Engine sputtering when idling, and when in drive/reverse

Hi,

That could be the result of a few things. First, an engine vacuum leak can cause a rough idle. Here is a link that explains how to test for one:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Next, if it is the idle speed changing, that could be related to the idle air control valve. That is what controls the idle speed.

Let me know if it is the idle speed changing so I know how to direct you. Also, I would like you to scan it for codes. You don't need a scan tool on this vehicle. Here is a link that explains how to retrieve codes:

https://www.2carpros.com/articles/toyota-trouble-code-definitions-and-code-gathering-method-1990-1995

Let me know what you find as far as codes.

Take care,

Joe

Thanks for the reply. How do I know if the idle speed is changing, what exactly do you mean by that? I will check it for codes today and get back to you. Thanks again for all the help.

So I checked for error codes and there are no error codes. The check engine light just blinks constantly when I attach the jumper wire to TE1 and E1, which according to the Haynes manual means there are no error codes.

Hi,

By idle speed, what I mean is the engine RPMs increasing and decreasing? Also, have you had a chance to check for engine vacuum leaks?

If not, do that. If there are none and it is the RPMs changing, we should at least try to service the idle air control valve (IAC). Here is a link that explains how it's done:

https://www.2carpros.com/articles/idle-air-control-valve-service

Before you remove the IAC, please confirm there are no vacuum leaks. To remove the IAC on this requires the removal of the throttle body, draining the coolant, and so on. I don't want you to go through that unless we are confident it's needed.

Here is a pic of the IAC on your vehicle. Again, it's under the throttle body.

Let me know what you find.

Take care and I'll watch for your response.

Joe

See pic below.

Thanks Joe, I’ll check for vacuum leaks. Side note, this issue came about immediately after I changed the transmission fluid. Do you think that could have caused this problem? (Either too much or too little fluid?). I checked the dipstick and it says it’s fine but I think it’s weird that this problem came about immediately after I changed the fluid.

Hi,

Anything is possible. It isn't difficult to accidentally disconnect or damage a vacuum hose.
When you check the ATF level, is the engine at operating temperature, running, and in park?

Let me know.

Joe

I check it when it’s cold and the ATF level is at the cold mark on the dipstick. I'm reluctant to drive this car until I get this issue fixed because I don’t want to cause any damage. I attached a video of the RPMs…the needle is slightly moving but hovering around 1000 RPMs. Is that considered the idle speed increasing or decreasing? It doesn’t look like it’s really increasing or decreasing to me but maybe it is. What do you think?

Hi,

I watched your video. It's moving slightly, but nothing I consider odd. Also, as long as the engine was running when you checked the fluid, that's fine.

Now, the idea of the idling issue, has the vehicle been tuned up recently? Were you able to check for engine vacuum leaks? Is the milage listed original to this engine?

Let me know.

Joe

Yes, that mileage is original to this engine, and this car has had a ton of work over the past year (seems like a lot of parts are going out at the same time). This car has had very regular preventative maintenance done to it over its lifetime. I am doing the vacuum leaks tomorrow.

Okay, let me know the results. Also, it may be a good idea to remove a couple of spark plugs and inspect them as well as spark plug wires.

Let me know what is found.

Joe