89 blowing black smoke, idling rough, etc

rjeast · #1 10-18-2005, 04:55 PM

I have an 89 Jeep Pioneer. It has 4.0 v6.

Anyway, my sons wanted to go *mudding*. Basically we just go splashing around in mud puddles but thats the extent of it so nothing major. We were splashing and the jeep died. I popped the hood and a few wires near the back were on fire (looks like a melted vacuum hose). Anyway, I blew em out and it started right up.

Now the gauges (battery and temp) are all wonky. They go up and down. The temp gauge is the most worrisome. The fan is on and it doesnt really appear to be overheating.

Also, when running it idles rough and blows black smoke. I realize this is probably due to running too rich. Any ideas on how to fix it? On the top of the block where the oil cap is there is a hose in front and another in back. Neither one seems to stay put very well and oil has been being thrown out of those. We are going to replace them but we have them fitting securely now. Can these be causing vacuum leaks? Sorry for not knowing the technical terms but I dont have a picture of the motor to use for reference. Any help would be great.

Thanks,
Ryan

myjeepsux420 · #2 10-18-2005, 06:24 PM

Sounds more like the engine has a blow by problem. The rough idle is likely to be related to a vac. leak, but oil coming out of the hose is more related to the blow by problem. How many miles are on the engine?

rjeast · #3 10-18-2005, 06:27 PM

There is something like 230,000 miles on it. So definitely a ton miles but it has ran awesome until just now.

89ltd · #4 10-19-2005, 04:05 AM

the hose behind the oil cap should be drawing vacum from the intake manifold and the one in front of the cap should be drawing fresh air from the air filter box. Don't know where your fire was but if it was at the map sensor on the fire wall it would make a drastic difference in the way it runs and smokes. Need better description of what was damaged.

89ltd · #5 10-19-2005, 04:12 AM

are you sure its a v6, or the inline 4.0L ?

rjeast · #6 10-19-2005, 10:41 AM

Is there an online map of the motor anywhere so I can be more specific? It very well could be the map sensor so maybe I should get a repair manual and see if that is it.

Thanks

rjeast · #7 10-19-2005, 02:35 PM

Ok so the fire was at the MAP sensor so we are going to replace it. Do you know the names of the hoses from behind and in front of the oil cap so we can replace those as well?

Thanks for your help.

rjeast · #8 10-19-2005, 11:23 PM

Ok we replaced the MAP sensor and it idles great and no more black smoke!! We also replaced the vacuum line that burned. We still need to get a new rear grommet and new left side vacuum harness (since they dont stay in the holes). BUT it runs and runs good.

Every since the fire the gauges are messed up though. The oil pressure and battery gauge stay at the far right but the temperature gauge is all over the place. Any idea on those?

Thank you very much for helping us out

89ltd · #9 10-19-2005, 11:51 PM

I have to ask you again, is it an inline 6cyl. 4.0L or a v6?

rjeast · #10 10-20-2005, 12:34 AM

it's a 6cyl 4.0

GregA · #11 10-20-2005, 02:21 AM

There is a PICTURE HERE that shows what I believe is the top of the motor. It shows the MAP, back vacuum line & oil cap (along with other stuff).

I believe there is also a link on that page that will take you to the vacuum diagrams.

Hope this helps. Take Care,

89ltd · #12 10-20-2005, 11:53 AM

the hose coming from the grommet at the back of the valve cover (fire wall) is called the ccv hose. It has a 2.6 mm hole in the end that goes into the valve cover and the other leads to the intake manifold for vacum. The grommet at the front of the valve cover leads to the rear of the air filter box. On my 89 I found a 90 degree grommet at the auto parts store that fit perfect into the valve cover. 1/2" heater hose fit into the grommet perfectly , and at the air box the other end of the heater hose fit perfectly over top of the hose coming out of the air box. If you have that hooked up right, you should feel a slight suction on the end at the air box when it is idling.

rjeast · #13 10-20-2005, 12:10 PM

Ok thank you very much for your help. I am sure it would not be on the road right now had you not told me about the MAP sensor. Thanks again.

Saudade · #14 10-23-2005, 09:06 PM

Did you check the rest of the wiring back by the fire location? There is a coolant temp sensor at the rear of the cyl head near the MAP.

POST REPLY TO THIS THREAD