96 4runner with 3.6 and 150k miles. Truck ran great til I decided to "make it better" - by cleaning throttle body and doing deck plate mod.

It ran fine originally at first (maybe 20-50 miles), then started running rougher and rougher (during a 500 mile trip to the mtns and back). I found i did not replace a vacuum line - it's a 1/2 inch (maybe bigger?) line coming out of back of intake tube, near the throttle body. The hose goes into a metal line, then goes back to rubber, then around to the driver side valve cover, where it plugs into a nipple along a "rail" at the top of the driver said valve cover. See the picture.

The CEL turned on about 1/2 way through the trip, and the truck ran rough with poor acceleration, stuttering, etc.

I put a jumper wire in the diagnostic box between te1 an e1 (yes, this 1996 has one (see pic) and I couldn't find an obd port near the steering wheel). When I turned the key, the cel didn't flash, it just stayed lit. I pulled the efi fuse to reset the memory, but it had no effect on the cel. The cel still says lit with the truck running or with it off and the jumper in place.

Pic one is of diagnostics box with green jumper wire. Pic two is my hand holding the hose that was unplugged. Sorry, pics are kinda small. Still messing with the sizing.

Replacing the hose made the truck run better, but it's still running rough.

Any help appreciated.

 

resize my friend

 

dumb question - but i can't find how to "resize" the pics - anyone have a link to this info? Guess I kinda found the "resize" - still not right, but usable.

 

go to imageshack and pick 640x480 (for message boards) and upload it. Then post the (THumbnail for forums (1))

 

Whats up with the jumper wire??? Just take it in to autozone and they read the codes for free. Im not sure what the jumper wire will do to help?!.

 

OK - if you can tell me where to find the obd port, I'll take it to autozone. Problem is, i don't see a obd port.

 

Compliments of 4x4wire:

 

X2 its up there might have to dig a little.

 

That is the positive crank case ventilation hose (PCV). While you probably didn't drive long enough for sludge to form from the lack of positive (forced) ventilation what it also did was let extra air (unfiltered BTW) into the intake down-stream of the MAF (mass air flow sensor). That no doubt screwed up the air fuel ratio while running with the hose off, possibly running dangeriously lean. I'd be worried that you may have burnt a valve or something. Try a compression test to check.

 

If you're lucky maybe you just burnt a spark plug or two. When Mark (Midiwall) burnt a valve on his supercharged 5VZ he also had a couple plugs burnt IIRC. Here's a pic of his burnt valve:
http://midiwall.com/4Runner/pics/200...Rebuild_04.jpg
and his story:
https://www.yotatech.com/forums/f123...ebuild-100924/

I'd remove all the plugs and look at them, but as long as you have all the plugs out you might as well screw a compression tester in there too for peace of mind. Hope its not serious, good luck.

 

Thanks for the photo of the location of obd port. Rented a obd reader from Autozone and it showed a "misfire cylinder 3". I cleared the code, and the truck runs better (but still doesn't seem quite right). Only driven it about 2 miles, but isn't throwing a code. I'll drive it to work today and see if it throws a code.

Either way, i'll change the plugs and see if that smooths things out.

2 Quick questions - 1. which cylinder is #3? Is it 1-2-3 from front to back on driver side, 4-5-6 front to back on pass side? 2. what is recommended spark plug? (i've seen reference to ngk 4302).

Thanks for all the help!

 

rear of vehicle

5-6
3-4
1-2

radiator

check/replace your wires too, if they're old. The production date of genuine toyota wires is written directly on the wireset. genuine parts = win

 

Hooked up OBD and it says "misfire cyl 3" and "po303". I cleared the codes and it ran a little better, but still not good. Threw the same code after about 5 miles.

I changed the plugs and it runs MUCH better. All plugs were pretty worn and the gap was much more then .044 from wear.

After changing the passenger bank, the truck ran much better. Changed the drivers bank and it runs about the same. Overall, truck runs much better, but still has a stutter with mild accleration from about 200- rpm. It's now drivable, but doesn't run as smooth as it did before I left the vacuum hose off. It also hesitates and stutters on hard acceleration.

I didn't check cylinder pressures cause i was in a hurry and couldn't find my pressure tester. Now that it's still running rough, I wish I had.

Any ideas? Check cyl pressures? Should I pour seafoam into pcv and see if that smooths things out? How exactly is this done? Remove pcv valve and put hose in it's place and pour away?

Anyway, thanks for the ideas so far.

 

What's the mileage, and date of manufacture of your existing plug wires?

 

My '99 did the same thing, it turned out to be the MAF and the 02 sensors. OK, that was expensive! But it fixed the problem.

 

Be very careful doing that! I know one guy that hydrolocked his engine doing that. I put my injector cleaner (BG 44K) in the fuel tank like the directions say.

I still think you may have a burn valve. How many of those 500 miles was with the hose off? Any long steep grades at full thottle?

 

You might want to clean the mass air flow sensor. That maybe a part of the issue. Also the MAF's that are on 96's are a hefty chunk of change. 300$ for a remanufactured one from napa, checker, autozone.....etc And a brand new one from the stealership is around 600$. *becareful when cleaning it, you dont want to harm the wires inside it*

After your done cleaning it out, pull the EFI fuse for about 5 - 10 minutes to let the ecu reset itself. Or even pull the fuse while your clening it. So you can put it all back together to take it for a test drive.

Ohh and use electrical parts cleaner, carb cleaner and other products tend to leave a film on the sensor which will cause it to wigg out in some cases.

 

Hint: Test the fuel injector on cylinder #3

 

Thanks for all the input and ideas. I changed plugs and wires. I was lazy and only tested compression on cyl # 3 and it came out to 150 psi, so I figure the valves are ok (at least on that cyl). I've cleaned maf and tb. It's running much better, but still has a hesitation and sometimes stutter with slight acceleration from about 60 miles per hour (I mostly notice when i've got cruise control on and come across a small hill).

How do I check the fuel injectors?

I've got a buddy with some sort of advanced obd - you plug it in while driving and it will tell you all sorts of stuff. I'll try to visit him in the next few weeks (to bad he lives 2.5 hours away).

Overall, the truck seems to run as well now as before i left the intake hose off. When changing plugs, the #3 plug was a bit browner then the rest. Also, I had three nd plugs (1,3,5) and three NGK plugs (2,4,6). I wonder if this are the original plugs. The truck has 150k on it, but the guy I recently bought it from didn't seem to do much in the way of maintenance.

Thanks again for all the help and ideas.

 

That is the way the plugs come from the factory, bank 1 has different plugs than bank 2 for some reason. BTW you may have done it but when you test the compression you're suppost to take all the plugs out so when you crank it there are 5 open holes and one hole testing. That's why I said as long as you have the plugs out anyway...but oh well glad its running better now. Maybe its something minor, good luck.