Weird...

Yeah, I always carry a spare eeprom with a known good bin, also, my burner rides along..

Sorry my bin didn't help.. BW

 

I'm back to $8d for now.. Until I figure out the problem..
Read post below.



-- Joe

 

Bruce,

I reproduced the problem in $8d.

I removed some fuel in the 1600-2400 rpm range, and the problem was imediately present. As bad, if not worse than with $58.

Here is a snapshot of the compare. Again, the problem was with removing fuel. Perhaps because of timing being too high in these areas (your comment earlier).

<PRE>

20 25 30 35 40 45 50 55 60 70 80 90 100
1600 0 0 0 0 0 0 -10.2 -20.7 -21.1 -21.5 0 0 0



20 30 40 50 60 70 80 90 100
1600 0 0 0 -10.2 -21.1 -21.5 0 0 0
2000 0 0 0 -23.4 -44.5 -45.7 0 0 0
2400 0 0 0 -12.5 -23 -25.4 0 0 0
</PRE>

Here is the timing snapshot of these areas:

<PRE>

20 30 40 50 60 70 75 80 85 90 95 100
1600 38 43.9 43.9 43.9 41.1 38 35.9 33 29.9 26 23.9 23.9
1800 36.9 38 43.9 43.9 41.8 40.1 34.1 34.1 29.9 27.1 23.9 23.9
2000 39 41.8 46.1 46.1 40.1 40.1 38 34.1 30.9 28.8 25 23.9
2200 37.6 43.9 46.1 46.1 40.4 38 36.9 33 29.9 28.8 26.4 23.9
2400 38 42.9 46.1 46.1 40.1 38 34.1 29.9 28.1 26 23.9 23.9

</PRE>


As you can see, the problem exists in my 46.1d areas of 50-70kpa. I Guess one would assume, the timing is soo high in those areas it is causing a lean miss condition?

-- Joe

 

I may have missed it someplace along the way, but what heads are you running on this engine? Thanks,

RBob.

 

72cc sportsman II, 2.02/1.60. With the TRW 2256 piston, its 8.96:1 compression ratio.


-- Joe

 

I finally found a picture of the sportsman II chambers. They are a modern design that is typically a faster burning chamber. I say typically because it always varies. And typically like a little less timing then the older design chambers.

RBob.

 

Interesting.. If you compare my timing to a stock 305 TPI manual bin, you'll notice most of it is the same. I only adjuted the higher KPA (90-100) columns. I figured what was good for a higher compression 305, will be good for me. I guess not eh?

Question: Would you just decrement the entire timing table, or select certain areas?

-- Joe

 

Different engines like different timing. I would be reluctent to compare a stock 305 TPI engine to your engine.

As far as timing (and not being there or being able to drive the car) I would reduce the areas of 46.1 degrees SA to 42 degrees SA. One reason is that 46.1 deg is a tad high and the change of 6 deg SA from 50 KPa to 60 KPa may be contributing to the bucking.

In your previous post where you showed the change in fueling to re-create the bucking. Is that in VE%? It would seem that a 45% change in VE would cause a problem.

RBob.

 

Thats a direct compare using Tunercat. To get those values, I was playing with a combination of tpi_roc's spreadsheet, and vemaster.

I'll try reducing the timing and see how it works out. If I can lower the timing in these areas, and drop the fuel there.

I'd like to try and run more WOT boost timing though. The car seems slower with only 24d of timing under boost.

-- Joe

 

I'm retarded. The bin I started with (last year) was a 350 manual vette bin, not a 305 manual bin. Thats why the timing was soo freaking high.

I imported some timing tables from a 305.. Gonna tweak them a bit and try 'em out. If they seem to work well, i'll adjust ve.

-- Joe

 

anesthes, have you had any luck yet? I've been trying to trace a similar problem to you, I'm getting between 7-11 degs spark retard constantly no matter what gas I'm running. I'm also getting a ton of knock counts and I keep getting the knock sensor code. I'm pretty sure it's a sensor problem, although the car isn't with me, cause the positive cable to the battery ended up getting grounded and almost burnt my car down completely. Anyway, I think your problem really is coming from a screwy k.s.

 

I just want to point out, there was 4 problems and I figured them out (thanks to a lot of help from Grumpy, and RBob).

1) My blower makes tons of noise at idle with the smaller (3.33) pully. At idle, the impeller speed is around 5500rpm which sounds like a freight train slamming on its brakes, then derailing. Vortech said "Deal with it". This causes knock counts at idle (800rpm).

2) The bucking was caused by too much timing at cruise. I still have a small tiny bit around 1500rpm cruise, but I shouldn't really cruise down there anyway.

3) The stump on acceleration was timing + fuel. Timing transision too high, not enough fuel. The car was leaning out, then geting rich.

4) The "thumpyness" between shifts was the lack of a true throttle follower in $58.

Once I get a perfect tune (and log inj pw's + spark at every poissble rpm x map combo) I'll give $58 a try again. One of the biggest problems I noted with $58 was the async/quassi fueling. It appears to switch right after idle to async. My injectors are not "so big" that I need quassi, so i'll try to turn that off in the future.

My windows machine had a hard drive failure 2 days ago, and I lost all my $58 work. Some would say this was a sign from *** to start all over anyway. I'm stuck with only a aldl laptop (which I moved all my tuning stuff to), and a Linux box.

-- Joe

 

I have a question about the lean miss.

Is the only way to get rid of it is to lower spark?

If you increase the VE in the area, to richen that area, won't the computer just end up pulling the extra fuel out as the blm change?

Thanks
Tom

 

ttt

 

Could someone verify or refute what I said? Rbob, Grumpy, 3.8TransAM?

Just want to make sure what i am thinking is correct.

 

A lean mixture burns slower and is more difficult to light-off. More SA generally helps in this regard.

If the closed loop controlled AFR is too lean then the O2 window calibration values can be changed.

RBob.

 

Great! Increase spark.. this is what I ended up doing. (when I lowered it, I still got a slight miss.) It has gotten better with more spark.
I am at about 47 deg in the spark advance table with no knock.

How much is too much advance? (eventhough I have not gotten any knock yet). My engine is a 305, LT1 Cam with world torquer heads that have been ported and polished including the combustion chamber?

I never had any sign of this when I had my auto trans. I have only noticed it now with the manual trans between 3-3800 rpm and 40 ish MAP.

 

You've probably missed the tune.
At 47d your putting too much heat into the oil, and bearings. You might get some good mileage for a while, but you'll probably knock the corners off the pistons at that rate. Your also getting real close to cross firing within the cap at that. Which can lead to problems in 5+7.

The **Knock Sensor** isn't really a **knock sensor**. It just looks for noises that sound like knock. Distort the sound enough and the sensor is deaf to them. Not to mention they can be often miss tip-in preignition.

 

OOps I am 44d not 47d. am I still to high?

At what point would be considered too high for my setup?

I believe that I read that the 305 uses more timing than the 350 because of the smaller cylinder. Is this also correct?



what is 5+7?



Thanks

Tom