Spec; MSD chip, 803s, 31 actuator, L6 ECU, T3, group A coil

Not sure if I have a problem or not, wanted to check before I skin my knuckles. Car needs throttle to start from cold and throttle nursing for the first min or 2. Read recently that no fuel injected car should need throttle to start..if it does theres a problem with act or ect sensors. ACT sensor nice and easy to get to, ECT is a pig and looked the most likely to be suspect as its under the coolant pipe so more likely to be damp / bad contact, both showed 6 ohms at whatever temp is was in my garage yesterday and lead 5v unplugged (both as per book)

Question - Do i need to pull them both out and test them over the full range 20, 30 degrees etc. or does the above suggest this is fine? And do all stage 2+ cossies need throttle to cold start?

Hoping its the later as its f ing cold in the garage at the mo!

thanks in advance

 

It's more likely to be a duff iscv, if the reading is correct at one point it is 99% likely correct at all temp points.
Once the engine is warm check the CO is what stu says for that chip, normally around 2.5%, you could always tweak it up a touch, as it sounds like it may just be a bit lean.
It's very hard to get the cold stuff 100% right for every car with an off the shelf chip, as there is always variations.
In short it is a chip not a live map, if it was mapped individually then you would not need throttle, so long as iscv working ok, have a look also for any air leaks as these will lean the mix, you could also tweak the tps reading a touch so it gets slightly more fuel.
Cars can start perfectly stone cold with no throttle and with no iscv if set up correctly on a decent ecu.
tabetha

 

Thanks Tabetha, I'll get the co checked. Assuming CO is ok is there any downsides to me using throttle to help start thereby ignoring iscv? ISCV is a pig to get to on mine and the car is a sunny weekend toy

 

my erst always need throttle to start aswell mate no matter wot weather lol

 

Dosen't matter if it's FI or not if setup right it should start with no throttle, to your question no, as opening the throttle same principle as the ISCV would do so no harm.

ECT can be likely suspect, although be careful when testing these as output is not linear.

Is the ISCV ok, done the usual cleaning and lube of it?

Martin

 

No thermistor in the world is linear, this is the only real downside, they do output a large signal though, this is why they are used, there is no amplification needed, generating with it the unwanted side effects of amplyfying everything such as noise, offsets, drifts etc, these are about the most un linear devices known to man.
The thermistor/temp sender is the same one as the air temp sender, just in different housings.
Using the pedal to keep it going will do no harm, but it does get a different signal as fuel is added due to tps reading, and more air flows as well.
Just check the co when hot, if this is ok, then you can try a slight tweak.
If wanted you can work out the resistance versus temperature with
R=Ro exp(Beta/T-Beta/To) formula, if interested.
tabetha

 

Thanks for responses. To get a cossie in a dax rush you have to put a bulge in the fibreglass side panels and they cut / weld put the throttle body in upside down! As such ISCV is nigh on impossible to get to...will have a go when i'm feeling masochistic, but will definitely check co asap. As you can imagine though I'm not driving it much at the moment!

 

If mapped correctly it will still idle perfect when there is no iscv.
The cold running is hard to get right, as the mapper only has one chance, as it's typically only there one time, but if a ecu you can tweak yourself then you can always add a bit of cold fuelling etc to help.
tabetha