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Help me diagnose some problems with the Lumina, please?


1990lumina

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Hey guys! In an attempt to like this car a little more I wanna fix a few of the quirks with it that really annoy me sometimes.

 

1. Idle: When the car is first started it idles very nice and smooth. After the motor warms up past a quarter of the temperature gage it starts idling quite rough...you CAN'T feel this in the steering wheel - but in the floor and seats, etc, it is quite apparent. I dunno if it's a failing coilpack that stops working 100% when it starts warming up in the engine bay, or if I have a bad injector or something - but ifg it was an injector shouldn't it run like shit all the time, and have problems starting??

The car fires up PERFECT, and the idle stays around 700rpm or so, but it'll drop down to 500rpm, and back up to 800rpm and level out again around 700rpm. If the car is in neutral is vibrates even more, and seems to run worse!

I am not to sure what to think about this...remember, it's only AFTER the motor warms up does this happen.

 

2. The car is pulling to the right quite a bit after I put my summer tires back on. With the winter tires the wheel was shaking and pulling left and right constantly all winter..so this slight pull to the right is a nice improvement - but you know, this car feels more and more like a turd when things are pulling and vibrating all the time. When I had the wheels off, I tried pulling the wheel back and forth and up and down, and nothing was moving. When I tried side to side (9 and 3 'oclock on the tire) the whole steering rack was moving - I know because the steering wheel was spinning left and right too lol...hopefully it's just an alignment though.

 

3. Another motor related issue I think. When I'm sitting at a red light when the whole interior slightly vibrating (motor is warmed up), there is some type of clunk or "thunk" out of no where sometimes. I'm not sure what it is, and it doesn't seem to affect the operation of the car - but yet it seems like it's a mechanical type of thunk. Although with the engine noise this car has already it's hard to tell where it's coming from.

 

I think this is it...thanks for any type of pointers/help guys, girls!!

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Hey guys! In an attempt to like this car a little more I wanna fix a few of the quirks with it that really annoy me sometimes.

 

2. The car is pulling to the right quite a bit after I put my summer tires back on. With the winter tires the wheel was shaking and pulling left and right constantly all winter..so this slight pull to the right is a nice improvement - but you know, this car feels more and more like a turd when things are pulling and vibrating all the time. When I had the wheels off, I tried pulling the wheel back and forth and up and down, and nothing was moving. When I tried side to side (9 and 3 'oclock on the tire) the whole steering rack was moving - I know because the steering wheel was spinning left and right too lol...hopefully it's just an alignment though.

 

I think this is it...thanks for any type of pointers/help guys, girls!!

 

tie rod ends perhaps...

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No the O2 sensor hasn't been changed since I got the car...it's on top of the rear manifold right?? I may replace it when it warms up a bit (couple days)...how expensive is a new one?

 

This reminds me - the SES light came on one time when it was idling rough like this...but I restarted the car and it went away. Will the code be stored in the ECM still?? I haven't reset it, but the light isn't on anymore either. If it'll be stored, I'll go paper clip it right now!

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No the O2 sensor hasn't been changed since I got the car...it's on top of the rear manifold right?? I may replace it when it warms up a bit (couple days)...how expensive is a new one?

 

This reminds me - the SES light came on one time when it was idling rough like this...but I restarted the car and it went away. Will the code be stored in the ECM still?? I haven't reset it, but the light isn't on anymore either. If it'll be stored, I'll go paper clip it right now!

 

Yup should be still stored.

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Hmm, well I went and paper clips it...flashed code 12 over and over but nothing else..so I guess there was no code stored...I would if the light has to be on a certain amount of time to store a code....oh well

 

I'll look into the O2 sensor idea, sounds logical..that might help get some MPG too I'd imagine. Will I need a special tool to remove it from the manifold?

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o2 sensors for OBD I are pretty cheap, when I got mine it was about $20. The OBD II ones are $60+ It's no harder to do than spark plugs, jusst make sure you have the right tools.

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Could be the ICM if the problem is only when the car heats up. Could the thump sound be a misfire?

 

I'll try and get a video or it tomororw...it's almost like metal and metal hitting

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actually, the code was stored, but the codes are erased if they are not seen again after so many times that the car is restarted.

 

change the O2.

 

you should tilt the engine forward (as described in FAQ) and I have been successful everytime in changing the O2 with a vice-grip. if it is really stuck, I've read that running the car just long enough for the manifold to be warm/hot may help it separate.

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