348 Hot Start Issue: I Have Tried Everything!

Strong work.

 

Just send them all off to Mr.Injector. Just did all 12 of mine and they come back with new parts, painted, and a before and after report. His turn around time to Northern Idaho was a week total.

Mine, before and after. Will reassemble this week back on the car.

https://www.mrinjector.us/
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In addition to the slots (windows) on the top timing belt covers, quick check of the cam timing can also be made by looking at the factory assembly marks on the camshaft plugs and the rear cam bearing caps. I am not 100% sure that these marks are indicators of the cam timing but I have read/heard that they are (for quick verification during assembly). The picture below shows a "chisel" mark on the cam cap and there should be a similar mark on the cam aluminium plug. No mark on the plug is seen on this picture because I have taken it after installing a new plug but it can be seen on the second picture showing my original factory plug I removed from this camshaft.

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Original plug with a mark on it:

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Sorry it's been a few days had company from out of town and haven't been able to work on the car regularly but have some significant Improvement. First of all I figured out the flooding on bank 1-4. I cannot believe I overlooked it but somehow the 1-4 bank FPR started leaking through the vacuum tube. I checked it a million times and it must have started leaking and then started catastrophically leaking. I replaced it and bank 5-8 just on principle and the car actually runs better than it ever has.
Having said that the initial hot start problem still persists! All of the crazy codes have gone away with the exception of two. I'm getting 4121 Cat Ecu on Bank 5-8 and I just have it unplugged for now temporarily but I'm getting code 4114 TDC recognition pretty consistently on Bank 5-8 and occasionally on 1-4 with the car running. In my mind this is the Smoking Gun hopefully. Hoping someone knows what this might mean? I can clear the code and take the car for a test drive and with the car STILL running these codes are still coming up pretty consistently. Not sure what could be causing it. I currently have the original CPS's in but I have tried swapping positions and I've also tried the Kia sensors with no difference at all whatsoever. It makes me wonder how important the Gap is on the sensors it is a really wide range on the tolerance .35mm to .90mm. Is it better to have the tolerance tight or loose? Do both sensors need to be identical or near identical in tolerance? Right now I'm set near the middle at .5 mm. Greatly appreciate any advice!

 

The Crankshaft Position Sensor (CPS) has two functions:

1. Generates a signal (waveform) induced by the gear wheel's "regular" teeth passing the sensor. This signal represents the engine RPM.

2. Generates another signal ("irregularity" within the RPM waveform with higher amplitude and a longer period) induced by the segment on the gear wheel spanning over 4 teeth in which 2 teeth are "missing". The point (vertical red line) at the end of the irregularity, shown on the drawing below, is recognised by the engine ECU as the point from which to calculate the rotational point representing the TDC. The TDC is at 114 deg. from the point at the end of the "irregularity". The engine ECU calculates the TDC using the information on the engine speed (rpm) obtained from the "regular" waveform.
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Definition of code 4114 states "TDC control unit recognition" or "Internal recognition inside the TDC control unit" (translated from Italian). This appears to refer to recognition of the "irregularity" (its end point) which is the reference point for calculation of the TDC. The "TDC control unit" can only mean the engine ECU. Why the term "TDC control unit" is used and not the term "engine ECU" is not clear. Perhaps (not unusual in the Ferrari manuals) the wording is copied and pasted from some earlier manuals for Ferrari models in which the ignition is not controlled by the engine ECU but by a separate ignition module which uses the signal from the CPS.

Anyhow, it seems that code 4114, displayed without code 1121 accompanying it, does not mean any fault in the CPS or its wiring, otherwise code 1121 would also be displayed and the engine bank would not even fire. It should be noted that, if the code reading is performed with the engine not running, both mentioned codes may be displayed in which case it would not mean any actual faults. Having these codes when reading is done with the engine running would mean faults somewhere.

So, having code 4114 alone, could mean (judging by the code definition) problem inside the engine ECU, i.e. inability of the ECU's electronics to recognise the "irregularity" in the signal coming from the CPS and, consequently, inability to establish the TDC position. This is, at present, just a possibility and needs further testing/investigation.

You should now swap the engine ECUs and see if code 4114 will then consistently show on Bank 1-4 and occasionally on Bank 5-8.

On the CPS gap, anything between 0.35 and 0.90 mm will be fine (I would go for the mid-value) but both sides should be as close as practicable to the adopted gap (for smoother engine idle and running). And non-magnetic feeler gauge should be used to avoid false reading.

 

The drawing below shows another presentation of TDC reference point (the red line, at the end of the "missing teeth" segment) and the actual TDC position. When the point on the gear wheel marked with the red line passes the CPS, the engine ECU starts counting the oncoming teeth and, when the tooth representing 114 deg. later passes the CPS, the engine ECU "knows" that that point represents the TDC (of pistons 1 & 4 or 5 & 8 depending on which CPS we are looking at). I have marked the point that represents the TDC by the blue line. Based on scaling from the drawing, it appears that one tooth+valley represents 6 deg. of rotation so 19 x 6 = 114 deg. So, if your engine ECU has forgotten how to count to 20, you'll have a problem.

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Outstanding information as usual! Really appreciate it. I have swapped ecus and it still does seem to occur more frequently on 5-8 rather than 1-4 so it does not appear to be ECU related. I'm currently running the original crankshaft position sensors which appear to be in perfect condition I am going to try swapping them to see what happens. I also just ordered a brass feeler gauge and I'm going to experiment with different settings starting with adjusting them more to the minimum of .35mm and then compare that to more towards the maximum of .90mm and maybe even in between just for comparative purposes. It is astonishing that there's such a huge allowable tolerance .35 to .90 is quite a large variation in my mind. Although right now both are approximately .50m. Also going to rotate the crankshaft and inspect the toothed wheel for any debris or possible damage to the teeth to rule that out. Will report back for sure

 

You can try with the CPS gaps at 0.4 mm but I would not go any smaller. I last set the CPS (Kia) gaps at 0.6 mm and the engine starts perfectly, hot or cold, and runs very well.

The amount of gap is not critical because the strength of the electrical induction in the CPS, caused by the passing teeth, will not vary much between 0.35 and 0.90 mm gap. And the engine ECU is more looking at the frequency of the CPS signal, not really at the strength/voltage of it (as long as it is above certain minimum).

If you still get 4114 after you have performed the actions you mentioned in your post above, the suspect could then be some deterioration of the wiring between the CPSs and the engine ECUs weakening the CPS signals. There could be some resistance developed along the CPS signal paths due to corrosion at the connector terminals, at the CPSs and/or at the engine ECUs. I would first make sure that the connector pins at the loom side connectors for the CPSs are good. These connectors are exposed to heat, oil, dirt etc. which could affect the quality of connection.

 

Okay new information to share. First of all I purchased a used exhaust ECU from eBay and code 4121 is gone permanently and I officially have NO codes popping up on a regular basis.
Took the car on several spirited test drives but the hot start problem persists after shutting down and trying to restart 5 or 10 minutes later.
Although code 4114 was coming up on Bank 5 through 8 regularly and bank 1 through 4 occasionally now it is only popping up "occasionally" on 1-4 during the hot start problem. Since then I experimented with different crankshaft position sensor tolerances ranging from 0.35mm to .90mm and I currently have both set at 0.40mm and will retest tomorrow and report back. All my connections are clean, oil free and corrosion free. Pulled all rubber boots back and connections look pristine.
There really isn't much left to do. I guess at this point I think I'm going to pull all 8 injectors and send them off for cleaning and testing. But again will report back test result with the new CPS tolerances at 40mm

 

I refer you back to thread #26 . ( page 2 )

Hot start is very difficult to reproduce while working on the car .

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I do like those fprs quite nice! But I've got two brand new OEM style 3.8 bar fprs and I just don't want to go adding aftermarket stuff to the car until I figure this hot start problem out. I believe the next thing I'm going to do is send off the injectors for cleaning checking and service it should be done on principal anyway after all they are 33 years old. Will definitely report back.
I absolutely appreciate all the help and advice up to this point.

 

Just a few thoughts:
Theoretically the metal of the CPS will expand under (engine) heat, and the gap should even decrease to a little less than 0.4, which is already small.
So I would rather try a larger gap, you never know.
Having the injectors cleaned and refreshed is always a good idea. You could also try to swap the bank1 injectors to the bank 2, see if the incidental code follows.
If not, the injectors will not be the problem. (or the code is not related to the problem).
I forgot if you already swapped the MAFs, as they are a known problem source. A MAF can read a percentage off, which will not be noticable during driving, but more during starting.
Also, did you do a smoke test on the vacuum lines? When starting the vacuum is the largest (low rpm), and a small leak will then be more of effect than during driving with higher rpm's and less or no vaccuum.
On my 550 I had several very small leakes, which when fixed let the long term fuel trims fall back into the accepted values. It still did not fix my high long term fuel trim on one bank, but the ECU could compensate it into acceptable territory.

 

I wouldn't worry about going to the minimum gap specified by Ferrari as it has, most likely, already accounted for any change to the gap due to material expansion caused by heat. It is also possible that the CPS gap actually increases with heat because the expansion of the engine material (aluminium, having rather high thermal expansion coefficient), to which the CPS is attached, may move the CPSs away from the gear wheel. Anyhow, we are talking about changes to the CPS gap with temperature of no more than 0.0001 mm (or thereabouts).

 

All excellent advice. I'm going to stick with 0.4 on the CPS. I have tried swapping the MAF and the code does not follow.. I am going to do a DIY injector clean with carburetor cleaner, tubing, 12 volt leads.....old school..... and I will swap them Just for kicks to see what happens from bank to bank. I just don't want to send them off just yet I want to be able to keep troubleshooting cuz I've got the time right now. Will definitely report back ASAP. Did not do a smoke test but pretty confident there are no vacuum leaks I've thoroughly thoroughly checked using starting fluid technique.

 

Well I know I'm going to catch hell for this but here is my DIY attempt at cleaning the injectors. They all ohmed out perfectly, but some of them sounded a little mushy on the opening click so I rigged up some tubing and a can of carb cleaner and cleaned them out! Hope to have them installed and retest tomorrow. Will definitely report back.
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Awesome

 

You need mimic the cars fuel pressure(s) . .

 

I bought one of these (AUTOOL CT150 Ultrasonic Fuel Injector Cleaner Tester Nozzle Cleaning Machine | eBay), not bad.
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That's an awesome machine. What kind of solvent or solution does it use?
Anyway I cleaned all eight injectors amd tested the car the damn hot start problems still persists
.... it's just unbelievable. No more codes at all ever and it will consistently restart if I put the pedal to the floor with a few tries. There really is not much else left to check or
do(

 

You have to buy the special cleaning / flow testing fluid separately. With regard to your injectors, to eliminate the possibility that some of them might be leaking, you will need to either send them to a specialist shop or get one of these machines and do the leakage test yourself.

 

I have been following this thread. I have a 94 spider, hot start issue.
I’m assuming POLO35 still has the hot start issue.
I haven’t done anything other than FPRs.
I was gonna install a relay for the starter in attempt to increase voltage.