91 Camry 4 Cylinder stutter/hesitation/miss

[YardPig]

1991 Camry 4 cylinder

New cap, rotor, ngk plugs, wires, new coil, new timing belt, new fuel filter

Idles like a kitten cold or hot

Runs ok cold, once it gets warm/hot it has a hesitation leaving the line.

You can also feel the hesitation/miss/surge if you are sitting in park and bring the rpm up and hold it steady.

Have cleaned throttlebody/AIC.

Lots of power, smooth throughout the power band, pulls strong all the way to the top, a bit of surge noticeable if you are crusing at higher speeds.

Really pulling out my hair on this one, any other ideas??


Take care
Shawn

[red_rocket]

o2 sensor?

[2wickedtoyz]

fuel filter?

[Mike Morris]

When you did the timing belt was it put on correctly? IE not one tooth off?

[YardPig]

I edited my original post to include fuel filter.

The timing belt is correctly installed.

The stumble/stutter is pretty minor, but it's there.

I am thinking it is o2 sensor by the first person's post and from what I have read elsewhere on the forum. I am going to replace and see, it's original as far as I know.

I will attempt to unplug the egr vacuum hose and see if the problem dissappears, same as the o2 sensor.

Shawn

[Mike Gerber]

Although most missfires are caused by ignition sytem related components, they can also be fuel system related. A problem with 1 or 2 of the injectors could also cause a missfire. I would run some Techron by Chevron through a couple of tanks of gas and see if that helps the situation. There could also be a problem with the electronics of 1 or 2 of the injectors, so obviously injector cleaner will not help that.

"Runs ok cold, once it gets warm/hot it has a hesitation leaving the line."

Since the problem is not there when the car is cold and surfaces when it warms up, then I would definitely consider the O2 sensor. The O2 sensor should be out of the loop when the car is morning cold. After reaching a certain temperature, the O2 sensor begins to send back readings.

I would try the injector cleaner first, since it's much cheaper and easier than replacing the O2 sensor. Then move on to test and/or replace the O2 sensor.

Mike

[Darwin686]

Its sounds like you might in fact have a carbon build up in the engine, possibly a clogged fuel rail, or bad throttle position sensor.

Another thing to check is do you have any oil in your spark plug tubes? If so you need to get those tightened down.

There are two quick and easy solutions that might help with this. Seafoam your engine or what i prefer to do is deep creep it. Its only 10 bucks either way you go with it. If you pull your o2 sensor and carbon is caked and i mean caked on it deep creep the engine. it is really easy to do. On the top of your valve cover on the left hand side you have a vacum tube going to the brake booster loosen the clamp but leave the hose on. Start the car and have yoru can of deep creep ready. Pull off teh vacum hose and spray like hell for about 10 minutes. the moment you stop spraying yoru engine will die. Put evverything back together. let your car sit for like 10 minutes and then start it. Its going to act like it wants to die give it gass and a cloud of black smoke will coem pouring out the tail pipe. Just reve the engine for a few minutes or until it acts like it isn't going to die. get and and go for a drive and keep driving until all the smoke is gone. Come to a stop ans see if your engine will die. If it acts normal. yoru good to go.

[YardPig]

It ended up being the egr and the 02 sensor and it never threw a code. Thats twice a toyota egr has given me a hesitation off idle, my ls400 did the same thing. All fixed.

Shawn