Help, rough running,lower power
Thread Starter
Pro
Joined: Nov 1999
Posts: 659
Likes: 0
From: Woodland Ca
Help, rough running,lower power
I have less than 10k miles on a complete rebuild engine and 124k overall on the car.
All of a sudden 2 days ago, the car started running rough. It's not any harder to start, or to run at idel. But once on the road under power, it sounds different expecially at low rpm's. I can notice the vehicle having a slight shake also, and it doesn't seem to have the same power.
Oil pressure and temp, water temp, all seem to be normal.
Where should I start to look?
Could it be as easy as a fuel filter change and a fuel additive/injector cleaner?
Can the distribitor be causing this? How do I check for this?
Thanks for all the help!
All of a sudden 2 days ago, the car started running rough. It's not any harder to start, or to run at idel. But once on the road under power, it sounds different expecially at low rpm's. I can notice the vehicle having a slight shake also, and it doesn't seem to have the same power.
Oil pressure and temp, water temp, all seem to be normal.
Where should I start to look?
Could it be as easy as a fuel filter change and a fuel additive/injector cleaner?
Can the distribitor be causing this? How do I check for this?
Thanks for all the help!
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Help, rough running,lower power (BIG K)
With that many miles you could have a clogged pre-cat or main cat. That can be checked by tapping into the exhaust pipe on either side of the cat.
You can check fuel pressure by attaching a gauge to the Schraeder valve and laying the gauge on the windshield under a wiper blade for a test drive.
A bad ignition wire can also cause lack of power. You can check for this by misting water (not too much though) around the wires at night and looking for the corona.
You might also check the base timing. Retarded timing will cause a lack of low end power.
You can check fuel pressure by attaching a gauge to the Schraeder valve and laying the gauge on the windshield under a wiper blade for a test drive.
A bad ignition wire can also cause lack of power. You can check for this by misting water (not too much though) around the wires at night and looking for the corona.
You might also check the base timing. Retarded timing will cause a lack of low end power.
Thread Starter
Pro
Joined: Nov 1999
Posts: 659
Likes: 0
From: Woodland Ca
Re: Help, rough running,lower power (65Z01)
Thanks for your responce 65Z01. I was thinking that the cats would be OK because the car passed smog. I will take a look at them. I guess if I hear a lot of rattling around when I bang or tap on them that the cats are the problem?
What do you think is the best source of replacement?
I'm not familar with useing the fuel gauge(?) on theSchraeder valve. Is there a trick other that what you have stated?
What should I look for to "misting" H2O?
What do you think is the best source of replacement?
I'm not familar with useing the fuel gauge(?) on theSchraeder valve. Is there a trick other that what you have stated?
What should I look for to "misting" H2O?
Thread Starter
Pro
Joined: Nov 1999
Posts: 659
Likes: 0
From: Woodland Ca
Re: Help, rough running,lower power (BIG K)
I took the car in to a smog/muffler shop that I've used in the past and had both the pre-cats and the main checked. He said that the problems that I'm having can't be coming from them...I have too much power for that and it would keep on dieing. It's not.
So I'm off to check on the prices of the ignition module.
I don't have a presure gage to check the Schraeder valve, so I would have to buy something either way.
Any thougfhts?
Thanks
So I'm off to check on the prices of the ignition module.
I don't have a presure gage to check the Schraeder valve, so I would have to buy something either way.
Any thougfhts?
Thanks
Advanced
Joined: May 2003
Posts: 60
Likes: 0
Re: Help, rough running,lower power (BIG K)
Have you pulled the spark plugs? One may be fouled, and if not you can check the plugs for a consistant color. If one is different that can at least point to a potential problem.
Race Director
Joined: Oct 2001
Posts: 12,832
Likes: 209
From: Canton GA
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Cruise-In IV Veteran
Cruise-In VI Veteran
St. Jude Donor '03-'05-'06-'10-'11-'12
Re: Help, rough running,lower power (FullShred)
Check the plugs and wires. I recently replaced both on my Z and a day later, I had a terrible hesitation and backfire under heavy load. Turned out that one of the plug wires had popped off from the plug. :bb: I was thinking the worst! Check all of the plugs and wires, both ends. Also, make sure the wires aren't rubbing against something.
Thread Starter
Pro
Joined: Nov 1999
Posts: 659
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From: Woodland Ca
Re: Help, rough running,lower power (ShawnZR-1)
Thanks ShawnZR-1, I will check all the wires. I bought the GM wire looms and BOY! are they funky! Do you know where I can find some good ones and any better ways to relocate them?
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Racer
Joined: Feb 2004
Posts: 265
Likes: 1
From: Irwindale Ca
Re: Help, rough running,lower power (BIG K)
Hello, what I usually do when my motor is weak or has a consistent misfire is I would unplug each wire at the distributor while the engine is running One by one, make sure to wear well insulated gloves because youll get a good shock. If the engine stumbles worse, thats not the problem combustion area. When you find the wire which does not stumble, thats the chamber that is missing. Then just start checking combustion components ie, sparkplug for wet or foul, wire for short(just replace with a spare),check the cap it might have a hairline fracture, of course the injector to that cylinder plus the pressure and if all else fails, check the compression to the cylinder , you might have dropped a valve or something. If it were your ignition module the car would cut out and never start again. I had a compression reading of 90 at my missing cylinder once. Bad valve. Smooth idle with no powere could be the cats. but i would concentrate on finding that missing cylinder. Again be sure to wear insulated gloves. You wont die from the shock but it will wake you up. They dont call me mad mike for nothing. hope this helps. :seeya :hurray:
Thread Starter
Pro
Joined: Nov 1999
Posts: 659
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From: Woodland Ca
Re: Help, rough running,lower power (madmike)
Thanks madmike. I will actually have time to do some work on the car today.
I like your aproach. Direct and to the point.
When you say insulted, do the gloves need to be rubber or will leathewr work?
I like your aproach. Direct and to the point.
When you say insulted, do the gloves need to be rubber or will leathewr work?
Racer
Joined: Feb 2004
Posts: 265
Likes: 1
From: Irwindale Ca
Re: Help, rough running,lower power (BIG K)
hello, thanx for the compliment. About the gloves, I use leather, it helps but sometimes i get a jolt. I wish they made wood gloves :) . Anyways, i think you just have a wire melted on the exhaust manifold. Try laying the wires away from the hot manifolds with zip ties or if you have time you can by some wire harnesses to make it look pretty. Check the cheap stuff first. Replace the sparkplug and wire. If you have a spare cap, replace the cap. The injector takes a bit of breaking down to get at it. When i did the test on my friends vette, it was a bad injector though. I dont know how to test the injector in the vehicle, but it was a matter of eliminating everything else, even compression to diagnose the injector. After replacement he had full power. keep your hands away from the front of the engine, set handbrake and chock the wheels. Nothing near the firewall will dismember you but the exhaust mani is hot and those infamous shocks from the dist.(ouch) well good luck. let us know what happens :thumbs: