So the other day I noticed that my afr was going from the richest possible on my guage 7.4 to the leanest 21.9 and everywhere in between. Its like constantly going from one number to the next and all over the place. I don't know what the problem is. Idle might seem a little rough, but I have big cams and It really doesn't seem much different than normal, if any.

I hooked up the data logger thinking maybe it was the gauge or something, but the afr is crazy on the log too.

My idle fuel trim is at like 12 something which I know is not good.

I'm getting ready to do a boost leak test. Any other suggestions?

Oh, and I have an Agency power bov that doesn't hold pressure well under a boost leak test. The people at Agency told me that its not made to hold pressure "under that type of test". So I put my stocker back on for the tests. Then replace with agency when I'm finished. Its worked out in the past and the car has run well prior to this so... wish me luck on the boost leak test I suppose.

 

I think I'm attaching the logs, but don't know if they're gonna show up or not.

edit: nvmd, can't figure it out.

 

Have you changed anything lately?

Has it been fine since you were tuned?

 

Well, its been "pretty much fine" since my tune. It was good. Then started cutting out a little bit on a hard launch...then completely died on me and wouldn't start. Got towed home, figured out the main fuel line on the Buschur double pumper fuel kit had popped off. Got it put back on and the car ran great, just like after the tune.

A couple days later it started like bogging down on me when I would get into the throttle a little bit. My afr would also go up.. Then I started throwing codes. Found out it was one of my injectors, so the mechanic checked all the connections, cleaned the little connector adapter deal and everything seemed good to go. The car was running well again.

A few days ago it kind of seems like it was "cutting out" (don't know how to explain it: like a hesitation shortly after WOT). I haven't thrown any codes lately and don't have a clue what to do. Sounds like it could be something with my injectors again, but also maybe boost leak/vacuum leak?

The afr is crazy. I just went out and drove it around the block. It was all over the place from 8 to 21.9. It really didn't feel like it was running bad at all tho?!?!? I only got about 3 or 4 psi though, I didn't really get on it, but when I was giving it gas, it never settled down. Just all over the place and then sitting a lot around 8 and 21.9 lol. This is dumb, I have no idea whats going on.

 

simple things as your wideband o2 sensor going bad, reason because you are not experiencing any issues with the car itself.

 

Okay, So I just spent some time in the car messing with throttle and watching a/f gauge. the gauge seems to be working because when its around 21.9 the car sounds like it has massive cams then when it goes low: 9's (it "seems" to run smoother). I did notice that when in neutral and giving it gas (up to 3000 or so rmps) I'm seeing vacuum of about 20-25 psi? I don't know if thats normal or not. I definitely think something is up. Boost leak, injectors maybe?

Could the o2 sensor cause the car to actually go from extremely rich to extremely lean?

I'm so lost on what do to right now. Still haven't done boost leak test, but it just seems like a leak wouldn't cause it to be so crazy as far as 7-22 afr...


edit: nvmd the attachment. I tried once again, but failed..Still don't have a clue. Guess I gotta start somewhere.

 

Do you have evoscan and a laptop ? , if so what are your fuel trims at ? if you do not then maybe try resetting fuel trims.

 

i reset the fuel trims and it didn't help. In the process of trying to do a boost leak test now. I've looks for loose vacuum lines or anything like that, but can't find anything.'

Idle fuel trim : 11.523
Cruise fuel trim: 3.3203

I hate wasting time with boost leak tests, but I guess I need to eliminate something. This car is frustrating.

 

Finished the boost leak test and everything turned out well. No leaks... Car is still running like crap though. I don't know what else to do at this point. Guess I'll try to limp her over to the shop in the morning.

Suppose I could check the fuel pumps and make sure everything is secure, but that wouldn't be able to explain the rich afr when it bounces all over the place. Seems like it would be staying more towards lean if one of the hoses was loose.

I guess its down to injectors, fuel pump (leaning away from this idea more now thought) or o2 sensor maybe?

When I do my idle logs, every now and then this will show up in my "trouble codes" (o2 - 20%) or something like that. But it isn't throwing any CEL's

 

Just drove it around. Felt just like it did the other day when I threw the injector code. Welp, I threw a code. Don't know what it is yet, but I'm assuming the injector code. Looks like I'm going to try to limp it over to the shop tonight, so they can get on it first thing in the morning.

I really love this car when it works right, but I guess you gotta spend the big bucks to have something that's reliable. Bugatti here I come!

 

That idle fuel trim isn't very good at all.

that could be causing your idle to be ****ty and all over the place.

When you say that your a/f is all over the place while cruising around, you're talking about steady throttle and the a/f is wandering all over?

 

Have you checked your fuel pump relay and your fuel pressure regulator hose? Also have you tried recalibrating your wideband to rule that out?

 

thanks for the input guys, I think just talking about it with everyone, hearing your thoughts, and talking w/ my mechanic helped me to final get this stupid issue worked out.

I was worried that it was injectors, and wasn't wanting to really drive it.

Decided to recalibrate the o2 and it worked fine after that. Idle seemed to be good and when driving around with no boost, the afr was good.

Problem was under WOT. It would pull hard for a brief second and then afr would jump up to 15 or 16 and I would let off.

I finally decided to check the "hobbs switch" (senses pressure and then turns on second fuel pump, i believe at 5 psi, but not sure) because it seemed to me that there just wasn't enough fuel when it really needed it. Sure enough, the negative connection on the "swtch" was disconnected. I knew right when I hooked it back up that this was the issue, and the car has been driving fine ever since.

I can't believe how simple this was, and why I didn't think of it earlier in this debacle is beyond me. It frustrates me because it was something so simple yet had me down for a weekend, and then some. I guess it could have been worse though.

As always, thanks for the help and ideas guys.