fuel map temperature correction

[oilteq]

Cold air is more dense and carries more oxygen than warm air.  What, if any, fuel map corrections are you making.  I am on flat ground in the Midwest, so my fuel map runs on throttle position and RPM--no MAF or barometric pressure sensors.  My ECU was set up by a guy in Texas, which is probably why the engine runs fine in the summer, but poorly during cold weather warmup.  I am making changes to the ignition map and fuel map based on temperature, and thought I should also look at the air temperature.

 

It is interesting to note that after warmup, the engine runs fine, even though the air temperature reading does not move between start up and full operating temperature.

[NSXguy]

You probably just need to tweak your cold start enrichment values to sort out cold start issues. There should be a fuel enrichment table based on engine temp ( which have probably not been dialed in if the car was from TX as the car/engine would not have seen the cold start temps you see in Iowa). This table is used to compensate for poor atomization and wall wetting effect of the fuel at really low engine (coolant temps)... that explains why it runs poorly at cold start and runs fine(better) at operating temp. 

 

PS- you should not need to make any changes to the ignition maps. If all of this is not intiutive; i suggest have your tuner sort it out. These days, there are solutions for remote tuning or you can take some logs, send to your tuner and they will make the changes for you to load back into the ecu. 

-Dez. 

Edited December 23, 2023 by NSXguy

[ashyers]

What ECU are you running?

 

I spent a bunch of time on cold start stuff to get it to work well. I don’t have an idle air bypass so it took some patience.

 

Depending on what “knobs” you can adjust you should be able to get it to work.

[oilteq]

Thank you for your comments.  No doubt, part of the problem is that I am my tuner.  Cold starting is not a problem.  The problem is it runs like crap until it gets to full operating temperature. 

 

As I start out on a day with temperatures in the 40s or low 50s, it will cut out at about 2000 RPM.  As it warms up, I can get to 2200 RPM before it cuts out.  Then 2400 RPM and so forth.  It will not give me my full RPM range until the coolant temperature has reached 190, which is about 5 or 6 miles.  The first 3 miles are risky because I have no acceleration and am forced to drive at slow speeds on 2-lane blacktops.  In looking at the warm up maps in the Haltech 1000, it is obvious they were never given any consideration.

 

As I understand it, timing that is too far advanced at operating temperatures will cause excessive heat and engine knock.  In cold weather, the objective is to get some heat into the cylinder.  Advancing the timing during warm up speeds up the process.  I am changing the cold temperature advance at low RPM, and not at all above 40% throttle. 

 

I agree the fuel map needs a little bump in the cold.  I am making an adjustment based on coolant temperature.  It seems I should also adjust a little, based on air temperature.  Coolant temperature changes until full operating temperature is reached.  Air temperature stays cold all day.

 

It has been raining here, which is good.  It washes the salt off the road and we need the moisture.  On the other hand, the road stays wet on cold cloudy days and I have not had a chance to do any testing.

[MV8]

I suggest not changing anything but temp/time correction factor. The mixture the engine wants doesn't change with temperature; just how much reaches the cylinder as vapor. There should be a percentage of enrichment based on the first 30-60 seconds of starting. An example would be a correction of 1.10 (10% richer) at 60F for the first 10-15 seconds (or 1.25 at 30F, etc), gradually decaying to nothing between 10-15 and 45-60 seconds. Percentage should also gradually decreases along the temp line as it approaches 180F or whatever your normal operating temp is.

 

EDIT: Hooray! Look what I found:

 

Edited December 23, 2023 by MV8

[oilteq]

Thank you for the video link.  He is using a newer version of the ECU, but the part about the warmup corrections getting baked into the closed loop AFR target was helpful.  Because of his comments, I also found that post start enrich can go for up to 10,000 seconds.

 

Again, I am not having a problem with startup.  It starts and idles okay.  However, the engine is limited to low but increasing RPM until it is at full operating temperature.  I will play with the post-start enrich and see if that makes a significant difference. 

 

Thanks again.

[NSXguy]

I think you should have your tuner or a tuner sort it out because:

1- if you need to do anymore more than cold start enrichment, then the engine wasn’t properly/completely tuned to begin with and should have a session on a dyno or street tuning with logs taken. In which case, it’ll get  tuned at operating temp, then go back and clean up the cold start enrichment 

2- cold start enrichment as I’ve referred to is not used for “cold starting” per se… in the tuning world it is called that but it’s actually Engine temp fuel compensation and  is one of a few tables could be used to address poor atomizing of fuel at colder temps. there could also be a post start fuel comp table that also adds injector PW for a few seconds after the engine start and then phases out. The ET fuel enrichment runs much longer until you reach operating temp(typically should be 0 fuel comp after say 60/70 deg)  

 

3- there is typically a different cranking table that dictates tps and fueling for cranking (starting) at different temps.

 

an easy way to tell if it’s an airflow/fuel model issue is to check (if you’re running in closed loop) how much short term/total fuel correction the ecu is having to do. If it’s significantly off (>5%) then, you need to address. 
 

if everything is good mechanically and with the tune, you shouldn’t be seeing knock at those rpms as you should be no more than 20-25degrees. Is a knock sensor fitted? 

 

 

Edited December 24, 2023 by NSXguy

[wemtd]

I Think i missed someting: are you using the Haltech Sport 1000 ?. 

Have you adjusted the 'cool temp corr' table and still having rough running until up to temp or something else?

- Another long-shot is to double check your wiring. For a while i had poor/rough running until everyithg was nice and warm (ran rough under load). Then wire to cylinder #4 failed copmletely, and rough running resolved with loom repair.  All along problem was the failing wire working better once warm & expanded. . 

 

p. 

[MV8]

Wemtd, I'm thinking that this is the haltech 1000 elite hardware since the 1000 nexis would use the latest software and the sport 1000 is a platinum for "plug and play".

 

Oilteq,

Make sure the fuel to coolant temp correction table is enabled/checked. The table should chart temp versus tps and not temp versus map (map is probably the default table). Make excel or word file notes of any changes you make to enable or adjust so you can easily go back.

 

 

Edited December 24, 2023 by MV8

[oilteq]

Sorry for the slow response--out of town guests and such.  I think I have a ~2009 Sport 1000.  The Fuel-Coolant Temperature Correction table is present, but has not been filled in. 

 

I can test post start enrich, but warmup driving will have to wait.  It snowed today and they dumped salt on the roads.  Now I have to wait for it to rain again to wash it off.

 

[wemtd]

Remind me again of your engine, throttle/carb, etc arrangement.

[oilteq]

17 hours ago, wemtd said:

Remind me again of your engine, throttle/carb, etc arrangement.

2.0 Duratec, Jenny throttle bodies, stage II cams. ECU runs off throttle position and rpm.  No knock sensor, no barometric pressure, no MAF sensor.

[wemtd]

 

I have 2.0 Duratec, different throttle bodies and a sport1000  so some things may be different. I think you may have an internal MAP sensor?

Hopefully this gives you a starting point so you aren't stumbling around in the dark 

    

[Suggestions from any Boffins for me is also much appreciated]  

 

 

 

cut & paste isn't working satisfactorily for me tonight.....     I'll 'add lightness'

 

 

Fuel - air temp corr                         Fuel - Cool temp corr

            Load - Fuel kPa                               Load - Fuel kPa     

ats  °F   -100    -25   -0.2              CTS °F      -100.5   -75   -50.3    -40     -25     0

240       -2.6      -2.6    -2.6                 243            5         5         5        5        5      5

199        -2.0     -2.0     -2.0                 214             0        0         0        0        0       0

180       -1.7      -1.7      -1.7                 184              0        0         0        0        0       0            

156        -1.3      -1.3      -1.3                160              0       0          0        0       0        0

133         0          0          0                   154             2         2         2        2        2       0

96           0         0          0                    140             4         5        5         4       4       4

51            2.0      2.0       2.0                 120             6         7         7        6       6       6

45          3.5       3.5       4.2                 100             7          8        8        7        7       7

30           7.1        7.1         7.1                 90              8           9        9        8       8       8

0              7.5      7.5         7.5                80              9          12      12        9       9       9

-29          7.5       7.5        7.5                 70             15         16      16      16      15      15

                                                              60             20        21      21      21      20      20

                                                              50             22        22      22     22      22      22

                                                              30             30        27      25     24      23     22

                                                              18              31        28      26      25     24      23

                                                            -29              31        28      26      25     24      23

 

 

 

 

 

best of luck!

 

[NSXguy]

are you guys running open throttle bodies which will require Alpha N or a plenum with a map sensor which will require Speed density? Your hardware config will drive a different tuning strategy for each scenario.  

[oilteq]

Thank you Wemdt for the correction maps.  What does your Fuel-Post Start Enrich table look like?  Are you using the Ignition-Post Start Offset table?

 

When the previous owners of my car had an electrical problem, they would take it to a shop that would bypass the faulty wiring instead of tracking down the problem and fixing it.  I took apart the wiring harness and pretty much started over, including rewiring and relocating the ECU.  There is no MAP sensor.

[oilteq]

I know there is more than one way to skin a cat, but this makes me crazy.

 

The video above says, “Can I suggest that if your system has the Coolant Temperature Correction map as your very first port of call, rather than the absolute last thing you touch, then maybe you could take some notes and give this system a try.”

 

The Haltech manual says “…try to do the majority of your compensation using the coolant temp map and only use the post start map after the coolant temp map is properly programmed.”