Car does not shift to reverse

gear_systems.jpg

➠Claire: "What causes my Honda Fit Gearbox not to shift in reverse gear? A litre of red🔺 ATF instead of CVT was poured to it and the car has since been shifting well for 5 months."

➠Mike: " This is internal. Using the wrong TF will cause ±three things; poor lubrication, overheating, most crucially transmission failure. The damage might be irreversible even even by flushing the transmission. Suppose you flushed out the wrong fluid, the effects aren't immediate but eventually, because you'll be having a mixture of two TFs, the transmission will need to be rebuilt. 

 Try this, Claire;

Try double shifting, where you have to depress your clutch two times b4 engaging the gear. Note that this is just a temporary means of consoling yourself since your transmission is heading for a full diagnosis. Also, driving with a faulty transmission is a big mistake as it will improve the damage. 

 If the gear lever engages but the car itself doesn't comply, i.e doesn't move backwards, and you can feel that the gear has engaged but loosely with a play, whether the car is on or off, and the same happens or doesn't with the other gears, start by taking a look at the shifter mechanism under the center console. 

 I'd love to think that the Fit uses a cable linkage between the shifter and the transmission, so the end of the cable sheathe loosening could cause what you're observing.

 A minor degree of looseness is always expected because matter such as gears age, wear and stretch, but the Fit has a pretty straightforward shift linkage, so it shouldn't generally be excessive. Now that it is, or it seems excessive, don't try to fix this alone. 

 Give it to a good car Doctor or a specialist with 'Fit' Transmissions. "

➠Claire: "Someone has been suspect faulty clutches. Can the clutches be dead while the car still moves?"

➠Mike: " Yes, you may still be able to drive,  but it will be slow on take offs especially from a stop. However, if it really is a clutches failure, then it should come together with other problems that relate."

➠Claire: Yes, the car is slow on take off and the gearbox makes unusual sounds. What are the other symptoms? 

➠Mike: "Only when the transmission has been removed from the vehicle and completely disassembled can transmission clutch failure be confirmed.

 A slipping transmission is the most common sign of clutch problems. The engine will suddenly race without the vehicle moving faster, most commonly during a gear shift. The clutch plates may wear out and that comes with an incredible smell also due to heat stress. The color of the TF will report if the wear is deep."

How to do a Compression Test for IC Engines

A close look at Infiniti's VC-Turbo variable compression engine

  It is very vital that the petrol/ air mixture in an IC engine is compressed to the correct pressure during the compression stroke for one to have maximum engine performance. 

  The purpose of a compression test is to determine the condition of piston rings and valves without having to dismantle the engine. Worn piston rings and worn valves will lead to compression loss, and as such, this information is part of a necessary trouble shooting process. That said, nevertheless, loss of compression is not only caused by the above two mentioned.

The following is a guide to performing a compression test. 

Note: It is neccessary that the test be done on each and every cylinder of the engine.

1.  Check with your manufacturer’s specification for  correct compression pressure. This is per standard approximation usually between 8-10 Bar for petrol engine & 18-25 Bar for diesel.

2.  Remove  spark plugs (for petrol). Respectively, remove injectors or heater plugs ( for diesel). 

3.  Fit your compression gauge to cylinder head. 

4.   With trottle in maximum, put to open position (petrol engine)or, with ignition isolated, fuel shut off (diesel engine), Crank the engine by the starter motor for 5-6 seconds and note readings. While doing this, ensure that there is no pressure that escapes the system.

5.  If the readings are within manufacturers' specification range, it is therefore an indication that the engine is in good condition. If, though, the reading for one or all cylinders are below  manufacturers' specification, a wet compression test needs to be carried out in order that you determine the cause of compression loss. 

The procedure for a Wet Compression Test is the same as the above with the exception that this time, before the readings are taken, a few squirts of oil are squirted into the cylinder being tested. Some recommend 5 squirts oil and that is reasonable provided the word FEW will have been done justice to. Squirting the oil into the cylinder helps to seal the piston to the cylinder whilst a "process" of a pressure test is being carried out.

The probability of the outcome is one out of three. It is either that;

 1.  The pressure reading is the same as first test; or 

2.  The pressure reading increases from first test to within manufacturer's specification; or 

3.  The  pressure  reading increases slightly but still  below manufacturer's specification. 

These come up with simple corresponding possible explanations: 

If the reading remains the same, loss of compression is due to worn or leaking valves since a sealed piston will not have improved the pressure. 

If the reading on the guage increases, loss of compression is due to worn rings, since the  oil has sealed the piston and prevented loss of compression. 

Thirdly, if the reading increases by a little margin, so little that it still does not meet the standard specification per manufacturer's detailing, then the loss of compression is due to BOTH piston rings and valves. 

Consequently, the engine will require a major overhaul. However, if the compression test indicates that  the valves are the cause for the loss of compression, valve clearance should be checked first against manufacturer's specification because insufficient valve clearance would cause loss of compression when the valves are not seating correctly.

NB: These two compression tests will work as seen for both two stroke and four stroke engines.

If you need this information in PDF format I'll make it available for you on submission of your request in the comment section below or via email or WhatsApp

When does an Engine "Pop"?

Generally, An engine pops when it is improperly tuned. More specifically, in what is often called spitting, backfiring, or coughing, the following would have happened:

1. A spark plug "sparking" when it isn't its turn and the exhaust valve is open. Suppose there is air/fuel mixture that is too rich in the engine cylinder and there is unburned fuel in the exhaust system, cross firing from one spark plug wire to another can occur if they are touching each other. When this happens while the exhaust valve is open, it will ignite the rich / unburned mixture in the exhaust manifold and tail pipes and result in a big bang.
2. Not correct valve timing, esp timing that is too late [etarded] can cause this same thing as above in addition to an engine that is running too rich. When the exhaust valve opens, the mixture isn't done burning so it ignites the unburned fuel in the exhaust system and causes a loud bang.
3. A faulty distributor sends causes a spark to be done by a plug that isn't ready for it yet
4. The air/ fuel mixture is too lean, especially in the morning . Backfiring will happen through the Carb
5. A bad ignition system, for intance, cross firing. The pop will come out with a flame from the exhaust

Car producing a ticking sound upon start up?

There are a number of reasons owing to this:

• 
  

  

  engine piston

  Damaged reciprocating components of the engine such as pushrods, valves and pistons. If these are worn out or damaged in kind of manner and are not replaced the sound may migrate from ticking to whining or clunk, evidently showing more signs of damage.
• 
  

  

  oil pressure light indication on dashboard

  Not enough lubrication on components. If there is a low amount of oil in the system, this may cause a ticking noise from components in the valve train. Low oil is usually accompanied by overheating and damage on the seals and gaskets. If these happen concurrently, then you'll know what to suspect primely.
• Valves not properly set or adjusted. The pushrod which controls the rocker arm from the camshaft needs to be at precise distance from the valve, and if not, it will cause a ticking noise from the rocker assembly
• Warn out bearings. Bearings hold components to a reasonably fixed position. If a bearing warns out and loosens, the corresponding rods will move unnecessarily and thus causing a ticking noise.
• Injectors firing. This you'll need to worry about less because injectors will always need to open and close to allow in and out passage of fuel. Under high pressure and a well functioning pump, a ticking sound will be heard unless if it appears too absurd

My car shows a gear sign on dashboard, it does not show any trouble codes on diagnosis

It may be just a temporary issue. Try this,

Put shifter in park, put the park brake and turn the engine off. Wait a few seconds and restart the engine. If the gear sign still shows, then it's a more serious problem than it looks.

 If such is the case then your transmission is probably slipping.

Drive the vehicle while trying to maintain a constant throttle position as it accelerates upwards thru all the gears. If the transmission is shifting properly, it should be in 4th gear by the time you reach 60 to 80 kph on level ground. Repeat the procedure 3 to 5 times Rescan the PCM for trouble codes, if nothing appears again then the problem could have been a onetime occurrence. If a trouble code appears you take it from there and fix as necessary.

Even if it resultantly appears to be a onetime thing,… that is not an incentive enough for you to trust that your transmission is okay. 

It owes partly to bearing, clutch or hard part failure, and this will come with a grinding, whirring noise but again, not every time.

What are the Effects of a Faulty Speed Sensor on a Modern Car?

"An engine speed sensor retrieves and sends data to your car’s computer system."

Transmission speed sensors are used to calculate the actual gear ratio of the transmission while in use. There are generally 2 of these VSSes that work in conjunction to provide accurate transmission data to the vehicle's powertrain control module.(PCM)

The 1st is the input shaft speed (ISS) sensor. This sensor is used to monitor the speed of the transmission' input shaft. The other is the output shaft speed (OSS) sensor.

If either of these two sensors falls out of alignment or experience electrical issues, it impacts the operation of the entire transmission.

After registering data, the two transmission speed sensors, send data to the PCM,which compares these two inputs and calculates which gear the transmission should engage for efficient driving. The actual gear ratio is then compared to the desired gear ratio.

If the desired gear and the actual gear do not match, then the PCM will set a diagnostic trouble code (DTC) and illuminate the Check Engine Light.

A defective car speed sensor may cause different problems and just below are the most common ::


1. Harsh or improper shifting
When there are symptoms of a bad transmission speed sensor, the powertrain control module cannot control the shifting of gears within the transmission properly.  This may cause transmission revs higher before shifting gear or late transmission overdrive and inability to go into that top gear. Harsh shifting may damage internal components such as valve bodies, hydraulic lines, and even mechanical gears in some cases.

2. Inactive Cruise Control
The transmission speed sensor does not only control the input and output shaft speed. Meanwhile, it also plays a role in monitoring the cruise control. When there are some engine speed sensor problems, an error code will be sent to the car’s Engine Control Unit (ECU). Then the cruise control will be shut down and does not engage when you press the button. The speedometer also may work frantically or sometimes stop working altogether.


3. Check Engine Light comes on
If your car has some engine speed sensor problems, the Powertrain Control Module (PCM) will set a diagnostic trouble code and illuminate the Check Engine Light on the vehicle dashboard. Then the check engine light will come on sporadically and intermittently when accelerating. The overdrive light also may go ‘On’ or ‘Off’ for no apparent reason.