bent pushrod/misfire?

**Mikat1** · 04-11-2011, 01:16 PM

Howdy folks. Just curious if a bent pushrod would cause a misfire. My car is missing pretty hard going through the gears in full throttle. I have recently replaced the plugs/plug wires 02 sensors and did an injector balance and everything came out OK. Please offer any feedback / advice that you have. Thanks

**Mikat1** · 04-11-2011, 06:16 PM

don't everyone chime in at once

**2000dreambird** · 04-11-2011, 06:26 PM

could be anything really, i had a grand Prix that was misfiring because the boot on the spark plug wire had traveled up the wire a little ways, this caused the plug to arc out on the block instead of firring in the cylinder

**jsmith564`** · 04-14-2011, 06:33 PM

i have to get inside my motor, i have a vibration issue that might pass for a missfire.

we'll see pretty soon. i have this weekend off.

**35th-ANV-SS** · 04-14-2011, 06:56 PM

You would hear a bent push rod. It would sound like a constant ticking. Why do you think you have a bent push rod? Did you over-rev the motor?

Misfire is usually: bad wire, bad plug, wire not fully seated on the plug, or a vacuum leak. In your case, since you changed the wires and plugs already, I would guess a vacuum leak.

Have you checked your fuel pressure? If should read 58psi. If it isn't, you aren't getting enough fuel which could be a fuel pump issue, fuel filter, or a bad injector.

**Smittro** · 04-15-2011, 03:33 AM

A weak coil or coil ground can cause intermittent misfire also..

**Mikat1** · 04-16-2011, 03:33 PM

Originally Posted by jsmith564`

i have to get inside my motor, i have a vibration issue that might pass for a missfire.

we'll see pretty soon. i have this weekend off.

Good luck with that. hope its not too bad for you.

Originally Posted by 35th-ANV-SS

You would hear a bent push rod. It would sound like a constant ticking. Why do you think you have a bent push rod? Did you over-rev the motor?

Misfire is usually: bad wire, bad plug, wire not fully seated on the plug, or a vacuum leak. In your case, since you changed the wires and plugs already, I would guess a vacuum leak.
Have you checked your fuel pressure? If should read 58psi. If it isn't, you aren't getting enough fuel which could be a fuel pump issue, fuel filter, or a bad injector.

fuel pressure is good, just replaced the filter, did an injector balance and they all perform well

Originally Posted by Smittro

A weak coil or coil ground can cause intermittent misfire also..

haven't over revd the motor, assumed it was a bent pushrod because I fixed everything else it could have been lol. not sure on the vacuum leak. Don't know how to find one if I did

looking into it

**C5natie** · 05-05-2011, 04:35 AM

Could be a broken rocker arm. Especially if its broken on the intake side, itll just feel like a miss and vibration when you rev it.

**chuckie669** · 05-05-2011, 04:51 AM

Just because it was recently replaced doesn't make it free and clear from being the culprit.

Id start with the most recently changed things. Check and make sure one of your wires didn't wiggle loose. Had a buddy with a bad mis. Wore a thick glove to protect from heat and put pressure on the wire boot at the coil and then the plug. One was pulsing differently from the rest. Pulled, checked and replaced it to fix the issue.

Guessing your not throwing any codes yet.

**0rion** · 05-05-2011, 06:35 AM

if you haven't bounced off the limiter I doubt it's a pushrod.

**Jay37** · 05-05-2011, 11:48 AM

I'll tell you how I check for vacuum leaks, I understand stand "it's not safe" so do it at your own risk, I only say that so this thread doesn't get filled up with people concerned about my safety. Although I have never had a problem.

Just put gas in a spray bottle, and spray all your air hoses with the car running, and if your rpms change that is a vacuum leak.

**35th-ANV-SS** · 05-05-2011, 11:51 AM

I've used brake cleaner.

**Keith01** · 05-19-2011, 04:12 PM

WD40 works also.

**ldurham** · 06-09-2011, 07:00 PM

I wouldn't use Brake clean or WD-40.Get a bottle of carb/throtttle body cleaner and spray it all around your hoses and intake manifold. If you have a vacuum leak it will suck in the cleaner where ever the leak is and you will hear a change in your RPM's.

**km346** · 06-14-2011, 08:09 AM

Originally Posted by ldurham

I wouldn't use Brake clean or WD-40.Get a bottle of carb/throtttle body cleaner and spray it all around your hoses and intake manifold. If you have a vacuum leak it will suck in the cleaner where ever the leak is and you will hear a change in your RPM's.

THIS... carb cleaner isn't corrosive to paint/rubber like brake cleaner, or as dangerous as spraying gasoline.