Rewaco FX4 / FX5 air cooled VW 1800 injection. Anyone got one?

[Retepnikrap]

Rewaco FX4 / FX5 air cooled VW 1800 injection. Anyone got one?

Hello
I have a rewaco VW 1.8i and could do with some help.
i need to replace the temperature sensor which is screwed into the head on the right side of the engine (looking from back to front of the trike) right near cylinder #1 and has a 2 wire plug on it with a brown and white wire. Not listed in the parts manual and rewaco tech support don't talk to any Joe off the street.

my broken sensor is not the correct one so details I have are no good to me, sensor is easy to get to and can be removed easily for inspection, if anyone could get me the details on their sensor I would be eternally grateful. Maybe the same sensor on the 1600 injection but not 100% sure.

Thank you

 

[Bikerbozo]

Since it is a mostly stock engine( I'm assuming), I would say check a VW car manual from whatever car uses same engine. Maybe also go into an auto parts store with motor specs.

 

[stinger608]

Being an 1800 injected engine, it is the latter model bus engine, I'm almost certain. It should take the same temp sensor as the latter 70's and early 80's Vanogan.

Check with your local VW dealer or even a local parts store. They should have a listing and images of the part for comparison.

 

[pisoiu]

I have a RF1, not FX but I can assure you most parts are standard engine parts and as others said, they can be found anywhere there are VW parts.
The rewaco tech support won't talk with any Joe only if there is a dealer in Joe's area/country. Otherwise they are very helpfull. In my country there is no dealer and I had no problem ordering from them all the parts I needed to fix my trike which was badly damaged in a crash.

 

[Retepnikrap]

I have a RF1, not FX but I can assure you most parts are standard engine parts and as others said, they can be found anywhere there are VW parts.
The rewaco tech support won't talk with any Joe only if there is a dealer in Joe's area/country. Otherwise they are very helpfull. In my country there is no dealer and I had no problem ordering from them all the parts I needed to fix my trike which was badly damaged in a crash.

The problem is that my faulty temperature sensor was fitted by the previous owner, firstly I am pretty sure it was not the correct sensor as trike had some starting issues and after running through all other potential issues I am left with this sensor. Because it had been replaced previously I have no guarantee that it was a perfectly suited replacement and taking into account the issues I had before (I broke) the sensor I don't want to risk replacing like for like without checking the spec of the factory fitted sensor.

There is no doubt that most of these parts are factory parts fitted to standard vehicles, the purge valve on mine for example is from a ford fiesta. The fuel injection ECU is a Trijekt unit. The information it receives from this particular sensor is quite critical to the cold starting and overall performance, there are however so many that look exactly the same but have different working values, temperature range, response times etc etc, so getting the correct one is not straight forward especially when you don't know the specification.

I even tried the VW air cooled community but it appears that this temperature sensor on FI VW busses and cars has only one lead not two and is round the other side of the engine, so no joy there. The only hope I am left with is to get the numbers and make first hand from the temperature sensor on a working FX 1800i, not sure how many are around as the vast majority seem to be carburettor models.

Just about to email Trijekt to see if they can help but in the mean time if anyone has an FX 1800i in the garage and can check I can't tell you how grateful I would be.

thank you.

 

[pisoiu]

Can you post a picture of it?
I was looking at the engine wiring diagram for FX5, it looks like injection engine (it has injection nozzle controls) and the only temp sensor I see is an oil temperature sensor. But I see no code for it except NTC notation which comes from negative temperature coefficient thermistor.

 

[Retepnikrap]

Can you post a picture of it?
I was looking at the engine wiring diagram for FX5, it looks like injection engine (it has injection nozzle controls) and the only temp sensor I see is an oil temperature sensor. But I see no code for it except NTC notation which comes from negative temperature coefficient thermistor.

Hi
Yes I see in the wiring diagram it says that this component is NTC.
Trike is an injection, I have attached images of sensor in and out of the trike.
As previously mentioned I physically broke this trying to remove it, before I broke it the trike was very difficult to start when cold, with the sensor out of circuit (plug removed) would not start at all, whilst it may transmit oil temp to the gauge I also believe it gives temperature information to the fuel injection ECU to help it determine the mixture require to start depending on temperature. (I may be wrong, I am not that familiar with fuel injection).

Either way it is definitely open circuit now so before I can continue I need to replace it.

thank you

ps. the pictured sensor was replaced by previous owner a short while ago, I am pretty sure that whatever the technical spec is that it is not the same as factory supplied. Also component shown is made by AB Tektronik, I have contacted them and this sensor is not available any more and they can't offer a direct replacement, my search continues for a factory fitted replacement.

 

[pisoiu]

Hi,

I see. If I were you, I would do the following steps: (I am sure you tried some of these steps but..)
-try to contact you local dealer
-if unsatisfactory reply, try to contact rewaco, explaining them that your local dealer did not helped you. They are quite sensitive to this argument.
-as a last resort, if you have some electronic skills, I would try to find that good value. Basically that sensor is a thermistor which must have a certain ohmic resistance at 25 celsius temperature and most probably you have the wrong type. Other parameters may be less important right now. You can measure the resistance of this sensor when everything is at room temperature and procure several resistors with values near the value of the thermistor you have. Let's say your thermistor is 100 ohm at 25 celsius, procure resistors of following values: 33 ohm, 47ohm, 120, 180, 220, 270, etc. Connect them in circuit and see where your engine starts (from room temperature, don't let it get hot) better. When you find it, you have a reference for the component you are looking for. Of course, I cannot assume responsibility for this procedure, it is just a suggestion.

le: I see now the nominal resistance for 94098 is around 2.2kohm. You can try with the following values: 1k, 1.2k, 1.5k, 1.8k, 2.4k, 2.7k

 

[Retepnikrap]

Hi,

I see. If I were you, I would do the following steps: (I am sure you tried some of these steps but..)
-try to contact you local dealer
-if unsatisfactory reply, try to contact rewaco, explaining them that your local dealer did not helped you. They are quite sensitive to this argument.
-as a last resort, if you have some electronic skills, I would try to find that good value. Basically that sensor is a thermistor which must have a certain ohmic resistance at 25 celsius temperature and most probably you have the wrong type. Other parameters may be less important right now. You can measure the resistance of this sensor when everything is at room temperature and procure several resistors with values near the value of the thermistor you have. Let's say your thermistor is 100 ohm at 25 celsius, procure resistors of following values: 33 ohm, 47ohm, 120, 180, 220, 270, etc. Connect them in circuit and see where your engine starts (from room temperature, don't let it get hot) better. When you find it, you have a reference for the component you are looking for. Of course, I cannot assume responsibility for this procedure, it is just a suggestion.

le: I see now the nominal resistance for 94098 is around 2.2kohm. You can try with the following values: 1k, 1.2k, 1.5k, 1.8k, 2.4k, 2.7k

Still waiting for dealer to get back to me, I thought I would do some digging while I waited. Never thought about the resistor route.
I did get a reading from my previous sensor before I broke it, it was cold but could not say exactly what the temperature was, anyway I measured 4.5Kohm, took out the sensor and warmed it a little in front of a bright halogen and the resistance changed to 1.8Kohm. I deducted from this that the sensor was working but as previously stated I believe it is not the right part and the value range is not the right spec for the fuel injection system.

I don't want to do any harm to the ECU so a little worried about shorting a resistor across the terminals but as I think about it, resistance is resistance so should be safe and a good way to identify the optimum resistance required for a cold start. Take a 2.4k resistor for example is a 2.4k resistor a 2.4k resistor? Or are there different types of 2.4k resistors? Voltage to sensor I guess would be 5v or maybe 12v, my money would be on 5v as this seems to be the voltage given out by the ECU to other sensors.

Still hoping for a forum member to whip theirs out and read me the make and numbers printed on it, if not maybe the dealer will come good. Failing that I will explore the resistor route to determine optimum starting resistance.

thank you

 

[pisoiu]

Until somebody will tell which part it is, I will continue a bit with the resistor.
I would be 99.99% sure you will not harm the ECU itself. That part is just a variable resistor and the reading of its value is done at very low currents. Basically there must be inside the ECU a source of known constant current (in the milliamps range), which applied to a resistor, it determines a certain voltage across its terminals. That voltage is read by the CPU with an ADC converter. The part I am worried about is the ECU may take wrong decisions based on this information and somehow harm the engine by supplying wrong commands (bad timings to injectors, etc).

le: a resistor with the exact value as the right thermistor for your engine will make your engine to behave exactly the same as long as the engine remains cold. The problem will start when the engine will rise its temperature, because the ECU will not be aware of this, that wire is linked to resistor, not to the sensor which will change its value as a function of temperature. This is why I said to avoid engine getting hot when making these tests.

 

[Retepnikrap]

thank you

is a resistor sensitive to the direction the current flows? Or can I insert any of the resistor legs across the harness plug terminals?

Are there different types of resistors? Is there a specific type I need for this test?

thank you

 

[pisoiu]

A resistor is a passive device. These devices generally don't care about direction, with very few exceptions (polarized capacitors). Yes, there are several types of resistors. I would not recommend SMD (surface mount). Look for resistor with terminals and with rated power of at least 0.5w. Not because you will need their power rating but because they are bigger, not that easy to break.

 

[Pegasus1300]

Dumb question I know but you didn't mention them in your quest. Could these people be of any help?

http://rewacoownersclubuk.webs.com/

 

[Retepnikrap]

Dumb question I know but you didn't mention them in your quest. Could these people be of any help?

http://rewacoownersclubuk.webs.com/

Have contacted them, they are nice people and trying to get the info for me. Just been digging elsewhere trying to find the answer as soon as I can.