Who has the "right" way to wire up a starter push button. A friend wired one up to a fuse that is turned on by ignition then to the solenoid. When his car is cold it takes alot of cranking to start. I am guessing it is not running the startup map. Is there a way to toggle switch this or what?
Thanks
Keith

 

Just splice the original trigger wire for the starter solenoid to the trigger wire that your friend installed.

 

This is definately an option, but I believe he is also having hot start issues and I have heard the you HAILERS have some sort of write up to toggle switch between the running and startup maps.
Thanks
Keith

 

If I has a series four car that had a hard time starting cold, I'd back probe pin 3B on the small plug of the ECU (all plugs connected up) and turn the key to Start. Anytime the key is HELD to start batt voltage should appear on the meter.

If that happens, then that's the way it's supposed to work. Proves the signal wire on the starter solenoid is spliced/tied to the pin 3B on the ECU. So if voltgae shows up with key to Start, then I'd backprobe the middle plug, pin 2I (green/white wire) wire with the engine fully HOT. The reading should be a half volt dc. IF the reading is five volts........then the water thermo sensor plug is probably disconnected. If the car won't start so you can get it HOT, then backprobe 2I in the middle plug and the reading will be anywhere b/t 2-3 volts which would be normal to me with a cold engine in the summer time. But 4.5 to 5vdc indicates a disconnected water thermo sensor on the back of the water pump housing. This being disconnected can only cause cold start problems, not HOT start problem because the ECU will default to 176*F (normal running temp) so it matters not if the plug fell off in a HOT start try.

A difficult to start engine that is hot might have its BAC plug disconnected. BAC's help during START. They go and stay wide open if the key is HELD to Start.

An RTEK2.0 should fix any hot start problem. Cost dough though. It and the Palm etc.

IF 3B is getting batt pwr when the key is HELD to start and your having hot start problems, depin the 3B wire from the ECU plug while the engine is still HOT. Then start the car and go driving and stopping to restart the engine. IF the engine starts each time, you might make a fuel cut switch to the circuit opening relay or make the switch go to 3B where you can flip the switch to interrupt the pwr to 3B when starting hot. Just a simple on/off switch with two connections. One connection going to the black/blue wire that you depin from 3B and the other wire on the switch going to 3B on the plug. Probably have to not depin 3B but cut 3B at least four inches from the plug. Then one cut end of that wire to one connection on the new switch and the other half of the cut wire to the other connection on the new switch.

One other thing. IF a button or other method is used to start the engine and you bypassed the original trigger wire that was on the starter solenoid, some other thing has also happened other than 3B not getting the START signal. What other thing is, is that that same trigger wire should also send batt voltage to the Circuit Opening Relay anytime the key is HELD to start. That powers up the fuel pump.

So it's possible the *new* start button has bypassed the ECU and Circuit Opening Relay. Means the fuel pump isn't powering up and supplying fuel to the fuel rail. This wouldn't matter too much if the engine has been running in the last half hour or so, becaue the fuel rail should hold pressure for at least thirty minutes.

That said, it's possible there's enough suck from the engine to pull the vane in the AFM aft enough to trigger the fuel switch inside the afm which in turn pulls in the circuit opening relay to feed the pump. Been there, seen that happen before.

 

So it would work the opposite way also. If the car starts fine hot and takes some cranking when cold and if pin 3B is not getting 12+ volts when cranking andyou were to give pin 3B 12+ volts it would bring up the startup map. Making it start like normal?

 

Yeah. But you'd only want it to see batt voltage during Starting. I'd take a look with a meter to see if its getting batt voltage when the key is HELD to start......or not. If it is already, then that's not the problem.

A disconnected water thermo sensor will give you the same bad Cold starting conditons.

 

It ended up being that pin 3b was not getting voltage while cranking. put a toggle on it not it starts like a dream everytime...
Thankyou HAILERS!!

 

Life's good today.

 

is that switch on the 3b the same as pulling out the egi fuse? because that would be good as i hate having to pull the fuse out to get the car started when its hot.

 

Not the same thing. 3B on a series four is a signal TO the ECU from the start circuit, letting the ECU know that the engine is ...being started. During START the ECU uses a internal fuel map instead of the AFM for fuel delivery.

If 3B does not see the Start signal, then the ECU uses the AFM for fuel. That results in not enough fuel being delivered during COLD Starts.

Lack of a signal on 3B will make HOT starts Better, because the afm is used for fuel and the amount of fuel delivered is dramatically less . Lots of HOT start problems are due to too much fuel being delivered by the internal ECU start map, which causes the flooding.

I've depinned 3B in the past to rectify a HOT start problem. Problem doing this is, when the engine is cold, starting will be difficult. Mabe not so difficult in a warm climate like Florida or southern calif. I know not.

See the attached chart out of a RX training manual for how starting works. By the way, the water thermo sensor and amount of rpms also effect whether or not the Internal ECU start map is used. See attached chart.

You could make a fuel cut switch (do an advanced search on this site using FUEL CUT SWITCH and the name NZCONVERTIBLE) or make a similar switch but use the switch to interrupt the signal on pin 3B, or buy a RTEK2.0 from Digital Tuning which eliminates flooding.

The pin on series five is not 3B and flooding on series five is done by HOLDING the pedal to the floor and cranking the engine over (turns the fuel injectors off).

 

Two jpgs of a PALM connected to a RTEK2.0 showing the injector pulse width during start. You can see how the amount of fuel delivered is much less when the pin 3B is disconnected vs the 3B connected to the ECU.

I did this same test using a Fluke88 long before they came out with a RTEK anything. Just run the fuel rails dry and then unplug the fuel pump connector at the fuel pump. Then try starting with the 3B connected and then disconnected. You get the results seen in the jpg above, whether using a Palm/RTEK or Fluke set on pulse width.

You can see the engine is hot by looking at the water temps and the air intake temps on the Palm.

I used to be CLUELESS on fuel delivery during Starting, until NZCONVERTIBLE posted the Training Manuals for the early RX-7 which has that chart I posted in the post above. Then the lights turned on in my head as to what was happenig during start.

 

Although very informative, we kind of drifted off-topic.

In the interest of less experienced members coming up on this thread while searching, can we agree that...

The best place to wire in a push start button is to tie into the wire coming from the ignition switch start position? That way, the computer will be in on what's going on and will get the crank signal.

(paging Hailers...)

 

************************************************** ************************************************** ******************************
The Thread Owner has found pin 3B wasn't getting the start signal and now it does and he's pleased as punch that his car is fixed and he's lost interest on wiring a push button start switch.


The Aussie, RX-7 HEAVEN asked a question and I answered it so he wouldn't have to make a seperate thread.

 

ok thanks for the info, so a fuel cut switch or the switch on the 3b wire will help the car start when its hot?????

i might check that voltage thing on the 3b sounds very interesting.