COLO4Runnr

Guys I appreciate all of the advice offered here. I have been searching like crazy and trying some different things to try and get this truck up and running again. I will provide some history and hopefully I can get it figured out.

I bought this vehicle from a guy moving home to Brasil after his Ph.D. He loved the vehicle and was really sad to see it go. It has 154XXX miles on it. I have currently owned it for 3 weeks and have had nothing but problems. The second day I had it the fan bearings locked up and shut it down. Not knowing a thing about cars I towed it to the mechanic and replaced the fan, all belts, timing belt, and thermostat on it. Ran decently after but had some problems with power and seemed the idle was having a tough time. It would occasionally shut down on start up until I pumped the gas and reved the engine, then it would run fine. I took it back to the shop for further diagnoses and all spark plugs were replaced with the air filter (2 of the 6 were cracked). It has a slight leak on the pwer steering pump and real small leak on the head gaskets.

It seemed to run well until I made a trip to denver. About 40 miles out the A/T Oil Temp light came on so I pulled over and let it cool. The next 20 miles I had to do this again. Once I got into town it seemed to shift hard and jerk through gears. Drove back to Ft Collins fine later that evening. 2 days later at work I came out and noticed all my power steering fluid was gone. I got some filled it up and lost it within 5 miles. Thanks to the forum I found out it was a leaky vacuum valve on the pump. Based on some other advice here I decided to plug the hoses and seal the valve with a fitting bolt. After that it idled at 1000 RPMs consistently and shifted like it hasn't before. I was confident it would run well.

Took it out East on Saturday and it drove great. However on the return trip I could not get it to shift up into 2nd gear, even with the RPMs almost redlined. After shutting it down and restarting it several times I got it to shift and made it home. The next morning it was doing the same thing so I pulled it into the garage. Now the idle jumps between 0-500 RPMs and will cut out at zero. It seems to idle better in neutral but really jumps around in R or D.

So that is where I am at. After searching I thought a TPS was the issue, I unpluged it last night and it did not idle any better. At this point my suspicion is a fuel filter or cat (mechanic told me I was pushing 3-3.5 lbs back pressure). What are your thoughts? Any help would be appreciated. As a side note and Toyota junkie in the Northern CO wants to come and take a look I will provide the beer!

COLO4Runnr

Well last night I pulled the catalytic converter to see how it would run.

Still has the same issues, only thing it did do was make it loud and wake up the neighbors.

I noticed with the cat detached it would idle in park and neutral at 1000-1250 RPMs. However once I dropped it into reverse the idle cut after the RPMs fell to zero. Right after I tried to restart it. It cranks and turns over but RPMs don't jump and it quickly stalls.

On the list for tonight is jump fuel pump, check resistance on the vane air flow (VFM) and TPS. Might check for a vacuum leak but do not know the proper technique to do this.

Any pointers or other ideas as to what it could be are appreciated.

COLO4Runnr

Anyone???

I did some more work last night below are my results:

ECT sensor replaced (a trip from another guy that seemed to find that as a fix to simmilar issues)-seemed to idle better in park, as soon as I dropped to reverse RPMs dove and engine stalled.

Bypass fuel pump- could hear it running, started up fine but same deal RPMs plummeted and it stalled. This time I got a check engine light but have no way to read the code.

Checked resistance on the VAF sensor- everything fell within spec.

Any additional tips would be great I am really out of things to try. I'd like to check for vacuum leaks but it'll have to idle to do that.

fdp101452

Have you checked for stored codes?

rworegon

Sounds like a vacuum line may have a crack, is loose, or not routed correctly. Give them all a good visual inspection and feel them for cracks or ends that are split.

Could be the COR (Circuit Opening Relay) is acting up. Use the link in my sig and look at the FSM.....diagnostics need to be done before shot gunning more parts, IMO.

jbtvt

If by bypassing the fuel pump you mean jumping +b and fp you actually bypassed the COR and eliminated that as a problem. Any change between cold and warm performance/idle? If so a sensor is more likely. Definitely check fuel pressure and vacuum leaks, afm resistance check wouldn't hurt.

Check codes by jumping e1 and te1 and counting flashes, search for full procedure.

COLO4Runnr

So after a morning of tinkering we got it to idle ok. The vacuum lines have undergone many a visual inspection and I cannot find a leak.

It seems the big issue is when a load is applied. It will idle fine in P and Neutral but as soon as it is put into drive or reverse, the RPMs plummet and it stalls.

Any other ideas as to what this might be?

COLO4Runnr

Well I found my problem.

The EGR Vacuum Modulator. Feel a little dumb because it was right there in plain sight. We pulled the hoses and and it must have reset the valve. It now runs, just not with a ton of power. Going to replace the part tonight and hopefully I get her to run some 50k more!

jbtvt

Congrats, and thanks for updating.

rworegon

Nice work COLO...hope it's running good now.

COLO4Runnr

Seems to be running better now. However it does have a little trouble on start-up. I took it out to run some xmas errands yesterday and at the last stop I had a small issue. Once it fired up the idle wanted to plummet, I reved the engine a couple times which brought the idle up to ~1000RPMs (where it should be based on the power steering valve being plugged). Then it ran fine.

This morning I started it and let it run (it was cold out) when I hopped on the main road I couldn't get it to shift into second until a touch after 5000 RPMs and then it ran fine after that.

My question is, Might I still have a vacuum leak somewhere that will not allow my system to hold pressure? Is the EGR valve not working properly (valve not resetting until considerable vacuum is applied? Other thoughts?

The EGR valve is a pricey part and I want to be sure that it is in fact bad before I replace it. Looks like the only way to check it per FSM is witha vacuum meter. Is there any other way?

brianh699

Have you removed your intake plenum and throttle body on this truck? Your right around the mileage where alot of 3vze's see alot of carbon build up in these areas causing idling issues due to plugged vacuum ports.

COLO4Runnr

I pulled the intake hose off and cleaned that part of the throttle body thoroughly, including the intake valve.

I thought about taking the throttle body off but it appeared to be quite a job (the above has been the first work I've ever done on a vehicle), but might just need to take a Saturday and do it.

Anyone think that my issue could be related to a bad VSV?

Gevo

Its easy to test the vsvs. Just follow fsm and you can take that off the list. With these engines, anything related to vac system can be the problem.

Alfonso Martinez

Hi..Sorry to hear your having problems with your 4 runner, I have a 94 4Runner that my sister unloaded on me because she was having simmular mechanical problems,. So the mechanic advised her to junk.it. Needless to say I took the vehicle and did all the mechanical work myself. What I noticed about the engine was that it is very sensitive, and everything had to sync. So after crossing all of my t' and dotting my I, I realized that my problems was most likely fuel related. As it turned out, I found a reputable mechanic who discovered that that fuel injector o rings were missing. I suspect that my sister's mehenic fudged the job in order to bring back business. So after replacing the o rings life was brought back to my 4 runner and has since been running great.

94 4 runner rescued from being junked. Did all engine by myself except for the missing o rings on fuel injectors.