Help needed - mechanics can’t figure it out

I have a 98 4Runner and it started to lose power when speeding up. They’ve checked everything from gears, fuel lines, computer and who knows what. They are telling me to basically quit on it: however, I am attached to it although it has 373000 miles on it. I am looking for some insight or guidance.

 

I assume you had adequate fuel pressure if they checked the fuel lines? Fuel pump would still be my first assumption though. Might have enough umph left to keep it at idle and lower speeds, but it’s not keeping up when the throttles down.

Most anything else I can think of would probably throw a code eluding to what’s going on.

 

Try another mechanic. A weak fuel pump will do something like this. How old is the fuel pump? If it is original..worth a shot to replace it with a quality Denso.

 

How about air filter? It sure sounds like a fuel related problem.

 

sounds like an incompetent mechanic. take it to a different shop. a real mechanic will troubleshoot it and then it would be up to you as to whether or not it’s worth it to spend “x” amount of money in it. did they do a cylinder compression check?

 

I would normally buy your logic but I can tell you all the joy we had with our Gen 2 Runner when we were sorting out her drivability issue that was NOT throwing a code and my husband is an ASE master mechanic that worked for Toyota. After many many hours and hundreds of parts and relays we put in her it ended up being the circuit opening relay and the main relay. If it had been a customer car, the labor hours would have superceded the value of the car.

 

My suggestion would be looking at putting a fresh engine in it. At almost 400,000 miles, that engine might be just worn out. Would be cheaper and better just to replace than rebuild at this point. Also check that your catalytic converter isn't failing and blocked. We did away with ours and it was new!

 

Just my uneducated guess. With that many miles could the catalytic converter be partially clogged? If fuel is present it must either be spark or airflow. With the always possible exception of a bad wire etc.
Good luck & keep us posted!

 

This was my thought as well. Definitely worth looking into.

 

Ive had this happen in a VW. All of a sudden just no power. Idled fine, just couldnt accelerate. Easy to check. Just unbolt the header and take it for a very loud drive.

 

My 99 4Runner did the same thing when trying to speed up. Ending up being the fuel filter. Change the fuel filter and it ran fine.

 

If you think it might be the CC....just drive it at night...if its clogged...itll be cherry red....

 

Yes, CC is another culprit and easy to check.

There are only a few things on these cars that will allow it to idle fine, have no power at speed and NOT throw codes. Which have all been mentioned here.

Air - Clogged Air Filter.
Fuel - weak fuel pump or clogged filter.
Exhaust - Clogged cat.

And honestly, with clogged air filters or weak fuel pump you probably more than likely get a misfire code at some point. (you didn't specifically say there are no codes)

Clogged cat is the one that always seems to pop up that causes this problem. Rule that out first.

 

My bet was clogged cat. How about an update? did you figure out the problem?