ignition modules:

Image Unavailable, Please Login

You can get the "feel" of the coil prices here: Spareto

Image Unavailable, Please Login

 

Great info. Thank you. So the ignition control modules will actually be here today so I'll test them if that doesn't work we'll go with a new set of Bosch coils. If that doesn't work I guess I might be looking at one or both ECUs. Just curious if one or both ecu's is bad would it recognize itself as bad and throw any kind of code? What are the options here is there a repair service anywhere? Or do you take a chance on eBay for a thousand bucks each?

 

Things have gone from bad to worse switched out the ignition control modules switched out the throttle body position sensors no difference at all whatsoever and in fact things are actually worse it will start up fine perfectly in the morning when cold but when you restart it now will not even start even when putting the pedal to the floor it just backfires and sputters..... even when the engine is cold immediately after that first initial start it's just ridiculous! I'm just about ready to flatbed this thing down to Tim Stanford Ferrari in Fort Lauderdale. This will be the first time in 20 years of Ferrari ownership that I've had to take it to a shop it's painful

 

You don't want to have at least one more try with new ignition coils?

 

Well I absolutely appreciate this thread still being alive clinging to life! So I've got some new information. It starts up fine ice cold in the morning but will not restart once it warms up even if you put the pedal to the floor it just backfires and I don't want to blow a gasket or damage something these backfires are unbelievably violent! But I do have new information I bought an infrared gun and my driver side cat flange is running around 270 deg and the passenger side cats are only 170 deg! I believe this is evidence that there is an ignition problem on the passenger side I'm going to continue researching this get back under the car check my crankshaft position sensor for that sade and check the wiring for any faults or anything obvious and I will definitely report back. I did for the heck of it swap ECU from drivers to passengers side and that made no difference. I also performed my fuel pressure test and I was right at 55 on the passenger and approximately 50 on the drivers. I am planning on replacing the coils but for a quick test I'm going to switch driver side to passenger side and see what happens I will definitely report back

 

When car is hot and not starting will you humor me and spray some starter fluid in the intake opening behind your head and the start car and report back here.

 

Yes sir I did as you said. And surprisingly it actually did start but then when I turned it off and tried to restart it backfired again horrifically and in fact I'm no longer going to put the pedal to the floor when starting because I'm afraid these backfires are going to damage something.
Anxious to hear your response. Have two new coils coming Sunday Bosch

 

So it will start on command if you use starter spray. You can repeat that? Your problem is electrical. We battled these ghosts almost from delivery! Let's see if we can prove it? There is a round connector from the FI harness that 3/4 turn locks into a female near the oil filter. Get a poker and bent the living fu8k out of the pins so when reassembled you can guarantee a decent contact as the male and female pins scrape corrosion off each other and contact.

There is another round connector driver left at about the rear shock tower. Do the same thing with that connector. Now start car tell me what happens? Let's see if we get lucky.

 

First off I am so desperate I'll try anything and I appreciate your help. Yes there is a right connector and left connector, round, for the injection system right next to the oil filter and as a matter of fact ironically the left hand side was corroded I've cleaned them as best I can but I will definitely try spreading the pins that is a great idea I'll do it on both. I'm afraid I'm not aware of the one near the shock Tower? Probably won't get to this till tomorrow or my wife will kill me!

 

I don't have a 348 in front of me. I could be confusing a different model with round connector by shock tower behind and sort of under. My memory is not good anymore.

 

It's a circular 9 pin connector made of plastic. Here's a modified one...

Image Unavailable, Please Login

Just near the rearmost point of the back window.

Miro @m.stojanovic regularly posts a pinout of the plug. Later models have more robust rectangular plugs, but I don't think yours is late enough.

I can't think of anything on this plug which would produce your issue though. Alternator?

Image Unavailable, Please Login

Also known as plug 115.

Coolant temp is for the instrument panel gauge only

 

Yes sir I think you're right that pin connector doesn't really have any relation to my problems however Fat Billy's suggestion of spreading the pins on the connectors next to the oil filter aka the injector harness is an excellent one! I'm going to do both harnesses right and left hopefully tomorrow and will definitely positively report back. I think I'm getting close. Here are a few service notes in random order.
First of all I'm no longer taking the car on test drives I'm merely letting it warm up in the garage up to operating temp and waiting for two fan Cycles to come on to make sure the engine is at operating temp.
And by doing so the clutch pumpkin cover never even gets barely hot to the touch this way I'm 100% sure that this starting issue is not related to the clutch voith.
When I first started this Odyssey I had a slew of check engine lights not knowing if some were old or some were new but all are gone and or have been corrected. The check engine light system is a little tricky to learn a lot like the blinking spaceship on the ET but once you've done it a few times it becomes very easy and it's actually a pretty impressive system.
I do have new Bosch clutch coils coming Sunday and I'm going to change them just on principal.
And again to reiterate my fuel test showed 55 PSI on the passenger side and 50 on the drivers so fuel pumps seem to be working well I don't think a 5 lb difference on a 33 year old car is a big deal.

 

The fuel pressure is controlled mainly by the FPRs and "trimmed" by the intake vacuum (higher vacuum, lower pressure) so the difference you are having could be due to some difference/tolerance in the (cheap) FPRs you are using at the moment or due to somewhat different intake vacuum LH to RH you may be having. It could also be due to your RH fuel pump being unable to deliver pressure higher than the FPR pressure. Anyhow, not critical for the diagnostics you are performing, unless you measured the mentioned difference only soon after starting a cold engine and not also later after the engine has run for some time.

The reason why I mentioned checking the fuel pressure after the engine has run (idled) for some time is because I had a case on my 348 that the engine would start fine but, after 3-5 min. of idling, it would display the CEL on one bank and start running uneven. As I (luckily) had fuel pressure gauges installed (pics below, 3.0 Bar fuel system), I could see immediately that the fuel pressure was initially equal L & R but, after some time of idling, the pressure at one bank would start dropping from 42 psi down to ~ 20 psi. I ran the pumps "manually" and could hear that the pump for the offending side was making strange noises.

Image Unavailable, Please Login

Image Unavailable, Please Login

Image Unavailable, Please Login

Image Unavailable, Please Login

 

Yes, bad contacts in this connector will not affect starting and running of the engine unless the bad contact is on the thick white wire (Pin 8) which goes to the starter solenoid. However, this will cause no cranking (turn key to "start" - nothing).

 

Hmmmm. What did you do to solve this problem? The reason I ask is the more troubleshooting I do the more stuff I keep finding. So my driver's side PSI is 50 and when I shut the engine off it drops to about 25 and then very very slowly will bleed off pressure to zero. The passenger side however is 55 while running but when I shut the engine off it immediately and I mean immediately goes to zero which would indicate a bad check valve in the fuel pump. I can't even wrap my head around if this is part of my problem or just an unrelated anomaly

 

Hot starting , have you tried just turning the ignition on for 20 secs then starting ?

To prime up the fuel regulator (s) . Thinking like a carb F car if left for a while you have to prime the bowls in the carbs .

 

Unfortunately on the 348 model the fuel pumps do not engage until the engine begins to rotate and the crank sensors become activated. Although as soon as you bump the key the pressure immediately shoots to 55 PSI instantaneously so I do not believe that is an issue.