Of late, every time that I take the car out it has has no power, and feels like it it is limp mode even though there are no warning lights on the dash. The good thing about this is that the problem is happening every time and from cold start.

I therefore arranged to get the car to Racing Red for its annual service and rego check hoping that if the error is persistent it could be diagnosed more easily. So, I powered the car up and it still had the issue. I limped the car across town to Racing Red, which is extremely challenging given the absolute lack of power, but the issue remained throughout the drive. As I passed through the last set of light, about 100  metres before the turn off to Racing Red, guess what happened? The fault cleared itself and I was back to full power. It is as though the car knew it was going to the doctor and was now ‘all good’!

Luckily for me Sal reported that the car exhibited exactly the same symptoms the following morning for him. Finally! Someone else was able to see the problem. He has tried some troubleshooting, including changing the fuel pump but the problem remains. He believes that it is a wiring issue and is now troubleshooting that.

I can tell you that it was very ‘botty-clenching’ to limp the car to Racing Red but it is good news that Sal can at least see the problem and troubleshoot. Fingers crossed, that it is an easy fix. I’ll let you know.

Went out for a drive today and upon return the ‘chuggs’ returned after returning to the car after parking up for a few minutes. No refueling this time, just a stop, wait a few minutes and return. I tried stopping and restarting the car but that made no difference.

This is the 4 or so drive and just under 3 months since the last occurence of the ‘chuggs’. So I thought I’d throw some AI at the issue and see what it says

The 1996 Ferrari F355 GTS manual is a celebrated vehicle, renowned for its exceptional performance and the engaging experience offered by its manual transmission. This report aims to analyze the intermittent engine issues recently developed in the user’s vehicle, providing a detailed troubleshooting guide based on available information.

The reported symptoms include difficulty starting, a noticeable lack of power, and a sensation of the engine being throttled. These issues manifest primarily after the engine has reached its operating temperature, particularly following a full refueling after a long drive. It is noted that the user has already taken the initiative to address the problem by cleaning the fuel injectors and replacing the spark plugs; however, the issue persists, and no warning lights have illuminated on the dashboard.

Analysis of Symptoms

The combination of symptoms presented by the user offers several clues regarding the potential underlying causes of the engine issues.

The intermittent nature of the problem suggests that the fault is not a complete and permanent failure of a major system component. Instead, it likely points to a condition-dependent malfunction that occurs under specific circumstances. This could involve a sensor providing inaccurate data only when certain parameters are met, a mechanical component experiencing temporary binding or malfunction due to heat, or an electrical connection that degrades under thermal stress.

The fact that the problem arises after the engine is hot is a significant indicator. Heat can profoundly affect the performance of various automotive components. For instance, increased temperatures can alter the resistance of electrical circuits, change the viscosity of fluids such as fuel, and cause mechanical parts to expand, potentially leading to binding or altered clearances. This symptom strongly suggests that the component or system at fault is sensitive to thermal changes, with its performance diminishing as the temperature increases.

The reported link between the issue and refueling, especially after a long drive, is a critical piece of information. Refueling can impact the fuel system in several ways. Introducing cooler fuel into a hot tank can lead to increased fuel vaporization and a rise in tank pressure. If the fuel tank venting system is not functioning correctly, this pressure might not be regulated as intended, potentially affecting the fuel pump’s ability to deliver fuel consistently. Alternatively, a fuel pump that is already operating at a higher temperature after a long drive might be further stressed by the increased volume and potential temperature changes associated with a full tank of fuel.

The “throttling sensation” described by the user implies that the engine is not producing the expected power in response to the accelerator pedal input. This feeling of restriction could stem from an insufficient supply of air or fuel reaching the combustion chambers, an issue with the timing of the ignition or fuel injection events, or a signal from a faulty sensor that is causing the engine control unit (ECU) to deliberately limit engine output.

Finally, the absence of any warning lights on the dashboard indicates that the ECU has not detected a fault severe enough or persistent enough to trigger the malfunction indicator lamp. However, this does not rule out the possibility of underlying issues. Some intermittent problems, sensor readings that are slightly outside the normal range but not critically so, or malfunctions in systems not directly related to emissions control might not immediately activate the check engine light. Therefore, further investigation beyond relying solely on dashboard warnings is necessary.

Potential Causes and Troubleshooting Guide

Based on the user’s description and the research material, several potential causes could be contributing to the intermittent engine issues. A systematic approach to troubleshooting, starting with the most likely scenarios, is recommended.

Fuel System Investigation

Given the correlation with refueling after a hot drive, the fuel system warrants a thorough initial investigation.

Fuel Tank Venting System

The fuel tank venting system plays a vital role in maintaining the correct pressure within the fuel tank. As fuel is consumed, the system allows air to enter, and as fuel vaporizes due to heat, the system allows these vapors to be directed to the charcoal canister, preventing excessive pressure buildup or the formation of a vacuum. A blockage or malfunction in this system can have significant effects on fuel delivery.

If the vent is obstructed, a vacuum can form as fuel is used, hindering the fuel pump’s ability to draw fuel, especially after a long drive when a significant amount of fuel might have been consumed. Upon refueling, the introduction of a large volume of fuel into a hot tank can increase vapor production. If the venting system is already compromised, it might not be able to handle this increased vapor, leading to pressure imbalances that affect fuel delivery, particularly when the engine is hot and demanding more fuel.

One user on a Ferrari forum reported resolving “chugging” issues after large refuels by tightening the fuel cap more securely. While this is anecdotal, it suggests that even a seemingly minor issue like a slightly loose fuel cap could interact with a marginal venting system, causing pressure irregularities that impact engine performance.

The user should begin by visually inspecting all fuel tank vent lines for any signs of kinks, blockages, or damage. These lines are designed to allow the tank to breathe, and any obstruction can disrupt this process. Additionally, the fuel cap itself should be examined to ensure the seal is intact and functioning correctly. A faulty or improperly sealed fuel cap can also contribute to pressure imbalances within the tank.

Another component to consider is the fuel tank rollover valve. This safety feature prevents fuel from spilling in the event of an accident. However, if this valve malfunctions, it could intermittently restrict the venting of the fuel tank, particularly when the tank is full or under high temperatures. While less common, a faulty rollover valve could explain the symptoms reported by the user.

Fuel Pump and Filter

The fuel pump is responsible for delivering a constant supply of fuel to the engine at the required pressure. Over time, fuel pumps can become less efficient, especially when subjected to high temperatures for extended periods, such as during a long drive. A pump that is nearing the end of its lifespan might struggle to maintain adequate fuel pressure and flow when hot, particularly when also having to draw fuel from a full tank, which can present a greater load.

One forum discussion detailed a fuel pump failure in a 1996 F355 due to the degradation of internal rubber components after the car was left unused for an extended period, highlighting the potential for age-related issues with these components.

While the user has cleaned the fuel injectors, a partially clogged fuel filter or the presence of contaminants within the fuel tank could still restrict fuel flow to the engine. Even small amounts of debris can impede fuel delivery, especially when the fuel is hot and its viscosity might be slightly higher. Although cleaning the injectors implies the fuel has passed through the filter, it is possible that the filter itself is becoming restricted or that there is sediment in the fuel tank that is intermittently being drawn into the fuel lines.

Another user reported a case where fuel “separated” and damaged rubber components within the fuel pump assembly, leading to fuel starvation. While this occurred after a prolonged period of inactivity, it serves as a reminder that fuel quality and the condition of the rubber components within the fuel system can impact performance.

A discussion on a Ferrari forum mentioned “fuel pressure loss occurring after engine shut down” and suggested “leaking injectors flooding the cylinders” as a possible cause for hard starting when hot. While the user reports difficulty starting, the symptom of low power could also be related to insufficient fuel pressure during engine operation, especially under load.

To investigate the fuel pump and filter, the user should consider checking the fuel pressure at the fuel rail. This test should ideally be performed when the engine is cold and again when it is hot and exhibiting the symptoms. A fuel pressure gauge can be connected to the test port on the fuel rail to measure the pressure. Readings that are significantly below the manufacturer’s specifications would indicate a potential issue with the fuel pump or a restriction in the fuel filter or fuel lines.

Air Intake System Examination

Problems within the air intake system can also lead to the symptoms described by the user. The Mass Air Flow (MAF) sensor and the Throttle Position Sensor (TPS) are key components in this system that could be contributing to the issue.

Mass Air Flow (MAF) Sensor

The Mass Air Flow (MAF) sensor measures the volume and density of air entering the engine. This information is crucial for the ECU to calculate the precise amount of fuel to inject for optimal combustion. If the MAF sensor is providing inaccurate readings, the air-fuel mixture will be incorrect, leading to symptoms such as low power, difficulty starting, and a feeling of the engine being throttled. Notably, snippet 65 indicates that the 1996 Ferrari F355, likely equipped with the Motronic 5.2 engine management system, utilizes a single MAF sensor.

A MAF sensor can malfunction intermittently, particularly when it gets hot, without necessarily triggering the check engine light. The ECU might only register a fault if the sensor readings are completely outside of an acceptable range. Slightly inaccurate or erratic readings might still cause noticeable performance problems without being severe enough to set a diagnostic trouble code. A real-world example from a Ferrari engine rebuild project identified a faulty MAF sensor as a contributing factor, suggesting that MAF sensor failure is a known issue in the F355 model.

To test the MAF sensor, the user can use a multimeter to measure its voltage output while the engine is running at idle and as the engine speed is increased. A properly functioning MAF sensor should exhibit a steady increase in voltage as the airflow into the engine increases. Erratic voltage readings or a lack of change in voltage with varying engine speed would indicate a potential problem with the sensor. Several online resources and videos provide detailed instructions on how to perform this test using a multimeter.

Additionally, a dirty MAF sensor can sometimes cause inaccurate readings. The sensor element can become contaminated with dust, oil, or other debris, which can impede its ability to measure airflow accurately. The user could try cleaning the MAF sensor using a specialized MAF sensor cleaner, which is available at most auto parts stores. It is essential to follow the instructions on the cleaner carefully and to avoid physically touching the delicate sensor element. Inspecting the wiring harness and connector for any signs of damage or loose connections is also a good practice.

Throttle Position Sensor (TPS)

The Throttle Position Sensor (TPS) monitors the angle of the throttle plate and transmits this information to the ECU. The ECU uses the TPS signal to determine the appropriate amount of fuel to inject and the correct ignition timing based on the driver’s input via the accelerator pedal. An intermittent fault within the TPS can lead to the ECU receiving incorrect information about the throttle position, which could manifest as the “throttling sensation” and low power reported by the user. Snippet 31 lists the F355 GTS as a model that uses a specific TPS, indicating that issues with this sensor are relevant to the vehicle.

To test the TPS, a multimeter can be used to check the voltage output of the sensor as the throttle pedal is slowly pressed and released through its full range of motion. A healthy TPS should produce a smooth and linear increase in voltage as the throttle plate opens. Any sudden jumps, drops, or flat spots in the voltage signal would suggest a fault within the sensor.

Symptoms of a failing TPS can include poor fuel economy, engine rough idling or sudden stalling, startup and acceleration issues, and abrupt bucking or jerking. While the user has not reported all of these symptoms, the startup and acceleration problems, along with the distinct throttling sensation, are consistent with a potential issue with the TPS.

Ignition System Review

Beyond the spark plugs that the user has already replaced, other components within the ignition system could be contributing to the problem, especially considering the symptom of the issue occurring when the engine is hot.

Ignition Coils

The 1996 Ferrari F355 GTS manual is equipped with individual ignition coils for each of its eight cylinders. A heat-sensitive ignition coil can fail intermittently as the engine temperature rises, leading to misfires and a reduction in power. Snippet 7 specifically mentions that changing an ignition coil resolved a similar power loss issue in another F355.

When an ignition coil begins to fail due to heat, its internal resistance can increase, or it can experience an electrical breakdown, resulting in a weak or absent spark in the affected cylinder. This would lead to incomplete combustion, causing a noticeable drop in engine power and potentially difficulty starting. A forum discussion regarding a Ferrari 355 that developed a misfire as the engine heated up also pointed to the ignition coils as a likely cause, mirroring the user’s experience.

While directly testing ignition coils under load requires specialized equipment, the user could attempt to check the resistance of each coil when the engine is cold and again when it is hot and exhibiting the symptoms. Significant differences in resistance readings between the coils, or readings that deviate from the manufacturer’s specifications, could indicate a faulty coil.

Crankshaft Position Sensor (CPS)

The Crankshaft Position Sensor (CPS) plays a critical role in the engine management system by monitoring the rotational speed and position of the crankshaft. This information is essential for the ECU to accurately time the ignition and fuel injection events. An intermittent issue with the CPS, particularly when it becomes hot, can lead to the ECU receiving incorrect data, resulting in poor starting, low power, and potentially engine stalling. Snippet 37 confirms that the F355 BERLINETTA and GTS models utilize a specific crankshaft position sensor.

Although one snippet mentions that a failing CPS might initially show symptoms when the engine is cold, it is also known that heat can cause these sensors to malfunction. The user should inspect the CPS for any visible signs of damage, such as cracks or melting, and check the wiring and connector for any looseness or corrosion. If access and equipment permit, the signal output of the CPS can be tested using an oscilloscope while the engine is running or during attempted starts when the engine is hot. An intermittent loss of signal or an erratic signal pattern would indicate a problem with the sensor.

Other Potential Factors

Flywheel Issues

Snippets 5 and 5 discuss a known issue in Ferrari F355 models (and some earlier 348s) related to the flywheel. A lack of grease in the flywheel unit can cause hot starting problems. The ECU detects an imbalance through a vibration sensor and might prevent the engine from starting. While the user reports low power after starting, and these snippets primarily focus on starting difficulties, it is worth noting this potential issue.

A key indicator of this problem is often grease or oil dripping from a small grill located under the flywheel housing at the rear of the engine. The user should inspect this area for any signs of leakage. While this issue is more directly linked to starting problems, a significant flywheel imbalance could potentially contribute to overall engine performance issues, though less likely to be the primary cause of low power after the engine has started.

Diagnostic Procedures and Tools

To effectively troubleshoot the intermittent engine issues, the user should consider the following diagnostic procedures and tools.

Checking for Stored Error Codes

Even though the check engine light is not currently illuminated, the engine control unit (ECU) might have stored diagnostic trouble codes (DTCs) that could provide valuable clues. These codes are logged when the ECU detects a malfunction, even if the issue is intermittent or does not meet the threshold for activating the warning light.

The 1996 Ferrari F355 GTS manual, depending on its original market, might have a Ferrari-specific 3-pin diagnostic port located near the engine ECU or, in some instances, a standard 16-pin OBD2 connector. Research suggests that European models might primarily use the 3-pin connector.

To retrieve any stored codes, the user will likely need either a Ferrari-specific diagnostic tool (such as an SD1, SD2, or SD3) or an adapter cable that allows a generic OBD2 code reader to be connected to the 3-pin Ferrari port. Snippets 41 and 41 provide information on the pinout for connecting a generic OBD reader to the 3-pin connector.

Examples from Ferrari forums show owners successfully using diagnostic tools like the SD2 and Autel AP200 to read and clear error codes. Checking for stored error codes should be a priority, as it can significantly narrow down the potential causes of the problem.

Importance of a Workshop Manual

Consulting the official Ferrari F355 workshop manual is highly recommended for detailed diagnostic procedures, wiring diagrams, component specifications, and troubleshooting guides. This manual serves as the definitive technical resource for the vehicle, providing Ferrari’s specific instructions for diagnosing and repairing various issues.

The workshop manual for the F355 is often available in PDF format, making it easily searchable and accessible. Having access to this manual can greatly assist the user or their chosen mechanic in accurately diagnosing the problem and ensuring that any repairs are performed correctly.

Technical Service Bulletins and Recalls

The user should investigate whether Ferrari has issued any Technical Service Bulletins (TSBs) or recalls for the 1996 F355 GTS manual that might be relevant to the described engine performance problems. TSBs often address common issues reported by owners and provide specific diagnostic and repair procedures. Recalls typically involve safety-related defects that Ferrari will rectify free of charge.

Research indicates that there was a recall for F355 models related to improperly installed fuel line clamps that could lead to fuel leaks and fires. While this specific recall is not directly related to the user’s symptoms, it highlights the importance of ensuring that the vehicle has had all applicable recalls performed. Additionally, snippets mention a potential fuel block recall affecting earlier models which might also be relevant to the 355.

Checking with a Ferrari dealer or online resources for any outstanding TSBs or recalls for the user’s specific vehicle identification number (VIN) is a prudent step. 

Tables

Potential Causes and Initial Troubleshooting Steps

Potential Cause	Possible Symptoms	Initial Troubleshooting Steps
Fuel Tank Venting	Intermittent starting/low power after hot engine and refueling, especially full refuel.	Inspect vent lines for kinks/blockages, check fuel cap seal, consider rollover valve function.
Fuel Pump	Intermittent starting/low power when hot, potentially worse with a full tank.	Check fuel pressure when cold and hot, listen for unusual pump noises.
Fuel Filter/Contamination	Intermittent low power, though less directly linked to hot starts after refueling since injectors were cleaned.	Consider fuel quality and potential for tank contamination.
MAF Sensor	Intermittent low power, poor starting, throttling sensation, no warning lights.	Test MAF voltage output at idle and with increasing RPM using a multimeter, clean the sensor, check wiring.
TPS Sensor	Throttling sensation, low power, intermittent starting issues, no warning lights.	Test TPS voltage output for smooth changes as throttle is opened and closed using a multimeter.
Ignition Coils	Intermittent low power, poor starting, especially when hot.	Check coil resistance when cold and hot (if possible), look for signs of damage.
CPS Sensor	Intermittent starting/low power, especially when hot.	Check CPS for damage/loose connections, consider oscilloscope testing of signal output if available.
Flywheel	Hot starting problems (primary symptom from research), potential for associated vibrations.	Check for grease/oil dripping from the flywheel housing at the rear of the engine, listen for unusual starting noises or vibrations.

After refuelling the car a few weeks ago and having now gone on a few drives I’m happy to report that the ‘chuggs’ have not resurfaced. However, I do expect them to return when I refuel next.

I do notice a slight hesitation and ‘glugginess’ when I start the car but it its only momentary.

Let’s see what happens on the next refill.

I really hoped that the new fuel cap seal would have solved my issues and it certainly did seem to while the car was at the mechanic. Unfortunately, after a long drive and refuel, the problem is still present.

Car started fine cold and drove for about 1.5 hours on the freeway without any issues. Arrived back, stopped for fuel. Fuel cap really, really hard to remove. I thought I was going to have to drive away and return when I had unseized it but I did manage to get the cap off finally.

After putting about 3/4 of a tank of fuel in I returns, turned the key and the ‘chuggs’ returned. The ‘1-4 Check engine’ light displayed for a minute or two and car definitely had a loss of power.

I drove off without attempting a restart to see if the issues would clear itself as has happened before, but no. I returned home, stopped the car to shuffle things around and do a spot of cleaning inside the car.

When I restarted that car a few minutes later it seems good again! I parked the car up after connecting the trickle charger.

In summary then, coolish day (20 ish degrees C), early morning, long drive (1.5 hrs), 3/4 of a tank of fuel and the ‘chuggs’ returned. Driving did not clear the issue but car seemed to have more power than it did before when it got the ‘chuggs’. A stop, wait a few minutes and restart seemed to return it to normal.

Given that the car has been refuelled it will interesting to see whether when I take it out next I again get the ‘chuggs’ or is it now only upon refuelling? I have drive the car since it has been returned without issues but this is the first refuelling I have done after a long drive aka, what I was doing before when I got the ‘chuggs’.

Annoying that it was tested under similar conditions by the mechanic and no fault found but as as soon as I get it back, bamm, same problem.

This one’s not over yet it seems!

Here’s a video of the final test of the F355 by the mechanic before picking it up recently. No sign of the ‘chuggs’ which is good news.

As yet I am not fully convinced that issue has been totally resolved. I’ll still need to drive a few times and see. It will be interesting to see whether after a fill up on a long drive the problem does not re-occur. Time will tell.

https://www.youtube.com/shorts/eOm8Pj2CCXk

After asking around I found another mechanic who was willing to take on the project of solving the ‘chuggs’. I therefore picked the car up from Ferrari and drove it to him.

 

Having described the issues he went straight to the seal inside the petrol cap. Took one look and said that it wasn’t the right seal and that may have been contributing to the issues. I can tell you that I will be both extremely happy and extremely annoyed if that does in fact turn out to be the case.

The old (wrong) seal had a metal cap as shown above, whereas the correct seal

is all rubber with no metal parts as shown above.

I left the car with him for a week and he tested it thoroughly using all the processes I encountered that caused the ‘chuggs’. The main one was getting the car hot and then refuelling.

Throughout all the tests the car performed faultlessly and based on that assessment I picked it up and brought it home. Again, without issues. To be honest it started much stronger that it had and drove well on the return trip.

It would seem to me that perhaps the fuel cap seal is just the last (hopefully) in a long line of issues that contributed to the ‘chuggs’. I think the main issue was that the injectors were in fact dribbling prior to a good ultrasonic clean (detailed here). However, getting a variety of things fixed/replaced like the charcoal canister, greasing the mass fly wheel, etc. all contributed to the overall resolution.

So, fingers crossed, the ‘chuggs’ have been solved but I won’t be fully confident until I have driven the car a few times, refuelled and repeated the typical process I saw when the ‘chuggs’ materialised. How many drives/weeks will that be? Not really sure but for now I’m happy to have the car back and be able to drive it again. Let’s hope that indeed the issues have been resolved.