Sudden rich condition out of nowhere
09-09-09, 12:02 PM
#1
Lead Lap
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Sudden rich condition out of nowhere
Ok, car is a jdm 2jzgte stock usdm twins, stock jdm ecu, adjustable fpr.
I have been getting sudden pig rich conditions when I drive the car for more than 25-30 minutes.
Before that time my a/f relatively stay above and around 12 even at an idle of ~700 rpm.
At 25-30 minutes, it suddenly drops to around 10 at idle drops very gradually to a little less that 500 rpms.
Fuel pressure at stock 25 psi.
Engine doesn't appear to be overheating. Looking at the stock temp guage, it stays operating temperature.
BUT during the swap the temp guage was missing a ground and read hot till I grounded it.
Following is the source.
https://www.clublexus.com/forums/per...with-pics.html
Could this mod have anything to do with it?
Is this normal?
I have been getting sudden pig rich conditions when I drive the car for more than 25-30 minutes.
Before that time my a/f relatively stay above and around 12 even at an idle of ~700 rpm.
At 25-30 minutes, it suddenly drops to around 10 at idle drops very gradually to a little less that 500 rpms.
Fuel pressure at stock 25 psi.
Engine doesn't appear to be overheating. Looking at the stock temp guage, it stays operating temperature.
BUT during the swap the temp guage was missing a ground and read hot till I grounded it.
Following is the source.
https://www.clublexus.com/forums/per...with-pics.html
Could this mod have anything to do with it?
Is this normal?
09-09-09, 02:59 PM
#4
Lead Lap
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with JDM ecu and 550cc inj, my AFR's would drop to about 10:1 once warm. startup was around stoich and then would taper around 12:1 untill warm.
are you sure 25psi is the factory fuel pressure setting? I was thinking more closer to 40-50 psi range.....
are you sure 25psi is the factory fuel pressure setting? I was thinking more closer to 40-50 psi range.....
09-09-09, 03:07 PM
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According to USDM fsm its 22-32. Funny thing is. I have a mine's tuned ECU which I opened up and it said 550 on the chip but can't confirm on injector. BUT I'm not running it since we don't have 100RON gas here which it is probably tuned to.
Any Idea on how to check if it is 440 cc? don't see any numbers on them.
Last edited by lemmiewink; 09-09-09 at 03:33 PM.
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09-14-09, 08:10 PM
#8
If it's "out of nowhere", then... I don't really understand what the injectors have to do with anything... unless one is stuck open. So asking what kind of injectors you have is kind of irrelevant. Check the resistances of the coolant sensors, one is for the gauge and the other is for the ECU. If one is out of spec and is reading much hotter than what it really is, it could cause problems like that. Might also want to try another 02 sensor if you're still bone stock ECU (Mine's included). Are you experiencing anything else? Boosting different, and CELs, etc?
09-14-09, 08:18 PM
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mine will do the same thing when i dont drive it for a while. i dont know what it is yet. im thinking a bad 02 sensor. some days it will drive pig rich unltill i shut it off for a while then its back to normal
09-14-09, 11:10 PM
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If it's "out of nowhere", then... I don't really understand what the injectors have to do with anything... unless one is stuck open. So asking what kind of injectors you have is kind of irrelevant. Check the resistances of the coolant sensors, one is for the gauge and the other is for the ECU. If one is out of spec and is reading much hotter than what it really is, it could cause problems like that. Might also want to try another 02 sensor if you're still bone stock ECU (Mine's included). Are you experiencing anything else? Boosting different, and CELs, etc?
Will check the sensors. Nothing else is different. Boosts ok. No CELs. Its just supper rich if I drive for an extended period.
09-14-09, 11:17 PM
#11
It sounds like either a coolant sensor resistance being wrong, or IAT sensor on the mani being off, 02 sensor going bad, or something to that effect. There's only a certain number of things that can give you those symptoms with no CELs and everything is still good elsewhere.
BTW is it any harder to start than normal?
09-15-09, 10:41 AM
#12
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Missed that, my bad.
It sounds like either a coolant sensor resistance being wrong, or IAT sensor on the mani being off, 02 sensor going bad, or something to that effect. There's only a certain number of things that can give you those symptoms with no CELs and everything is still good elsewhere.
BTW is it any harder to start than normal?
It sounds like either a coolant sensor resistance being wrong, or IAT sensor on the mani being off, 02 sensor going bad, or something to that effect. There's only a certain number of things that can give you those symptoms with no CELs and everything is still good elsewhere.
BTW is it any harder to start than normal?
09-15-09, 04:44 PM
#13
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Things to check are
o2
IAT
coolant temp sensor
Is it possible that my engine IS overheating? Just not showing it on the temp sensor.
09-15-09, 08:11 PM
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search around the soarer, supra, 2j forums for why and how the 2j richens the fuel mixture.
usually coolant temp and o2 sensors.
if the coolant guage works as normal, its the o2 sensor/s.
the O2 sensor has to be before the cats to get the propper o2 reading and it does take some time for the sensor to read accurately, 5 - 10 mins or so.
guess clean the sensors with electrical connector cleaner before replacing
usually coolant temp and o2 sensors.
if the coolant guage works as normal, its the o2 sensor/s.
the O2 sensor has to be before the cats to get the propper o2 reading and it does take some time for the sensor to read accurately, 5 - 10 mins or so.
guess clean the sensors with electrical connector cleaner before replacing
09-15-09, 09:16 PM
#15
I had a similar problem due to the fact that I had an o2 unplugged on my 1uz.
But, it would idle and drive fine with a cold start. On a hot start it would idle and drive fine untill (I assume) it went into closed loop.
The coolant sensor affects the AFR ratio more than you might think, definately worth looking into. Or, just go ahead and replace it! They are not expensive.
KC
But, it would idle and drive fine with a cold start. On a hot start it would idle and drive fine untill (I assume) it went into closed loop.
The coolant sensor affects the AFR ratio more than you might think, definately worth looking into. Or, just go ahead and replace it! They are not expensive.
KC