Hi Everybody,

Ok heres teh question - car is tuned a/fs are all good. Now on light load and then sudden heavy load, it has a huge stutter.. what is the possible discrepency here. You can be cruising along and then hit the gas and it shudders the whole car, its definately a tuning thing and im stumped as to what it could be

On Heavy load and boost the a/fs are in the high 10s. when It fluctuates on idle (im getting that hunting idle thing because its a series 6 motor in series 5 body running series 6 first gen powerfc) the afr is 12.2-13 which from what i understand is very rich. People tell me that you can run lean as on no load or slight load and thats fine. It also makes a noticable improvement in economy.

Secondly, from what i gather The primaries are 880cc 12a injectors, and the secondaries are a veyr light blue 1000cc nippon denso hks rebadge item. What are other people running as the injector lag / timing settings? I think it may have something to do with the stuttering from sudden acceleration.

Finally, i love blowing flames. What can you do rather then turning the fuel cutoff off to blow huge flames. When i did turn the fuel cutoff off, it stank like raw fuel from the engine area and didnt noticably increase teh flame size or regularity. Also from outside reports, they are not yellow flames, but blue ones??(!) which means on decell that its running too lean perhaps? that also may have something to do with the stutter and causing the transition from being lean to rich (from vacuum to positive pressure)

Any ideas throw em up. Help is appreciated!

 

no ideas?

Ive got the datalogit..

 

You did not post the boost for the high 10AFRs!
My best idle is high 12s and is smooth. I run 16-16.5AFR for cruise.
I run 11.2AFR for 14-15.5psi boost.

I suggest that your injectors are not set up properly which takes the datalogit.

You need to log ADVANCE and AUX zones at the time of the stutter. You will have to use the CHART function to really see what is happening as the Map Watcher is inadequate for this type of analysis.

Post your map! What injector rails are you using?

 

Ok ill do that! The map is enclosed.

If you see anything that makes no sense let me know...or rooms for improvement.

Mods are , 3mm hurleys, dowelled extend ported 880cc inj 1000cc inj t45s turbo vmount s4 rotors s5 housings s6 intake mani Powerfc with datalogit.

 

Setup Problems:

IGL has negative values in lower left area. Even though they most likely will never be used, it is sloppy. P10,N7 and P11,N7 are bad values.

Boost area P12 - P20 has flat timing for high end. That looks like it was set up by using a distributor which flat lines after max advance. Timing requirements change across the complete rpm band for all engines.

Split for boost is good, but too much split for the rest of the map which is about 75% of the map.

After a recal:
(1) your boost area is so much leaner than my almost stock ports with a GT35R .
(2) your cruise area is so much richer than mine.
You have been using the PIM RPM and PIM Voltage maps to tune fuel by all RPMS and all vacuum/boost levels which is not the way to tune. This area is used for quick test changes or minor changes to a small area. You have changed all of the values there. If you make a fuel change for 3000, it applies for all P rows at 3000 rpm, on or off boost.

Stock map sensor and for Settings 3 MAP REF tabel, you still have the stock unrealistic values.

Setting 5 inj setup.
880 primaries with 0 lag which means they run rich. That is why you used the 1000 prm area to remove fuel in the PIM RPM map.

The PRI/SEC Trans % and Sec Trans (ms) show that you have not logged and looked at what your injectors are doing when the secondaries come online.

You need to start from scratch; tune idle to ball park with primary inj lag and omly PIM rpm if all esle fails, tune cruise by individual fuel cell tuning, then do the same for boost.

 

you wouldnt believe how much that is is appreciated. I will take notes and improve on whats going on here. Basically i took a map from the datalogit site and then set that as a base then got it tuned.

Ok, so in p12-p20 what should the timings value be? What should the split be for not on boost. as you can see its 15 off boost and 10 on boost. The primaries i have discovered are actually 800cc sard jobs (nippon denso rebadges) .

I would like to set the pims back to 100. When i was on the dyno with the tuner he said that this is the easy way to tune as it takes % of fuel out across the range.

Another question. On the newer datalogit software, where it shows air to fuel ratio on the map, how reliable or accurate would that be?

I am using the stock map sensor. Settings 3 map ref, what should that be?

 

Q1 I would like to set the pims back to 100. When i was on the dyno with the tuner he said that this is the easy way to tune as it takes % of fuel out across the range.
A1. Yes but it affects the complete map. If he adds fuel at 5000rpm for boost, it also does the same for the complete N column of the fuel map. He is lazy. His way is only good for one boost setting. You can not tune for 10, 12, and 14 psi boost ranges that way if you want great results.

Q2 On the newer datalogit software, where it shows air to fuel ratio on the map, how reliable or accurate would that be?
A2. What feature are you talking about? All DLs show AFRs on the Map Watcher if a WB is connected to the DL box. That is the only way to tune. It tells you exactly which cells are lean or rich. Accuracy depends on how good the WB is and sample rate.

I have PMed you.

 

Thanks for your Input. On the version of the datalogit software i have you can choose afr or lambda from a drop down box and it will display the afr per each cell.

I would like to set the pim values back to 100% but then a whole retune will be in order.

I think its best if its left there for now until a tuner from queensland (surname dyson) comes over. he knows his rotaries and ill get him to completely retune over. Since i have a datalogit and wideband i thought it would be good to get somebody else to look over what has been done, and try to work out on sudden acceleration the big stutter. Above 6 grand on no load --> heavy load it doesnt do it just under 5000rpm..

If i change the timing for the whole map, for example cut and past from another map, will that affect the a/f's or can it be done. The a/f will have nothing to do with the timing of leading and trailing itself?

Appreciate your help. If you can take my map and clean it up i will pay you if you have paypal! But getting somebody to tune a car across continents is possibly not such a good idea.. your opinion!

 

Q1 On the version of the datalogit software i have you can choose afr or lambda from a drop down box and it will display the afr per each cell.
A1. The new universal DL allows CORRECTION (0-5v WB) , or LAMBDA (0-1vNB) percentage change of fuel for tuning.
The AFR mode I am not experienced with. I notice that after a recalc all the values are set to 14.7, so I don't know how you set your baseline/desired AFRS and how you use this form of tuning which is new to me.

Q2 try to work out on sudden acceleration the big stutter. Above 6 grand on no load --> heavy load it doesnt do it just under 5000rpm.
A2 Mine will stutter at very hi revs under light load because I never tune there and realisticly you should not be there either. Staying in a low gear under light load and hi revs is not part of normal driving. I am talking about being in vacuum, not light boost.

Q3 If i change the timing for the whole map, for example cut and past from another map, will that affect the a/f's or can it be done. The a/f will have nothing to do with the timing of leading and trailing itself?
A3 Timing will only affect AFRS if it is way retarded and the the O2 sensor is close to the exhaust ports. The fuel and O2 not consumed will eventialy burn off by the time it exits the tail pipe. Changing timing is safe for your AFRS!

 

Thanks Chuck for the hints and tips.

Couple of questions for you. The injector lag settings made a HUGE difference. now its as smooth as silk, but the timings are still as you say hitting 10 degrees and staying there for the whole map.

When putting the wideband o2 sensor, is it ok to be directly in the dump pipe just after the turbo? will that affect the reading?

 

Putting the O2 sensor after the tubos is fine, and it's location will not affect the readings.

 

Damn, checked the thread to see Chuck's response since I always learn something from his posts and he's helping guide another PFC user down the right road. Great job Chuck, thanks for taking the time to help so many people out with the PFC. Without you and Kyle to guide me through the most basic PFC settings, I'd still be doing the lazy man routine and using the PIM voltages to tune with

Tim

 

The only way O2 readings are placement affected, is when it is between the turbo and engine and the timing is so retarded that the fuel is still burning when it exits into the exhaust.

Now for the more informed owners out there. Have you ever monitored your idle IGL when running normal Mazda idle timing. It is low. There is a DL only accessable table that retards timing when the water temp is below 65C. It retards by 15 degrees. This is the one that I said to change to 5 for easier starting.

With 15 retard and the extra cold start fuel, the fuel is most likely still burning as it exits the rotor chamber into the turbos. I think Mazda did this to heat up the precat sooner as it makes the cold idle worse.

 

Chuck, I think i have experienced what you are referring to. Sometimes when i cold start my car, it tends to stumble and hunt for its idle. I then have to up the PIM 1000 rpm value up past 100% to 106%, so the idle stabilizes until the car warms up. Is this the situation you are referring to?
So this would be something that could be changed by way of the datalogit, so i wouldn't have to add fuel?

 

You have a cold lean fuel idle problem. Read page 31 of the PFC manual!
There are two reasons for this, but the manual only lists one. Can you give us the other reason for needing more fuel for a cold engine?

If you have a DL and change the retard from 15 to 5, the engine will burn the fuel more efficiently and produce more power.

 

Hey chuck,
I didn't see the part on setting the injectors correctly. They're still 100% for all vacuum (550cc inj) and 880 on boosted area. That'll cause the engine to run rich at idle and crusing.

 

Desmond has not posted anything about his injector setup, and is only complaining about having to add fuel with the PIM maps to cure a cold start problem. If tuned properly for a warmed up engine and the problem is cold starting, then you should not be using the PIM maps for cold start adjustment.

The PFC only reason given for more fuel for cold starting is that the air has greater density. This is only part of the problem. A cold engine does not totally evaporate all gas injected. Some gas still goes in and stays as a liquid and adheres to the surfaces. Extra fuel is also needed to overcome this second problem. When the engine warms up, puddling does not occur.

The Air TEMP vs INJ table takes care of fuel requirements due to air temperature changes. The Water Temp Correction table takes care of poor evaporation.

 

oh, I open his map and saw that the primary injectors were set to 100%. thats why I asked

 

I have 550s and 850 and i wasn't complaining, merely asking a question. I finally got my wideband hooked up and realized that i was running fairly lean at idle at almost 18 afr. I've temporarily added fuel using the PIM maps and the car idles much smoother and doesn't hunt for idle. I was just wondering if my injector map was way off from what others had. From the limited amount of maps i have seen, none of them have 100 all across the map. Ill look into it some more, thanks.