Just did the plenum replacement, took 4 days but whatever. Didn't take pictures, learned that lesson the hard way i suppose. So I just got her running yesterday, and after a bout with the alternator, I got her running. Got a few problems...

1. Idles in waves, goes up, then down ( almost dies ), then up, then steadies . If I put the hose from the 2nd picture back in, it dies after a couple of waves.

2. I lost a higher gear. Normally when I go 75 on the highway, it shifts around 65+ into a higher gear, it doesn't anymore, but that may be ( probably ) something else.

3. Really bad sucking sound, maybe I ignored it before, buts it's really noisy.
Sounds like it's coming from the throttle body, but I can't be sure. I used a gasket maker ( rolled up gasket cork ) to make the new Throttle-Body gasket, but I'm not sure if it sealed properly.

4. Not sure If my vacuum lines are setup properly. Seems right to my diagram, but if you guys could post a few pictures of yours, it would be appreciated. I plan on putting small metal screw-tightening clamps on them all as well.

5. Small, but throws codes, 12 and 22.




Vacuum Hose Diagram





Only way it idle's and doesn't die is if I remove this hose from the bottom-most port.





This is the Drivers side port setup, everything seems in order.





Removed the PCV hose to show the T-intersection from the throttle body

 

Good job it took me 4 days and I tagged all the parts with blue tape which I could barely read when I went back to them. Bottom pic. The elbow hose goes on the top nipple. The smooth hose with the T goes on the one under it and the other leg of that T leads back to your EGR vacuum hose. If that fails reverse the nipples that they are on but it shouldn't matter since the intake is a barrel. As for the noise you may have a leaky or cracked hose. or the sensor on the fromt of the TB may have bneen damaged it has a very tiny rubber elbow (which does not come with the hew part if you buy one!) for a vacuum connection. It may be pulled off. I can;t think of the name of it????? It is the one right on the front of the TB. Duh right there in the diagram its the MAP sensor.

 

Don;t forget this resource page either https://dodgeforum.com/forum/1st-gen...e-manuals.html You can find your codes and vacuum diagrams. 12 means the battery has been disconnected in the last 50 starts. 22 is engine coolant temp sensor signal outside acceptable range. That is one of those sensors in the intake at the base of the rad hose connection. I replace both they are less than ten bucks each.

 

It just occurred to me that if you have two sensors in that area of the intake you make have crossed the wires. Seems unlikely as they should have different connectors but its worth checking.

 

They do have different connectors. I think i might've knocked it during the rebuild. The MAP sensor hose is secured with clamps. You can kinda see it going under the filter in the bottom picture.

 

If you were to remove the MAP sensor there is a very tiny rubber elbow between it and the TB. That is what I theorized might have come loose. My TB gasket was that paper gasket stuff so I'm thinking cork as long as it wasn't too dried out should be fine.

 

Coolant sensor wasn't plugged in, took care of that. Bought a proper gasket for the throttle, the cork one I made failed. After that I put hose clamps on the questionable vacuum hoses. All problems gone.

 

Cool! I'd like to know if this improves the MPGs and how it performs.

 

So about a month before the repair, if I played smart and friendly to the pedal ( automatic transmission ) I could pull 16+ MPG. For no apparent reason though, it dropped to 14.5MPG. It was at that point that I decided to replace the plenum gasket. I'll post my MPG'S when I fill up my next tank. May be a bit before I get stable readings because I put in fuel injector cleaner to deal with me mixing up the fuel injectors on the rebuild, I heard you're supposed to keep them in the same spots. I'll give it a month.