HELP!! Car won't shift until ~4000rpm!!! HELP!!

[ned4spd8874]

I have a 1995 240sx se. Lately, it has been idling a little high when I stop. And today it started not shifting until it was at around 4000rpms! Then if it drops down below 3000 or so it downshifts! So basically, the car is constantly running at high rpms.

It just started this today after a huge rain. I thought something was wet, but everything is pretty dry now and still have the problems.

I checked the fluids and the transmission fluid was fine, but the oil was low. I filled that up and drove it around for a little while, but no difference.

HELP!!!!

[ned4spd8874]

Also, the check engine light is on...how can I check the trouble codes??

[s13sr20chris]

Many thanks to Richard Lestage who posted his version for the SOHC!We've used his format for the DOHC and thank him for his efforts!!

We suggest that you read this in it's entirety before rolling up your sleeves and doing this procedure. It may seem a bit complicated at first, but when you understand how the ECU stores and displays the Malfunction Codes, you will find that the process is pretty simple and easy to do.

Only a screw driver is required to read the trouble codes stored in the ECU (Electronic Control Unit). The following instructions allow you to easily read and erase the Malfunction Code on your beloved's ECU.

These instructions come from the 1991- 16 Valve Factory Service Manual.

Reading the codes requires accessing the ECU and placing the unit in one of two self diagnostic modes using a small flat head screw driver. The codes are displayed by a single RED L.E.D. in the ECU and the Check Engine Light.

1. Accessing to the ECU

The ECU is located at the right of the right side footwell. The "side" is determined as you sit in the car facing forward. (For cars in North America, the right side would be the passenger side)

You need to remove 2- "rivet" type fasteners of the right doorstep in order to get the kick panel out. To remove the plastic fasteners, unscrew the center part and pull out the other part. 2- metal screws and another "rivet" type fastener hold the kick panel.

Under the panel, is the ECU with its connector. Unfortunately, you have to access to the side of the ECU that is against the firewall. Remove the two screws at the top and bottom of the ECU and gently turn it to get to the Model Selector and RED L.E.D. Don't unplug the ECU to do this!

BE CAREFUL!

There should be a small sticker by the Mode Selector that tells you to turn it clockwise to set the Modes and to be sure to return it all the way counter-clockwise to the original position when the car is in use. You will also see the RED L.E.D. inside the ECU.

IF YOUR STICKER IS GONE:

Mark the original position of the Mode Selector. This is a VERY IMPORTANT position for the Mode Selector! (This should be fully counter-clockwise).

2. The Diagnostic Modes

--------------------------

There are 2- Modes and 2- Conditions for the Engine to be in for running diagnostics:

All Modes are with the Ignition Switch in the ON positionMode I (Engine OFF)- Bulb CheckMode I (Engine ON) - Malfunction WarningMode II (Engine OFF)- Stored Self Diagnostic ResultsMode II (Engine ON)- Exhaust Gas Sensor Monitor

Note: The ECU will automatically return to Mode I when the ignition is switched OFF. When the ECU is changed from Mode II back to Mode I by using the Mode Selector, the malfunction code(s) stored for Mode II will be erased. More on this later.

3. Changing Modes

Note: Switching Modes is not possible when the engine is running.

* Turn the Ignition Switch ON.* The ECU is now in Mode I.* To switch to Mode II:

Turn the ECU Mode Selector fully CLOCKWISE, hold for at least 2-seconds and then return the Mode Selector to it's original position. You are now in Mode II.

* Return to Mode I by turning the Mode Selector fully CLOCKWISE again, holding for another 2-seconds and turning it back to the original position.

Note: Doing this will ERASE any Malfunction Codes that are stored in the ECU for Mode II.

Example: If you found a Malfunction Code of 34 when you very first switched to Mode II and then cycled back to Mode I, then again to Mode II, you'll get a 55 (everything's OK) code. This is assuming that you didn't start the car between changing modes. When you start the engine, any current malfunction codes will be store by the ECU until you erase them or they get dumped.

Malfunction Codes are stored by the ECU for 50 times of cranking the starter. Then they are erased. If the same conditions are present, the Malfunction Code will be stored again for 50 cranks of the starter. And so on...

4. Reading the Malfunction Codes:

The Malfunction Codes are indicated by the number of flashes by the RED L.E.D. and the Check Engine Light. You can read either one. They flash the same information. For example, when the RED L.E.D. flashes once and after a short pause flashes twice, this signifies the number "12".

Note: If you find that your looking at a RED L.E.D. and a GREEN L.E.D., you've got a different ECU than is described here. See the FAQ on this same page that was written by Richard Lestage for the SOHC ECU!

______________________________________________

ALL TESTS ARE PERFORMED W/ THE IGNITION SWITCH "ON"

Mode I (Engine OFF)- Bulb Check:

In this Mode, the RED L.E.D. in the ECU and the Check Engine Light stay ON. If either remain OFF, check the bulb.

Mode I (Engine ON) - Malfunction Warning:RED L.E.D. is OFF = OKRED L.E.D. flashes =

For California Models Only:

Code # Description

12 Air flow meter circuit13 Engine temperature sensor circuit14 Vehicle speed sensor circuit31 E.C.U. (E.C.C.S. control unit)32 EGR function33 Exhaust gas O2 sensor circuit35 Exhaust gas temperature circuit43 Throttle position sensor circuit45 Injector leak

For Non-California Models:

RED L.E.D. ON = The ECU's CPU or the Crank Angle sensor is malfunctioning.

______________________________________________________

Mode II (Engine OFF)- Stored Self Diagnostic Results

Code # Description

11 + Crank angle sensor circuit12 E Air flow meter circuit13 E Engine temperature sensor circuit14 E Vehicle speed sensor circuit21 + Ignition signal circuit31 E E.C.U. (E.C.C.S. control unit)32 * E EGR function33 E Exhaust gas O2 sensor circuit34 Detonation sensor circuit35 * E Exhaust gas temperature circuit43 E Throttle position sensor circuit45 * E Injector leak54 Signal circuit from A/T control unit to ECU (A/T only)55 No malfunction in the above circuits

* = California models onlyE = Check Engine light will show this code.+ = Check items causing a malfunction of the crank angle sensor 1st, if both #11 and #21 are displayed at the same time.

Mode II (Engine ON)- Exhaust Gas Sensor Monitor

* Warm up the engine and see that the Temperature Gauge is in it's usual position.

* Run the engine at about 2,000 RPM for about 2- minutes under no-load conditions.

* Make sure the RED L.E.D. or the Check Engine Light goes ON and OFF more than 5- times every 10- seconds; measured at 2,000 RPM under no-load. (This is easiest to do while sitting in the driver's seat and watching the Check Engine Light.)

After the diagnostic, Turn the ignition 'off' to return to mode I.

**********************************************************

This may seem quite complicated, but if we can figure it out, you'll have no problems!

A&W

'91 s13?

[ned4spd8874]

Awsome! Thanks a lot...looks like I got some work to do in the morning!

[ned4spd8874]

This is what I learned on the way home tonight.

*The O/D Off light flashes 16 times when I start the car.

*When I shift from (P)ark to (D)rive, the car lurches forward.

*It will not shift from 1st, 2nd or 3rd until the rpm's are at or near 4500.

*Overdrive does seem to kick in at highway speeds.

*When driving at highway speeds (70-80mph) I can turn the O/D Off and it WILL shift down; then up when I press it again.

[s13sr20chris]

that sounds charachteristic of a speedo signal problem or possibly line pressure.

[NISTECH]

also go through this thread.

zerothread?id=96505

[ned4spd8874]

Well, I got the diagnostic code and it said it was the TPS. The check engine light started comming on when this problem started. So I bought a new TPS and will be putting it in today. I'll let you all know what happens.

[ned4spd8874]

Well, replacing the TPS doesn't seem to have made a difference.

When I shift from Park to Reverse or Drive, it shift really hard. Could my transmission be going?

[InsanityInc]

Automatic transmissions rarely die as a whole, usually your torque converter just goes bad. However, while your problems do suggest that your torque converter is working improperly, that doesn't necessarily mean that your torque converter is broken, as it could be getting told to operate improperly.

[NISTECH]

sounds as if you are at full line pressure as chris mentioned. take a look at the dropping resistor see if its plugged in and that it is not an open circuit.

[ned4spd8874]

"take a look at the dropping resistor see if its plugged in and that it is not an open circuit."

Where is this located?

[NISTECH]

small silver rectangular box bolted up near the strut tower.

[onosqv]

sounds as if you are at full line pressure as chris mentioned. take a look at the dropping resistor see if its plugged in and that it is not an open circuit.

Is having the line full pressure wanted or unwanted (in terms of preserving transmission life)? I have heard conflicting arguments - some saying it will kill the transmission, others saying it will all the transmission to last longer. Thanks.

[onosqv]

small silver rectangular box bolted up near the strut tower.

To help his description, here is a page w/ pictures:

http://www.240sx.org/faq/articles/shift ... n_auto.htm

image (driver side strut tower):

[ned4spd8874]

Yeah, this is plugged in. I have unplugged this before because someone once said that it makes the car shift faster. Which it does, but that is not the case this time. It's as if it's unplugged and on steriods!

[NISTECH]

I have seen no definitive proof it will hurt the trans. In theroy though this is an extreame force on the planetaries and clutch packs during engagement. So the theroy is it would cause accelerated wear on those components potentially breaking the hard parts if they became weak. Doing it certainly will not increase the life span of the trans there is no way that can even be theroized.

Ohm check your resistor and see if it has resistance. Also read through the auto trans link I posted earlier. There is some really good info in there on diagnosing your problem.

[ned4spd8874]

I having trouble figuring out which connector is the rev sensor...there are about 5 in a row and don't want to disconnect the wrong one.

[ned4spd8874]

Okay, I figured it out. It's the only sensor with only three connectors on it.

Unplugging it fixed it! Thanks a lot!

Now I gotta get that sensor or wiring fixed. Hope it's not too expensive. Thanks for all your help!!!