Need Advice from the Experts

[MAD King]

Hello,

My 1998 Lumina is maintained, but I don't know it this is the way it has to be. When I stay at the red light the engine feels like it is dying the next second, but it doesn't. It feels like a Harley Davidson. Same way. You think it is dying in the next second, but it doesn't.
Is this normal for a car with 170.000 mls on it or am I very sensitive for that?

Thank you

[danielsatur]

When the throttle plate is closed (idle), the engine still needs air!
1) Clean air filter, and IACT.

[MAD King]

Originally Posted by danielsatur

When the throttle plate is closed (idle), the engine still needs air!
1) Clean air filter, and IACT.

Air filter is brand new and white like snow, but what is IACT?

So it is not normal what the engine does?

[danielsatur]

The IACT contols the air @ idle, when you turn the air cond on, it gives more air & rpms for the Air cond to run without notice to the driver during the idle condition.

[MAD King]

Originally Posted by danielsatur

The IACT contol the air @ idle, when you turn the air cond on, it gives more air & rpms for the Air cond to run without notice.

I can't find anything about iact on google. Where does this sit?

[maxwedge]

Clean the throttle body remove and clean the idle air control on the throttle body.

[MAD King]

Originally Posted by maxwedge

Clean the throttle body remove and clean the idle air control on the throttle body.

Already cleand. Looks like new and silver.

During the search about the IACT I found some site which says it can also be the O2 sensors, because if where coolant in the system the sensors might be damaged. I had coolant in the system before the engine were fixed. I am now trying to find out how many O2 sensors a 1998 Lumina has.

[ptcfast2]

Originally Posted by MAD King

Already cleand. Looks like new and silver.

During the search about the IACT I found some site which says it can also be the O2 sensors, because if where coolant in the system the sensors might be damaged. I had coolant in the system before the engine were fixed. I am now trying to find out how many O2 sensors a 1998 Lumina has.

It has 2 O2 sensors. One right behind the rear exhaust manifold sticking out of the exhaust pipe. The other one is right after your catalytic converter under the car (the only sensor attached to the exhaust under the car...can't miss it).

[MAD King]

Originally Posted by ptcfast2

It has 2 O2 sensors. One right behind the rear exhaust manifold sticking out of the exhaust pipe. The other one is right after your catalytic converter under the car (the only sensor attached to the exhaust under the car...can't miss it).

Autozone says it has three. One upper, one lower and one after the converter.

I didn't look yet and was going to replace them next week. I read they have to be replaced every 100.000 mls anyway.

[ptcfast2]

Originally Posted by MAD King

Autozone says it has three. One upper, one lower and one after the converter.

I didn't look yet and was going to replace them next week. I read they have to be replaced every 100.000 mls anyway.

I know for a fact the 3.1L has 2 sensors. Once pre-cat and one post-cat.

Is this a 3.1L or 3.8L Lumina?

[MAD King]

It's a 1998 Lumina 3.1. I think the Luminas till 1995 have only two.

[ptcfast2]

Originally Posted by MAD King

It's a 1998 Lumina 3.1. I think the Luminas till 1995 have only two.

Mine is a 1998 3.1L as well. They only have 2 (pre-cat & post-cat). I'll even whip out the GM service manual and scan the exhaust system diagrams to prove it.

[MAD King]

I only have one post-cat, but I am not sure on the manifold ones.
They said two . One lower and one upper.

[ptcfast2]

Originally Posted by MAD King

I only have one post-cat, but I am not sure on the manifold ones.
They said two . One lower and one upper.

They probably meant upper and lower as pre/post-cat. Many people refer to it as upper and lower, and I've always thought it causes confusion. Technically the pre-cat sensor is higher up in the engine bay, and the post-cat sensor is the lower one as it's on the underbody of the vehicle.

So....one sensor would be post-cat (sticking out the side of your exhaust - drivers side right after the coverter). Other pre-cat one is up in the engine bay, near the rear exhaust manifold by the firewall, sticking straight up out of the of the exhaust.

Removing the pre-cat sensor can be a pain. You can remove it without rotating the engine, but make sure you have the right socket/ratchet/extensions else you might round the sensor off. Mine was rusted so badly to the exhaust that I had to take the car to a shop to remove and have new threads put in.

[MAD King]

That makes sense. You don't have any pictures of the pre-cat sensor by chance?
Would like to know where it is located exactly.

Thx