FD taking longer to start when hot and left for a bit...

[markrx7]

hi all, to be honest it sometimes does it when its cold as well as hot but not often.

right a bit of history for ya..

right put a new engine round xmas time in, well it was brand new from mazda in 2005 and its done 27k miles total (including the 2k its done in mine) had it compression tested at 25k and it got nice and high...

anyways, this problem has started since i started using it more after putting the new engine in...

it will usually start from cold straight away, and if i stall it or turn it off and start it again it will start on the button everytime straight away as quick as most piston engines etc.
but if i leave it for 5mins or longer it takes about 4-5 seconds of cranking time to start? however once started its mint, and it drives really fine and pulls hard. Hayward rotary can vouch for this but i just havent had the time to take it to them to sort it, and with the heater matrix just going its gone down in the priority list.

could it be just heat soak?

and also could it be linked to if i blip the throttle slightly then it stalls.... which is really embaressing! and this happens quite regulary!

[BlitzBoy]

Is your heater matrix losing fluid? what water temps are you getting? if your matrix is losing fluid or not circulating the water correctly then you risk overheating the engine

[Dr-Rotor]

and also could it be linked to if i blip the throttle slightly then it stalls.... which is really embaressing! and this happens quite regulary!

 
TPS is on the wrong voltage. Do you have a PFC with hand controller? If not I will have to find out how you check it but if you do then look up your VTA1 & VTA2 in the ECT section under sensors/switches.
 
VTA1 is usualy the problem. It should be 0.75-1.25 when the car is at operating temp with just the ignition on. Full throttle should give a high 4.0 value. Never 5 as that is to high. At no time should any of the VTA\'s be highlighted on the PFC. This means they are 1 of 2 things. Out of range on the volts or damaged.
 
If you dont have a PFC I can find out for you how to check the voltage on the VTA. Dont worry, if you car drives well still there is nothing wrong with the motor. By what you said when you blip the throttle and it stalls that means your VTA1 voltage is too low and the car stalls because VTA is TPS (Throttle Position Sensor) The position of the throttle cannot be tracked properly by the ECU causing it to stall.

[Ste C]

Hello mate, did you manage to sort the problem out? I had a very very similar problem, mine wouldnt even start at full temperature but started fine when from cold and he drove fine. I followed exactly what Dr-Rotor has said here and upto now fingers crossed she is working fine again.

[Dr-Rotor]

Thats good to hear. Im glad its all working.
 
That TPS is a nasty littler bugger. Catches many people out. I only learnt about this TPS thing when I was fixing a mates car. His car would work perfectly with the stock computer but would cut out when warm with the PFC in it.
 
I pluged my laptop into it and did a little bit of logging. It recorded the VTA1 as a low voltage and showed up red. So I read up in the manual as to what votls it sould be seeing. I adjusted it and it has worked perfectly every since.
 
One day while we were tuning another FD on the dyno I noticed the TPS voltage was jumping around all over the place and the car would idle like crap. We tired to adjust it but it would not hold the voltage. So the rotary mechanic that dose all my engine work just unpluged it. The car emediatly ideld smoothly and we were able to tune it.
Never thought it would work without the TPS but it did. Even the mechanic was amazed as he normaly tunes Micro tech and Haltech ECUs and they dont work without the TPS.