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1979 AMC 304 Rough idle.

1979 AMC 304 Rough idle.
Ahhhh yes, thank you, you clearly understand the attraction of a CJ. There are a lot of positive innovations in the new Chrysler Jeeps, that can not be denied. There is something about the simplicity of a CJ.
 
I'm back to work this week. So no piddling with the jeep. Drove it to work yesterday too. Engine ran decent after warmed up. Two other thing stood out none realated to this topic that will need addressed soon. Brakes and alignment.

So since I have reloacted the coil and it's no longer under the breather, I think I will cut a new gasket for the baseplate, and take the stock spacer out. I will have to figure out what to do with the pcv though. I want to make dang sure this spacer is not leaking. I also may have a line on a carburetor also. It is for an inline six though so I assume the jetting will be different. By the way, what is the stock jetting for a AMC 304 ?
 
Get the carb that the engine should have.
The 6cyl carb will not be a good choice and most likely not even fit onto the mounting plate.
LG
 
LG. How did you run your pcv? Or anyone for that matter. I have a larger port off the back of the carb itself that is capped. Maybe I could run it off that?
 
I run a 6cyl and the PVC is plumed in it's stock/OEM position for an '85.
The PCV System

LG
 
In a stock configuration

Air sucks in through a pipe that attaches to the air filter housing. This is NOT filtered air.

The hose goes to the oil filler cap which is a filtering device.

The air goes in the engine and does what it does in the engine.

It comes out a big 3/8" or so port on the back of the intake manifold.

Then it hits the actual PCV valve (some of the valves have a vacuum port that sucks/purges air from the Charcoal Canister). Make sure the valve is the right way, the flapper opens with air going into the carb and closes if the air tries to go the other way.

The hose steps down in size entering the actual carburetor on the drivers side where the air goes into the combustion chambers.
 
Got to tinker with the jeep today a little. Found that the spacer has to be used because of the longer studs. They interfere with carb linkage without the spacer. I could have went and bought new studs but didn't. Decided to seal the carb and spacer gaskets with sealer.

There is an intake vacuum port behind the carb. Runs to the passenger side lower carb vacuum port. I eliminated this vacuum line and plugged both the port on the manifold and on the carb.

I decided to cut the charcoal cannister completely out of the vacuum loop. One went to the pcv and another to a port on the passenger side top of the carb. I plugged both of those ports.

Installed new egr valve.

I can say this all helped. It still coughed and misfired in third gear on a hill, but it was much harder to get it to do it. I also noticed it had better manners during acceleration from a stop. I also noticed that I could step further down on the throttle with a response, but from 3/4 to full throttle it plateaus right before it misfires or cuts out. It still does both just takes a little harder to get it to do it.

I still want to set the timing back closer to factory specs and bump the idle up and re adjust the idle screws and see where that leads. I can always put it back. Now that I.have the vacuum advance running to a timed port on the base of the carb. Before it ran through a vacuum sensor. May make a difference.
 
I'm start'n to wonder if you're run'n out of gas, more than a vacuum issue. :confused:
It seems that the deeper you're into the 'pedal', is when it starts act'n up now.
LG
 
LG, I'm leaning towards carburetor. The idle screws being adjusted so far out to run. Wonder if that could be a result of a fuel line restriction also. Fatter idle screw compensating for lack of fuel or fuel pressure. May have been looking t the clue from the wrong direction?
 
Run a fuel line pressure ck.
Look for smashed fuel line from the tank to the fuel pump.
Look for a 'kinked' line also.
LG
 
Lumpy Grits said:
Run a fuel line pressure ck.
Look for smashed fuel line from the tank to the fuel pump.
Look for a 'kinked' line also.
LG
Click to expand...

A friend of mine at work had a semi crushed fuel line on his Cj I found out. He said it was that way from the factory, just got to the point where it started effecting the engine performance. Haven't got to that point til right now. I'll get on it right after I get it back from the alignment shop tomorrow. Got a new gas cap tonight also. Much much tighter fit than the old one. Also have a whole new sending unit coming tomorrow. Think the fluctuation in the guage might be a clue also.
 
Being I ordered the sending unit yesterday and my gauge not working properly, I decided to just change the sending unit anyways. Wasn't a perfect fit, had to reuse the locking ring but other than that gauge now works correctly and it still didn't make any difference. Still having a misfire only in third gear under load up hill. It seems to lose power even if in third and hitting a hill it just winds down even giving it gas and then you get the misfire. I can say, it doesn't require the complete warmup it needed before to drive. It will drive when cold now. So that's a good sign to me I'm going in the right direction.

I checked every inch of the fuel lines front to back and all look really good. So no kinks or smashed lines.

Again, 1st and 2nd are strong, this is only happening now in third gear on a hill. Really it's down to two things in my head. Timing and or carburetor. Everything else has been touched and or replaced.

I don't mind swapping out all these parts. It's one less thing to go wrong down the road and they are all under warranty so if they do, it won't cost anything but time to replace them.

So, now, I think I will mess with timing tomorrow and set it to factory specs and tune the carb from that point and see what happens. I will also check and see if the timing chain has any slack also. From that point, the only thing left is carb.
 
Oh and one other thing that might mean something. I hit a shallow dip in the highway and the rpm came up so I stayed in the gas and kept the rpm's up and it didn't seem to have issues on the next hill even when stepping further on the gas.
 
OK-with that info.:eek: I'm now convinced you have an electrical issue, somedangwhere. :confused:
That jolt from the road established a better contact.
My CRS is in bloom now:D-Tell me what was done to the coil and if you are still run'n that horseshoe connector.
You should clean and renew all engine, frame & body ground(GND)connections.
I would also strongly recommend that you run a dedicated GND lead from your dash panel to the NEG(-)battery post.
You may also be having an issue with your altenator as well. I would suggest having it tested for voltage and amp output. Test for BOTH, as voltage means nut'n if the amps ain't there.

LG
 
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Nah LG, I didn't hit a bump, I drove down one hill into and went up the another side. It was a narrow "valley" kind of thing. It got the rpm's up to around 2800 in third and I just kept momentum and rpm's up going up the other side. I was also able to still step into the gas pedal with some response and no misfire.

But. The hill before that. It's a flat area that runs into a long uphill. It wound it down and misfired on that. I just couldn't keep the rpm's up. Like it didn't have enough power. To the point where you want to drop it to second. But I shouldn't have to. I was running around 50mph or so.

Still, good useful ideas LG. I need to run a ground from the firewall to the engine. It doesn't have one. I also don't like where the battery ground is either. I need to move it. I do also need to clean up the alternator wiring, leaves a lot to be desired along with all the ground wires in the engine bay. They need cleaned or moved to better grounding locations. Some are loose. Need a good foundation. :chug:
 
Lumpy Grits said:
OK-with that info.:eek: I'm now convinced you have an electrical issue, somedangwhere. :confused:
That jolt from the road established a better contact.
My CRS is in bloom now:D-Tell me what was done to the coil and if you are still run'n that horseshoe connector.
You should clean and renew all engine, frame & body ground(GND)connections.
I would also strongly recommend that you run a dedicated GND lead from your dash panel to the NEG(-)battery post.
You may also be having an issue with your altenator as well. I would suggest having it tested for voltage and amp output. Test for BOTH, as voltage means nut'n if the amps ain't there.

LG
Click to expand...
I'm thinking LG is right on the money. Electrical problems are and can be strange and crazy symptoms. Was talking to my buddy yesterday (master mechanic/40 years experience) who has owned probably 8 different jeeps. He was working on 15 year old vehicle on off last 2 weeks. Well maintained with verified history came in with seamed like Transmission problems and engine running great. In the end after countless time and frustration and several others checking and and factory reps agreeing to what he did, it still was not fixed. it was a ground buried in the engine area. Somebody else had worked on the vehicle 6 months earlier and the ground had not been tightened enough and had backed off and was intermittent problem.
 
Belizean said:
I'm thinking LG is right on the money. Electrical problems are and can be strange and crazy symptoms. Was talking to my buddy yesterday (master mechanic/40 years experience) who has owned probably 8 different jeeps. He was working on 15 year old vehicle on off last 2 weeks. Well maintained with verified history came in with seamed like Transmission problems and engine running great. In the end after countless time and frustration and several others checking and and factory reps agreeing to what he did, it still was not fixed. it was a ground buried in the engine area. Somebody else had worked on the vehicle 6 months earlier and the ground had not been tightened enough and had backed off and was intermittent problem.
Click to expand...

I totally agree. Proper grounding is a good foundation that everything works off of. I plan on getting some ground straps today and add some grounds and fix some others. Right now, the only ground on the jeep runs from the post to the AC bracket. Not a good ground. It's aluminum. It should run to the block. There is a smaller wire that runs from the post to the fender well beside the starter solenoid. It's extremely loose. That will be fixed. I also plan on adding a grounding strap from the block to the firewall. I'll add a strap from either the starter to the battery or block to frame or both. Main think is a good ground from body to frame. I'll look at the manual and see what came stock.
 
Run your main battery GND to the top bolt of the starter! Have secondary GND's go to the frame and firewall. You want the same wire gauge as the battery cable is.
Don't forget the dash GND. You can use 10-12 ga. stranded there.
I also recommend secondary body to frame GNDs towards the back of the body on each side.
Do this before any other mods.
LG
 
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