Only one cylinder firing
 

Finally finished the brake job and now my engine isn't firing properly. Earlier in the week it was running great, all of a sudden only one cylinder is firing. The plugs are sparking(I pulled them and checked.) and the injectors are working. I can't figure out what could have happened literally over night to cause this. Any thoughts??? Am I cursed?

How do you know for sure the injectors are firing when they are supposed to be? What is the fuel pressure? If the fuel pump is in the front, did you hit/break the wire to it? Good luck

I took out the injectors and watched them pulse fuel while turning over ignition. I guess it's possible it's not timing right. How would I check that? It was working 2 days ago. What could have made such a drastic change?

I would go back to the basics.

* Check/verify the timing
* Check for vacuum leaks
* Check the valve adjustment

timing of injector pulses are controlled by the trigger points in the distributor. i suppose it's possible that there is some problem there but i don't understand why the injectors fire into cups as you saw and not fire when installed in the intake runners. if you switched the injector leads, i would think it would still run, just maybe not run well.....

Are you certain that there's only one cylinder firing, or are you just saying that because the motor just barely runs and it sounds like crap? Have you pulled the plug leads to see which ones make a difference in the way the car runs? (Use insulated-handled pliers to do this; the spark can jump to your hand if you just grab it with your fingers--and that HURTS!)

--DD

the spark can jump to your hand if you just grab it with your fingers--and that HURTS!)

yeah, and as you can see by Daves 'fro in his pic, ....:D
(sorry dave, just kidding...)

Dave, that's exactly what I did. Only pulling one plug made any difference. Also, I pulled the plugs and 3 of the 4 were wet and smelled like fuel, one was warm and white. I am a bit perplexed, but am trying to check everything piece by piece.

Does the engine idle? then more than one cylinder is working. I don't think a flat four will idle on one piston. If the idle is really low and you smell alot of gas and you can pull plug without any affect...look at the triger points. they can fail to a point were they start dumping fuel at the wrong time and can also stay open and not supply fuel... this would allow you to pull a spark plug, that is sparking, without any ill affect on the engine. ie. it still runs idles rough ...I would start to look at the trigger points

Check all of the wiring in the engine bay. A disconnected wire or a poor connection can cause all kinds of weird problems.

I'd also check the fuel lines--you were up in the front of the car working on the brakes; perhaps you kinked a fuel line?

Also check the fuse panel up under the dash. Remove each fuse and check it--they can pop and still look OK. Also look for unplugged or poorly connected wires.

--DD

I'll check the wiring tonight when I get home.

I'd pull the distributor cap and see if the rotor is okay (not burned), than look at the inside of the cap to see if is burned or not, then measure the resistance on each plug wire (should be the same), then measure the dwell setting, then measure the coil resistance. Something had to have changed and it was from sitting unless you or someone else did something and forgot about it? Brake jobs usually never affect how the engine runs. Good luck

How do I check the resistance?

If you're getting good spark at all the plugs I would look at the fuel system. If the car has been sittng for a while the injectors may have worked fine at first but may be gummed up with old gas. Also check all FI wiring including the ground where the injectors attach to the engine case. Also old FI seals could crack and cause a vacuum leak.

OK, I'm not sure exactly what I did, but it's running again. I was just going over everything in the eng compartement again. I disconnected and reconnected the several wiring harnesses to the fi system. I double checked all the fuses and grounds. I had done this all before, so I wasn't expecting much. What do you know? It's running again!!!!!! I honestly have no IDEA what the problem was. That part kind of scares me, but I'm too busy being happy. Now then. I need to set the timing. Should I also adjust the valves before my maiden voyage? Or should I drive it a little first? Thank you all for your insight.

Brian

*914 POLTERGIEST*:eek:

Congrats! It was probably a loose wire or three...

If it's been more than ~6000 miles since the last valve adjustment, it might be a good opportunity to check 'em again. If it's been more than ~15,000 miles, it is definitely time to check 'em.

If you don't know how long it's been since the last valve adjust, assume it has been 15,000 miles.

--DD

Maybe the car didnt like its new 'shoes' ;)

I think I may have found the culprit. When I said I hadn't disturbed anyting, I forgot my friend had been vacuuming out the pedal cluster area, while I was rebuilding it. Today, he mentioned that he had knocked a couple of fuses out and replaced them. I'm thinking one might not have been making a good connection. Maybe it was just intermitent. Anyway, I'm just glad it's running.

You are all probably tired of hearing about my problems, but... Now the engine has no power. I took it out for the first time and when I had to go up hill, the engine strained and then died. The rpm's go up when I press the accelorater, but when I engage the clutch, it slows and dies. By the way, it took some carb cleaner go get it running today as well. Any thoughts?