RPM jerking

There was a day that I noticed the D4 flashing and some seconds later it wouldn't move. I stopped the car checked the transmission oil which was OK, I then went back started the car and everything was OK again.

What do you think could be the problem? does it mean that I may likely loose my transmission.

Another one is the transition between the 1st and the 2nd gear is always too harsh.

Please, your response

Yinkebo

Hi yinkebo,

When the D4 light blinks while driving, an error has been detected by the PCM so you need a diagnostic scan to find out what is causing it.

Get the exact code and let me know so that appropriate action/suggestions can be made.

Hi KHLow2008,

When I had the experience, what I did was just to stop the car and check what was wrong and by the time I returned to the car to start, it was gone.

I then took the car to my auto mechanic, we changed the oil despite, serviced 3 sets of solenoid units yet the transmission remains harsh.

What do you suggest I do next?

Yinkebo

Hi KHLow2008,


another recent one this;
My diag. tool showed code P0420-catalyst Efficiency below threshold (Bank 1).

Please, what does it mean? How can I locate the position of the catalyst.

What I did here is tightening/tensioning my power steering belt which was making noise and I erased the check engine, still waiting if it would come up again.


Yinkebo

Hi Yinkebo,

DTC P0420: CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD
NOTE: If some of the DTCs listed below are stored at the same time as DTC P0420, troubleshoot those DTCs first, then recheck for DTC P0420.

P0137, P0138: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S (Sensor 2) Heater

1. Reset the ECM/PCM.
2. Start the engine. Hold the engine at 3,000 RPM with no load (in Park or neutral) until the radiator fan comes on.
3. Except F23A4 SULEV engine: Test-drive at 40-55 mph (64-88 km/h) for approx. 2 minutes. Then decelerate for at least 3 seconds with the throttle completely closed. Then reduce the vehicle speed to 35 mph (56 km/h), and try to hold it until the scan tool indicates FAIL or PASS as the TWC test result. F23A4 SULEV engine: Test-drive at 50-55 mph (80-88 km/h) for approx. 2 minutes. Then decelerate for at least 4 seconds with the throttle completely closed. Then accelerate to 55 mph (88 km/h), and try to hold it until the scan tool indicates FAIL or PASS as the TWC test result. Is the test result FAIL? YES -Check the three way catalytic converter (TWC). If necessary, replace the TWC. NO -Intermittent failure, system is OK at this time.
© 2007 Mitchell Repair Information Co., LLC.

Hi KHLow2008,

Thank you for all the communication.

Which is the best way to reset the ECM/PCM.
Is it by removing the battery head?
Is there a better way to do it.

Thank you

Yinkebo

Hi yinkebo,

The best and easiest way is to use a scanner to erase the codes.

Next is to remove the 7.5 A BACKUP or CLOCK/RADIO fuse underhood fuse box for more than 10 seconds.

I would recommend disconnectiing the battery terminals only as a last resort.

Hi KHLow2008,

Thank you for your prompt response.

Please, what does this catalyst mean?
What does it do on the car?

Thank you.

Yinkebo

Hi yinkebo,

Catalytic converter is for emission control. It works by heating itself up to burn off any unburnt gas/fuel when the exhaust gas is passing through it.

Hi KHLow2008,
I have tried out the 1st two steps in your last reply because my car has ULEV emission control system but after a few hours drive the light came up again.

Please, what should I do now or what should I change? If I have to change, how can I locate the component?

Thank you

yinkebo

Hi yinkebo,

Get a scan done and give me the exact error code. I need it to confirm what to advise.

Hi KHLow2008,

The exact DTC is P0420: CATALYST EFFICIENCY BELOW THRESHOLD (BANK 1).
That is the only code that has been on again and again even after trying out your instructions. You know it will be good if we can clear it so that if another code comes one can easily know.

Pls answer my previous questions along with this reply.

Thank you

Yinkebo

Hi yinkebo,

Resetting and the problem comes back means the catalytic converter is bad and needs to be replaced.

It is the exhaust part just after the engine.

Hi KHLow2008,

i shall do just that.

Thank you

yinkebo

Hi KHLow2008,

I have a van, NISSAN QUEST with transmission problem.

When it comes to a halt and one wants to move immediately the GEAR refuses to engage until after some seconds and this makes it to jump forward.
Checked the oil; colour ok, level ok, yet I changed it but no improvement.

What do you think I should do next.

Thank you.

Yinkebo

Hi yinkebo,

What is your year model, trans and engine type of the vehicle?
If you have posted the question in the Nissan category, let me know and I will check it out.

Hi KHLow2008,

For Nissan Quest, the year is 1994, 4cylinder with 125,526Miles.

I shall be waiting for your take on this. Thank you.

Yinkebo

Hi yinkebo,

Check the following,
Engine idle RPM or throttle sensor misadjusted, incorrect line pressure, fluid temperature or engine RPM signal, damaged N-D accumulator or forward clutch.

Hi KHLow2008,

Thank you for your prompt response, this helps me to understand more about the workings of my cars and am able to contribute when my mechanics want to fix them.


Among all the items you have listed its only the TPS-Throttle Position Sensor I know but do not know how to give it the correct setting.

How do I check the line pressure, fluid temperature and correct it if possible?

How do I locate and test the N-D acummulator, engine RPM signal, forward clutch?

Thanking you as I wait for your response.

Yinkebo

Hi yinkebo,

Line pressure is tested by attaching pressure gauges to certain points located on the trans housing and running the vehicle along the gears to get the reading.

Fluid temp is not easily done as you need a sensor specifically for fluid temp testing.

The rest are found in the trans and line pressure test can give some idea on the working of each item.

Engine rpm signal is the from PCM and diagnostic equipment is required for easy access.

Hi KHLow2008,

Can a diagnostic tool work on a '94 model of Nissan Quest?

What values of these parameters are we talking about, here; line pressure, engine RPM etc.

Thank you so much for being of help, you are a darling but let me, let you know my problem here. I am writing you from Nigeria and most of our mechanics did not do any formal training and so do not know these things so, if we have problems on our vehicles that they could not solve, we will be forced to either continue to manage it, abandon it or sell it of without telling prospective buyer the problem.
That is why I do this to help myself. Like the pressure gage may be difficult to get around and so the pressure may difficult to measure.

However, do not hesitate to give me the value expected, it would still be useful.

As diag tool I have ACTRON C9175 type.

I shall be expecting your reply soon.

Yinkebo

Normal scanner would not work, You need a diagnostic tool that is capable of reading datas.

There are some valuea that you can fo voltage test etc.

Hi KHLow2008,

How do I get that kind of diagnostic tool? Is my scanner (actron c1975) not capable of doing anything to help.

Thanks

yinkebo

hi Yinkebo,

I have attached some test that you can do.

ENGINE REVOLUTION SIGNAL CIRCUIT TEST

With ignition switch in ON position, and engine off, check voltage between ATCU terminal No. 24 and ground. Voltage should be 0.9-4.5 volts. If voltage is not as specified, repair circuit as necessary.

FLUID TEMPERATURE SENSOR TEST
1. Check resistance between fluid temperature sensor terminals. Resistance should be 2500 ohms at 68°F (20°C), and 300 ohms at 176°F (80°C). If resistance is not as specified, replace sensor.
2. Disconnect solenoid harness connector in engine compartment. Check resistance between terminals No. 33 and 35 when transaxle is cold.
Check voltage between ATCU terminal No. 33 and ground, while warming up transaxle. If resistance and voltage is not as specified, repair circuit as necessary.

FLUID TEMPERATURE SENSOR DIAGNOSIS
Terminal ------Temperature -------- Resistance --- Voltage
33 To 35 --------- Cold (1) -----------2500 Ohms ------N/A
33 To Ground ---Warming Up (2)--- N/A ------------- 1.5-.5

(1) Cold 68°F (20°C).
(2) Cold 68°F (20°C); Hot 176°F (80°C).


LINE PRESSURE SOLENOID TEST
1. Check resistance between solenoid assembly connector terminal No. 4 (Red wire) and ground. Solenoid resistance should be 3.2 ohms. If resistance is not as specified, replace solenoid.
2. With ignition switch in OFF position, disconnect solenoid harness connector in engine compartment. Check resistance between solenoid harness connector terminal No. 1 and ground. Resistance should be 2.5-5 ohms. If resistance is not as specified, repair circuit as necessary.
3. Disconnect ATCU connector and check resistance between solenoid harness connector terminal No. 1 and ATCU terminal No. 2. Resistance should be 11.2-12.8. If resistance is not as specified, check resistance of dropping resistor, located under air cleaner. Resistance should be 11.2-12.8 ohms. Replace resistor as necessary.
4. Check resistance between solenoid harness connector terminal No. 1 and ATCU terminal No. 1. Resistance should be approximately zero ohms. If resistance is not as specified, repair circuit as necessary.

THROTTLE SENSOR CIRCUIT TEST
Check voltage between ATCU terminals No. 34 and 35 while depressing accelerator pedal slowly. At closed throttle, .2-.6 volt should be present. At wide open throttle, 2.9-3.9 volts should be present. Voltage rises relative to throttle valve opening.

THROTTLE VALVE SWITCH CIRCUIT
Checking Idle Switch Circuit
Check voltage between ATCU terminal No. 14 and ground while depressing accelerator slowly. When depressing accelerator pedal to wide open throttle, one volt or less should be present. When releasing accelerator pedal, 8-15 volts should be present.

Checking Full Throttle Switch Circuit
Check voltage between ATCU terminal No. 21 and ground while depressing accelerator slowly. When depressing accelerator pedal to wide open throttle, 8-15 volts should be present. When releasing accelerator pedal, one volt or less should be present.