Starting to get to the end of things to try out.

Mods in signature.
When cruising at lower rpm, I get driveline shake when I let off the gas. Basically, between 900-1300 rpm, my car will not decel or coast smoothly. It will shake. It will pull from 700 rpm on up if it has 2% TPS or greater, but between 0-1% TPS is where I'm getting the shakes.

I've got my VE tables nailed (less than 2% ST Trims).
Idle spark and base spark both match at 34 degrees at this rpm and load range.
Makes no difference whether I'm in speed density or MAF mode.
MAF airflow, Dynamic Airflow and Idle Airflow all match.

Trimming back the throttle cracker seems to help, but it hasn't eliminated it. Haven't fooled with DFCO, but should I?

In a nutshell, my car has no driveline shake (kinda like it's on/off the throttle) as long as it has 2% TPS or greater, but at or near 0% TPS, it wants to shake. Any ideas on where else to look? FWIW, I'm an EFI Live newbie (V 7.3), but an HP Tuners (v 1.6) veteran.

 

1. If you are tuning your VE table off of your STFTs with LT headers, that is going to pose a problem. With LTs, your narrow band O2 sensors just aren't accurate anymore, ESPECIALLY under low throttle conditions.

2. Are you running a MAF as well (e.g. no full-time SD mode)?

To give you an idea, when I tune my car in Open Loop SD, my A/F ratio (as shown by my wideband O2 sensor) is dead nuts on 14.63 across the board. I re-enable closed loop, and my A/F ratio jumps right to 15.3:1 cruising, 15.8:1 at idle. This is because my O2s are a little sleepy with my Kooks headers.

 

Oh, and my guess, based off of what I see on my stock internaled car, is that the bucking is being caused by running lean.

 

Oh, and take a log under those conditions, and see how the logged numbers compare to your DFCO entry/exit conditions (normal, not clutch transition).

 

Push clutch in, problem solved..... lol

You have the stick shift bucking at low RPM's, all sticks do that at times, hell even my completely stock 2002 S-10 Extended cab 4cyl 5 speed does that some times at 1,100 RPMs.

If I read it right, it's the nature of the beast and since you have a good size cam, it will be worse.

 

Is there an ideal entry exit speed or conditions for me to set?

 

My narrow bands are the hotter Bosch C5 rear O2 sensors and they still have cats behind them. I trust them pretty well. Besides, the PCM is having to live with them, so I might as well get my ST Trims as small as they can be. By the way, I'm running with no MAF at this time, but I still am using open and closed loop...just no long term fuel trimming.

The biggest problem I have is driving through school zones. My car will not stay smooth at a constant 20 mph. It bucks and shakes even though my ST Trims are less than 5% + or - and my timing at 0% TPS and 4% TPS is still around 34 degrees. Basically, the VEs seem very close and the timing seems to be pretty consistent. I know some people say it's something I have to live with, but I've seen others tune T-Rex cars to run super smooth at these lower rpm. I just need to know the areas where I need to continue to fine tune.

 

Did you tune/adjust your idle tables? The desired vs actuals and such that were discussed on here quite a bit a few months ago may be a good source of information...especially if you drilled or adjusted your throttle body.

 

Yes, I've done all of that. Adjusted the base RAF, the idle AF vs. IAT, the IAC effective area. All are good. All 3 airflows match (dynamic, MAF, and desired idle). Car runs MUCH better, but now it's down to this one last nagging detail. Any coasting or low TPS driving between 900-1300 rpm gives plenty of bucking...especially going through school zones.

 

Well, for starters, just disable normal DFCO and see if it helps. I have the same O2 sensors, and they didn't make a difference for me (I'm hoping yours run better)...it still runs lean at or close to idle conditions (15.6-15.8).

 

What about your throttle cracker and throttle follower tables?

 

As I mentioned in post #1, I have the throttle cracker trimmed way back from stock. It's about 30% of what it was originally. Doing that seemed to help. I haven't tried decreasing it further, but I might try that next. What happens when you set the throttle cracker to 0? I haven't touched the throttle follower settings yet.

 

wow i have a 2000 s-10 same bucking !!! I would hate to see it if I modded it !! thats funny seriosly its not the " NORMAL' driving condition anyway, arent we all Mario Andretti!!

 

P.S. ive had best luck in Throttle Cracker