ca18det nasty lean issuse ! - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

914Slide · 11-13-2016, 07:00 AM

I have had it to wits end with this thing, the car ran great for about 2 years. During the last track day it started running super lean under load like 18+ on the aem wide band sensor. The weird part is if you start it up cold and do a few runs it will pull hard and read 11s in the afrs, once i drive it for a few WOT miles the afrs will be great, then suddenly your climbing rpms and the afr rapidly will spike full lean so i let off and it will go back to normal most of the time 14.7 on the dot. Idle is rock hard and it starts right up even hot starts. I checked the ecu for codes and i get 55 all good!

Car is a ca18det, fmic, stock turbo, stock waste gate with the vacuum line directly connected, tubed manifold i just found a small crack in it yesterday,no bov, stock ecu,tomei fpr with a gauge, new wallbro 255 with a new sock and filter all hardwired to a relay in the trunk, battery back there too, oem air box

Things i have replaced after the problem started happening in effort to solve this issue.
coolant temp sensor,new ground cables/cleaned all grounds, unplugged o2, hardwired fuel pump with a relay, new fuel pump/strainer/filter/lines and clamps, new silicone vacuum lines, New spark plugs, no boost leaks around 20hg vacuum, checked the pcv, cleaned maf, new air filter, swapped ecu.

It just has me stumped all four spark plugs are white on the tip bad so i know its really lean. If i drive nice a easy keep the boost low the afrs are normal. She ran great until i shut it off went to lunch that day and when i came back to go back out and rip she was fully lean i figured it was just the gauge it was a really wet day so maybe it was messing with it because it would come back to normal waiting in the pit. I checked the timing its about 8 btdc however my cas is suck in place so i left it since it ran fine all this time. i was thinking maybe the timing belt may have jumped a tooth i haven't touched the motor in 3 years. It starts and runs so good on cold start/idle/ light cruise i have no idea PLEASE HELP I DON'T WANNA KILL MY POOR LIL CA !

Karlhammer · 12-01-2016, 08:24 PM

have you done compression? or checked injectors?

11-13-2016, 07:00 AM	#1
914Slide Leaky Injector Join Date: Nov 2013 Location: ny Age: 30 Posts: 99 Trader Rating: (0) Feedback Score: 0 reviews	ca18det nasty lean issuse ! I have had it to wits end with this thing, the car ran great for about 2 years. During the last track day it started running super lean under load like 18+ on the aem wide band sensor. The weird part is if you start it up cold and do a few runs it will pull hard and read 11s in the afrs, once i drive it for a few WOT miles the afrs will be great, then suddenly your climbing rpms and the afr rapidly will spike full lean so i let off and it will go back to normal most of the time 14.7 on the dot. Idle is rock hard and it starts right up even hot starts. I checked the ecu for codes and i get 55 all good! Car is a ca18det, fmic, stock turbo, stock waste gate with the vacuum line directly connected, tubed manifold i just found a small crack in it yesterday,no bov, stock ecu,tomei fpr with a gauge, new wallbro 255 with a new sock and filter all hardwired to a relay in the trunk, battery back there too, oem air box Things i have replaced after the problem started happening in effort to solve this issue. coolant temp sensor,new ground cables/cleaned all grounds, unplugged o2, hardwired fuel pump with a relay, new fuel pump/strainer/filter/lines and clamps, new silicone vacuum lines, New spark plugs, no boost leaks around 20hg vacuum, checked the pcv, cleaned maf, new air filter, swapped ecu. It just has me stumped all four spark plugs are white on the tip bad so i know its really lean. If i drive nice a easy keep the boost low the afrs are normal. She ran great until i shut it off went to lunch that day and when i came back to go back out and rip she was fully lean i figured it was just the gauge it was a really wet day so maybe it was messing with it because it would come back to normal waiting in the pit. I checked the timing its about 8 btdc however my cas is suck in place so i left it since it ran fine all this time. i was thinking maybe the timing belt may have jumped a tooth i haven't touched the motor in 3 years. It starts and runs so good on cold start/idle/ light cruise i have no idea PLEASE HELP I DON'T WANNA KILL MY POOR LIL CA !

12-01-2016, 08:24 PM	#2
Karlhammer Leaky Injector Join Date: Jan 2015 Location: Minnesota Age: 36 Posts: 60 Trader Rating: (4) Feedback Score: 4 reviews	have you done compression? or checked injectors?