Cascade Crew

[scott in wa.]

88 iroc with a 91, s/d setup, Holley stealth ram,

We worked on the car this weekend
We gave up on the fans for now and wired them in with one manual switch on one fan, the other comes on with ignition on.
They work, and the temp is good. Will fix the later.

Brakes,
I have the vacuum booster line hooked to the back of the plenum, it looks like we have 5 inches of vacuum at idle, when we rev it up to say 2, or 3 grand, when the engine decelerates we do get about 20 inches in the reservoir.
But, when you hit the brakes say twice it goes back down to 5 inches.
It still feels like manual brakes.

1. If I move the vacuum port lower on the plenum, where I have the MAT sensor at, will it make a difference???

2. If you have the stealth ram set up, where do you have the brake vac line running to??? Bottom or back of plenum????

3. Tuning
We are able to data log, the system does go into closed loop. We did this at idle in the drive way.

O2 sensor is all over the place, 800/900 up and down along with the injector pulse width, I saw 1.5 to 3.5 on width, fuel pressure set at 47psi
With 24lb injectors. Its running rich at idle then when you rev it up it goes lean. Help?
Headers are glowing a little when hot at idle, noticed it at night.


I look at the base timing, I think its 6 degrees in the chip, when I unplug the esc wire then time it, is 6 degrees the proper timing? (Stupid question)


Thanks
Scott

[Dewey316]

In closed loop, the O2 sensor should jump around from rich to lean. Look at your BLMs, those will tell you what the car is doing. You are probably going ot need to start driving the car, to really get a feel for how it is running, just revving it while it is sitting, does not give very good readings, as the engine has no load.

[Twilightoptics]

Your base timing at 6 is good, but you need to make sure that the engine is advancing when you rev/change load.

Rich at idle is normal.. you'll need to tune it out. With the hotcam you shouldn't worry much about overlap. Adjust the kpa in the rpm sell and map you're idling. Make it smooth. Small changes from cell to cell.

Idle timing should be atleast 20º in say 400-1000rpm at the cell above, and below your idle. That should help smooth it out.

As for reving it up and going lean... add more acceleration enrichment.

Best thing to do is get all your BLMS as close to 128 cruising at all the different loads. THEN fine tune your AE and your coolant modifiers by never touching the main map again.

[Twilightoptics]

BTW, my brake booster line is on the back of the plenum.

Timing and tuning will make big changes to how the engine sees the vacuum. Unless you have a big leak, don't worry about it too much. Mine's certainly not powered up like stock. Engine breaking is good.I have a much larger cam though, which decreases vacuum. Never checked what inches of vacuum I have but I idle around 55kpa, cruise 30-60kpa, engine brake is 10-15kpa.

[chevymad]

Like Paul is saying, when you get the engine tuned better the vacuum to the brakes will increase. With the headers glowing it sounds like its not getting enough timing advance at idle. Do what Paul says there too and I'll bet the vacuum will come up quite a bit, and the brakes will start working better. 5" of vacuum is very low. I don't remember the hotcam running anywhere lopey enough to actually have that little. So it should all be in the tuning.

[scott in wa.]

Well,
We insured the car last night, took it for a 1 mile or so drive, then let the kid drive it to a friend’s house.

So we are really just getting started at this point.
I will be printing this thread out and referring to this stuff this weekend when we do some data logging.
I appreciate the information, keep it coming.

Going to swap out the front disc brakes Saturday, have the new set off the old car.

Drives pretty good for having the whole front end off and swapping out the k-member, that was a huge job. It pulls ever so slightly to the right, not like before when you let go of the steering wheel it would put you into the ditch.
Front end is settling down now, I was worried about the gasser front end look, but its fading now.

I hooked a vacuum line from my suburban to the Camaro and brakes seem fine, 20 in/hg of vacuum, so it looks like a vacuum problem.
Also looks like I need a new rubber grommet in the brake booster, some times it leaks.

Car wants to go fast, but trying not to, for week or so with the new 3:73 gears in.

Speedo if way off, will have to change the Speedo gear in the tranny.
Going about 35mph, Speedo says 50mph LOL..
Thanks
Scott