99 eclipse cold start problem???

Hi, my car runs real ruff when started cold and makes a kind of wizzing noise for a short time, sometimes off and on. I had a local parts store use their scanner and they said I needed a new O2 sensor and coolant temp sensor. I installed both but still does the same. I had a friend scan my car and he told me the coolant temp was 180F stone cold and the O2 voltage was way low. He also said there is no egr command??? The car runs fine after it warms up.Any ideas guys??? thanks in advance. Jon

Hey now, I got to look under the hood this morning as the car was started for the first time today, the wizzing sound is comming from the intake as i could hear it through the cold air intake filter, its only there for about 10 seconds and quits. It never did this before.......any ideas??? I'm thinking its somehow connected to the egr???

Let me try a different approach, there are two sensors mounted in the water neck, I replaced the larger one but the water temp is still reading 180 when the car is stone cold??? What is the smaller sensor???

What model/year are we talking about?

On the thermostat housing there's the coolant temp and the sender unit for the dash gauge. If you replaced the CLT already, it should be fine.

The ECU tests the EGR at initial startup, however I've never heard it making any noise unless the valve or the gaskets themselves were leaking. Are you sure the "wizzing" isn't the starter stopping after cranking?

The larger one is the coolant sensor for the ECU, the smaller one works the inside gauge. check your wiring from the ECU to the sensor, these sensors are basically variable ressitors so if you have a wire issue that is creating resistance it will make the gauge read incorrectly. I would measure the resistence of the sensor dead cold and then measure the resistence of the sensor at the ECU threw all of the wiring to see if it matches up.

Thanks for the info guys. This car is a 99 GS model with the 2.0 motor. Maybe useing "wizzing" to describe the sound isn't right, its more like the sound of air being drawn into a long hollow tube. The scanner states no egr command and the coolant temp is 180F when cold like the first start of the day. I change the coolant temp sensor and the 02 sensor, maybe theres a second 02 downstream?

There is a second 02 sensor after the cat but has nothing to do with how the motor runs. Let someone else start up the car and try to figure out where the sound is coming from. Also if you look in a shop manual there should be a resistence chart that tells you what the sensor should be putting out at a given temp. Use a DMM and check that to make sure the sensor is good. Sometimes even new sensors dont work

Thanks again, I'm thinking that the new temp sensor is bad or the connecting plug as the rad cap was leaking on it and this is giving a false reading to the ecm, it thinks the engine temp is at normal operating temp(180F) so the egr command is not requested. I replaced the rad cap so now i'm going to check that plug real good.......

EGR really has nothing to do with engine operating temp. Again, it runs it's initial test at startup to make sure the system is working properly. If so, then it adjusts opening/closing under normal driving conditons/idle. It does this both open & closed loop modes.

I'm guessing the 'rad cap' is the thermostat cap? Even if that was leaking, the engine still heats up normally and the sensor still should see those temps. You can tehnically put it in a cup of water and with a logger watch the temp adjust.

Do what Silvr said and I would also recommend cleaning the contacts on the connector attaching to the sensor. Sometimes the leaking cap can cause some rust on the metal contacts. Although if that were the case, the car ideally shouldn't have a 180* reading then.

Hey David, I understand your info but I'm thinking that the coolant temp might be what the ECU uses to determine to request the EGR at cold start up. So if the coolant temp is reading 180 when the car is stone cold like first thing in the mornings, if this is why the scanner says no egr command???

The EGR gets a test command directly from the ECU at startup, no matter how warm/cold coolant/air temps are. You could technically overheat the motor, turn it off and back on again, and it would still run the test.

Since it's part of emissions, it has to run the test at each start to make sure it's present and that it's working properly.

Try unplugging the sensor and reading the temp. It should read very low like -40F or something like that. So it seems to me like the sensor is almost stuck at that resistence. If you let the car warm up does the temp raise on the ECU? Stock thermo stat is 195F so it should hit over 180 quick.

hey guys, i unpluged the coolant temp sensor and the car started fine when cold, I tried to clean the connectors in the plug but their so small all i could get is a wire in there and try to scrape it but it didn't do anything to help the connection so i'm going to get a plug from the junkyard and see what happens.........