cp-e winter fuel cut fix.

[dadasracecar]

So Lou at cp-e and I tried an experiment to cure the winter fuel cut. Basically it's temperature and load related. On my car I documented the temperatures, boost levels, and gears that I could induce fuel cut. The only way the car knows what temp it is is through the MAF and the IAT. Lou decided to focus on the IAT. We pulled the IAT plug out of the MAF connector and tapped the wire with a potentiometer. We could then read the IAT using a scan tool. I did several runs in 4th at WOT with the boost set at 18 psi and my tune. All runs were done in 4th to minimize variables. The ambient temp was around 48 deg F for the 64-77 deg runs. The ambient temp was ~37 for the 80 and 82 deg F runs. The following is a list of IATs and the approximate rpm where FC occurred:
64 4400
71 4700
75 4950
77-8 5050
80 5150
82-4 5300 - very infrequent

Using the dashhawk or another scan tool that can read real time parameters, you can easily dial the temp you want. The issue with dialing it to high is that the car will pull timing. We tried at 100 degrees and it was pulling about 10 degrees of timing at redline.

Also, as has been discussed, the air density changes with temperature and setting an IAT of 40-50 degrees higher should alter any fuel calculations performed by the ecu. I was scared of this and have been watching my afr in closed loop very carefully. It seems the car places priority on the wideband O2 sensor as my afr is always very near stoich (14.5-8) at idle and closed loop even with the iat set at 84 deg.

The document below describes what is to be done. It instructs you to cut the IAT wire and solder it to a potentiometer. You don't necessarily need to cut it if you're handy at pulling the plug from the maf housing. Just be careful not to eff up the housing. I pulled the plug out and used a scotch lock on the wire. THis makes it easy to disconnect the potentiometer and push the plug back in the housing when it warms back up and a fuel cut fix isn't necessary.

Finally, I get a cel about every 10th time I start the car. It's a IAT circuit out of range or something like that. If I turn the ignition to on, wait a second or two, and then start the car it seems to happen less frequently. I clear it with the Dashhawk.

For all you cp-e haters, don't say they never did anything for ya...

View attachment wfcf.pdf

 

[AutoXRacer]

I'm glad its a temp issue!!! (2thumbs)
Living in Florida, I guess I'll never see fuel cut!!! (lol2)

 

[clos561]

knowledge has fuel cut, (notcool) maybe he just got a weird car, hopefully i dont get fuel cut with cp-e dp when i get one

 

[AutoXRacer]

knowledge has fuel cut, (notcool) maybe he just got a weird car, hopefully i dont get fuel cut with cp-e dp when i get one

I just installed my CP-E DP this past weekend...no fuel cut.

 

[ATE BALLER]

There is also boosted air temperature that is taken from either the map sensor or the throttle body (not sure which one). I can read it with my ae scanner. The differences that cause the cel are probably related to that, not the outside air temp. You could probably trick that sensor in a similar way. I won't be doing this now since I don't have fuel cut, but if/when I do from more mods, I'll deffinately keep this in mind.

 

[laloosh]

ive been kind of hinting at this for weekes now. iTs good for for what it is, but im sure poeple won't like cel lights. Also see if you get fuel cut on really cold days, im talking like btw 15-25 degrees likes its been in jersey the last week. NOt this freak week with 60 degree weather.

As for the cel. Cpe states that its caused by the ecu knowing the difference btwn the outside temp sensor and the maf iat sensor correct? When they say the outside temp sensor do they mean the sensor that read ambiant conditions and displays it near your radio? If thatst he case i think they are wrong. A member relocated his ambiant temp sensor to read under hood temps and got crazy readings over 120 degrees all the time, never threw a cel

 

[Mid_Life_Crisis]

Where can I get more details on how the circuit you were working with actually works under normal conditions?
The document suggests a starting point of 1.9 volts. Do you have the voltages from the different temperature emulations? Including the 100 degree one?
If I can get a schematic for the car's circuit, it should be a simple matter to make a circuit that will utilize the factory thermistor and fake a signal that will still vary with temperature changes, but effectively make the car think it is always between, say 45 and 90 degrees.
This approach would keep some of the protection of the temperature compensation designed into the system, but reduce its effect.

 

[Haltech]

Like i orginally said, it was IAT temperature related. Glad Lou got you fixed up. I think we can call this the MZR Cold Bug issue.You guys can also go with the resistor mod used on mustangs if you dont want to mess around with the potentiometer. You could easily make a box and a switch with 12 different resistor values. Each value will change the IAT temp from low to high depending on how you wire it up.

 

[Craighjr]

Interesting solution. I don't have to try it yet though. I haven't driven my car to much since the cold hit, but I haven't had fuel cut yet. I am assuming that this is because I went down to 15 psi. I would imagine you could run these wires into the cab of the car and use something like a electric guitar pot to control the resistance. You could fine tune the restiance then. I think that you could turn off the pot at each start up and then bring it up while watching the values on something like a dash hawk. That would probably help prevent the check engine lights for the iat circuit fault then.

 

[tru-boost]

i'm usually a risky fella, but i would not do this. you hit that cut for a reason, its a safety feature. i'm sure i would have lost my rods all over the freeway by now if i did this mod. you will lean out doing this. luckily the ECU is still smarter than you. thats why its pulling timing. the car thinks the air is warmer and less dense, so it adds less fuel. once you go heavy throttle and in open loop, you will go way lean. luckily the o2's will see that and pull timing. pulling all that timing probably cost you 30HP. i would rather keep my fuel cut, and keep my internals....internal. i still think the best solution is to have enough fuel to feed the cold dense air.

laloosh... you still hit cut even after removing the tune you had. i though you said it stopped after zeroing it all out again.

 

[jp4130]

So Lou at cp-e and I tried an experiment to cure the winter fuel cut. Basically it's temperature and load related. On my car I documented the temperatures, boost levels, and gears that I could induce fuel cut. The only way the car knows what temp it is is through the MAF and the IAT. Lou decided to focus on the IAT. We pulled the IAT plug out of the MAF connector and tapped the wire with a potentiometer. We could then read the IAT using a scan tool. I did several runs in 4th at WOT with the boost set at 18 psi and my tune. All runs were done in 4th to minimize variables. The ambient temp was around 48 deg F for the 64-77 deg runs. The ambient temp was ~37 for the 80 and 82 deg F runs. The following is a list of IATs and the approximate rpm where FC occurred:
64 4400
71 4700
75 4950
77-8 5050
80 5150
82-4 5300 - very infrequent

Using the dashhawk or another scan tool that can read real time parameters, you can easily dial the temp you want. The issue with dialing it to high is that the car will pull timing. We tried at 100 degrees and it was pulling about 10 degrees of timing at redline.

Also, as has been discussed, the air density changes with temperature and setting an IAT of 40-50 degrees higher should alter any fuel calculations performed by the ecu. I was scared of this and have been watching my afr in closed loop very carefully. It seems the car places priority on the wideband O2 sensor as my afr is always very near stoich (14.5-8) at idle and closed loop even with the iat set at 84 deg.

The document below describes what is to be done. It instructs you to cut the IAT wire and solder it to a potentiometer. You don't necessarily need to cut it if you're handy at pulling the plug from the maf housing. Just be careful not to eff up the housing. I pulled the plug out and used a scotch lock on the wire. THis makes it easy to disconnect the potentiometer and push the plug back in the housing when it warms back up and a fuel cut fix isn't necessary.

Finally, I get a cel about every 10th time I start the car. It's a IAT circuit out of range or something like that. If I turn the ignition to on, wait a second or two, and then start the car it seems to happen less frequently. I clear it with the Dashhawk.

For all you cp-e haters, don't say they never did anything for ya...

View attachment 122769

Please understand that this information didn’t come easily, and it took many painstaking hours of trial
and error in order to figure out what causes fuel cuts (we have been working on it for months now).
We don’t make money by researching, we make money manufacturing. That’s what keeps our lights
on around here. So we’ve donated many hours of our time trying to benefit the community and help
everyone enjoy their cars! I mean, we can only imagine how frustrated we’d be to have a 300whp
car…THAT CAN’T BE FLOORED IN COLD WEATHER!!! Anyway, to the good stuff…


Are you kidding me? This is some of the most ghetto tuning I have ever seen. All this tricking the ecu into doing things getting out off hand. I can't wait to see what these cars can do with a proper well developed tuning.

"Donated" hours? How is proper customer support now considered a donation of time cp-e?

 

[Haltech]

With a IAT resistor mod, you can make the computer see a warmer temperature, which will pull timing in colder weather. Im lucky that i live in a mildly warm climate all year round and dont experience these things. I do agree that the "CUT" is a safety feature, but i find it odd that its experience with just a mild bump in boost. This is the learning stage and we have many months of figuring out this computer. With more tuning devices coming into play, eventually this may get ironed out. Crossing fingers.

 

[ATE BALLER]

i'm usually a risky fella, but i would not do this. you hit that cut for a reason, its a safety feature. i'm sure i would have lost my rods all over the freeway by now if i did this mod. you will lean out doing this. luckily the ECU is still smarter than you. thats why its pulling timing. the car thinks the air is warmer and less dense, so it adds less fuel. once you go heavy throttle and in open loop, you will go way lean. luckily the o2's will see that and pull timing. pulling all that timing probably cost you 30HP. i would rather keep my fuel cut, and keep my internals....internal. i still think the best solution is to have enough fuel to feed the cold dense air.

laloosh... you still hit cut even after removing the tune you had. i though you said it stopped after zeroing it all out again.

You pretty much summed up my thoughts on this after thinking about it for a while. I still think the ecu is resorting to fuel cut almost completely based on the rail pressure regulator not seeing levels that can support the ecu's demands. Temperature will effect this because the colder it gets the more fuel it must get in there. If the rail pressure starts to drop even a smidge, fuel cut. This mod is a band-aid for this. MAP will effect this because if it sees a ton of air pressure it will need to dump more fuel in than it can since it knows more air will get into the cylinder during each cycle; fuel cut. The band-aid for this is a map clamp. Having tuning is causing fuel cut (I believe) because that is causing several of the sensors to not correlate correctly, as determined by the ecu's programed standards. I honestly think the best way to go after the fuel cut issue is to solve the actual problem; by bringing the fuel system up to par with the rest of the set up.

 

[dadasracecar]

i'm usually a risky fella, but i would not do this. you hit that cut for a reason, its a safety feature. i'm sure i would have lost my rods all over the freeway by now if i did this mod. you will lean out doing this. luckily the ECU is still smarter than you. thats why its pulling timing. the car thinks the air is warmer and less dense, so it adds less fuel. once you go heavy throttle and in open loop, you will go way lean. luckily the o2's will see that and pull timing. pulling all that timing probably cost you 30HP. i would rather keep my fuel cut, and keep my internals....internal. i still think the best solution is to have enough fuel to feed the cold dense air.

laloosh... you still hit cut even after removing the tune you had. i though you said it stopped after zeroing it all out again.

THis is complete bulls***. I have the datalogs to prove it. I watch the afr and the timing with the standback and the dashhawk. It still runs 10-12 degrees of timing at redline in 4th just like the car did stock. My afr does not change at redline. I know b/c when it warmed up to the mid 60s recently I put it back to stock to test. Timing and afr were identical. This post is complete speculation with lack of real data. Thanks for the input...

 

[dadasracecar]

Are you kidding me? This is some of the most ghetto tuning I have ever seen. All this tricking the ecu into doing things getting out off hand. I can't wait to see what these cars can do with a proper well developed tuning.

"Donated" hours? How is proper customer support now considered a donation of time cp-e?

Umm, jackass, Lou made the pot contraption and did all the calculations to figure out what was going on. Jordan sat with me holding the scan tool (at the time I didn't have a dashhawk) and watched the timing advance to make sure the car wasn't pulling timing. I spent time taking datalogs and isolating the conditions that cause fuel cut and the IAT settings necessary to prevent it. Jordan wrote up the instructions on how to do the mod. They aren't making a dime on this so their time was donated.

 

[driver311]

I appreciate your time and dedication to figuring out this ******* engine and ecu. Its pissing me off bad. LOL

 

[Powerslave]

+1 they have spent alot of time trying to help out, I don't understand why people give cp-e a hard time? Prices are reasonable, quality is good, and Jordan is awlays trying to help out. nothing is perfect and its not like the evo and the sti where its already been done a zillion times

 

[JumpingJackson]

Are you kidding me? This is some of the most ghetto tuning I have ever seen. All this tricking the ecu into doing things getting out off hand. I can't wait to see what these cars can do with a proper well developed tuning.

"Donated" hours? How is proper customer support now considered a donation of time cp-e?

I guess it would be less ghetto if they slapped a sticker on it and charged you 75 bucks?

Proper customer support WTF? This is a fix given to everyone for *free* CP-E customer or not. Last time i checked its not CP-E's job to give customer support to all mazdaspeed owners.
You b**** and moan because they *spend* their R&D time to make a solution for cold temperature related fuel cut. Get off the CP-E hater-boi wagon please.

If you dont like it then dont use it, but dont bash them just because they give something to the community. More information is always a good thing.

 

[www.cp-e.com]

First and foremost, thanks to those with the appreciative comments. We were incredibly excited to release this info to everyone, and many of your comments make our work worth while. So thanks all!!! (headbang)

I'm not surprised that some still aren't satisfied with us distributing free fixes for a very persistent problem, and that's really okay. We're going to continue to try to figure out this vehicle, and we'll work with the portion of the community that wants to work with us. If you don't want to work with us, or don't have anything constructive to add, I'm going to ask you nicely to leave the thread. You don't have to agree with us on all points, but please don't start trouble. We're trying to learn and share ideas here.

In regards to the comments Haltech and ATEBaller made, those are the two leading theories at the moment. We tend to believe that the ECU was programmed using a visual based programming language that lacks the fine control over feedback loops that manual programming inherently has, and that this cold weather fuel cut is totally unintentional. I think the fact that there are many triggers for fuel cuts has confused things to a degree, and we're going to work to see exactly what's going on. We're busy with another project at the moment, but once Lou is finished (he's putting a Standback on a 335i at the moment) we'll revisit the fuel cut issue and run some more tests. We'd like to explore ATE's comments about fueling, and hopefully we'll have some answers soon.

In the mean time, those who are going to give this mod a shot, we'd really like to hear your feedback, especially if you have tools like a DashHawk. We'd love to see what everyone finds, and what everyone's thoughts are. There are some very smart people on the forums, and I'd like to hear what they have to say. Let's please keep this clean, and more importantly, let's figure this fcuking car out!!!!!!

(spin)

 

[allmotor95pgt]

jordan u are the man. thanks for helping me figure out my tps issues on my standback.