hey guys. im tuning on my newly installed 350 from a 305 and im trying to get the proportional gain stuff figured out. im using the $0D code. ive read the paper by rbob about it but im not sure im understanding it. im posting pictures of the 2 tables that i can adjust in tunerpro. if you look at my old 305 bin it seems that the values are about double of what they are on the 350 bin i started tuning with. this is in line with what the paper rbob wrote says to do. so by lowering the values in both table it slows down how fast it corrects fuel? im getting surging at crusing speeds and light throttle so can i keep lowering both of these tables to try and solve this? it seems when i analyze the datamaster file that when it surges the timing is shifting up and down by 5-10 degrees and sometimes the injecter pw goes to 0 for 1 datapoint then right back on again. it also looks like the o2 x-count stop for that 10 -15 second time span that its surging. any ideas? thanks

 

I finally looked at your logs in the thread on the TBI board. The reason you are seeing the surge and the cross counts stop is because you are dropping out of learn mode and the BLM's are defaulting to 128. Look at the "BLM Enabled" bit during the log and you will see it drop out during cruise. It should not do that. Also, when this happens, the O2 voltage is at around 950mV indicating very rich. IIWY, I would start over with a '95 350 $0D .bin that matches your rear gears and tune from there. HTH

 

i unchecked the bit at l400d like you said to try and went back to tuning with the blms. i seem to have got the blms closer and its running and accelerating better. but the surge is still there. my 305 bin was bjxl i believe. i have 3.42 gears with auto. what bin should i start with? also when you say its going out of learn mode, does that mean its going into open loop? and what would cause that? thanks

 

another question i have is the o2 threshold tables. in my stock 305 bin the rich,lean, and rich/lean mean threshold tables are set at 520mv on all 3. but the 350 bin is set at 434mv. fast 355 had my bin set to 464mv. if my stock bin was at 520 should i set my new bin that way? also if there is supposed to be a high, low and mean table, why are they all set the same? thanks

 

BJYL is a 350 .bin with 3.42 gears for a '95. Start there. Change the injector constant to match what you are running as well as the cylinder displacement constant. IIRC you did not have EGR hooked up either so disable that and start tuning fuel as discussed earlier, then timing, etc.

Going out of learn mode does not mean open loop. There can be several reasons that learn mode is dropped. Entering PE dieables learn however I could not see an obvious reason that your setup is dropping learn. I did see a couple of changes in your later .bins that were curious. For example L4108 was changed from $E4 to $80, Why? Also, L44E6 and L44F8 were zeroed. Again, why? Just curious. I'm not sure how zeroing an upper table lookup value would affect the lookup routine. I guess I'll have to look the code over.

 

O2 thresholds are primarily determined by two factors. Where the O2 sensor is placed in the exhaust stream and whether or not it is a heated O2 sensor. Exhaust gas temperature greatly affects the O2 sensors accuracy in reporting the stoich value. EGT can affect the upper and lower limits of the stoich value by as much as 200mV. A 520mV threshold tells me that the sensor is pretty far downstream in a cooler area of the exhaust stream. As you can see, sensor placement is a big factor in determining O2 thresholds. To accurately adjust them requires a WBO2 IMHO. The upper and lower limits determine a window that defines where if the O2 voltage falls within the window, no changes are required. The mean value is the crossover point for determining if O2 voltage is rich or lean. By setting them all the same ensures that fueling corrections are always taking place since the O2 voltage is always rich or lean since there is no window. HTH

 

i started from scratch like you said, and after 5 chip burns tonight its much better. surge is mostly gone at cruise. idle seems smoother too. i can really see the performance increase from upping the timing over the stock tables. but getting the fuel right i can see will be tough. you and fast355 have been a big help. thanks alot. it seems all i do is read these forums to try and understand what to do with these tunes.

 

i spoke to soon. this morning on my 20 mile freeway drive to work, the surging is definitely still there. i need to get a log of what its doing going down the freeway since thats were its mostly happening. i will just keep plugging away at it.

 

Take note of what is happening in the logs when you start surging. It looked like the RPM signal and therefore the injector signal ceased at random times. You might have a pickup coil problem, a loose ground, bad connection, or bad module. I am curious if your surge is in the computer at all. Might be something mechanical causing it.

 

I never saw the RPM signal "cease" but rather saw it spike randomly. On the earlier logs, the "Data O.K." flag in Datamaster was flashing as the RPM spiked. Every time I have seen this it was due to either bad spark plug wires or the coil wire laying on the harness and inducing the voltage spikes into the data. I still think the surging is fuel or timing related. Another log will help to see. HTH

 

You are right, it did not cease. The RPM spiked and the Injector PW went to 0. Saw it multiple times. Same thing happened to me and both the coil and module went out a couple of weeks later. The result of the "SPIKE" is a SHARP JERKING sensation as you are driving. You feel it also at idle at times.

The surge may very well be Fuel or Timing.

The proportional gains will cause a surging condition.

TOO much EGR too soon will cause surging and low engine power as well.

 

Where are you seeing the PW go to zero. Look at the last log. Run 10. Every time the RPM spikes, it is only for one record which means it is a phantom RPM spike. The RPM cannot jump up 3,000 RPM in 10mS then back down in the same amount of time. The RPM spikes never occur when the "surging" happens. They are not related. On the old logs, every time I saw the surge, the "BLM enabled" bit dropped out and the BLM's went from some very rich value, like 110 up to 128 instantly and the O2 voltage would not cross over 450mV. Also, EGR is disabled in the .bin. getsideways, since you started over with a stock BJYL.bin, you need to post the latest log and .bin. That is the only way to see what is really going on. HTH

 

thanks guys. i was busy last night and couldnt do anything. but i will definitely put up a new log with bin in the next few days. also the coil and wires are both brand new msd i hope nothing is wrong with them. if it was a bad ground wouldnt it do it intermitantly at all rpm's. it is specific to low rpm light throttle cruising. thanks again.

 

hey guys. i just picked up my truck from getting the tranny rebuilt and new stall today. the shop installed a transgo stage 2 shift kit, corvette servo, and some stronger internals. also got a 2000 stall. i wish i would have went with a higher stall i think after driving it. the shift firmness and how fast it shifts is alot different. it probably shifts to hard into first. can this be adjusted in the chip without doing any damage to the tranny? also i did make some adjustments to the tune with the timing table and prop gain stuff. this made the surging at cruise seem to go away but it started surging at light load acceleration now. i upped all the cells above 2800 rpm and 70 kpa by 5% and im going to try that. i cant datalog tonight cause the battery in my laptop is dead and i dont have a cigerrete plug for it. so maybe i can log tomorrow and put up my latest bin and log. im still a long ways off with the tune but im getting better with your guys help. thanks alot.

 

well here is the latest bin and datalog. for some reason i had a low tps code. i noticed the tps was not at zero at idle sometimes on the log. this is causing fits when im at idle. not sure what causes this because sometimes it was at zero. i guess i have a sticking throttle. anyways. im still way off on my tune. i keep trying to adjust my fuel cells but im just way off. what do you guys think? thanks.