At a loss on 96 T100 rough running
 

Ok, I'm new to Toy's but not new to overall vehicle tech.
I've searched until my eyes hurt on the 3.4 rough idle/running problems and couldn't come up with any conclusive information.
I just bought this truck yesterday, has 189K and v6 automatic.
Things I have done thus far:
1) checked all air/vacuum lines, I even sprayed wd40 while running to see if it helped detect a leak.
2) installed new spark plugs
3) read codes, misfire on 1 & 2
4) cleaned throttle body, mass air, and tps
5) cleared codes and CEL, ran around the yard and CEL came back on, misfire on #1
My next step is going to be new plug wires and boots
I am thinking I could check the radiator for exhaust but as near as I can tell levels are good. The kid I bought it from didn't drive it hardly at all, he never registered it and he bought it in Dec. 11.
Any other suggestions?
thanks,
dave

ps, I have noticed on a lot of the threads on this problem that the issue is either never fixed or the poster never reports back to say what they did to fix the problem.

Running rough at startup (cold) or when it's warm?

Are you sure the spark plug wires are hooked up correctly? 1 and 4, 3 and 6, 5 and 2. Odd numbered plugs have the coil on plug (COP). ;)

Misfire on #1 and #2 would indicate 2 possible problems. Did you check the spark plug boot on the COPs to make sure they weren't cracked? Remove them from the coil and clean them up carefully. You can git replacements from Advanced Auto...call them fer availability. Did you try swapping the #1 COP with one of the other ones and see if the problem follows the COP? ;)

Did you check/clean the idle air control (IAC) valve? Did you check it to make sure the shutter had the full range of motion? ;)

Other options are to pull the injectors and have them tested/cleaned/rebuilt at yer local injector shop.

Did you check the timing belt fer cracks/wear or alignment? Do you know when the last time the timing belt was changed? There should be a sticker on the timing belt cover that would indicate that if the tech annotated that. :D

Could timing belt cause this?

You might try pulling one plug wire at a time and observe how the engine runs, e.g. pull plug wire from cyl#1 and if there is no change, pull #2 wire and if there is no change pull #3 etc. If the engine runs worse after pulling a wire from a particular cylinder that particular plug wire or the injector could be the culprit. The plug wire was within specs but I didn't hear any 'ticking' from the injector. That's how I found the and resolved the problem in my son's Nissan. Good Luck

Can't really unplug the pass side as the coil has the boot right on it.
thanks though.
I am going to put new wires and boots on tomorrow, and new plugs, the ones I picked up don't have the dual ground. In fact Advanceauto didn't know what plugs I needed, they gave me single grounded ones.

Bam,
I have no clue when or if the belt was changed, there is no tag stating so.
I did check the wires to be sure they were on the right plugs.
The plugs I put in are single , so were the ones I took out, any suggestions on what NGK dual plug to use?
I ordered the wires and boots at Advance today, they will be in tomorrow.
Is the IAC the one facing the pass fender underneath the big air intake? if so , I did clean it and the shutter rotates freely about 15 deg, is that about right?
I will look into the injectors if the wires and plugs and boots don't do it.
I also checked the ohms on everything this afternoon and everything checks out within spec. as near as I can tell from my Haynes manual.
thanks for all your help :)
dave

Do not use the single grounded plugs. The plugs are silly cheap from the dealer.

Return the wires too if the are not Denso or NGK. This engine does not like much of anything other than Toyota OEM, Denso, or NGK for plugs, wires and the like.....trust us on this one.

The wires will be NGK which from what I read on here is good.

You'll be good with the NGK.

Pull the timing belt cover and check the timing belt. There should be about 8 bolts that hold it on. You might have to move the upper radiator hose clamp to pull the cover forward enough to see the cam gears/alignment marks. Snap some piccies of it and post them. ;)

The IAC should be under the throttle body. One wiring harness connected to it and 3 hoses (2 coolant and 1 vacuum air). The shutter valve should rotate around 90°. The electric motor is covered in a greenish plastic cover. This is what it looks like under the throttle body...
Attachment 191878

Throttle body flipped over...
Attachment 191879

BTW...where are you located? Do you have an EGR setup? That's usually found on California spec 5vzfe engines. If you do, you might want to check the EGR tube... ;)

Another thing to check is the Fuel Pressure Regulator vacuum hose. ;)

Thanks for the heads up, I will check and take pics later today of the timing belt and gears.
I'm in NY, I believe the truck spent it's life in VT
Where would I find the fuel pressure regulator hose? I don't think the Haynes book is too good,they try to cover too many models so a lot of the stuff is generic.
New wires, boots and plugs today, hopefully that will fix her.
At least one thing about chasing this is I get to know my way around the motor pretty good....LOL.
thanks and wish me luck,
dave

ps, I did clean the IAC, the rod inside moves freely, it maybe 90deg like you say, I can check it again today.

The fuel pressure regulator hose goes from the fuel pressure regulator (soft line) to a hard line that runs in between the air plenum and then to yer intake hose/resonator.

You can see the hard line here...
Attachment 191880

You can see the fuel pressure regulator and the soft line just to the right of the blue tape near the top of the piccie...
Attachment 191881

SOB!!
I installed the new plugs, wires and boots today. I also cleaned all the mounting points for the coils. It started right up, let her warm up and it sounded good, got in, put it in gear and it started running like crap!
I picked up a fuel filter for it today, darn rust! I have some knocker loose on it.

I took it up the road a little ways and once I got moving, 15-20 I punched it and it down shifted into low, it started acting like I hit the rev limiter but the tack was only a little over 3k, it acted to me like it ran right out of fuel.

The timing belt and gears look to be in very good condition. It's very tight. I took pics, I'll put them up later.

My manual says it could be a few things, timing, my code scanner reads the timing while it's running and that seems to be within spec. The fuel filter, bad fuel or something in the evap system. I did get a cel and read the code to see misfire on cyl one (again). Am I headed for an injector? I used a large screwdriver as a stethoscope and I could hear it ticking.

How would I check for a clogged converter?
If I get time tomorrow I'll see if I can siphon some gas out and check it out. I added some techron the other day and 5 gals of fresh gas today

thanks for your help and patience,
dave

pics as promised:
Attachment 191888
Attachment 191889
Attachment 191890
http://i49.photobucket.com/albums/f2...DSCI0042-2.jpg

Dave, gives us some wider views and pics of other areas. It might help us spot something amiss.

I am having the same issue with mine .. I checked my timing belt and its was toast and off by a long shot. so i replaced it and its sounded smooth as silk until I started to move and the miss was very evident. hope its not the head gasket

Dave...snap some piccies after you rotate the engine so we can see if the timing marks on the belt and the cam gear line up or not. ;)

I see no evidence of a head gasket issue.
A buddy of mine who has owned nothing but toyotas stopped by this afternoon and did an ohms check on the #1 cylinder injector (got the code for the #1 missfire again today) and it wouldn't register at all, so I ordered a new injector and it will be here tomorrow. The #3 injector registered in spec. Keeping my fingers crossed.
I did get the new fuel filter installed, man was that old thing dirty!:eek2:

What all do I need to do/know to change the injector?

Bam, if I have to take the cover off again to I will rotate the engine enough to check the marks.

On another note, I had my wife turn the key two clicks while I was under the truck with the fuel filter off to flush the line from the tank and nothing happened! I was under the impression that the fuel pump should prime the system with the key in that position, am I wrong?

thanks again,
dave

YEAH ME! :bump:
I put a rebuilt injector in the #1 hole today and she purr's like a kitten!
Of course I had to tear it back apart due to the other two O-rings leaking, after a quick trip to AA and 4 bucks later we were back in business.

She still falls flat on her face at about 4k, I'm thinking maybe the fuel pump is either dirty or plugged. Once I get her plates I can drive it to my bros, he has a nice two post lift.

Could the fuel pressure regulator cause this? Other than that she goes smoooth.

I really appreciate the help and respect the time you guys put in to help me.
I'm sure I'll have more issues once I start driving it a little :)
thanks,
dave

I would pull the rails and other injectors and make sure everything is clean. If any debris got in there...it would gunk things up including the fuel pressure regulator. A quick way to check the fuel pressure regulator is to use a fuel pressure gauge and see if it leaks down after the rail has been pressurized and the engine is turned off. There's a few videos on YouTube that shows what you should see... ;)