rough idle and backfire

[dhen]

Hi,

Got my engine back together and it's idling rough and backfires. I sounds like it's missing and I had trouble getting it started. I know the timing belt is on right; I even double-checked it. Swapped out the control module, dropping resistors and my VPC components with known good spares.

I'm going to do a compression check and check the timing with my timing light tomorrow, but I would like to hear other ideas, because I'm stumped. What could cause this? O2 sensor? Stuck injector?

Thanks

[TheMAN]

maybe dead coilpacks? the CA's coils aren't the greatest
also make sure there's no vacuum leaks

[dhen]

Forgot to mention that I swapped them out, too.

Thanks

[leadpaw]

Check and adjust your timing with the timing light before proceeding to do anything else.

[boost_boy]

Leaky valves causes backfire, especially at idles. You may really want to check that compression. Could very well be the cam timing, too. I know you say you checked the timing, but you may want to double and triple check cam timing as again, check the compression before you attempt to open anything.

[dhen]

OK, I think I might have solved this.

Before I go on, I disconnected the battery overnight and the car ran better the next day. Weird.

Anyway, according to my timing light, my timing is retarded by a tooth on the sprocket on the crankshaft. The thing is, I am 100% sure that I had the lines on the timing belt lined up with the dots on the gears/sprocket. The sprocket was loose and I jammed a shim between the sprocket key and the crankshaft. (My machinist said that this should work. The alternative is a new crank.) Is it possible that this threw the sprocket a tooth or so off center, or is that just wishful thinking?

I'll mess with it more this weekend.

PS I got a loaner compression checker from Auto Zone. It said I have 95 compression across the board. The last time I checked it, about 3 months ago, it was 155 across the board. I've barely driven it since my first check, and it seems weird to me that all the valves would go bad in exactly the same way, so I think I just got a crappy checker. Either that, or I have a seriously fycked engine.

[float_6969]

REALLY sounds like the cam timing is off. IDK how many times I SWORE that it was on and and I was wrong.

If the cam timing is off, the compression will be low.

[s13drifter88]

I agree with float, sounds like your cam timing is out

[dhen]

It was the timing, but not for the reasons you might think. The timing belt was on correctly, but you may recall that the timing sprocket on the crank was coming loose. Well, that threw the timing off a few degrees. I'm still playing with it to get it right, but it's running better, so I'm on the right track.

Oh, and I welded the key that holds the sprocket in place. That b**** isn't going to give me anymore trouble...

[s13drifter88]

Hope you never have to replace your oil pump lol

[dhen]

Hope you never have to replace your oil pump lol

Fair enough comment, but I'm looking at a new crank at some point....

[s13drifter88]

Yeah that'd probably be a good idea but I know what a new one costs and money's tight right now