Cascade Crew

[scott in wa.]

well I hope you all had a great holiday, ours was geat.

Kid got his fancy fiberglass hood, a week late and damaged, so we are shipping it back for another. what a pain.!!!!! UPS freight sucks!!!

But anyway.: here it goes.
Car is running kinda crapy,

I have been tinkering with the car a little.
350 S/D stealthram, 58cc throatle body.
msd digital 6a, jacobs coil.
LT4 hot cam, roller rockers and lifters

Here is the problem
When cold it runs ok, but when warm there is a spot in the throatle where is will spit through the throattle body, and it hesitates a bit right there.
almost has to do with load on the motor at that spot.

What I did over holiday
I moved the o2 sensor into the shorty headers, and put a new o2 in.
took all day, it was a pain, but had to be done anyway.
runs the same, no differance.

Put new rotor cap and rotor on, old one was a little corodid.
runs the same

Put new auto lite 25's in gaped at .047, need to re-gap at .035 and see if it makes a differance.
runs the same

Ignition??
Iam at a loss.
thanks
scott

[Dewey316]

Hook up the scaning software, and try to get some data from when it happens. If it happens on throttle roll in (adding throttle) it is probably pump-shot.

It may also be timing related in the chip. IIRC paul had to add a huge ammount of pump-shot for this HSR, I had a add a huge ammount when I went single plane also.

Some datalogs would be really helpfull here.

--John

[scott in wa.]

pump-shot.??

So this spitting Iam talking about, you guys have had it as well?
kind of a spit, maybe a pop. when you step on the gas a bit.

will do some logging next chance I get, this weekend.

thanks
scott

[Dewey316]

Sounds like pump-shot.

It should be listed in your chip, as AE Enrichment. or something like that, You may have two diffrent fields for it, one is going to be msecs vs delta MAP and one would be msecs vs delta TPS%.

Tuning the pump-shot stuff, is kind of hit and miss, and a lot of trial and error. It is also hard to get good readings on it. So, just look at the curve that is there, and try to keep a similar curve. Start by adding like 50% more at each point, and see how it does.

[scott in wa.]

Humm ok..

Don't want to beat a dead horse but Iam just trying to under stand this.
So pump shot is just an acronym you use that means ad timing?????
Iam just not familiar with this

I will look at those tables tonight in the chip.

Thanks
Scott

[Dewey316]

Its adding gas.

it is the same thing as the accelerator pump in a carb. It adds gas when you open the throttle, to balance out the sudden influx of air.

[scott in wa.]

Ok, got it..
Thanks for your patients with that.
So by adding advance timing you are really adding more fuel??
Thanks
Scott

[Dewey316]

the AE or pumpshot, doesn't effect timing at all. It only effects gas.

The POP you are describing, is because the car is going lean, and firing early while the intake valve is still open.

If it surges when you are going along without moving the throttle, or backfires then, I would guess it is timing.

Start out by upping all the values in the AE fields by 50%, then go for a drive, and see how it does.

This is another good reason to dyno, you can see what your air-fuel-ratio goes to when you open the throttle on the dyno, this will help you tune the pump-shot (AE).

[scott in wa.]

WOW,
Thanks I needed that.


And yes, I will be at the dyno if at all possible.
Even if I have to rent a flat bed to tow the car down there.
It will be educational as well as fun.
Don’t know who is coming yet, me and my oldest for sure.
Its his B-day today, CRAP HE’S 19 already. Man…..
I hope to spend the night at a motel as well.

The hood will not be on, but that’s ok…

[Dewey316]

Scott,

When you guys descide, let me know, I can get you motel info so you can get a reservation.

You guys are always welcome to stay with some of us if you prefer.

[LB985IROC]

[blue89]

I had a problem with my V6 car a while ago. It would "pop" through the intake when under half throttle'ish. Turned out to be a lean intake backfire caused by an inaccurate MAF sensor. I discovered it when I forgot to plug the MAF back in after playing around with it.

[Twilightoptics]

That stumble, assuming no mechanical problems, is a lack of AE.

Happens alot with the HSRs.

[scott in wa.]

Ok, I looked at the mask and the bin last night.
It’s an Super 8d mask
7730 ecm
It got a few constants with the title A&E in the heading.
It also has a little more in the tables section.
I will have to write these down a post them later but there are many, so Iam not sure what one to change.

Its tables for sure???

Iam using the turner pro r/t software.

[Dewey316]

I don't have 8D, but yes, it should be tables. There should be a table for TPS and a table for MAP.

If you can screen shot what tables you have, We can sure help you with the values.

[scott in wa.]

will do tonight at home on the laptop,
I will send them tonight
thanks
scott

[scott in wa.]

Hope you can post for me.
I sent them to Dewey
thanks
scott

[Dewey316]

I'll upload the pic when I get time. I e-mailed you back.

From looking at the options, the 2 you should change are the Mult vs Delta TPS, and the PW Mult vs Delta MAP.

I would give those a try, and see how the car drives.

[scott in wa.]

thanks
scott

[mrpopo573]

Wow this is actually really interesting to just read through. What a tuning job...how are the power gains with HSR in good tune? Schultzy you have this right?

Just curious.