Ray Aguilar

Hello,

1995 4Runner 4cyl - 22re - 4x4 5 speed

This truck is my baby. And she's not doing well right now...


Symptoms:
When its cold, its starting to hesitate to start, but ends up starting just fine. Until it warms up, the idle and noise are a little rough, but not to any extremes.

This truck has lost, what seems to be, half of its power. I doubt I could get it to take off from second gear and on the interstate I have to keep, like, 3/4 to full throttle to hold 65mpg. At times, during accel, it seems like it is running normally, but I still think its just lost half its damned power.

During deceleration, the motor makes this weird whirring noise as the rpm's fall. It sounds like Rummm......Rummm......Rummm......rummm, until it gets back down to idle (if you read that out loud, thats extact what it sounds like ). This noise is coupled by some slight popping. Not a huge backfire, but slight popping that makes me think its running lean. Thats just a guess, I have no other evidence for the mixture being lean or rich right now.

Known problems:
1. Small exhaust leak near head-pipe. (has had it since I've owned the truck)
2. Slight oil leak from the oil-pan.
3. Once a month for the last year, the truck would feel like it would miss during accel. Just a slight hesitation that you could feel.

Recent work:
I just changed the brake pads, 1 caliper, and bled and brake lines about a week ago.

My hunch:
My hunch is that it feels similar to when I had a vacuum leak on my F-150 (I actually forgot to plug a vacuum hose back in when I changed the alternator on it). That truck lost power and had this weird idle and power loss.

This truck has a similar feel, so I immediately started searching for a vacuum leak. I have not done a completely thorough search, but I have already found that one of the 4 little rubber vacuum hoses coming off of the front of the EFI was cracked. It was so bad, it might as well have just been disconnected. I believe it was the hose for the EGR port, but I am not sure of that. I fixed it, and it has had no change in any of the symptoms. So it didn't fix anything.

Questions:
Do you guys think I am on the right track with the vacuum leak stuff? I would be really interested to know what you experienced yota guys think are the most common vacuum leaks to check.

Also, if you guys think it might be something else, tell me I'm an idiot and to move on to other troubleshooting. I am a good motorcycle mechanic at best. At least, I know the terminology, engineering principals, and science behind car/truck motors. I just don't have much experience working on cars as much as I do bikes.

Finally, let me know if I can do any inspections, tests, take any pictures, audio, or video that might help you troubleshoot this with me. I can run outside and get it done very quickly.

This truck is my favorite vehicle I have ever owned. I have had several new F-150s, a Hummer H1, and several other cars. But for some reason I fell in love with this ugly old gal a long time ago. I will never sell it, and I will keep and repair this truck until the day I die.

Thank you so much for any help you can give me.

ktetch

Have you pulled the plugs? IIRC, a lean running vehicle would give a white ashy deposit on the plugs.
It's a personal foible, but it's one of the places I always start, since it's right at the heart of the engine, but easy to get to.

Ray Aguilar

Not yet. Someone suggested the truck is old enough that I should replace the plugs and wires anyway. So I figured I would look at them to see if I could tell if the mixture is off.

I did try to pay attention to the engine temp. I figured if it was lean it might run a little warmer. Is that true.

ktetch

It will run hotter, but I wouldn't think it'd be that noticeable on the coolant gauge. Not unless your coolant system is not working well.
getting new plugs+wires will help, but having a look at the ones there is a quick+easy first diagnostic step

combatcarl

The rummm rummmm noise could be drive shaft vibration, but I'd do plugs n wires, plugs will tell you what is happening inside. Run an unlit propane torch, or use ether, and chase all your vac lines. Watch out for the fan...it'll surprise you... it'll idle up when you pass over a leak. Could be an ECT sensor, or TPS, at worst. Mine is beginning to hum at some road speeds, my driveshaft needs some love.

Ray Aguilar

Well,

I now have evidence to say that I'm running really lean.







I am going to try and look for more vacuum leaks. But I am open to suggestion.