Its a problem I have had for a while just much more evident now that I put 4200 stall in this winter and forced to lock converter much earlier.
I have changed Timing from 32 degrees to 36 in that range 1800-2300 approx. Seems to have helped but I really did not want to add much more unless it necessary.
Any suggestions?
Or is this just something I have to live with using a large cam, short runner intake?

 

Might try 28d.
Possibly into a lean miss?.

When you run a loose converter, tall gears, etc., it makes it hard for the engine to build heat (chamber, manifold wise). At real light load, vaporization is great way to get drivibility. Your combo isn't very condusive to building much heat.

And, just to be clear, I don't mean coolant temps..

 

Ill give it a try, But it seems better @ 36 opposed to 32.
Should not be a lean miss, BLM is 124-130 . Which is actually richer than 14.7 due to overlap.

Thanks for reply

 

But, it might be one bad thing covering another, that's way I always try both ways on trying things.

14.7 might be too lean for your combination. Stoich is primarily for the converter. And/or the lean transistions to average the 14.7 might not be ideal.

 

Good point Grumpy,
Maybe after the Timing I'll try open loop with some fuel.
Right after your first reply went to try and snow showers hit.

Been driving around on slicks so can't do snow, Hope roads will dry for tomorrow.

 

I have this exact same problem. It occurs (for me) between 1200 and 1800 RPM and under light load (cruise, light acceleration, and transition between light acceleration and light, non-DFCO deceleration). Above 1800 RPM the symptoms disappear.

Grumpy, you modified my bin, taking out some timing and adding fuel in the lower MAF tables. This did not help the problem (but did help another unrelated issue I had)...

I'm stumped about what's causing it. I have a completely stock valvetrain and basically a stock engine (L05 roller block with TPI).

Its *gotta* be something simple (maybe failing EGR sol)?

I keep meaning to sit down and do some emulation tuning but just haven't had much time (hmmm, I wonder why).

I'd love to get this solved, its annoying (and at times the bucking can get heavy).

BTW - fuel pressure is stable and consistant. I'm not convinced its the fuel pump.

 

I've seen that symptom many times on carbed motors. Always turned out to be lean miss.
You should be able to hear it and feel it.
I've always been able to in park at least.
You feel it go smooth, rough for a couple hundred rpm, then smooth out again.

 

I've experienced this as a lean miss when running very high AFRs in highway mode. So, I would tend to think it is a lean miss too.

Now, with that said, I am running between 40-50d at cruise (that includes the base timing). I basically started with the vette spark tables and then had to add a couple extra degrees.

Tim

 

I had a lil talk with a guy that does some oem level tuning stuff the other day.
It seems that the refineries are brewing gasoline to spec., but the spec., has rather lose tolerances. What may run fine in several brands of cars just doesn't work well in others. AND, some places are now getting oxygenated fuel, that never before have, nor are required to.

While all the gasoline shares the same pipes, it's the additive packages that sets the different brands apart.

And just as a interesting side note, some of the newer engines are just running 15d or so at cruise, and 25d at WOT, at 6K RPM, and they don't even reach the 25d till max RPM.

 

Well weather permitted some testing today.

39 degrees timing seems to have done the trick, I would have tried the lower timing but car picked up a good amount of cruise power. I still plan to try just because 39 degrees scares me, especially at low RPM.
Seems like alot of beating on the piston/rod bearings for no reason.
Then again factory tune is right there with it, so must be ok.

 

I had a similiar problem

It resulted from trying to pull too much fuel in overrun and gave me a slight surge when holding a low speed around 12-1500rpm's

I ended up slowly bringing some fuel back in at the edge of overrun/cruise to smooth it out, seems to be holding its owns thus far.... timing is in low 30's in that range as well and some of it dips to mid 20's depending on the kpa , etc....

LAter
Jeremy

 

Having the same problem on mine.. 5spd car, with a no give ram 6 padel ceramic clutch..

BLMS are 129-140 at low kpa (45-50) cruise. I think a lean miss for sure is my problem. Car bucks like crazy, especially taking off.

I'm gonna try adding more fuel. If that doesnt help, it seems more timing may??

-- Joe

 

Timing helped mine, little scary running 40 degrees, but it works.

 

Hrmm.. I've been running stock sy-ty timing.. which is a LOT less than my $8D timing was.

My motor has even less compression than a L98, so using the stock 800-2400rpm, 30-70kpa timing should be a good starting point. the sy-ty stuff looks really really low compared to the $8d stuff.

-- Joe

 

Stock sy-ty, 30-70kpa

30 40 50 60 70
600 26 26 23.9 20 15.8
800 26 26 23.9 20 15.8
1000 17.9 27.1 25 25 16.5
1200 17.9 28.1 26 26 20.7
1400 21.8 34.8 32 29.9 28.1
1600 26 34.8 34.8 32 29.2
2000 28.1 38 34.8 32.7 29.9
2400 29.9 38 32.7 30.9 29.9


Stock $8d 30-70kpa (with columns for 2200, 1800 left out)

30 40 50 60 70
600 20 20 20 20 17.9
800 20 25 29.9 28.1 23.9
1000 23.9 29.9 35.9 35.2 34.1
1200 28.1 35.9 40.1 38 35.2
1400 39 41.8 41.1 38 36.9
1600 43.9 43.9 43.9 41.1 38
2000 41.8 46.1 46.1 40.1 40.1
2400 42.9 46.1 46.1 40.1 38


For a 8.96:1 motor this should be fine. Under full boost, I'm running 23-25d.

 

First rule is giving the engine what it wants. While you can start with anything you want, using what works for others, can result in problems.

And don't forget the Sy's used 30 PPH injectors so tip-in preigntion is less of problem since you have more fuel available on AE. Not to mention the AE stuff in the Sy code is much better, IMO.

AE and the way spark is ramped out are something that go hand in hand, well, to some degree.

 

I run 41 deg ctruise from the ARAP bin and brought down a hair. No knock, no hesitation or boucyness.

Like Grumpy said give it what it wants. If you aren't glowing the headers, and you aren't knocking, what's wrong with 41deg of timing without a load?

I had this bucking problem like Trax with highway mode. Though the bin had highway fuel and spark enabled and made me about 15.3:1 with 51deg timing... Disabled that REAL fast.

It would be buckin and lack of power like something was really wrong till I got on it to get out of highway mode. It even caused an occasional SES light.

 

Something is making the knock sensor go erratic.. it gets tons of knock counts, regardless of fuel and timing condition..

-- Joe

 

Dowel pin on the cam hitting the timing cover? Etc things like that. Is your knock sensor in too far making it overly sensative!?

 

Worked fine before bigger blower, new exhaust (headers to tailpipe), and $58.. Can't say I know which one is causing it.


-- Joe

 

That'll drive ya crazy to find.
Alternator bearings, water pump, serpentine belt are all maybes.

If it sets counts just sitting still try popping the serpentine belt off, and seeing if the kills them. That's a quick way to rule out the belt are any acessory item bearings.

 

I think its small backfires in the exhaust. It did it with blms at 108, and 128 though. weird.

I replaced the o2 sensor last night.. gonna do some more testing today..

I know this much.. At idle, it would generate up to 60,000 knock counts in a few minutes. I tightened up the exhaust (which had a few leaks) and not its less. Like only a few thousand.. Whats weird is, it will go 20, 50, up to like 1800 then reset, then count up again.. Weird weird weird.

Could also be the blower. The s-trim is outright anoying compared to the a-trim.

Could be the headers are thinner than my wrapped flowtechs were, and and pinging headers are doing it.

Yep, it will drive me crazy...

-- Joe

 

I'm happy to see that more timing worked. I'm not crazy. I've been running 50d in the cruise areas for a long time because the car likes it. It just likes it. Keep in mind that the normal ideas on timing don't necessarily ALL apply when speaking of combinations like ours (big cams, lots of overlap, etc). Big cams like more timing because it builds dynamic compression and increases torque. More torque = better

<FONT COLOR="RED">WARNING:</FONT> IF ANYONE DARES TO USE MY TIMING TABLES THEN PLEASE UNDERSTAND YOU COULD DESTROY YOUR MOTOR.

I never post my tables. Here's a first. This is my CURRENT timing curve. It works extremely well in my setup. I have a huge cam, big stall, big heads ... heck - big everything. This is not intended for a stock motor and won't work properly. There are a lot of ideas in why my curve is the way it is.

1) 95 and 100kPa regions are the same to ensure the same advance at WOT
2) Timing at WOT is advanced to MAX right away in order to provide a quick spin of the high stall converter (because there's no load). This gives a better 60ft. Don't try this with a stock stall torque converter or even a lightly stalled converter!
3) Timing reduced several degrees at WOT in the upper RPMs.
4) Cruise region has lots of timing due to the cam and stall I am running. Really - it's not that bad. Take a look at the stock vette timing curves!
5) I cruise at 50-60kPa. 40->30kPa is the overrun area where I have pulled a lot of timing to help with deceleration. I probably need to pull even more.
6) Your normal increase -> level off -> decrease as RPMs rise on most of the mid-load areas.

Tim

 

Even with those quaifiers, I wouldn't post a timing table like that. It is way too easy, or misleading for the new guy to see that reposted somewhere else without those qualifiers.

That's why I post only stockish type or low timing tables. Or suggestions on how to use low timing strategies effectively.

Not to mention the K/S that so many rely on is tuned for detonation, not pre-ignition, and with that much timing in cruise you can put alot of heat into the chamber, and have tip-in preignition. And unless the AE is done exactly right, someone can innocently knock the corners off the pistons.

I'll forgo even mentioning the 5-7 issues.

Just trying to be constructive, is all.

 

Is this done only to spin the converter faster or does the converter actually flash higher with this method?

 

I completely understand where you are coming from and why you are saying what you are saying. Point taken and understood ... and I respect the criticism. I'm just usually so tight lipped about my bin. People go for a ride in my car and they are amazed at the driveability. This spark curve is what really helps out some of that driveability at part throttle. You had mentioned earlier about the chamber running cool. I posted a table that heats it. It is risky ... but if the conditions are right then it can pay off handsomely. I edited my original post to clarify ... and placed another warning here.

<FONT COLOR="RED">WARNING:</FONT> IF ANYONE DARES TO USE MY TIMING TABLES THEN PLEASE UNDERSTAND YOU COULD DESTROY YOUR MOTOR. YOU HAVE BEEN WARNED.

Tim

 

I've had a slight surge under light throttle conditions. I'd go for a day or two and think I'd cured it, only for it to reoccur.

Turns out it was the Decleration Enleanment. In my code it had a min. MPH. So I just raised that from 4 MPH to 45 MPH. I'd been in there before, and thought I had it fixed, but it wasn't until chaning the min MPH that things are much better.

 

I was tooling around with the highway mode and set it to start at 255mph and my light throttle stumbling has completely disappeared. My A/F ratio gauge shows I'm running back and forth from stoich to lean. I was experiencing a lean miss which was causing the stumbling. Now my problem is when I start the car early in the mornings and drive to work, the car leans out and the car jerks really bad for the first mile or so until the engine warms up and then things are normal. My A/F gauge shows a very lean condition under throttle. I use Tunerpro and was wondering where I need to go to add some fuel to prevent that cold start "kick"

 

Open Loop AFRs.
And possibly the coolant spark correction.

Mine hates any cold coolant spark timing being added.

 

ive had the same problem for ages. The 5 speed doesnt help any. Thanks for the info im going to look into it.

 

Tminig didn't help it.

Removing decel enleanment, and DFCO didn't help it.

Now i'm trying adding more fuel.

-- Joe

 

Added more fuel. even tried it just in open loop. Car bucks like crazy.

In open loop, blms at idle, and part throttle were fairly constant at 125.

Whats weird is .. I was looking at the laptop at idle.. idle was around 950-1000 (even though desired idle was 800). Blms stayed around 124-125, but the o2 never got higher than .050v
THe rich/lean toggle flipped around.. Thats weird to me.

I'm starting to wonder if:

1) Its a fuel issue. I used to run 94 octane with a bottle of octane
boost. Now only 93 octane is available in the area, and i stopped using the octane boost.

2) If my new accel wires I put on last summer are junk, and this is an ignition problem. See the problem is, over the winter I changed from '730 to '749, new exhaust, ported the intake, new injectors.. So Who knows..

-- Joe

 

I'm starting to think the scanner data is wrong.

look at these two screen shots:

http://members.cisdi.com/~anesthes/7...ns/scanlog.jpg
http://members.cisdi.com/~anesthes/7...s/scanlog2.jpg

Notice the map, turbo boost, and vacuum fields.

-- Joe

 

Very well could be. I don't have a 749 to test the datastream definition on, so you'll likely need to edit it to be accurate.

Also, all MAP info, I think, is based on the stock MAP setup (which is not 3 bar, right)?

 

Mark,

I'm not really sure about the map. It should be 2-bar at least. Its really odd.

If I have free time tomorrow, I'll go over the $58 datastream documentation.

A hint of advice: can you post version information on the files on your website?

-- Joe

 

I really need some help.


Ok.. I tried adding fuel, adding spark. Wont help. I'm using datamaster now to scan.

basicly on a cruise it bucks, on decel it may buck. If you mash the throttle to accel it hesistates, then goes.. This type of behavior is going to break my new rear end gears.

http://members.cisdi.com/~anesthes/749-scans/friday.uni is the datamaster log.

The log has half the time in open loop (forced) then I changed bins and the rest is in closed loop. All the settings in the bin are the same. (more fuel then needed).

 

How did you disable them?.

Is it a TCC issue?.
Whatever attachment some one posted later in this thread just bombed me being able to read anything further on down.

After 40 days, and 40 nights it did download....

Try taking 10-15d out of your cruise timing, and starting over. This more is better timing stuff isn't the best answer.

 

The VE table doesn't look right. In that table the VE is highest at 40 and 50 KPa and falls off as the manifold pressure increases. Just doesn't seem like that is the way it should be.

RBob.

 

I downloaded the datamaster demo, and scanned for codes.
I got the following codes:

1) MAP too high
2) Map too low
3) O2 too rich
4) o2 too lean

Weird eh?

Using programmer. The option KDFCOSLK is the speed in which DFCO is enabled over. I set that to like 255mph.

To disable decel enleanment, I set KDEATH to the highest possible #. This would mean, to decel you'd have to change throttle position by over 100%.

The car is a manual.

HAha. I started off with a almost fresh bin. I grabbed the bin saturn posted a while back. didn't touch ve, or spark. Just set my idle options, etc. I tried it last night at idle. Car idles at 105blm. Gonna lean it out a bit and drive around.

Oddly enough, that got blms perfect at 128 at every throttle position..

 

Ok.

I modified the BPW on saturns near-stock bin, and got blms at idle and messing around in the driveway to be 128. Int's went up and down a little, but i'm sure its ok for now.

No codes right away, it seems. I'll drive around in a bit and see what its like. It would be nice if the bucking was gone, but I doubt it.

KNock counts still crazy.

http://members.cisdi.com/~anesthes/7...ns/saturn2.adl
^^^ log

http://members.cisdi.com/~anesthes/7...aturn-test.bin
^^^ bin

Thanks guys.

-- Joe

 

Bugger... I hope it doesn't show the Spark Ref angle incorrectly. The compare I did of my base bin to yours, has your set to almost 10*, should be zero. BW

 

Oh yeah, I set the angle to 10d because my timing is 10d initial. Didn't wanna have 10d extra advance in the table.

$58 has no idea wether or not the n/s (or park switch ) is enabled, right? I don't recall that in any of the pinouts. Mine is spliced together so I don't have to step on the clutch to start the car.

-- Joe

 

Hmm.. Mines set to 6* initial with the Ref set to 0*. I'd try it once with it set to zero and see if your bucking stops. It sounds like you have too much advance. BW

 

Maybe i'm being plainly stupid. BUt I thought the ref angle was your initial timing. So whatever was in the table for advance, say 30d for example, it would only advance 20d at that spot cuz it was allready at 10d?

-- Joe

 

This is the way I understand it. Setting the refangle to zero and the distributor base to 10 will add 10 degrees across the board.

Maybe the knock that is being picked up and causing a retard is the reason for the surging. That is the knock retard coming in and decaying out.

Typically a MAP code (33 or 34) will cause the ECM to use the default MAP term. This term is derived from the TPS and RPM. If this hasn't been calibrated to the engine this too can cause problems.

RBob.

 

Well holy crap. I ran saturns bin, even with blms pegged at 127-129, (int was kinda all over) the car ran soo bad I almost got stranded! Seriously. That will teach me to leave the other bin at home.. wow.

ANyway. Problem still exists..

Can I disable the knock sensor in the code?

-- Joe

 

I got no codes with saturns bin btw.. I think the codes before were just residual from tinkering.

I got tons of knock counts though.. and some knock retard. This makes no sense, since i'ts on average 20d less timing than mine.

-- Joe

 

Wrong resistance knock sensor?.
Open wire?.
Over torqued sensor?.
Unplug sensor, and disable the flag. Just as an experiment.

I say start over with a stock bin and see where you wind up. You may have missed something, not too obvious and gone off on a tangent.

 

Knock sensor is almost new. I used it for about 3 months when I went from maf to speed density.

I think your right about the bin. Though i'm gonna repin to '730 and try $8d tonight. If the problem exists in my old $8d bin, with the injector constant changed then i'll start looking at things like plug wires (which were changed in august), msd box messing up,
plug conditions.

I changed plugs 2 weeks ago. I'm running 2 heat ranges colder than stock, but then agian my heads call for 1 heat range colder.

-- Joe

 

Just got back from running the car with $8d and a 1 bar map (of course). Car ran great. BLMS were a bit high, so I'll crank down the inj constant and scan some more, but overall its much better than with $58. Shifting was effortless - I just shifted, no jerking bucking. No bucking at any rpm range really.

Only time it bucked, was when I was in 3rd gear, and let the RPM get down under 1,000. I imagine thats almost normal.

I dunno. I'm starting to think its time to dive into the assembler, add a second input for another map sensor. and modify the fuel delivery. (in $8D)

-- Joe