Good evening,

I have a '93 4Runner with the 3VZ-E engine. It's been having a weird issue for the past couple of weeks where it sometimes will barely idle, sometimes not at all, when the engine is fully warmed up. It also lacks power above 3100 RPM or so. Occasionally it will run perfectly when warm, but that is not usually the case.

I just replaced the fuel filter, with no change. I found a vacuum leak on one of the EGR modulator hoses, which I taped with no change. (I should check the rest of the hoses with propane or ether, probably will have time tomorrow.)

I ohmed three spark plug wires; two were 600-odd ohms and one was 1160, well within range AFAIK. I took out one plug and it looks OK, so I didn't bother checking the others.

I have been running a code 25 ever since I replaced the stock airbox with a cone filter. For awhile I had leaks in the air intake hose between the VAFM and the throttle body, but I fixed those. Code 25 still comes back though. I had also gotten a code 14 a week or two ago, but I cleared that and it didn't come back. Could that have come from the vehicle shutting off when I forgot to keep my foot on the gas at a stop sign?

I suspected the EGR valve, but I disconnected the three vacuum hoses going into the modulator with no change. I had tried testing the O2 sensor, but with strange results which I didn't write down and now forget.

This machine is a lot of fun, but it's got 211,000 miles and I don't want it to become a money hole. Is there anything else I can check without replacing parts one at a time?

In the mean time, I'll keep running this thing, though sometimes it feels like beating a dead horse.

 

Try this & get back with us:



If that solves it; your EGR vacuum modulator is the issue. There's a procedure in the FSM for testing/fixing it.

 

I removed that hose and made a good hard 3 mile run. Still barely idles. The hesitation above 3100 RPM is gone, and it revs fine up to 5000 (used to have trouble revving above 3100 too). However, I connected the hose again and it still revved OK, so I don't think it's related to the disconnected EGR.

I also ran a propane torch through the engine bay when it was idling low, but I couldn't hear it rev up at all.

 

have a vacuum gauge? kinda sounds like it could be a catalytic converter coming apart inside. at times it flows ok, at times it restricts flow. a manifold vacuum test will show a quick condition of the mechanical condition of the engine, and will indicate a plugged exhaust.

 

I can get one from work. Which manifold should I connect it to, and where?

 

tonight it was missing badly and wanted to shut off if I tried to drive it. there was also a clunking noise. I left it set, will deal with it later.