Round Two: Rough idle, runs like garbage ::SOLVED::
Redcolt88
Jeeper
- Posts
- 41
- Thanks
- 0
- Location
- Central California
- Vehicle(s)
- 1984 CJ7, 258 w/ tbi, T176, Dana 300 w/ 4:1, D30, AMC20, 2.5" lift springs, open diffs, 33x12.50r15s,
My first thread here on jeep-cj was about my jeep running very poorly, and my second thread is going to be about, you guessed it, my jeep running poorly.
skip to bottom to avoid back story.
The Story:
So after fixing the voltage drop issues plaguing my tbi system, I was super confident in the ol' CJ and decided to take it to the coast for the weekend, 2 1/2 hour drive from where I live. Between here and there, there is a few small mountain ranges to traverse. The first hour and a half was awesome, but that's where it went all wrong. Pulling the last, and largest, grade before Paso Robles CA, I started to lose power, so I shifted down to 3rd and had to spin 3500 rpm to climb the rest of the way. On the way down the other side of the grade the motor was cutting out badly. I pulled over at the Jack Ranch Cafe, the very spot that James Dean wrecked his motorcycle, and the jeep was running awful. It sounded like it had a top fuel drag racing cam and shook like crazy. I still had the fuel pressure gauge hooked up from my last bout of problems and I had 11 lbs of pressure, I pulled the spark plug wires off one at a time, not that either, at which point I noticed that I had oil coming from the distributor, the dipstick tube, the breather, the pcv valve, it was everywhere and I was about a quart low from when I started with when I left. Not knowing what to do, I called my sister to come get me and had to leave the jeep there over night. My dad towed me home the next day.
The Symptoms:
Jeep starts right up but idles very rough. It revs up when given throttle but does not smooth out.
The Process:
I replaced the pcv valve, and sprayed all the oil down with brake clean. I had a buddy come over to help out and the first thing he thought was vacuum leak. So we searched for a leak but couldn’t find one. He pulled off the vacuum advance line and told me to work the gas a little. The dizzy was getting almost no vacuum, thusly not advancing at the appropriate time. Got the howell install guide and found that the PCV valve wasn’t plumbed correctly and the vacuum advance had the same problem. We fixed the lines and fired it up. Huge improvement at idle but as soon as a load was put on the motor (driving) it was back to the same problem. After a lot of staring and thinking my buudy pulled a dollar out of his pocket and told me to fire the motor. He stuck his dollar right up againtst the tail pipe and when the jeep tried sucking the dollar up through the exhaust He told me we had a bigger problem than we thought. So know we are thinking burnt valve. I start to pull the spark plugs to figure out which one and on cylinder 5 i found this:
The Solution:
So after some careful and scientific consideration, we decided that broken off piece of spark plug was stuck in the exhaust valve keeping it from closing all the way. Fearing that the motor was toast anyways, we left the spark plug out and fired the motor in hopes that it would clear the debris from the valves. Went down and bought some new plugs and threw them in. Cranked the motor and BAM!, purred like a kitten. Tried the dollar trick and it almost blew the dollar out of my hand. Fixed.
The Theory:
This is my buddies theory so I can’t take credit. I wouldn’t have put 2 and 2 together if it wasn’t for him anyways. The vacuum advance wasn’t working properly so at times when it should have been advanced, the timing was way more retarded than it should have been resulting in early ignition, resulting in increased pressure which broke the spark plug, which got stuck in the exhaust valve which was cleared either when it happened or when we ran it without the plug in it.
I am really curious to see what you guys think. Are we way off here?
skip to bottom to avoid back story.
The Story:
So after fixing the voltage drop issues plaguing my tbi system, I was super confident in the ol' CJ and decided to take it to the coast for the weekend, 2 1/2 hour drive from where I live. Between here and there, there is a few small mountain ranges to traverse. The first hour and a half was awesome, but that's where it went all wrong. Pulling the last, and largest, grade before Paso Robles CA, I started to lose power, so I shifted down to 3rd and had to spin 3500 rpm to climb the rest of the way. On the way down the other side of the grade the motor was cutting out badly. I pulled over at the Jack Ranch Cafe, the very spot that James Dean wrecked his motorcycle, and the jeep was running awful. It sounded like it had a top fuel drag racing cam and shook like crazy. I still had the fuel pressure gauge hooked up from my last bout of problems and I had 11 lbs of pressure, I pulled the spark plug wires off one at a time, not that either, at which point I noticed that I had oil coming from the distributor, the dipstick tube, the breather, the pcv valve, it was everywhere and I was about a quart low from when I started with when I left. Not knowing what to do, I called my sister to come get me and had to leave the jeep there over night. My dad towed me home the next day.
The Symptoms:
Jeep starts right up but idles very rough. It revs up when given throttle but does not smooth out.
The Process:
I replaced the pcv valve, and sprayed all the oil down with brake clean. I had a buddy come over to help out and the first thing he thought was vacuum leak. So we searched for a leak but couldn’t find one. He pulled off the vacuum advance line and told me to work the gas a little. The dizzy was getting almost no vacuum, thusly not advancing at the appropriate time. Got the howell install guide and found that the PCV valve wasn’t plumbed correctly and the vacuum advance had the same problem. We fixed the lines and fired it up. Huge improvement at idle but as soon as a load was put on the motor (driving) it was back to the same problem. After a lot of staring and thinking my buudy pulled a dollar out of his pocket and told me to fire the motor. He stuck his dollar right up againtst the tail pipe and when the jeep tried sucking the dollar up through the exhaust He told me we had a bigger problem than we thought. So know we are thinking burnt valve. I start to pull the spark plugs to figure out which one and on cylinder 5 i found this:
The Solution:
So after some careful and scientific consideration, we decided that broken off piece of spark plug was stuck in the exhaust valve keeping it from closing all the way. Fearing that the motor was toast anyways, we left the spark plug out and fired the motor in hopes that it would clear the debris from the valves. Went down and bought some new plugs and threw them in. Cranked the motor and BAM!, purred like a kitten. Tried the dollar trick and it almost blew the dollar out of my hand. Fixed.
The Theory:
This is my buddies theory so I can’t take credit. I wouldn’t have put 2 and 2 together if it wasn’t for him anyways. The vacuum advance wasn’t working properly so at times when it should have been advanced, the timing was way more retarded than it should have been resulting in early ignition, resulting in increased pressure which broke the spark plug, which got stuck in the exhaust valve which was cleared either when it happened or when we ran it without the plug in it.
I am really curious to see what you guys think. Are we way off here?
