ca18det nasty lean issuse!

[914Slide]

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 only after it warms up the problem rises. The injectors diffidently have a different sounding tick to them all i have never changed or cleaned them? I have no idea PLEASE HELP I DON'T WANNA KILL MY POOR LIL CA

[corkscrew]

Have you checked the injectors

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I checked with some carb cleaner for leaks that's all, one or 2 slow injectors would cause lean on all cylinders with no misfire? i also put a screw driver on the back and could hear them all tick at different speed however.

[corkscrew]

Pull the rail, prime it, and see if any leak/spray/etc

[soundbwoy]

are you watching boost? a leak in the turbo air system can make the ca act strange (over boosting?) i'd see if i can hear any whistling noises coming from the engine bay.

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boost hits about 10 slowly drops off to about 8 i was thinking maybe from my cracked tube manifold causing the slow boost drop. I had one of the gaskets between the manifold and the turbo blow out and i did hear the whistle defiantly felt a lack of power/ boost then. I took apart the fpr cleaned it yesterday and put a new vacuum line on it. Also blocked off the pcv system.

[914Slide]

Originally Posted by corkscrew

Have you checked the injectors

Im really starting to think that the injectors maybe the issue since its only apparent when the car is fully warm. Maybe there is some sort of heat soak? I have no idea the origin or age of the injectors they look stock (yellowish white plastic tops). Seams like a reason to buy some new ones or upgrade.

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today i got the cam angle sensor unstuck and reset the timing to 12btdc seams to sound and pull alot harder less hesitation on boost. i raised the fpr about 2 psi and im getting about 10.2 on the wide band il have to see if it drops off fully lean still, il take it on a nice hard drive tonight maybe it was never a fueling issue like i had been chasing. oh man that would be cool!

[corkscrew]

Timing will definitely do that too. Happened on my sr when I had a broken knock sensor

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Originally Posted by corkscrew

Timing will definitely do that too. Happened on my sr when I had a broken knock sensor

Finally got around to taking it for a nice ride and what do you know same problemit seams like anything other than wot is absolutely fine i can even climb to red line with my foot about half on the gas. Pulling pretty hard and smooth all the way through when i put my foot down to try and go its like yea yea yea nahh flat on the wide band! what is going on with this thing?

[KAT-PWR]

Originally Posted by corkscrew

Timing will definitely do that too. Happened on my sr when I had a broken knock sensor

Knock usually retards timing/dumps fuel?

Boost leak = rich in boost

If the car is running fine but wideband is reading lean make sure you manifold isn't cracked and that your downpipe is seated/not leaking..

Then I'd start with fueling basics. I didn't see you say fuel filter was replaced. Verify pump pressure. You're sure it's a real Tomei FPR? Those were known for being knocked off.
CA is top feed? You can remove the injectors and buy a syringe, discard the plunger, stick a carb cleaner hose into the syringe nozzle/outlet and heat shrink it in place. Stick the injector in the other end. Have a friend pulse the injector while you spray carb clean through it. Only pulse them quick though don't hold them, use a resistor if necessary (I'm super unfamiliar with CA's)

[914Slide]

I will look in to the injectors as soon as i get a chance to pull them. all the filters are new and new pump. will one or two bad or slow injectors cause all cylinders to show very lean conditions (white plugs)? Its such a abrupt lean off the wide band ---

[KAT-PWR]

If one/two cylinders plugs look different that suggests injectors issues

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Originally Posted by KAT-PWR

If one/two cylinders plugs look different that suggests injectors issues

I wish it were so simple ! all four look identical nasty white tips (bcpr6es)ngk plugs. Less then 50 miles on them, they will do this if i go wide open throttle and the issue is present. I could drive it 100 miles babying the car and they would look fine, Driving easy minimal boost (1/4) throttle the plugs looked fine, but when i floor it it will rapidly lean off at full boost. The wide band shows this --- when the issue is present. afr comes back to normal 14.7 range when you let off and cruise lightly.

[914Slide]

https://www.youtube.com/watch?v=8TUT1LKtawQ

https://www.youtube.com/watch?v=8TUT1LKtawQ

Hopefully the link works for you guys. Shitty video i was by myself you can see it lean off mid burnout.

[914Slide]

Originally Posted by KAT-PWR

If one/two cylinders plugs look different that suggests injectors issues

My fpr is leaking, I cleaned it off and there's strong fuel smell i will be trying the stock regulator soon would something like that cause these problems?

I need to figure this out soon !

[KAT-PWR]

You can answer that...

Injectors flow more fuel at higher pressure
Less fuel at lower pressure.

[914Slide]

Originally Posted by corkscrew

Timing will definitely do that too. Happened on my sr when I had a broken knock sensor

I pulled off my knock sensor today and it wasn't connected to the harness ! i must have been barley on in the first place perhaps sending bad signals i know this thing works with some sort of resistance reading. I just ordered a new one on the way we will see from there.