- This topic has 6 replies, 4 voices, and was last updated 10 years, 2 months ago by
.
-
Topic
-
My 2005 Jeep Liberty 3.7L suffers from a slightly lumpy idle, but there are no codes and the spark plugs and coils are all good. I just hooked up a vacuum gauge, and given that the needle is vibrating very fast, something is clearly not happy inside there. Can anybody take a look at the videos below and give me an experienced read as to what? I’m thinking sticking valve(s)? The vibration of the needle is very fast, but it doesn’t come across all that clearly in the videos.
The first video is straight idle, the second one I rev the engine a few times.
[video]http://www.youtube.com/watch?v=Vo80NPDkjjQ[/video]
[video]http://www.youtube.com/watch?v=dj-PAINRElc[/video]
-
Replies
-
Looked at some gauge charts. http://www.vanpeltsales.com/FH_web/FH_images/FH_other-pics/vacuumgauge-chart.jpg
Someone with more knowledge could say about the slight vibration in the first video could say more but yeah it seems sticky (or other problem with) valves can cause that.
http://www.alldatadiy.com/alldatadiy/DIY~G~C41407~R0~OD0~N/0/80851247/83204708/83204719/110671822/34853741/100411974/34853743/34856124/124158162/145134835Perhaps running some engine flush could help with that? I am sure you will get answers either way if that is good or bad. Try simple, cheap solutions first of course.
IMHO, the engine gauge doesn’t seem to be acting TOO crazy.
So you have a couple options – If you want to drive this truck for a long time to come, then yeah might want to think about getting in there to do whatever work is needed to the valves or guides if they are the problem. If you just need the truck to last another year or two at most, things will probably be alright til then.The engine appears to have good vacuum. The fluctuations on the gauge are caused by slight changes in the IAC position I believe.
Those engines tend to idle a little rough as there is a long period between firing pulses on a V-6 as well as the engine mounts getting stiff from age.Here is an ETCG video that explains what a good vacuum reading should be.
[video width=550 height=309 type=youtube]d-jp1IIJVVk[/video]
[quote=”Dunebasher” post=115832]I need it to last about another year, that’s all – preferably without having to pull the heads…[/quote]
Aww heck you will be fine then. TBH, I wondered if the quick fluxuations might be just from engine vibrations, assuming the gauge was resting on the engine.
Pulling the heads and messing with valves might be necessary if you REALLY wanted that “extra 10%” (as they say) but even if not, I don;t see your engine blowing up anytime soon.
- You must be logged in to reply to this topic.