Cylinder Misfire - Toyota Nation Forum : Toyota Car and Truck Forums

BeaterCorolla · 01-13-2006, 03:41 PM

Hi. I'm new here. I'm trying to fix my wife's 97 Corolla with a 1.6L engine that has 160k miles on it. It has a CEL on, and the codes I pulled were for EGR air flow and misfire in cylinder 4. I replaced the VSV and EGR modulator, and that cleared the EGR codes. The misfire is still there. In fact, the engine has been progressivey running rougher over the past month. I replaced the spark plugs, plug wires, distibutor cap, and rotor. The misfire is still there. I started pulling plug wires with the engine on and found no major change in engine idle when I pull the plug wire for cylinder 4 despite seeing sparks from the plug wire tip. Now I'm suspecting the fuel injector. I stuck a screwdriver up to each injector and put my ear to the screwdriver. 1, 2, and 3 sounded loud with distinct clicks. 4 clicked but not quite as crisp. All have the appropriate resitance across their connectors. I may just be imagining things because the next day 3 and 4 started sounding very similar. I don't want to go through the trouble of removing the plenum and replacing the injector if that's not the problem.

1. Would the cylinder 4 injector still be clicking if it was clogged?

2. Is it ok to just replace 1 injector and none of the others?

2. How do I check compression in cylinder 4, and is this a more likely cause for the misfire?

I'm a Focus owner, and I figured if you guys are as good as the owners on the Focus enthusiast site, you'll solve my problem in no time

I hope someone can help me out, and thanks in advance for any help whatsoever.

BT

Froggmann · 01-13-2006, 04:47 PM

Before you start diving into the injectors I would make sure that cyl has compression first. If it does then pull out the injector and make sure there isn't any obstructions in the microscreen. If there isn't then if I were you I would go ahead and get ALL of the injectors rebuilt while you are in there. I'm sure someone around here or Focaljet will know of a good inexpensive rebuilder. While you are at it replace that fuel regulator as well. When that thing popped on my Bronco it took out 5 injectors one by one before I replaced them.

BeaterCorolla · 01-13-2006, 04:54 PM

Frogg,

Thanks for the advice. I'll look at the service manual to see how to do the compression test. Of all the focus enthusiast sites, you picked the right one. Nice guess. BTW, how does your regulator ruin your injectors???

BT

OEMonkey · 01-13-2006, 09:29 PM

1. yes, if it's a grounded injector it won't pulse at all.

2. yes, just make sure it's a known bad injector.

2. with a compression tester. basics- remove plugs, disable spark and fuel, equal number of cranks for each cylinder.

If you were getting P0300 then I would suspect it to be related to your previous EGR prob. but for P0304, you need to start w/ the basics before you start replacing parts. Check all circuits related to cyl 4 and are only common to cyl 4. Compression, plug wire(or coil if it's COP), injector, etc. Start by checking manifold vac.(since its the easiest) keep an eye on the vac gauge, it should be steady and not shaky. If it's shaky, suspect valve problems. You can also try swapping injectors fr other cylinders, clear codes, see if misfire code appears on the injector you just swapped. These are just basic, no dollar spent diagnostics. There are other ways but they require expensive shop tools such as an oscilliscope. Misfires are sometimes a bitch to diagnose, hope you figure it out.

Nad1370 · 01-13-2006, 11:03 PM

This would be one quick way to find out if it's an injector :

Swap #4 and #3 injectors. Should be easy to change. The rail is held by 2 12mm bolts.

If the misfire went to #3 then you know it's a bad injector.

Be careful not to damage/lose the o-rings on the injectors when your doing the work.
Releive pressure in the fuel system by taking the gas cap out.

freakinbox · 01-13-2006, 11:18 PM

this is what I like about having a carb'd engine lol 1 thing gives everyting fuel

Froggmann · 01-14-2006, 04:32 AM

Quote:

Originally Posted by BeaterCorolla

Frogg,

Thanks for the advice. I'll look at the service manual to see how to do the compression test. Of all the focus enthusiast sites, you picked the right one. Nice guess. BTW, how does your regulator ruin your injectors???

BT

Yea my GF has a 00 Kona, I have to keep an eye on it or else it will run into the ground. FJ is usually a good site to research the problems she has had with the car. As for the regulator, it was allowing too much pressure to the injectors which in turn ruptured the diaphrams in the injectors. My mileage went from a fun 13 MPG to a really fun 4 MPG. I'm just surprised the Cat didn't go south because of that.

Oh and Nad is on to something there just be sure to have some petrolium jelly to put on the o-rings when moving the injectors back and forth. While they are out inspect those screens. Fuel systems can flat get dirty!. As for depressurizing the fuel system just pull the fuel pump relay while the car is running.

freakinbox: I personally love FI Carbs can flat be a PITA once they get a little old. With fuel injection you at least will get plenty of mileage before it's componets start to fail. My Bronco was at 190 or so before I had to get into the fuel system for the first time.

BeaterCorolla · 01-15-2006, 08:28 PM

Update: I did a vacuum check of the intake manifold. I found a rapid vibration of about 4 in-Hg, textbook (service manual anyway) for worn valve guides. I'm not sure what this means. Can some guru explain more? Also, the manual says slight fluctuation may mean ignition problems, which is exactly what I have. For this, it recommends the "usual tune-up items."

1. What exactly are valve guides and why do they get worn?

2. How can this lead to a completely dead cyclinder?

3. If this is actually a case of slight fluctuation, should I go ahead with the injector install? It only costs $60 and my cheap labor

It's starting to sound like it's time to look for a new car. I was really hoping her car would last another two years until some funner cars come out like a MazdaSpeed3. Well, any help you guys can give will help out our decision. Thanks a bunch.

Nad1370 · 01-15-2006, 11:15 PM

If you have a misfiring cylinder, you will have erratic fluctuations on the vacuum guage.

First things first. Fix your misfire.Then see if you still have those fluctuations.

Guides are where the stems of the valves ride on. I really doubt this is your problem.
If you did a compression check and it was fine. Then I would go with the injector replacement.

BeaterCorolla · 01-20-2006, 05:55 PM

Update: Ok, so I installed the new fuel injector. Twice, since the first one I put in was defective! It's still misfiring, but I've gained a bit more insight. From a cold start, the engine purrs. Cylinder 4 injector is clicking loud and clear. Pulling the plug wire on 4 makes a noticeable difference. Engine warms up, and the knocking starts. Cylinder 4 injecter sounds muddy now. Pulling the plug wire on 4 makes little to no difference.

1. If this is a valve issue, will a compression check find this? Sorry, but I didn't do a compression test. I read something about a leak down test to be performed at a shop if the vacuum reading is erratic.

2. Back to the EGR. Could this be related to the EGR system since the problems occur after the engine warms up?

Right now, I'm planning on bringing the car into a shop to "officially" diagnose the problem. Then, if it's valve problems, it's getting donated or parted out. Hello tC or MX-5. Thanks for all of your help. I'm hoping the problem isn't that bad and the Corolla will pull through.

BeaterCorolla · 06-24-2006, 04:47 PM

So I finally had the car checked out. and they confirmed a valve problem. They quoted me $1400 for replacing the exhuast valves on cylinder 4. They did a compression test and only found about 80 psi holding in that cylinder.

We're not going to get it fixed and get a new car instead, but how long do any of you think the car will keep running? I've heard about a catalytic converter getting clogged and choking the engine. Is this possible? I'm hoping the car will keep running for another 10k miles.

Thanks

Flashmn · 06-24-2006, 05:25 PM

Freakinbox, yea the good points on carbs, they're alot simpler.... but when they start to act up, holy shit.... Twin DCOE webers are not fun to troubleshoot, lol, its like fuel injection, you got one barrel per cylinder and if one of them has a clog.. you get the picture

.

Check the resistance of the plug wires, just to make sure they're ok. Then check the distributor cap and rotor. Since when they heat up, all kinds of funny stuff can happen if they're not up to spec. Might not be an injector problem.