I have the APS TT and its been running strong for the past year. now I've decided to do some upgrades, I just installed the following;

- Deatschwerks 600cc injectors
- NGK 1 step plugs
- Crawford plenum
- AEM wideband


after installing the above the car wont rev past 1k rpm, there is a weird smell coming from the exhaust and CEL on. however it idles normally. I believe the car is in limp mode. I've disconnected the battery and will start her again within few hours to see what would happen. The wideband shows 10-11 afr at idle...

any idea what could cause these problems?

MAF sensor? throttle body? HELP ME PLZ...

 

Check to make sure your throttle body is plugged in. Make sure all hoses and connectors are plugged in. Ill think about other solutions, but iv never experienced this so im kinda pissin in the wind.

 

you are flooding the d@mn thing out. You can't just toss in larger injectors and expect it to run properly.

What was the reason to move to 600cc injectors?

with the 4 bar fpr that the aps fuel system uses, those are acting like larger than 600cc injectors. Your unichip will not be able to properly handle that large of injector. You will need to move to a 3 or 3.5 bar fpr if staying with the aps fuel system and unichip and will need a retune to adjust fuel trims. If you stay with the 4 bar fpr you need a new ems that scales for injectors or put your old injectors back in. If you are on stock block there really is no reason to upgrade injectors

 

too much fuel? mine car did the same but at 3.5k rpms when i had my nitrous jetting backwards (the fuel was 48 and the n20 was 26)

 

I feel special ed. I should of relized that....

 

My thoughts also....^^^^

 

I have a retuning session tomorrow. I'm just trying to troubleshoot what I'm experiencing at the moment.

the reason I went with larger injectors is because the APS ones were almost maxed out at 9 psi. I'm upping the boost to 10-11 psi (yeah i know i'm risking the stock engine...). I have the unichip q+, my tuner said that he was able to tune a 800cc injectors (GT-R r34) using the q+. tom will see how comfortable it gets to scale the injectors...

 

where in tx are you? who is doing the tuning?

 

What whp are you at at 9psi?

 

did you wash your car? funny as it sounds, mine went limp cuz water got into the electronics

 

With the q+, I think you should be fine controlling the injectors. that said, I have a hard time believing you were out of fuel at 9 psi on a stock compression motor. I pushed those injectors to 14 psi midrange tapering to 11 at redline on a 8.8:1 motor. You should easily get 10-11 psi out of them

 

One thing I've definitely learned in some of these threads: I'M LEAVING MY TOURING COUPE STOCK!!! NO mods for my flawless-running beast!
____________________________________________________________ _____
'04 Tour' Coupe/13k!!!/$22k!!! NO FEATHERING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

you cant just throw in 600cc and hope for it to run fine. anyhow the aps injectors should be good up to like 11psi. i dont see why its starving for fuel. general rule of thumb is 1cc = 1whp. also if your going to get to the limits of the stock block risking it with a unichip isnt really a smart thing. even if your tuner has tuned an R34 with unichip you have to understand our stock block is a little weaker. if your going to test it and hope for it to last you might want to go for a standalone. best of luck though.

normal afr at idle should be in the 14-15s 10-11 is just flooding the thing to death

 

No mods on a 350z does not equal a 'beast'

No mods on a 350z = driving a slow boat

 

Here's an update, it seemed like there was a loose connection in the throttle body, fixed, car revs smoothly now. funny how small thing causes this headache..

Took the Z for a tuning session, it made 425 whp @ 8.5 psi. however a new problem appeared, when doing WOT at high RPM's the fuel pressure goes to 54 psi then slowly drops to 32 psi as boost increases. what could cause this?? we didnt tune the car any further as its useless to continue with this fuel pressure drop problem. any idea??

 

usually means the pump can't keep up with the fuel demand. Could be the fpr is bad, or a pinched vacuum feed to the fpr. could mean a lot of things.

that said, I don't see you having issues with fuel at those boost levels. You should easily make 500+ with that fuel system and injectors on a stock compression motor.

Heck, we just finished a build with the base aps fuel system and 600cc deatshwerks and had to drop down to a lower FPR because there was too much fuel. This is tuned to 15 psi on a 9:1 motor

 

yea you cant just throw bigger injectors in there........ they need to rescale the map to use those injectors.

 

I was thinking either the fuel pump or the FPR. any idea if I can drop in Walbro 255 pump to use instead of the pump that comes with the aps fuel system? how can i be sure its a bad FPR?

 

pretty sure the pump is a 255

Try removing the vacuum feed to the fpr and see if that makes any difference. could be a bad vacuum feed.

again, we just had an APS TT setup tuned to 15+ psi on the base aps fuel system and 600cc deatschwerks. They had to swap out to a lower fpr because there was too much fuel

 

you mean the fuel pump that comes with the aps fuel system is 255? i tried searching aps website with no luck...

might also be a bad vaccum feed, need to check that too!!

what fuel pressure i should adjust the fpr to with the stock block and 600cc injectors (aps fuel system)?