Anyone know if a malfunctioning coolant temp sensor would cause my h22a to run too rich, and not throw an engine light? Can my ecu store current trouble codes without displaying the check engine light?

 

yes to all of that, but it wouldn't make a HUGE difference in the air fuel ratio.....but since they're already rich to start with, then it's very possible that it's telling the ecu that it's not warmed up yet and that will cause it to run rich......some codes cause it to stay on, some don't.........could be an o2 sensor too, but it will normally show up as code 1.....doesn't always trip a code though unless there is something recognizable in the circuitry, like a short or a break in the current.....

 

from what i understand diagnostic trouble codes can exist without malfunction indicator light coming on. the light will come on only for DTCs that effect emissions. thats why you dont have to do the tail pipe test when you get your inspection its being tested every day by your obd2. and if the o2 sensor is malfunctioning i have it will be dumping fuel like mad.

 

Its obd1, 4th gen

 

what makes you think your car is running rich
yes the engine runs rich at warmup, however there are several ECT sensors. im pretty sure if one is broken (wrong resistance or open wire) it will throw a code

best bet is to check the ecu for codes, just jump the blue connector behind your ashtray/radio area
you can get to the connector from the opening adjacent to the gas pedal under the dash

~boomer

 

Well I have already jumped the connector, there were no codes(with a bad ect it should have given a code 6). I was really at a dead end with this so I brought it to a shop, they say that my ecu was giving them a code for my coolant temp sensor, this confused me because I was unable to pull a code. They tell me that the malfunctioning ect was causing my car to run too rich, which was causing the lack of power I was experiencing. They also said that they had a way to bypass it, and when doing so it ran much better. If my ecu had been giving me a code I would have been able to fix this myself but with no code and just a general loss of power (which could really be anything) I had to bring it somewhere. I hope replacing the ect fixes my problem and I guess I will find out in a day or so. thx for your input.