My 91 is acting like is has no power on acceleration. You can floor it and it barely putts off. It is also running hotter than usual. Usual is ½ way up the gauge, now it's running at ¾ up the gauge. If it's Summer and you're running the A/C, it will actually overheat. I bought this car new so this is something different for me. The radiator is new, the cooling fans are working. New timing belt, water pump and distributor about a year ago. This problem started about 6 months ago. Started with the slow acceleration and the overheating came next. Fuel filter? Catalytic convertor? My mechanic is stumped. He says the convertor is next to the exhaust manifold and hard to access to check with a temp. gun. And of course the fuel filter is buried on the firewall. I know when timing is off, it can cause the dogged running, could it cause the heating problem too? I know the distributor has been replaced but that's been a while ago and sometimes things happen. Thanks.

 

How about spark plugs and plug wires?

Does the engine rev but no acceleration? Is the transmission slipping?

A mechanic can perform a back pressure test for a plugged converter or exhaust system. The internet has lots of video's on how to do this.

Do you mean fuel filter and firewall? The fuel pump is in the fuel tank. Remove the rear seat lower cushion and cover plate to access the top of the fuel and fuel pump access.

 

Wires, plugs, cap and rotor all changed. Transmission isn't slipping and it does not rev up just acts like it is bogged down. It will continue on and gradually gain speed until it gets to the speed limit. It starts right up but has no oomph after that. I didn't know with the fuel injection, if a clogged fuel filter might be starving it for gas. I'll look for a video for the convertor.

 

Could be a failing fuel pump, plugged can type filter in engine compartment (rare), EGR valve malfunction (opens too soon), bad TPS, plugged exhaust.

A mechanic can check for a plugged exhaust, EGR issues, low fuel pressure, etc.

Did the engine ever overheat into the red zone of the temp gauge?

Bogging is one thing, bogging and overheating is another.

 

It will get up close to the red zone if the A/C is running. If you turn that off it will drop down to above normal. I watched a video by Scott Kilmer, he had what looked like a virtually identical engine (they didn't show the car) and did a back pressure test by taking out the O2 sensor. Which showed the convertor was bad because the back pressure was too high. I don't know about the newer models but mine mounts right to the exhaust manifold (like the one in the video) on the front. He said in the video, that because of the back pressure, it would not only rob the power but cause the engine to overheat because of the exhaust gasses staying in the engine too long. So the mechanic is going to get a proper gauge and checked for a clogged convertor. I'll give you an update when we get that done. If a convertor fixes it, I will update you also. Thanks

 

Great!

 

Well, well. Look how time has flown. To sum up all of this: I got the car fixed. 5 days ago. It sat at the original mechanics place 2 weeks short of a year. Every time I called or visited he was going to get it in soon. After much searching I found a mechanic 60 miles away, who has his own shop and was a Toyota mechanic for 30+ years.
Steve had it about 5 days and the troubles were a couple of different things. The cat was sorta clogged but not so much as to cause all the troubles. Everything was gone through and checked and no parts that were good were replaced. He's my kind of mechanic. Honest and fair.
The heating problem was actually the original muffler. He shook it and it sounded like it was full of sand. Rust had collected inside and when it heated up, it clogged the holes in the inside and held the exhaust in and overheated the motor. Some was getting out but not enough. The cat had a little issue also and he "fixed" that. Now the exhaust is flowing perfect but the lack of power is still an issue. He checked the timing and found the other mechanic had set the timing at 10° but didn't have the jumper wire in while doing so (I think that's how it goes) and the computer reverted back to default, causing the engine to be actually timed at 10°-12°+ BTDC. That made for the loss of power.
The car runs like it is brand new. Doesn't even get 1/3 the way up on the temp gauge and I am so happy. I'm sorry that it took so long to reply but I didn't want to leave the thread just open. I hope this can help someone else who is having similar issues. Thanks to all.
Dave

 

Thanks for posting back with the fix.