Ive got an idea to fix the hard cold start associated with your relay Hailers. You said if the wire is cut that its hard to start when its cold. How bout putting a manual switch between them so you can start it cold when its switched on(completed circuit) and turn it off (broken circuit) to start it when its hot. Just an idea? Does that sound right? And I have this problem so Im very excited to see if this will fix the problem.
Jeremy

 

I did do the switch thing and it works fine if not great. It's just I'm trying to get away from any manual switches to start my car.

 

Thanks for researching this. As my engine goes through break-in hot start isn't nearly as bad, but situations like stopping for gas on a hot engine results in a need for fuel cut still. If some more miles and fuel system cleaning, etc, pass by and I still have this problem then I will definately be using a version of this

 

hey if this works could someone help me do it to my 88 GTU? it has that problem bad, like you have to let it sit for about one hour. then it will fire right up

 

was this ever fixed?

 

Ok. I gotcha Hailers. Great idea btw. 8)
Jeremy

 

can you just cut the 3b wire and and cap them incase you wanta put it bacc

 

Yeah. But the first cold 40-50 degree day the car will be hard to start because there's not enough fuel for starting. It'll start but it'll take a number of times.

I installed a toggle switch and that worked just fine, but it had not many advantages over a fuel cut switch, except once the engine gets warmed up you don't need to use the switch the rest of the day if the engine is warmed up, unlike a fuel cut switch which you'll have to use the rest of the day.

This works on cars that have low compression, not on cars that have screwed up fuel injectors. IF you do this pin 3B and you have bad results once the engine is warmed up, then your problem is probably fuel injector related OR???

 

i have a walboro pump that runs pretty rich will that help on cold days

 

anyone

 

Just give it a try. If things don't work out, then just put the wire back in/together again.

 

hmm...we're getting ready to put a fuel cut switch in my car...we may give this a try, and just use the fuel cut switch as the "hot/cold" toggle instead. This car rarely starts in 40 degree weather anyway. I'll definitely post back if we tray it and it works, because my car definitely doesn't like starting hot....starts like a champ when cold tho.

 

Well, like I said, make it easy on yourself. Just pull the wire out of the plug and drive the car for a day or so to see if it suits you or not. If yes, then just having a switch will do the job. You shouldn't have to use it more than once a day (cold in the morning), if your car is one that just won't start when hot.

Again, I've nothing against fuel cut switches, except it's my belief the problem lies with the Start Fuel Map, not dripping injectors etc. Get rid of the Start Fuel Map and things should be better.

 

I purchased a 88 N/A a fiew months back with 142,000 miles on it. I have put about 600 miles on it since and I had this same problem occur for the first time yesterday. Totally out of the blue. It went from no issues to running like crap during hot starts. Now this isn't my first FC and I am very familiar with pulling fuses. I think that your solution is ingenious HAILERS. But what I want to know is what could causes this to happen in the first place. And please don't say leaking injectors because I cant see that happening as fast this did. It also seams to bog badly when sitting in traffic for a while when hot. I replaced the plugs and wires aprox 400 miles ago, so rule them out. Where is this thermal or water temp sensor you speak of located? Could that be my ghost? Please Help!

 

I have this problem BAD ... sitting at a stop light after 15 minutes of drivng and 10 minutes warm up bogs my engine and sometimes kills it even sometimes , hotstarts are impossible , unless i pull fuses and then it runs bad mostly and dies shortly unless I rev higher
I'll try this tomorrow and see what happens .... and yeah which water temp sensor is possibly to blame?

 

The water thermo sensor on the back of the water pump housing can not be the cause of a HOT start problem but can be a cold start problem. The reason is that the water thermo sensor if it fails, fail or defaults to approx 176 degrees. Sort of a hot temp.

If that sensor was disconnected and the engine was cold, you'd not get enough fuel during the start.

If your having problems keeping the engine idling when hot, then this probably isn't your fix. This is just for a engine that is fully hot and has been shut off. Then minutes later you try to start the engine and the damn thing won't start unless you have a fuel cut switch that you put in OFF to deflood the engine.

Look at the pulse width in this jpg: http://www.teamfc3s.org/forum/showth...threadid=48699

Look at the pulse width in this jpg: http://www.teamfc3s.org/forum/showth...threadid=48698

With pin 3B disconnected and a damn hot engine, the pulse width is 5.96 ms.

With pin 3B connected the pulse width is 17.62.

So? With a engine that is prone to not start and flood when hot, do you want the 5.96 duration or the 17.62 duration???

FYI on a cold engine the duration is in the twentys if I remember right.

 

O.K. That I understand. But what could be the cause of this hot start problem? I understand your solution, and it is a great idea. But what could be the cause of such a sudden change in performance? Call me stuborn, but I want to address the situation form the stand point of repairing the problematic component. Not tricking the ECU into "thinking" everything is all right.

 

I agree with lov-2-rev

I do have the hot start problem and will look into doing this if the problem cannot be addressed.

 

I have thoughts about the Cause, but I don't think anybody wants to hear *Mazda Rotary Fatal Flaw*, so I won't say it.

I attach a couple of jpgs of a STARTING RX-7. Same car, maybe five minutes apart since I had to scan each Palm display. Look in the lower left corner for the pulse width.

First jpg of a start with pin 3B attached.

The second jpg is of a start with 3B disconnected.

And as far a MOTOGP goes......move over Valentino Rossi, Casey Stoner has arrived!

 

Valentino all the way!

 

has anyone tried this...? its a theory i dont want to go messing with my ecu on a theory...

 

Yes it works exactly as Hailers says..

I did this to my car after changing all of my injectors and still having hot start issues. I put a switch in the line. switch closed for cold starts switch open for hot starts. My only problem seems to be that it WILL NOT start cold unless the switch is closed (ECU sees 12v) this on on days in the 80-90 degree range.

Interesting side note. I actualy had all of this done about 3 years ago finding it out quite by accident. In about 1997 my car just wouldnt start any more i took it to a shop down the street and they put SOMETHING inline of that wire. It was a small (dimesize) circut with an additional ground coming out. So about 2001 i started having problems starting again. after messing with the circut they added i dicovered that the car would only start if i removed the ground wire from the device while hot. after a while i just removed the device and put it a switch in. It still would flood occasionally but I also had a fuel cut switch insalled.

I dont know exactly what this device was, but i am going to try and find it as it may be of use to someone.

There really has to be a way of fixing this hot start problem. A swich is still just a band aid, easier then the fuel cut but still a band aid. Hailers, Icemark, you guys have any permanent fix ideas???

 

Did you mean far Left? My ECU has three connectors - from left to right, small, medium and large.

The small one on the left has a black wire with blue stripe

My '87TII has gotten so bad that I cannot start when hot in less than 1/2 hr sitting. I put a switch in that turns off the injectors to un flood it, but when I switch it back on and crank it immediately floods again.

I'm going to try the disconnect and see if it helps.

Thanks!

- k -

 

I just answered your other thread.

The small ECU plug.

The wire is on the bottom row.

It's on the bottom row and to the far right. Pin 3B. Black wire with a blue stripe.

And, yes, it's a bear to start when the engine has cooled off because the mixture is now too lean. That's why I bought and assymbled a Simple Volgage Switch from JAYCAR so I'd not have to flip a switch anymore. And sure enough, I have not had to since I installed that simple voltage sw.

 

or another".

Hailers,

I scrolled through this thread and could not find your description for wiring the relay. Please repeat or provide a link to the threat where you do describe this.

Excellent service to the community for this one, by the way.