Well after 3 years of smooth sailing my car seems to be running lean above 3.5k under wot boost. I recently had an issue with the passenger side cam sensor and that leads me to think I knocked something loose. The first replacement sensor was faulty and game me the p0340 again and also the code for cam over advanced(cant remember the code).

It looks like my ss box is altering the fuel , when I hear it click the a/f drops to around 10.9 and progressively leans out to around 13.5 at 5500. I didn't push it further than that. The vacuum lines looked ok. I also put power to the aux fuel pump and it started up.

I guess I'm going to have to go on a dyno to see if my wideband is accurate or hook up a wideband to see if the ss box is actually turning on the aux pump. Times like this I wish I bought a fuel pressure gauge.

Any ideas on what to check next? And please I don't need any comments telling me that I need a larger in tank pump and injectors.

 

you've mentioned what you need to check:

ss box really turning the pump on
a/f sensor bad
vac lines

so if the vac lines going to the FMU are working properly and the ecu is kicking on the pump at the correct boost then something else is going on. I wouldn't see this being related to the cam sensor. Did you take the plenum and stuff off when you changed the cam sensor? you could have an air leak somewhere.

 

Checked vaccum lines . Their good. I was really hoping that was it.

 

If it were me, id verify the a/f with another wideband sensor or a wideband at a dyno

 

Yea that's what I'm thinking. I just checked the inline fuse that goes to the aux pump with a multimeter and Im getting 12 volts under load.

 

whats your boost gauge read out when this happens?

 

check your aux fuel pump mine was unplugged and did the same over 5k rpm

 

I was reading that the ss box reads the cam sensors for rpm on the map. Now I'm wondering if the sensor might still be the problem. I'm going to put the old sensor back in and see what my a/f does.

 

that sounds like a good plan.

i know the ss box uses rpm but i'd have to look in the manual to find out which wire. I don't remember it being a cam wire for rpm but it doesn't sound completely unreasonable.

 

Believe cam 1 and cam 2 sensors are wired to the SS box.

Even though you have vac to the FMU it may be faulty...

 

Yes went on a dyno and was only getting 55 psi of fuel. Vac lines are good. I gave pressure to the fmu directly and fuel pressure came up ,but it but it only started to move after it got 6 psi. Looks like the fmu went bad .

 

In the settings of the ss box you can adjust when the FMU kicks on the pump. I think factory it's around 5psi before the aux pump kicks on so that's working normal.

Find out why there is no boost getting to the fmu. Something is wrong with that vac line if you can put pressure on it and it works. I'd swap the lines out.

 

The ss box is set how it came. It turns on the aux pump at -4 . I actually put power directly to the aux pump and it didn't help. My issue is definitely that the fmu is not operating. Either their is buildup in there or still a vaccum line issue

 

Thanks for all the input guys.

 

vac line or maybe the diaphragm inside the fmu has dried out and cracked.

 

Luckily my friend has a new fmu that I'm going to try tomorrow

 

They have been known to go bad..

 

thats what it was. Ill post pictures of the fmu when i take it apart at work later

 

ya, that diaphragm kit from vortech isn't too expensive. I think like 12$ but you end up paying about the same in shipping because vortech hoses the customers on shipping.

I have the FMU with extra inline walbro from a vortech install i did on a friend's car a couple months ago. If you need one i can ask him if he would be willing to sell it. It also has the nice 6:1 rising rate ring in it instead of the factory 8:1. Keeps fuel pressures lower.....but now that i think about it if you're already tuned you would want to use your 8:1 ring so you don't have to have a retune.

 

Thanks but my friend had a new fmu that came with his kit he never used