the problem is next: car cruises and idles too rich, untill it reaches full operating coolant temp. it idles and and cruises at 10-11 afrs before coolant temp reaches 80*C. after exeeding this temp car operates normally, cruising and idling at 14.5 afr. never experienced it before and nothing have done to the car, to blame somethind.

what could be the cause of this ?

all cars run rich during startup. you're good. unless it stays that rich for more than a minute or two.

It could take up to 10 min for older oxygen sensor to get to operating temp. Why worry about a cold engine?

I dont drive my car on a cold engine. Always wait until it get up to operating temp before driving. If you're running afr's that rich at cruise (while warming up) you're going to run into issues with bore wash.

from 10s-11 for the brief warm-up period? it's not too bad. if his wide band is reading -- to 9s, then i would be concerned, though.

OP: speaking of warm-up period: are you letting the car warm up at all? and also, how long is it running at 10-11? it shouldn't be very long. maybe a minute or so?

That is way rich. While the computer does add fuel during cold conditions, it does not register that rich. Look at your maf comp vs coolant temp table, the values there likey need adjusted.

Bore wash startes at 12.5:1. This would really only be an issue with prolonged driving at that AFR.

Im sure it will be fine. Im just trying to convey that if you're driving around like that for a few minutes a day, several times a day, over time it might cause issues.

car warms up pretty soon, according to oem temp gauge. besides, its already warm here, so can't see why the maf shoul add any compensations to afr.
I have aftermarket temp gauge installed in upper radiator hose, so I'm writing these symptoms according to that temperature.

once again, It's pig rich until temp gets above ~80C in upper radiator hose. If I stop for some while, shut off the car and the coolant tep gets a bit cool (say 50*C ), afr starts over to be rich again, untill the car is fully warmed up

before, I had 12.5 afrs during warmup, even in winter and was running like this maybe a minute or so. after that short period it was always stoich no matter the coolant temp was 20*C or 70*C


p.s. the aftermarket coolant gauge isn't faulty. I have oil temp gauge too and they show pretty much the same temps always

check my another thread. can these two symptoms be in corelation ?
or can any faulty sensor cause these ?
https://www.evolutionm.net/forums/ev...onstantly.html

definitely, and i agree 100%. that's why i was wondering how long OP's car was running so rich. too long would be no bueno.

now it's starting to make a bit more sense. check your coolant temp sensor (i see someone else suggested the same). i had one go bad and my car dumped fuel like crazy. enough that i couldn't even start it.
not saying that's what is wrong, but it's possible.
good luck! let us know how it goes.

as for the fan, it can be unrelated. if so, it could be the switch. it's the main fan, not the A/C fan, yeah?

The MAF doesn't add fuel, the computer does, based on coolant temp. It adjusts MAF compensation based on coolant temp. The values in the coolant temp column go from very very very cold, to 182* IIRC. It could very well be your problem.



Also, warm on the stock gauge does not mean 190*

yeah those afrs are ok on cold start.

Adjust post primer enrichment and post primer enrichment decay tables if your coolant sensor is functioning and reading right. if it is broken just replace coolant sensor