By accident I happen to swap primary fuel injectors connectors with secondaries. So basically the engine was running from secondary ports. I have eliminated the secondary port valves so this is possible at start up. The first thing that was happening is that the idle was impossible to keep. Secondly the car would start every time after it dies without any problems. When driving it would buck and run like crap below 3000 rpm, once at WOT the car would pull extremely well with fast response.

So again in summary, lots of power, crappy idle, and it would start up every time weather hot or cold.

Placing the fuel injector connectors in their proper order the car idles fine, not as powerful as before and it has a hard time starting.

Can anyone explain this? The car is a 88 non turbo.

 

Shot in the dark. Primary injectors clogged or going bad maybe?

 

I did send send the injectors off for cleaning and testing, they are good.

 

Just a common RX problem, the flooding thing. I swapped Primary and secondary injector wires at the ECU plug once. It ran so bad I didn't drive it halfway out the driveway.

Your full throttle result makes sense since all four injectors are at the same duty cycle during full throttle over thity eight hundred rpm. Sort of normal operation at that point in time.

Flooding can be corrected using a RTEK 2.1. It has a feature that lets one select the amount of fuel delivered during Start and also takes into consideration the temperature of the engine when calculating that amount.

Stk ECU during Start looks at................the water temperatue via the water thermo sensor on the back of the water pump housing, the rpms being below 500 rpm, and the ECU seeing the start signal from the starters circuit. The water temperature being sensed decides how much fuel is to be delivered in ms while the key is HELD to START.

The stk ECU uses a internal Start fuel map to do this. During Start on a stk RX the afm is not used at all til the rpms get over 500 rpm, then the afm is used for fuel amount.

I found out sometime back if the stk ECU never sees the Start signal from the start circuit, then the internal fuel map is not used but the afm is then used for Start fuel amount. And that amount of fuel is dramatically less than the stk internal fuel map.

So by removing the start signal from being seen by the ECU, starting was virtually a normal thing. The drawback was that when the car had sat overnight on cold days the car was difficult to start 'cause the fuel amt was too lean during Start, but it would finally start up and after the engine temps came up to normal operating temps the car would start like a normal car for as long as the engine was still warm/hot.

As a side note........if the water thermosensor on the back of the water pump housing fails or if its plug falls off the sensor, the ECU defaults to reading a normal fully warmed up engine. Like 180 degrees or close to that figure.

 

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That is some good info.

Ok so I have a digital water temperature senor feedback so I am able to see the digital temperature reading of water right before engine start. If i choose to wire a switch to the water termosensor and turn it off when the water temperature is in the 60-70 range would that solve my flooding issue?
This leads me to another question, at what water temperature would the water termosensor need to be activate?

 

I'll put it this way..........once I found out what happens when you go to START a RX (thanks to NZCONVERTIBLE's training manual) I went to JAYCAR and bought a switching device as seen in the following: http://www.jaycar.com.au/productView.asp?ID=KC5377

I used the water thermosensors output to the switching device to trigger the devices relay to either complete the START signal on pin 3B of the ECU or open the circuit to 3B.

I used the temperature of 120* to trigger the relay. So that any temp over 120* meant that the ECU did not see the start signal to 3B and the afm was used for fuel during start and all was well from that time on.................til I bought a RTEK 2.0 which in later versions had the ability for one to select what amount of fuel would be delivered during Start and what temperature.

I could have just made a simple on/off switch to interupt the signal to 3B ......but that wouldn't be that much of an improvment over a fuel cut switch......although it would be better imho.

Some of the above might make sense. If not say so and I'll correct it.

 

^ For hot start explanations I point people to this thread of yours: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/looking-car-has-hot-start-problems-499744/. The discussion in there explains it pretty well. I may just add it to the FAQ since this question comes up so often.

 

Here's two jpg attached. One is labled CONNECTED and the other is labled DISCONNECTED.

This means that 3B is connected to the ECU during Start in one jpg and in the other jpg the wire at 3B is disconnected.

This was done using a PALM and a RTEK2.0 several years ago.

I got the engine up to operating temperature. The coolant temp from the water thermosensor is shown in the last quad on the screen.

So what I did was this. I turned the PALM on to show the items in the jpgs. Then I held the key to START. I disabled the fuel pump prior to doing so, so that the engine would not start doing this.

In the jpg showing 3B CONNECTED you can see the water temp is 208*F and the fuel injectors are open 17.62 ms.

IN the jpg showing 3B disconnected you can see the water temp is 189.5*F and when the key was held to Start the fuel injectors stayed open 5.96 ms.

So you have a stk car with the fuel injectors open 17.62 ms verses a pin 3B disconencted so that the ECU uses the afm for fuel and you can see the fuel injectors are open only 5.96 ms. A whole lot less fuel than a stk non messed with car.

I at one time used a JAYCAR switching device triggered by the water thermosensor voltage output to either make or open the Start signal on 3B and used the temp of 120*F as the point where the circuit would be open from there on up.

For the two jpg I just depinned 3B on the ECU for demonstration purposes. I'm sure I'd gotten rid of the JAYCAR by that time since I now had the RTEK2.0 with Palm device and didn't need the switching device anymore.

I've done fuel cut switches in the past prior to learning how the ECU delivers fuel during Start. Gosh (???) prior to knowing how things worked I messed with plugs, fuel injectors and especially the afm and the variable resistor, not knowing at that time that................I was wasting my time fiddeling with those items.

That page out of the training manual opened my eyes on how things work during start.

 

Just FYI, that feature isn't available for the S4 N/A.

 

Thanks for the heads up. I own two 1987 turbo II and one 1986 non turbo bone stock car. All have RTEK 2.0/.1 and I get confused easily. I'm not sure which car I was using for those jpg attached. Matters not since I was depinning 3B doing the jpgs years ago.

I have also gotten a reply from one fellow saying disconnecting 3B did not help his hot start problems. I've no idea why. Not my car.