jkuczek

I just replaced my timing belt, water pump, tensioner, etc and now that I have it back together runs rough anywhere below 1,000 rpms. If you rev it above 1,000 it sounds smooth with no odd noises. Also it was running perfectly when I took it apart.

I've searched and seen fixes for this problem from the OCV, camshaft position sensor, vacuum hoses not hooked back up and obviously the gears being off a tooth on the belt. Before I rule out being over a tooth I just want to make sure that this is acceptable as far as being lined up. If this looks good any input to what it might be would be greatly appreciated.

ShihTzu

iTrader: (5)

I would say that its definitly the timing belt, I had the same issue when I did my supra, even though the markings lined up, my belt was off. If you have a timing light gun, you can use that to verify it.

jkuczek

Since I don't have a timing light gun is there any other way to verify I have it on right when I take it off and put it back on again? I can't even tell which way to adjust the belt...clockwise/counter clockwise?

ShihTzu

iTrader: (5)

I'm not sure if there's another way, I've done this a handful of time, one thing I do is to make sure(looking from the front of the motor) the right side(driver side) of the belt has a good tight tension. I've noticed that sometimes when you install the tensioner, it could slip or cause the belt to jump.

masagsxr

Thats odd... When the cams and crank lines up every time, how is it that the timing can be off? Did you mess with the distributor at all? Maybe thats off? If not, check spark plug continuity and make sure its in the right firing order on the distributor and the plugs themselves.

krispl

Markings look fine. Crankshaft Position Sensor perhaps? Did you mess with it? I know that they are very sensitive.

jkuczek

I didn't touch the distributor or the plug wires at all. Although I didn't touch the crankshaft position sensor, it is right where you bolt the timing belt tensioner up. But it is kind of tucked back in an area where it would be pretty difficult to bump.

Is there anyway to test the crankshaft position sensor?

More info:
-there are no check engine lights on
-when you start it up, once it gets below 1,000 rpm it starts to run rough, it will sit pretty steady at what i think is 700-800 rpm while running rough for about 20-30 seconds, then will slowly drop in rpms and sound like it wants to shut off.

krispl

Is your MAF sensor connected?

toy4life86

iTrader: (4)

i got the same issue with my 400 my battery sat disconnected for about 7 weeks would that effect it real rough idle when reved smooth perfect no funny noises

jkuczek

Yeah the MAF is connected.

I played with it all day, I even had my neighbor come over (he used to be a Lexus Tech) and look at it. He said it sounds like a misfire but hooked some scan tool up and said it wasn't misfiring and it has to be out of time but was confused because all of the timing marks lined up.

Anybody else have any suggestions?

5t341th

iTrader: (16)

u can rent a timing gun at autozone or kragen/oreillys

FrankT

A timing light will only show ignition timing, between 7* and 22* depending on rpms and what the ECU determines.

I believe you are looking to verify mechanical timing and you do that by rotating the motor by hand and visually checking the marks on the belt, just like in you pictures.

There maybe something else, a cracked or loose intake tube?

I feel your frustration...

sjlexus408

iTrader: (4)

check for broken tooth on your crank sprocket dude, if you change your crank seal out for the first time you have a chance of snapping the tooth because there is a little plate down there which you cant really see if your car is not lifted in the air, you supposed to remove that piece first then the crank sprocket.

jkuczek

The pictures above are actually after it had been running rough. I lined the marks up, turned it two rotations and it was still lined up, so I fired it up but was running rough so I shut it off and then turned the crankshaft to check the marks again and that's when the pictures above were taken.

Sounds stupid but...Is it possible to be out of time with the timing marks lined up? Although I didn't take it off does the intake cam gear (VVT-i) affect it somehow?

The crankshaft sprocket is good. I spilled some coolant down the front of the block from the water pump and had to spend some extra time going around the sprocket to clean off between the teeth and they were all there.

By the way, thanks to everybody that has posted so far, I appreciate the help.

sjlexus408

iTrader: (4)

try unplugging the harness from the maf sensor, if it runs better then you have a bad maf sensor or any dirt,spider web or leave stuck in there can cause it to act that way.