At this point I'm almost ready to give up and sell the car.

I'm having a ton of issues that make zero sense. The car is fully bolted and tuned on E47 at the moment. Since the day after Christmas I've been having random boost spikes to 27psi when making pulls, the car would normally hit 24-25 and hold solid. Also at random times in the upper RPM the car sounds like a tommy gun, this is completely random. The car also has random AFR, watching the standalone WB the car will idle and hold around 14.7 with slight changes. Other times it will idle at 13-12.

When driving sometimes the car wi hold decent AFR then out or no where swing from 14s to 11.5 then back to 16.2 then back to 14s under constant speed, somewhat level ground and light throttle. Today the car went full lean while driving home, I pulled over to try and figure it out, she held full lean for about 5 min of idle then went back to normal.

I've replaced cam phasers, map sensors, and EVAP purge all within the last week.

I've run out of ideas as to what it could be, I've check for boost leaks and vaccume leaks also.

-Alex

 

Also no CEL at any point.

 

Maybe you should just go back to stock since modifying it has clearly killed it.

 

I'm going to refrain from saying something mean....

The car has been modded fully bolted for 40,xxx mi without a hiccup.... Just standard routine maint.

 

Then take it to an actual mechanic shop.

 

ever think o2 sensor? sounds like your tune needs adjusting anyways though. and spark blowout is the "tommy gun" sound.


also how is this LNF performance tech?

 

Ugh, alright I can say I tried... Do you have anything useful to say related to trouble shooting LNF motors or are you just on here to spray verbal diarrhea?

The key words to this is it is completely random, why take it to a mechanic where there are tons of people on this forum who have a vast knowledge of these cars and may have experienced this problem or even suggest a component I may have over looked.

Instead you have brought nothing to the table other than useless banter.

 

I was thinking possible spark blowout, o2 sensor did not cross my mind but that could possible make sense along with dialing the tune in more.

 

Since you are on ethenol, im thinking you have bad injector seals...look into it

 

My guess is its something to do with either the wideband sensor, an actual 02 sensor, or a clogged/bad cat

 

My question would be if it's an injector seal wouldn't it be consistent? all of these problems are completely random. I originally started to question if it were the seals

-Alex

 

The front O2/Wideband was replaced last summer and the car has been catless for over 50k

 

I think it would be random until it was completely blown/damaged...gl

 

What year are you?

 

O2 sensor for the weird a/f ratio, mine did that to but not as drastic. Spikes could be boost leak somewhere.

 

Injector seals like was mentioned already would be first place to look. The gunfire sound is mainly going to happen when at WOT or in boost. BUT, that being said, a boost leak could also explain the randomness of your issues, but not the gunfire sound in the higher RPM range.

Perform a boost leak test, check your MAP and TMAP if your not on GMS1 sensors, check the injector seals.

Spark blow out for me just cut power and felt like it was 'missing' but I didn't get the gunfire sound.

 

Is your standalone wideband on its own sensor from the stocker? See if there are differences in them if so.

 

profile says 08

My bets on Injector seals. Especially with E

 

+4 on the injector seals. At least one of them is bad. Start there. When that is fixed, you can move on to other issues, if they exist.

 

The "tommy gun" sound is likely either a bad injector(s) seal (as already mentioned quite a bit) or straight up injector misfire possibly due to fuel rail pressure drop which would be directly effected by the large boost spikes you're seeing.

The afr swings could be related to either a bad o2 sensor (as already mentioned), a failing injector seal could even be to blame here as well, or a possible leak somewhere.

As far as the o2 sensor goes, contrary to popular belief, the lambda sensor (upstream o2) in these cars is also something that actually needs pretty regular maintenance (replacing) when the car is tuned. Unlike most vehicles, these e69 systems stay in closed loop 99% of the time (even at wot) unless something funky is going on to force the system into open loop, so the lambda sensor is that much more vital for us. The maf and o2 are the life blood of your fueling system so both need to be in perfect working order to maintain accurate fueling. You may even want to inspect and clean the maf for the heck of it as well.

 

pretty much explained what it could be here.

If that doesn't work then suck it up and take it off corn oil or to someone who knows lnf's better than you. No one ever said running a car at 200% of it's capability was reliable for long periods of time, especially on what sounds like something that needs a retune.

Stock clutch or upgraded? Misfires up top could be to clutch slipping...but highly unlikely as it would do it down low as well(3500-4000rpm)

Also could need to clean your maf sensor as they can get oil on them from blowby on that valve cover hose.

 

Any chance this could be partially due to the valve gunk that's a common problem.

 

Not likely. The machine gun sound has not been linked as far as I have ever seen.

 

I get the stumbling at random times while cruising. For instance on the freeway I feel a light stumble, same thing when accelerating. Kind of feels like half a misfire. Thinking O2 for me. Fuel rail seals going bad cause this?

 

hope you get it worked out man.