1988 Turbo II with T04S. Fuel system is 720/1680, base fuel pressure 40psi. No emissions, including no ISC/BAC system, although I do have a fast idle cam.

When I first got the car running, cold starts took a really long time. So I started adding fuel to mostly to the +10 and +30 areas of the map. I did it incrementally, each time I went to drive the car, to make sure it wouldn't flood. Now it seems that the last time I added fuel it didn't help at all. And when I datalogged my cold start, it seemed like I was only getting about 64 msec when it should be closer to 80msec (coolant temp was +11C).

Here is my cranking map:



This is the stock cranking map:





First question: is there a quirk in the PFC where it doesn't seem to respond when you tell the cranking map to add more fuel? I mean when my +10 setting is in the 80's and my datalog indicates only 60ishmsec or so, it means I've either got a datalogging problem (admittedly, my crappy laptop was only getting 10 samples per second at the time) or there is something about the way the PFC scales the map that I do not understand. It looks like it tapers off the msec as you keep cranking the car, so my slow sample rate could have missed the 80ish msec frame.

When tuning cold start, I figured that as you keep adding fuel it should start a little quicker, but then if you cross some line it will flood out. I haven't had a flooding problem, but is it the case that if you give it a bit too much it won't flood but it will crank slower? Does that make sense?

Any input would be appreciated. I am just trying to understand what I should try next (leaner or richer, which parts of the map to alter). Or is this the best I can get it because I have no ISC? I know the ISC on a stock car should open all the way to improve cold starts, but giving the car a little gas doesn't seem to help all that much. Thanks for the input.

 

Never had to mess with any of this on any of the cars that I have worked on.
Make sure that your water temp sensor is working correctly.


Did you set Settings 4 IGN vs Water T Cool to no retard?

 

water temp sensor is brand new, OEM. IGN vs water T has no retard. when I say it takes a while to start... well it takes longer than it did when it was stock. It's not unbearable, just mildly irritating. You can see on the graph there that it's 2-3 seconds total. When it's warmed up, it will be nearly instant.

I am running manual idle control etc. my timing is set to 12 for the whole 400rpm column (N1), but datalogs indicate that cranking advance is 6 and then goes to 12 as the car comes alive. must be one of those things you have no control over. I dunno, maybe this is just the best I will be able to get it to start.

 

Make sure all this is set for best manual idle:
(1) all idle speeds set to 0
(2) O2 F/B Control turned off
(3) Idle-IG Cntl turned off
(4) O2 Feedback set to 1.000
(5) run a re-calc
(6) ISC connector not connected to anything (being an FC it shouldn't be
connected to anything)
(7) verify "ALL" sensors/pickups are working correctly
(8) The area around your idle cell should all have the same timing and fuel.

If your engine idles in P4,N3; P3,N1-N5 & P4,N1-N5 & P5,N1-N5 should all have
the same timing and fuel.

Remember that the stock system controled everthing to try and insure a steady idle. Now you have to manually do it. This way if the idle tries to bounce a little, it has the same run time parameters which will keep it smooth.

 

I've taken care of all of that... except I didn't bother setting O2 feedback to 1.0 because i turned off O2 F/B and I figured that it doesn't matter then. And I only have my boost area of the map recalc'd.

idle AFR's are in the low 12's and won't go lower because of the PFC limitations on injector pulsewidth I believe. I have my idle cells (and surrounding ones) set to 2.5 msec (base map tab base x INJ display) and datalogs show that it won't go leaner than 3. But I have bigger primaries and 40psi base pressure so I think the combination of all that is why it won't go a little leaner. But the idle is stable at least.

 

Kyle and I have seen the PFC acting like it was trying to adjust fuel even with the O2 FB turned off. It was with the ISC controlling idle, I just do it as a paranoid safety factor.