blue1

97 3.4l

I just swapped my timing belt, timing marks on belt lined up when I Installed it, cams still line straight up @ 0 deg on crank pulley, but motor will barely idle @ maybe 2-300 rpm, dies or backfires under any throttle. Marks line up every 2 revolutions of the cam.

Very little spark--plugs wet with gas

Threw P0340 code--Cam Position Sensor. Sensor looks good, reads within spec on the Ohm meter (1300). The little sensor "tab" is still on the RH cam wheel

Is there a way to check the harness end of the plug that goes to the computer? Any Ideas? I'm totally stumped.

rworegon

Was the crank and cams set at TDC before installing the TB?
Is the intake completely re-assembled?

I had the low idle, backfire thing once after a TB change due to a vacuum leak at the TB metal gasket.

blue1

All of the marks on the belt lined up with their respective marks on the cams gears & crank gear when I installed it. With the pulley @ 0 deg, both cam marks are straight up. I've looked for loose vacuum hoses, but havent checked for leaks w/propane or anything like that yet--I can't even get it to run long enough for that.

rworegon

It really does sound like you have a timing issue, IMHO.

Just to confirm: take a look at post 32 (pictures 4 through 6) for proper alignment of crank and cams at TDC:

http://www.nwtoys.com/forum/tech-art...ng-belt-4.html

All good on yours? Note the position of the dimple on the crank gear.

Did you clean and re-seat the Cam Position Sensor plug?

blue1

I took these pics all at the same time. I realize one looks a tiny bit off, but I think that is just the camera angle. I would certainly think its not a whole tooth off, but maybe I'm wrong. Is there any code other than cam sensor that would get thrown if I was off a tooth? I didn't get a pic of the dimple/oil pump mark, but it cant be any different that the mark on the pulley/timing cover, can it?

rworegon

Yes. The dimple and the crank timing mark on the pulley, as you show, can be different if the rubber layer in the pulley (harmonic balancer) separated during install. There are threads around here on that topic.

Jomoka

Yeah, that's a very sneaky sort of thing that happens on other sorts of cars as well.

It's not a bad idea to rotate the motor to TDC via the pulley and double check that the cams are lined up before taking the old belt off.

You can take out the sparkplug on #1 and *carefully* verify TDC with something long and skinny that will reach down through the hole and rest on the piston. Just obviously make sure what you use won't mess anything up or get broken off in there. Just use it to gently feel for the position where the piston stops rising and starts going down. Generally there will be a bit of a range where you can't feel it moving, split the difference between where you stop feeling it come up and start feeling it go down.

blue1

They pulley didn't seperate. Everything lined up the same way on the take-off belt. What do you think of the pics I posted up--marks looked good to me, but does it look off at all to any of you? Is there another code that would be thrown other than P0340 if it was off by a tooth? On other cars I've done belts & chains before and never had any problems--this has me stumped. The sensor tested good by ohms, is there any other way to check it? Is there way to check the wiring from the plug back to the ECU? I tried that on the multi-meter and got nothing (but thats probably not the way to properly check it)

rworegon

I'll take a look at the pics on the big monitor later today. Too hard to see on the phone screen.

You did not have this code before the TB change, correct? Do you have a copy of the FSM (Factory Service Manual)?

blue1

Ran great before the TB swap. Yes, I have FSM--didn't say much about the Cam Pos Sensor except to check its ohms--which were within spec

rworegon

Those pictures look ok to my eye. The cam gear labeled "R" is on the passenger side, correct?

Any chance the spark plugs wires are not on correctly?

I did notice the P0340 code has a bit in it about the crank position signal plate i.e. the teeth on the crankshaft timing pulley....any chance a tooth broke off? One would think it would cause a P0335 code, but maybe......

blue1

yep broke a tooth

I guess I'll get a new one and tear back into it.

Thanks for your help. I'll post back after I put it back together. Anyone have a spare crankshaft timing pulley laying around?

rworegon

Sorry, I don't have an extra one.

You're not the first that has happened too. Had you pulled it to change the crank oil seal?

As a cross reference, another thread with a similar broken tooth issue.

Initial issue in post 1 of the referenced thread:
"I have an unusual problem. Recently did a timing belt job. After completion, she failed to start. Cranks, no start. Troubleshooting revealed one of the 3 coils has no fire.

I have ruled out ECU, coil packs, wiring between ecu/igniter/coil packs, timing. Crank and cam sensors are plugged in.

I failed to disconnect the battery before doing the timing belt job.

Has anyone seen an igniter fail? Is there another likely cause that I am overlooking?"

blue1

Yeah, I pulled it to get to the oil seal. I found this thread which is my exact problem. https://www.yotatech.com/forums/f2/t...-wrong-238976/

rworegon

Ah, yes.....glad you found that thread. I remembered it being out there but did not find it when I did a quick search this morning.

blue1

Thanks for the help. Got the new timing pulley in and it runs great

rworegon

Excellent! Glad that fixed it.