Dx This

[Lextreme II]

Dx means diagnoses. Got my engine running today.. well... kindda. My engine one runs at around 2k to 3k. More or less than that will die. I have 315 cc/min in it with 5.2L. CEL is on but didnt plug in OBDII yet for Dx. SPF helped me swap out the harness and signs and symptoms are getting better but still have an issue. What do u think?

 

[spf_lexus]

My vote is for the 315cc injectors. I'm of the opinion that the stock ECU is smart enough to account for the cams, but adding larger injectors on top is giving the ECU a migrane. When it's idling it sounds very strong. The car also smells rich at the 2-3k idle. The cats were HOT after 10 minutes of starting/dying.


I drove the 4.7L with stage II cams on the stock ECU and it ran great.

 

[BigKriss]

In a situation like this I usually fit my Innovate 4wire quickly, at the end of the exhaust and it will show you exactly what you want to know.

Alternatively start her up, rev her until she dies-I presume its very close to the 3000K mark?-whip a plug out and see if its wet with fuel. If its wet, obviously the spark is being killed here. If its dry though, look elsewhere .
For some reason I dont believe its being over fueled. I wish I had experience with the stock efi system..

 

[sideshow]

you should know never to change injecotrs and keep factory ecu/tune
i doubt even 10% increase in inj size would work on std ecu

its like the idiots who raise the fuel press with std inejctors and ecu
u might get more power in 10% of the rev range but stuff up the rest of the 90%
so end of the day its a waste of time

try backing of fuel pressure to see if it helps

going larger capacity doesnt not mean u need way bigger injectors
you are probably better of keeping the std inejctors in there and upping the fuel press slightly

if u plan to keep std ecu then fit std injecotrs back in and slightly raise fuel press but 5 psi see if it helps then maye even 5 more
its much easier to adjust that then hope for std ecu to cope with the bigger injectors

how big are yr cams
ive seen 4age motors with massive cams and it hunts badly at idle
this is because older toyotas ran flap type air flow and as the lumpy idle varies vacuum so badly that the air flow flap swings like a 2 dollar hooker and then makes the idle even worse so not to sur ehwo the 1uz air flow will go if u have big cams
should be ok since it doesnt have a flap
just make sure u run the honeycomb gauze which helps stabilise the air

 

[spf_lexus]

the lumpy idle varies vacuum so badly that the air flow flap swings like a 2 dollar hooker and then makes the idle even worse so not to sur ehwo the 1uz air flow will go if u have big cams

haha nice analogy. I know the cams should work because lex has used the exact same profiles on a 4.7L hybrid which was also running OEM injectors and ECU. I test drove it and it was as smooth as stock.