OK, in my last thread I thought that my poor running issues were fixed. Well it seems I didn't test it enough. Now I find that when I start the car from totally cold it doesn't want to take the gas without sputtering a little and if I get the Rs up enough it will die coming to a stop. It did this twice yesterday. The things is if I let the car get completely up to temperature it runs great again with no issues or stumbling whatsoever. Does anyone know what sensors are involved in cold start up (no codes by the way). Also, does anyone know whether the AEM FIC is involved in cold start up in any way?
-
Protip: Profile posts are public! Use Conversations to message other members privately. Everyone can see the content of a profile post.
More Issues
- Thread starter BobK
- Start date
Pretty sure the FIC has nothing to do with cold start. My understanding is the FIC only makes changes under boost, everything else is the OEM ECU.
Bob,
Sorry to her about this. Hope someone here with experience can point you in the right direction.
Sorry to her about this. Hope someone here with experience can point you in the right direction.
Hudson and I chatted, and we think you should check the main relay or a loose ground.
How would either one of those two things clear up completely once the car warmed up?
Not sure about that one. Did the issues only happen once you got the new FIC?
Yes, that is when it started happening.
I have the FIC, and mine runs like shit until warmed up too. It just doesn't like the cold weather.
Fic will never run perfect. It's a piggy back of the ecu. I have had a lot of bad experiences even with AEM on previous cars. One day it's runs great and the next day issues . I need to upgrade my fuel management on my comptech SC and I'm very hesitant to buy an AEM. Its really frustrating to spend money on something that doesn't work well 
The strange thing is that it ran perfectly for over a year cold-hot it didn't matter. I haven't had a chance to contact AEM yet but they do have great customer service. I won't be around the car for a couple of weeks as I'm going back home for the holidays.
I asked him about it last weekend when he tuned my car. He hinted around that it was normal. Again, once it warms up to operating temp, everything is fine.
I don't think it is normal for the car to just die and sputter. There are many many FIC cars out there and this is the first I have heard of this.
Bob That's what Fogal and I were talking about. It seems weird that all of a sudden it just doesn't want to work . Check your harness. if that's Ok then maybe it is just one of those AEM things..
My FIC ran absolutely completely flawlessly on my bbsc. It was transparent, with no exaggeration. Car started like stock, ran like stock. I had it on for 2 yrs.
when i changed to the turbo, some problems became apparant due to a faulty wiring harness (oem, not FIC) and i too had some cold issues, though never really serious. just minor rough running till warm.
I switched to the stand alone AEM for OBD II that SOS sells and all my problems went away with tuning. Also, i was able to pick up 20 hp/20tq from 4-6k with vtec adjustment.
when i changed to the turbo, some problems became apparant due to a faulty wiring harness (oem, not FIC) and i too had some cold issues, though never really serious. just minor rough running till warm.
I switched to the stand alone AEM for OBD II that SOS sells and all my problems went away with tuning. Also, i was able to pick up 20 hp/20tq from 4-6k with vtec adjustment.
When Eric asked me about cold start I said the car should start and idle as normal, I also told him I always warm my car till cold idle drops so I had not noticed any issues when driving my car completely cold because I do not do that. Eric said the car ran rough when cold but cleared up as soon as it starts to warm. He did say it took a while to warm his car while my car does not take long at all to warm. We did discuss a sticking thermostate as a possible reason for the car not warming very quickly.
BobK, no tuner can tune around a mechanical issue, if your car ran perfect before and it is now not running good, something changed and it is not likely the tune. So unless you made changes to any of the mechanical systems without adjusting the tune you may want to look for something mechanical or electrical.
If you have a wideband (dual widebands are preferred) and a scan tool you can log with. Then log the car at cold start untill the cars coolant reaches 160 degrees, then post the data and we can try to figure it out.
You will need to choose the following PID's from your scan tool:
RPM, Short Term Fuel Trim Bank 1 & 2, Long Term Fuel Trims Bank 1 & 2, Engine Coolant Temp, Engine Spark, Load.
It will be a good idea to log the FIC for the entire time as well.
Before you start the car from completely cold, turn on the ignition key and let it sit for at least 2 min. prior to actually starting the car (preheat the wideband O2 sensor)
Once you start the car if you can not log the widebands then you will have to keep a note pad and write down the AFR right after start up and every 10 secs. untill the cold idle drops or the car starts to update the short term fuel trims.
Here is the rub with cold start tuning you have to collect the data, look at everything make a change to the tune, wait for the car to cool completely then start the process again if your adjustments did not fix the problem.
Even after doing all this the issue may still be a mechanical or electrical issue and in BobK's case the fact that the problem was not there and is now there after a year you most likely have a mechanical issue. We can guess all day long about that but the data may lead us to the problem and may save you time and money chasing a tune.
The NSX OEM ECU handles cold start completely different than most cars, from what I have been told. While in cold start mode the ECU batch fires all injectors untill the engine coolant reaches a certain temperature, then it starts to trim fuel in closed loop at that time the fuel is now sequential. The batch firing part of cold start is most likely the cause of the cold start issues when using the FIC with large injectors. Issues while driving in this batch mode may or may not be able to be resolved.
If I can help I will, but without the data it will be hard to help.
Dave
And "cold" is relative to, for folks living in Florida or the MidWest.
Just a 20F change in cold start temperatures can make a world of difference once you start messing with aftermarket engine management systems.
Interesting note on the batch firing when cold. This is probably one of the few reasons why Honda couldn't classify the 2005 NSX's as even meeting LEV criteria.
Dave
i have the FIC on 750 cc injectors and have no issues with cold start in chicago weather. I would suggest comparing someones cold start portion of the FIC map with identical injectors to see if there is any significant variation. In a perfect world the map reflects the exact proportion of old to new injector size in conditions without boost. If you have an AFR gauge watch for variations of greater than 1 from high to low afr at steady speed and load, it should not "bounce" more than .5 or so. The stall after revving really sounds like a tuning issue.
good luck
good luck
The issue may not be cold start as described, but rather cold running. The complaint as I hear it is not that the car will not start but when driven while the engine temps are cold the car does not drive the same as when the car is warmed to normal operating temperatures.
The FIC is a piggyback and not a stand-a-lone ECU like the plug-n-play AEM ECU. There is no cold start portion of the tune in a FIC. You have the ability to add or remove fuel from the commanded pulse width of the OEM ECU, and you have the ability to retard timing from the commanded timing of the OEM ECU. Those are your two variables unless you have added in the O2 offset tables into the mix. So in order to hit the proper fuel trims for the car at normal operating temperatures you adjust your fuel map while at normal operating temperatures. Your only time to play with cold start issues is at high idle as the car only idles there when cold, after the kick down to normal idle speeds you have to adjust your fuel map for normal warm operating conditions or the fuel trims will be very far from the desired 0%.
It would be interesting to know the guys who have cold running issues what there fuel trims are at normal operating temperatures and compare those to the guys who do not have cold driving issues at the same normal operating temperatures. It may be a long shot but there may be a correlation to the fuel trims being positive or negative.
If all the FIC OBDii guys could post up your long term fuel trims once your car is warmed to normal operating temperatures and let us know if you have this cold running issue we may be able to provide a solution to your tuner for this problem.
Eric since you are close to me and have this issue can you log the FIC when this condition exists and email me the log. I will review that log and see what the AFR is doing at the time.
Dave
Last edited:
Clean the ecu with carborater cleaner.
Yes, please. And after that PM me and I can sell you a new ECU.
Bur seriously, I think the problem must stem from a bad connection somewhere - if the car ran for all that time then how else could this be explained? Not as if the car was just tuned.
The OEM ECU is in open loop during start and for the first few min. after start, it will be ignoring the O2 sensors during this time and following the base fuel table. The base fuel table will be modified by the OEM ECU for ECT and IAT untill the O2 sensors have completed the preheat cycle and then the ECU will start to trim fuels. This could be 1 min or could be 5 min depeding on ECT.
The other issue we have is the batch fire issue, that is why the FIC uses a special firmware when used with the NSX. This may be a question for the AEM guys but there may be a limit to the fuel injector drivers in the FIC while in this batch fire mode.
Either way I still think there is a mechanical or electrical issue in BobK's case.
Dave
Similar threads
