dooby-do

iTrader: (2)

can anybody help, I have a 2.5 sti when I start the car in the morning fires straight up no issues what so ever, but if I turn the car of when its hot then it wont start again, I have to keep trying then after around 5 mins of trying the car will fire straight up. yesterday I stalled pulling away from a roundabout went to start it the car turns over fine just wont fire up then after a few mins of trying it will fire up fine and drive fine. its slowly getting worse any ideas of what could be causing it any help would be great ....

ossett2k2

iTrader: (9)

faulty CTS

dooby-do

iTrader: (2)

thanks for the reply I have also noticed the the Phormula Knock Sensor has been showing some odd readings since this has happened, could that be linked to the same issue

ossett2k2

iTrader: (9)

I'm not sure if this would be picked up on a knock monitor,what strange readings are you getting?
You got any fault codes?
The sensor can also be checked with a meter for ohms to temps to save you buying a sensor when that might not be the problem.

dooby-do

iTrader: (2)

under hard boost there is debt going on, only under very hard boost,, it is fitted with simtek, so spoke to the mappers and they have said it could just need a tweek on the map but hard to say without plugging it in.

dooby-do

iTrader: (2)

i looked online and this is what i came across hence why i said could it be linked.

HOW THE COOLANT SENSOR AFFECTS ENGINE OPERATION

Input from the coolant sensor may be used by the PCM for any or all of the following control functions:

* Start up fuel enrichment on fuel injected engines. When the PCM receives a cold signal from the coolant sensor, it increases injector pulse width (on time) to create a richer fuel mixture. This improves idle quality and prevents hesitation while the cold engine is warming up. As the engine approaches normal operating temperature, the PCM leans out the fuel mixture to reduce emissions and fuel consumption. A faulty coolant sensor that always reads cold may cause the fuel control system to run rich, pollute and waste fuel. A coolant sensor that always reads hot may cause cold driveability problems such as stalling, hesitation and rough idle.

* Spark advance and retard. Spark advance is often limited for emission purposes until the engine reaches normal operating temperature. This also affects engine performance and fuel economy.

* Exhaust gas recirculation (EGR) during warm-up. The PCM will not allow the EGR valve to open until the engine has warmed up to improve driveability. If EGR is allowed while the engine is still cold, it may cause a rough idle, stalling and/or hesitation.

* Evaporative emissions control canister purge. Fuel vapors stored in the charcoal canister are not purged until the engine is warm to prevent driveability problems.

* Open/closed loop feedback control of the air/fuel mixture. The PCM may ignore the oxygen sensor rich/lean feedback signal until the coolant reaches a certain temperature. While the engine is cold, the PCM will remain in "open loop" and keep the fuel mixture rich to improve idle quality and cold driveability. If the PCM fails to go into "closed loop" once the engine is warm, the fuel mixture will be too rich causing the engine to pollute and waste gas. This condition may also lead to spark plug fouling.

* Idle speed during warm-up. The PCM will usually increase idle speed when a cold engine is first started to prevent stalling and improve idle quality.

ossett2k2

iTrader: (9)

Looks like this could be your answer then,especially if you wasn't getting det before the warm start problems happened.
Not difficult to change and not expensive to buy but like I say you can check the sensor with a meter 1st.
If you do replace it then defiantly buy genuine oem sensor.

dooby-do

iTrader: (2)

cheers for the advise ill buy one as there not exspensive, and see how it gets on

alcazar

iTrader: (2)

You ARE keeping your foot off the throttle while starting from hot, aren't you?
Otherwise difficult to start due to flooding.

dooby-do

iTrader: (2)

yes I don't touch the throttle when I start the car when hot,

dooby-do

iTrader: (2)

another issue is once the cars up to temp if I turn it of and the go back and start it when its still hot the idel is a bit up and down and then will eventually stall takes a min for it all to settle down aslong as I don't let it stall

watty88

I had very similar issues with my 2.5sti and it turned out to be a coilpack, it was driving me mad for ages then sorted in 5mins.