tombat

Sorry my first post here is a plea for help, but I need help.

I replaced the timing belt on my 96 Tacoma, 3.4, 5VZ-FE - three times now and I'm not sure where to turn at this point. A little background - the truck has about 220K miles, I did the timing belt the first time at about 100K. This time I used all new parts - tensioner, idlers, water pump, cam and crank seals, thermostat, drive belts, and of course timing belt.

A specific question first.

Can the cams be one rotation out? That is if the timing mark on the cam pulley is lined up with the marks on the cover (#3 timing belkt cover), then it is in the correct location for TDC on the compression stroke. The way I see it, each rotation of the cam pulley is one rotation of the cam so if the timing marks are lined up all is well.

So here is what I did - sorry if the story is long.

First time:
Before pulling the belt, I turned the crank manually and brought the pulley to 0 on the timing mark. Cams weren't in the proper position so I spun it once more and everything lined up.

Since I replaced the oil seals, I had to pull the cam pulleys. After doing that and putting the pulleys back on, I noticed the right side no longer had the timing mark lined up. It must have jumped when the bolt broke loose. So I just brought it back up to the top and called it good.

When I tried to start the truck, it immediately threw a 0340 code which is camshaft position sensor and wouldn't run but would sputter a little so it was definitely firing. I pulled the upper timing belt cover, spun the crank to 0 and the cams lined up just fine.

At this point I'm, leaning towards damage to the camshaft position sensor wires. During re-assembly when I went to hook up the camshaft position sensor, I noticed it was a little short and I ended up removing the timing belt cover to loosen it up. I suspect I pinched the wires.

Second time:
I checked out the CPS and there was no obvious damage. In doing a little research, I realized I didn't line up the timing belt mark with the crankshaft pulley mark. I used the crank pulley to establish everything was lined up the first time. I assumed this is the problem and tear it down again.

On reassembly I notice the crank is a couple teeth off so I assume this was the problem. Well I get it all buttoned back up and nothing. Won't even fire. I know I have no choice but to tear it down again.

Third time:
As I'm doing the tear down I notice the timing belt is on backwards - I had lined up the marks for the left cam with the right cam and vice versa. Problem solved - right? I line everything back up, which required me to rotate the crank back those couple teeth I had moved it during the second time.

I get it all back together, turn the key and it sputters a little. Turn the key again and it fires up. I run it up to about 2000 rpm and leave it there for a couple minutes. I let off the gas and it dies. Won't really start after that.

I'm thinking computer needs to re-learn so I pull the battery cable and take a break. Go back out and after a couple cranks it fires up and I hold it about 2000 rpm for several minutes. I can feel a little miss but it is running. Of course it hass thrown a 0340 code again.

It's acting exactly like the first time I did the belt so I'm thinking I have another problem. I think the belt is on right - assuming the cams can't be a revolution out. I don't think it would run at all if the crank was out a revolution.

I'm leaning toward the camshaft position sensor being the problem.

As part of the timing belt replacement, I also put in new plugs and wires, removed and cleaned the throttle body, new fuel filter and new air filter. I'm assuming none of these would cause the problem.

Any suggestions would be appreciated because I really don't know where to turn from here other than swapping out the camshaft position sensor.

Thanks
Tom

TheDurk

I'd suggest a look at the FSM. It will tell you how to do a resistance check on the Cam Pos Sensor and how to check the circuit integrity between the sensor and the ECM. These are the two first things I would do.

http://www.ncttora.com/fsm/1996/SIL/...fe/cip0340.pdf

vital22re

iTrader: (2)

This motor is a non-interferance motor so dont' worry about hitting valves. pull your upper cover and spark plug number 1 out. Verify you have top dead center on the bottom end and then verify that your cams line up with the marks on the backing plate. If not adjust. If the marks look good. Turn the crank 2 full rotations and make sure your marks line up on the motor. Don't be concerned about the lines on the belt. Did you make sure the cam sensor is fully plugged in? make sure you check the sensor to make sure its in spec.

iselloil

Here is a little trick.Mark the old timing belt in three positions,at the cams, and crank. Mark the pulleys and belt.Remove the belt and transfer the marks to the new belt,and install.You can do it this way and never have to put the motor at TDC.

tombat

Thanks for the input.

FSM requires an oscilloscope to check the sensor - something I don't have. Heck, even if I had one I wouldn't know what to do with it.

I'm pretty sure the marks are lined up correctly. In fact I think I did it right the first time. I even pulled the right side valve cover to make sure the valves on #1 were closed when the mark was lined up.

The sensor is plugged in. My concern is when I had pulled the backing plate with the sensor attached, I bonked the sensor a couple times, not hard but maybe enough to be a problem.

I'm going to ty to source a new sensor today and see if that will solve the problem. I think I've convinced myself the belt is on correctly.

Thanks again for the feedback. Any other ideas, toss them out.

Tom

TheDurk

No, you just slap a DMM (Ohmeter) on it. Did you read the thing?

See step 5, here:

http://www.ncttora.com/fsm/1996/SIL/.../ignsy/ovi.pdf

tombat

Sorry - didn't read the link. I was stuck on the trouble code pages and didn't follow correctly.

Camshaft position sensor checks out good.

Truck fired right up this morning but with the same symptoms - wouldn't keep running. Try to give it gas and it would die.

I'm having a real tough time thinking the belt isn't lined up correctly - it's not that hard.

I'm at a standstill now. All I can think to do is tear off the intake, remove the valve covers and verify all is lined up correctly. I keep coming back to the part where the cam moved while I was removing the cam pulley. The mark was in about the 4 o'clock position and I just moved it back up to 12 o'clock.

So I'm back to the question, If the timing mark on the cam pulley is lined up with the marks on the cover, are intake and exhaust valve on #1 closed? Guess I'll go pull the valve cover and find out.

rworegon

Will it idle? Is so, does it sound normal?

You may have a vacuum leak at the gasket between the throttle body and the upper air plenum where that little metal gasket is. I had a vacuum leak here on one of my TB changes and was certain the timing was out....a new metal gasket and all was well for me.

tombat

That's certainly a possibility - it won't idle and does sound like a fuel problem. I did use a new gasket but maybe I put it on backwards - if possible. I'm also about ready to put the old plug wires back on.

rworegon

I don't think it's possible to put the metal gasket on backwards.

tombat

More troubleshooting.

I pulled the timing belt cover and the right side valve cover. Removed spark plug from #1.

Brought the crank up until intake and exhaust valves were closed - TDC compression stroke. All marks line up correctly.

Rotate crank and exhaust valves open and close at the top of the stroke. Crank is at zero and cams are 180 out.

Continue to rotate the crank and intake valves open and close as the piston returns to the top All marks lined up.

I checked that the pin that aligns the cam pulleys were in place and compared this and the cam position sensor mark with pictures I found online and everything looks right. I checked the alignment of the marks on the cam gears and they are in order.

I have to believe the timing belt is installed correctly.

I have the throttle body off and all seems well with it. I also had pulled the IAC and cleaned it and replaced the gasket - all looks well with it. Only other things I can think of are spark plug wires and fuel filter. Guess I'll have to swap these back out with the old ones and see if there is a difference.

Suggestion?

Thanks
Tom

rworegon

Sounds like the cams are positioned correctly. Are you usinfg the FSM? If not, use the linked FSM and double check the crank marks per page 21 step 10. All the 5vz-fe align at the same marks:

http://www.ncttora.com/fsm/2003/Repa...imbel/inst.pdf

They show the belt going on in step 7.

I have seen where the wrong mark on the crank timimg gear was being used to align at TDC.

TheDurk

Are you still getting the P0340? If you are, and you haven't checked the circuit integrity between sensor and ECM, you may be wasting your time doing all this other stuff.

tombat

It's dead on. All three timing marks are lined up perfectly and the zero position on the lower timing cover and the crank pulley line up as well.

If all that is correct then the belt has to be on right - correct?

rworegon

Yes. Are you still getting the 0340 code?

All vacuum lines, air intake, and electrical connections in their proper place and seated?

tombat

Yes - still getting 0340.

On the last attempt to start - before I tore down to check the crank alignment, I threw a 0100 and a 0110. Probably forgot to plug in the MAF.

Same symptoms - can get it to start but won't idle. When I get it to run, I can hold at about 1500 - 2000 rpm but sounds like there is a slight miss. As soon as I let off, it will die and not restart easily.

I sure think so - I've gone over it all many times. I didn't get the air intake on correctly once and threw a code.

tombat

OK, just thinking out loud here. There is an old saying - look where you last ˟˟˟˟˟. This is one of the potential hazards of making multiple changes at once.

Looks like we've confirmed the camshaft position sensor is good.

Looks like the timing belt is on correctly. Lot of things have to be removed to get to the timing belt but not really anything that seems like it would cause a problem - ac, power steering, alternator, fan, camshaft position sensor and a few other things. Nothing that seems like it would be a problem.

I also cleaned the throttle body and IAC and installed new gaskets. I removed and replaced again to check them out. IAC has a vacuum line and two water lines that are both installed. There is also a wire connector that's installed. Reading up on the IAC, the symptoms don't seem to match up.

Throttle body has a vacuum line, a connector and a couple cables. All seem to be in order. Bolts are tight - all looks good.

Air intake tube has been off a couple times and I know if they have cracks or breaks that can be a problem. I haven't specifically checked for cracks but the tube is very pliable so it is unlikely - but I'll check it anyway.

Air box and MAF have been off a few times. Hard to imagine any damage to the MAF. Also, I didn't remove these parts the first time I did the belt (which was a huge mistake - things were a lot more accessible with the airbox out of the way) and the truck ran the same as it's doing now.

New plugs and wires. Not to difficult to change out the plugs. Hard to imagine that being the problem, but I suppose one of the plugs could be defective.

It's also hard to imagine the wires being bad. They lined up just like the originals. I've even double or triple checked they are going to the same place as the originals. I was going to swap out the new ones for the old one but I did a resistance check on the old set and one was out. I may still do this. It's possible one of the wires is bad.

Then there are the coil packs. I'm really not to familiar with those so I guess I need to do a little research. Not sure the symptoms of a faulty coil pack.

I also replaced the fuel filter. Maybe fuel isn't flowing correctly through the filter. Guess I could put the old one back in.

I don't know. Help me out here. What's a good next step?

Thanks
Tom

vital22re

iTrader: (2)

verify your firing order/spark plug wires are correctly placed.

dntsdad

To remove the throttle body it seems easier to unplug the center coilpack below throttle body to allow it to slide off. Did you unplug it and not get it plugged all the way back on?

tombat

Did that - a couple times. I've laid the old wires next over the new wires and even followed the numbers on the wires to make sure they go to the correct location. The wires are actually pretty fool proof - you'd actually have to try to put them in the wrong location. The new set looked exactly like the original set.

I'm leaning towards the fuel filter as the problem. Seems like I'm not getting enough fuel. If I let it sit for a while and then try to start, it will fire right up and run for about 2 seconds, using up all the fuel in the cyclinders/injecters. To restart I have to bury the gas peddle and keep cranking and eventually it will go but it's difficult to get enough RPMs up to keep it running. If I get it to about 2000 rpm I can hold it there but the instant I give more gas or let up on the gas, it dies.

So I've dicided my next step is to remove the new fuel filter and inspect. If there are no obvious problems then I'll put the old one on and try that. If it's still a no go I'll have to check the fuel pressure.

Hopefully I can get to this tonight but I need to source a new crankshaft pulley bolt. The one I have has been off and on too many times for me to take any more chances with it. Then I have to put the front of the motor back together - drive belts, fan, etc.

This whole thing is a little disappointing. I bought this truck new in 96 and this is the first time in 15 years that I haven't been able to use the truck to get me to work.