A Belgian member needs help for a little problem (Civic Vx, D15Z1 engine).

[VEI]

Hello, I am a newbie. I come from Belgium.

It?s difficult for me to speak in English, but I will try to do my best...


My car is a 1994 Honda Civic VEi.

It?s a D15Z1 engine, as Civic Vx.

I have some little problems with the engine.


At low RPM (< 3200tr/min) and low load (I don?t know if it?s the good word, -> Low pressure on the accelerator pedal), I have a response time (lag ?) before the engine accelerates.
(I am pushing slightly on the pedal and nothing happens, during less than 1 seconde. Then, suddenly, it accelerates sharply).

I don?t have this problem when the engine is cold or high RPM or heavy load.

The ?check engine light? appeared 3 times this year. (Code 48, LAF sensor).


Did you ever had the same problems?

Are there links between the LAF sensor and my problems? Or is it 2 different problems?

[Danronian]

Sounds to me like the LAF might be almost ready to be replaced. Is the sensor old?

A slight lag in response time for the lean-burn on the d15z1 is something I've come to be used to when driving my civic.

[SVOboy]

It sounds like there might be a link between the LAF and the lag, can't be sure, of course, but that's what it sounds like at this point. The lag could be caused by bad o2 readings not delivering the proper amount of fuel quickly enough.

Welcome to the site!

[GasSavers_TomO]

It sounds like changing your LAF (Oxygen Sensor is also what it's called) is going to be a great starting point. Just be warned that it will be expensive as it is an L1H1 sensor. Your best bet would be to find one for sale on eBay from a seller that ships internationally.

[VEI]

Oh, the answers are quick on this forum !!!


Yes, I also suspect the LAF sensor.

I checked :
MAP sensor.
TPS sensor.
EGR valve.
LAF sensor.
…

I tried a other ignition distributor.

I have :
New air filter.
New fuel filter.
News Spark Plugs.
News ignition wires.


The LAF sensor has 165000km, like the engine.

The signal of the LAF sensor is good but impossible to control the response time.
And impossible to know if the value is not poorest in reality.

But I hesitate to replace this sensor. Some guys have the same problem with this engine but with a new LAF sensor (but I don’t know if it is really the same problem or a ignition problem).
And this sensor is really expensive.


Did you have the same problems (lag)?


I have two other little question :

What is the "clutch switch" (It is used to what?)

Is it normal that the engagement of the VTEC-E system is between 2500RPM (heavy load) and 4000RPM (low load)? In the documentation, this seems to be much lower...



My measurement (Voltage solenoid) :
http://www.youtube.com/watch?v=XfxgOPXx7H0

[GasSavers_TomO]

Your Vtec-E solenoid activation is in working order as shown by your video.

What brand and number is on the new spark plugs you have put in the car? The d15Z1 motor is very picky about plugs.

I can't recall the exact ECU pins, but I see you know how to use a Volt meter (awesome!). you can check the VX links in my signature and check the one titled "VX Lean burn Monitor". That will show you which ECU pins to connect to with the voltmeter and check the readout of the LAF. If it seems sluggish and takes a long time to react to the throttle change, it is getting time to replace it.

The lag that you described earlier was the same experience I was having with my VX when I got it. The LAF had about 280,000 miles (450,616km) on it at the time and was getting tired. It also had the wrong number plugs in it as well. I changed to the correct plugs and I changed the LAF and the lag problem was almost gone. There is still an inherent lag in the d15Z1 motor due to the nature of the lean burn cycle.

[VEI]

Originally Posted by TomO

What brand and number is on the new spark plugs you have put in the car?

NGK ZFR5F-11 (In Belgium, i have the choice between ZFR5F-11 (stock) and ZFR6F-11 (warm climate).

Originally Posted by TomO

I can't recall the exact ECU pins, but I see you know how to use a Volt meter (awesome!). you can check the VX links in my signature and check the one titled "VX Lean burn Monitor". That will show you which ECU pins to connect to with the voltmeter and check the readout of the LAF. If it seems sluggish and takes a long time to react to the throttle change, it is getting time to replace it.

Thank you for this link. Very good.
I have made this control 6 months ago. But my Values seems to be a little bit differents. I will retry this week to be sure.

[GasSavers_TomO]

Originally Posted by VEI

NGK ZFR5F-11 (In Belgium, i have the choice between ZFR5F-11 (stock) and ZFR6F-11 (warm climate).

That's odd, in the US the stock plug in the d15z1 is NGK ZFR4F-11.

I know that my motor had the ZFR5F-11 in it when I bought it and that caused some hesitaion due to the wrong plugs.

Originally Posted by VEI

Thank you for this link. Very good.
I have made this control 6 months ago. But my Values seems to be a little bit different. I will retry this week to be sure.

Great, glad to help out. I'm looking forward to your updated results.

[Gary Palmer]

Welcome to GasSavers. The clutch switch is a safety interlock switch which is used to make it so you have to depress the clutch, in order for the starter motor to engage. The switch is located under the dash, at the top of the clutch. (You can put a jumper wire on it, to bypass the switch/interlock, done.)

[VEI]

I have checked my LAF sensor.

My voltmeter was connected near the LAF Connector (not ECU). Normally this is the same voltage.


Sensor 2 (D14-D16) :

Idle :

Video :
http://fr.youtube.com/watch?v=hoUM8e7YIbI



Sensor 1 (D8-D16) / Sensor 2 (D14-D16) :

Acceleration :
/
Video :
http://fr.youtube.com/watch?v=J9agPyzWt9g / http://fr.youtube.com/watch?v=WQ5HQkI2Gn4

Deceleration :
/

Low RPM, low load (-> ?lag?) : The response of the accelerator pedal is not normal. The engine accelerates too slowly with some small hesitations (Except if I push harder on the pedal) :
/
Video :
http://fr.youtube.com/watch?v=7GyrJYB14rY / http://fr.youtube.com/watch?v=BaqbkLXk4bs

Do you think that is too lean?


Just after ?lag? :
/

The clutch switch is a safety interlock switch which is used to make it so you have to depress the clutch, in order for the starter motor to engage.

I have this switch but I can start the engine without depress the clutch.