My car is just crazy, bad ECU?

Yeah, I know desired is not an important parameter, but if my desired AFR idling is 14.1, then my AFR idling is 14.1, so it means something I think.

It looks like a crappy tune or unfinished tune, that would be an option, but I made a log like 3 weeks ago with the same map (when my LTFT was very negative), same temperatures, same road, same intake, and the AFR in wot was perfect.

 

I don't think you're understanding what I've said before and just going in damn circles over a miniscule AFR reading and not focusing on what could have caused your rich condition you were worried about in the first place.

Unless your car acts up again let this thread die. Like Enki said, I'm out.

 

I told you in #32 since I installed new secondary O2 sensor, LTFT stopped going big negative.

Since that day, I drove the car 5 or 6 days more, I resetted the fuel trims atleast 2 times, LTFT still not going big negative.

Was the secondary O2 sensor causing big negative LTFT? I don't know, but since that day I installed the new one, it's not happening that.

Do you forget what you read?

 

Listen man, I'm all about helping but you need to realize that these guys are just trying to help. Don't take what they say as an attack and more as constructive criticism. I'm glad your ltft's are better noe that's good. As for the lean wot, as long as it is not going over 12:1 hardly then you're fine and I wouldn't worry about it. Whatever is causing it was probably countered by the bad ltft which actually made it better. Now that the ltft issue is fixed it is showing a minor difference. I wouldn't worry too much man just possibly get a touch up tune now that your ltft stuff is figured out if you're that worried about it.

 

The secondary O2 sensor doesn't have anything to do with your fuel trims. The primary O2 sensor does. The secondary O2 sensor is for determining the state of health of your catalytic converter which you removed by the catless downpipe.

I have no been using a secondary O2 sensor for a few years now and haven't had a single issue with my fuel trims.

The ECU is right next to the battery. Batteries produce gasses unless you are running a AGM battery. Those gasses seep into the ECU connector and cause corrosion. I had a spill valve code on my car when I first put it together. When I checked my ECU connector there was green build up on the pin and terminal for the spill valve. I removed the ECU, cleaned the pin in the ECU and ran a new wire and pin from the female side of the ECU connector and bam. Issue resolved.

So what I'm saying is you could have had a corrosion or electrical issue to begin with and when you disconnected the ECU you broke that corrosion apart and now it is back to normal. Until the corrosion builds again. It doesn't even have to be a large amount that you can see.

ECUs rarely fail. Plain and simple. Do they fail? Yes. But the likelihood of that issue slim. These aren't old Mitsubishi ECUs or Honda ECUs where the capacitors get hot and pop spreading crap onto their circuit boards. ECU quality has improved dramatically over the years.

Get your car retuned and see what it does. If your trims become negative again past the 10 percent mark start looking into the reasons why. Also change your oil if they had gotten down to -25% at one point. It could have been richer than that. The ECU stops reading past a certain level. Just drain the pan and refill with fresh oil. It's peace of mind to know you won't have poor oil quality. Otherwise you could be chewing up bearings or other components and not know it.

 

Yeah, I know they you all are trying to help me, and I am grateful, I promise, but they are almost attacking me, you just have to read the comments.

If at this moment is working 99% perfect, then I will start installing all the things I got pending to install.

BNR S4
Cobb 3Port EBC
3 Bar Map Sensor
HTP 3.5 Inch Intake
New Intake Manifold gasket, New throttle body gasket, New PCV plate gasket, New Exhaust manifold to turbo gasket, new downpipe gasket.
Rebuild injectors + new orings + new washers + new metallic filters + upgraded seals
New PCV Valve + Occ (Using another PCV valve between IM and OCC as check valve)

And hope everything works OK. Thank you all.

I appreciate you all the help, really. But you have assumed that I knew that the secondary OO2 sensor does not affect the AFR, and I didn't know it, so I thought I solved the LTFT because the new secondary O2 sensor, maybe it was solved working on the MAF connector pins or maybe just reconnecting the ECU, yeah you are right.

I will look for a diagram of the ECU connectors and make sure one by one that all the MAF wirings and the first o2 sensor have good continuity and are in good shape, If they are not 100% perfect, I will repair and re-pin them.

I will put some grease like you said but I will move the ECU to upper fuse box because the 3.5 inch intake I am gonna install with the BNR S4.

I am using Motul, changed the oil 700km's ago, but I will change the oil again, due possible contamination.

It has been several days since the LTFT is maxing at -7% so I'm going to trust the car and I'm going to start installing all the things I have (including restoring the injectors and a new pcv valve), If I am lucky the small issue of the bit lean in wot is because a small leak between the exhaust manifold to turbo, or between turbo and downpipe.

Thank you so much again.