Problem i cant get to the bottom off.. collective thinking needed lol

[HYBRID]

Hi guys,

So here goes.. after i drive around for a while, (before lambda starts working ie car working on choke under 600deg egt) the car drops dead lean.. ie on the aem all u see is --- lol.. if i leave it idle to long instead of riching out.. its leaning out, not to mention i keep my idle at 1500rpms.. but when i get this problem car wont hold anything over 1000rpms?! & starts sounding like its gonna die out this problem clears if i hit at least 1psi of boost.. after that car works off the map sensor + runs closed loop.. no problems then on & ff boost... which is really strange.. the weirdest bit is i get NO fault codes... which is totally screwing me up..

heres a list of the things iv done to solve the problem.. it has improved slightly but not that much:

1.) removed sard fpr.. running stock, + 7m pump & 324cc inejectors
2.) emu removed (running on stock ecu so should be running rich did fuck all.. )
3.) removed narrowband signal from oem lambda as maybe it was earthing the lambda
4.) bought a new lambda sensor & installed it
5.) tps is fine
6.) map sensor is fine
7.) no misfires
8.) changed water temp sensor for a new one..
9.) dizzy, rotor arm, plugs leads & ignition system are all new..
10.) knock sensor & speed sensor are intact & working
11.) no loose wires on oem harness
12.) battery giving steady voltage
13.) timing is bang on 10deg tdc
14.) idle valve working perfectly..

Thats my list so far.. i was told maybe it could be the air intake temp sensor playing up.. but what would it have to do with the car fuking up when warm?! afaik it should rich out the system & pull back timing if its getting hot intake temps.. im not aware it has anything to do with the choke system...

this is really a tough one, & in the past 6 years iv never come aross this problem so i was thinking maybe somebody has encountered it & could help...

many thanks
kon

 

[HYBRID]

ok iv come across a very good article by toyota usa...

it could be hinting that the air intake temp sensor could be at fault... more interesting it could be shorting out.. ie not giving a correct reading.. have a look at this & tell me wot u think lads

http://www.autoshop101.com/forms/h32.pdf

kon

 

[GT_Ben]

Hmmmm....could be the culprit hybrid if youv changed all of the above!

If there not very pricey, change it and see if there are any positive effects!

Saying that, would the emanage ultimate not pick up a fault intake temp sensor. ie. intake temps all over the place?

Ben

 

[350ep70gr]

Kon

Are you sure you dont have a slight misfire or pre-igntition?Misfire can be identified in a datalog with wideband o2 by looking for a lean spot just after the RPM that it missed at. The lean spot is caused by the unburnt fuel and oxygen hitting the sensor just after a misfire event that caused that fuel/air not to burn. The o2 sensor sees the unburnt air and thinks it's lean and you'll see that lean spike on the datalog. If you hear an event like this and there is no lean spot just after on the datalog then it's very possibly knock or pre-ignition. but I'd try reducing timing around that point a bit and making darn sure you weren't lean at all. If you still have knock/pre-ignition try colder plugs it might help.Also a broken IAT gave me some overfuelling in the past so it might worth to check it also.

Chris

 

[Phil]

im suffering some overfuelling issues at the moment, especially on idle, so very interested to see info that this thread collects!

Phil

 

[HYBRID]

Kon

Are you sure you dont have a slight misfire or pre-igntition?Misfire can be identified in a datalog with wideband o2 by looking for a lean spot just after the RPM that it missed at. The lean spot is caused by the unburnt fuel and oxygen hitting the sensor just after a misfire event that caused that fuel/air not to burn. The o2 sensor sees the unburnt air and thinks it's lean and you'll see that lean spike on the datalog. If you hear an event like this and there is no lean spot just after on the datalog then it's very possibly knock or pre-ignition. but I'd try reducing timing around that point a bit and making darn sure you weren't lean at all. If you still have knock/pre-ignition try colder plugs it might help.Also a broken IAT gave me some overfuelling in the past so it might worth to check it also.

Chris

hey bud, iv removed the emu & im running on the stock ecu, with 324cc injectors & the aem wideband connected.. im not getting any recorded knock or det.. iv datalogged countless times, & there is no sign of anything wrong.. timing stays good ie variable timing during driving but it goes leeeeeean... this is on the stock ct9 at 5psi only.. lol so i doubt its got any timing issues... static timing at the dizzy is 10deg tdc... problem is it isnt overfuelling but underfuelling till i hit boost for the 1st time im driving.. which is crazy.. as after that till it gets cool again i dont get any problems which is weird...

kon

 

[HYBRID]

Hmmmm....could be the culprit hybrid if youv changed all of the above!

If there not very pricey, change it and see if there are any positive effects!

Saying that, would the emanage ultimate not pick up a fault intake temp sensor. ie. intake temps all over the place?

Ben

hey ben, theyre not very expensive.. just around 70euros iirc.. the thing is i tried datalogging it, but i have the knock/water temp installed on the emu.. i dont have the iat temp sensor included.. as u can only hook up 2 on the emu...

kon

 

[350ep70gr]

If i am not mistaken you face this problem when engine is cold! IAT gives a signal to the ecu along with the CLT and when both are cold from the signals,ecu assuming that engine is cold and try to inject more fuell to be evaporized as on low temp less fuell will be evaporized.So in my eyes could a fault IAT give you this (lean situation)problem by not telling the ecu that is a cold engine.Ecu calculate both signals (IAT + CLT) as it was one curve.
Those 2 sensors are like identical inside and you can test by a multimeter in different intake temp to see if you have different resistor readings.Also if you think that sensor is working you can mesure the whole circuit at the plug of the ecu.(in case a broken IAT wire)

Also if you wan to remove the sensor you can try this guide.


http://www.diyautotune.com/tech_articles/iat_clt_resistance_curve_calculation.htm


Hope it helps
Chris

 

[HYBRID]

thanks chris... there is only one tiny problem... it starts not exactly when the engine is cold.. in fact when the car is started 1st time in the day it will be ok, till around 2 mins of me starting the car.. lets say it would be getting say half way to operating temperature...

then the weird thing is that, if i stop the car, switch off leave it say 5 mins up to an hour then start again.. ill get the lean situation much before.. ie within seconds of starting..

this all goes away as soon i hit 1psi.. in fact sometimes for this to go i even hit 1psi when the car is cold to make sure it stops jerking.. its very strange as iv never seen it happen before.. then after u hit boost i can drive normally & this problem doesnt appear again.. thats y im finding it very strange...

im not giving up lol.. i need to check the resistance the sensor is giving to the ecu.. coz its either gonna drive me mad or i dunno lol..

kon

 

[Rory]

Just to rule your ECU out, have you tried another EP91 ECU?

 

[Spoonz]

this ounds a bit like a problem wehad but are's ended up bein the earth wired by the idle control valve but u checked all of that im guess??
Has rory said why dont u try another Standard ECU

 

[G6Turbo]

just an idea konrad but isnt ur distributor getting tired?

 

[FeNder]

i dont have the IAT connected , just a loose wire on the ecu , and its on the rich side on idle , kinda opposite to your problem !

 

[HYBRID]

Just to rule your ECU out, have you tried another EP91 ECU?

nope.. i know its weird but i havent tried that yet.. im leaving it as a last resort.. iv been thinking about it & iv almost ruled it out as this happened gradually as the temperature got colder here .. ie its prob a sensor at fault lol..

thanks for the input bud i will try another ecu if i dont get to the bottom of this.. which i will haha!!

kon

 

[HYBRID]

this ounds a bit like a problem wehad but are's ended up bein the earth wired by the idle control valve but u checked all of that im guess??
Has rory said why dont u try another Standard ECU

are u talking about the injector earth bud? cant think of any other earths there...

what was the case/symptoms on urs bro?

thanks
kon

 

[Toby@ToyTuning.com]

Bloody hell just noticed this a lot of variables to look into, are you sure timing is dead set Konrad?

If so then it may be sensor related like you say that's the problem with this so many things to look at and consider.

T

 

[HYBRID]

i dont have the IAT connected , just a loose wire on the ecu , and its on the rich side on idle , kinda opposite to your problem !

hmm... it is strange.. but as that article said (the one i posted) it could be it either causes a lean or rich situation... kinda sucks this problem lol..

 

[HYBRID]

Bloody hell just noticed this a lot of variables to look into, are you sure timing is dead set Konrad?

If so then it may be sensor related like you say that's the problem with this so many things to look at!

T

i know tobs.. its doing my fucking head in lol... yeah timing is spot on, we checked it 2 days ago & it is exactly 10deg tdc..

the funny bit is in all these years (6 to be precise) iv never come across this problem or ever heard of it happening to anybody with a starlet lol...

just my rotten luck lol..
kon

 

[HYBRID]

just an idea konrad but isnt ur distributor getting tired?

hey bud, iv just changed the dizzy cap & rotor arm 4000kms ago... so theyre still brand new.. car doesnt misfire or anything of the sort...

this is really a difficult one lol..

kon

 

[EP82]

have you checked your air flow meter? just a thought?