weird miss - Toyota Nation Forum : Toyota Car and Truck Forums

txturbo · 11-03-2009, 07:56 AM

91 Corolla....when I first bought it, it ran rough.I could pull the plug wires, one at a time and noticed #1 wasn't playing well with the others and it got worse as it got hotter, but when the wire was moved close to a ground I was getting spark. Tried a different plug, no difference. Car drove good with plenty of power, so it seemed that the miss goes away above idle.Checked compression, 185 on all but #4.That one was a little lower but isn't the cylinder causing the problem. I checked to make sure the valve clearances weren't to tight.A little on the loose side. So I put new wires, cap and rotor. Then it idled smooth and #1 was doing its share. But once it gets to a certain temp it begins to miss on #1 again. The only other thing I can think of is the coil. I let it cool down and it runs smooth again until it warms up. Once the temp gauge gets to the half way point, #1 cylinder is completely dead at all rpms.

90 GP · 11-04-2009, 06:15 PM

DId you test compression with cold or hot engine? With your symptoms I would suspect a leaky head gasket or a valve not fully seating once engine gets hot.

txturbo · 11-04-2009, 06:40 PM

Quote:

Originally Posted by 90 GP

DId you test compression with cold or hot engine? With your symptoms I would suspect a leaky head gasket or a valve not fully seating once engine gets hot.

I ran it today and now it seems ok. #1 cylinder is working even after warmed up. It does still idle rough. I think I hear a vacuum leak but can't seem to find it. I also need to figure out why the idle speed doesn't increase whn the a/c is turned on.

voganni · 11-05-2009, 12:31 AM

You may want to run some good gas treatment through it too. Might have a clogging injector. Especially if there's been a recent switch to alcohol blended fuel in your area.

txturbo · 11-05-2009, 07:51 AM

Quote:

Originally Posted by voganni

You may want to run some good gas treatment through it too. Might have a clogging injector. Especially if there's been a recent switch to alcohol blended fuel in your area.

Already did that. It seems better now, but still idles rough. I loosened the distributor hold down bolt and was going to turn the distributor a little to see if it was a timing issue and noticed it is already turned all the way counterclockwise. Turning it anymore clockwise makes it worse. I'm thinking maybe the cam timing isn't exactly right. It has had the head gasket and timing belt replaced in its past.I think today I will remove the hold down bolt completely and try turning the distributor a little more clockwise.If that smooths it out, I'll check the cam timing. All the ones I remember from the past, the distributors were usually nearly centered in the adjustment range.

Donald · 11-05-2009, 01:12 PM

Quote:

Originally Posted by txturbo

I think I hear a vacuum leak but can't seem to find it. I also need to figure out why the idle speed doesn't increase whn the a/c is turned on.

Both of the above might be related. The A/C idle-up valve vaccum line might have a leak.

Sometimes Toyota wraps vacuum lines with a plastic spyral wrap. I have had leaks hidden by this type of wrap, so you might want to remove this wrap if you have any, and check for leaks where it was.

voganni · 11-05-2009, 09:01 PM

Yup, mine's at about the 1/2 way point. You could easily be a tooth off on your cam timing. May explain the lack of power on #1 cylinder too!