dkmcgowan Posted July 16, 2015 Share Posted July 16, 2015 I know there are lots of topics on this and I have read most of them. This is my first non carburetor car I've had, so all new stuff to me. I have a rough idle. It runs better once it's warmed up and it's idling close to 650-700, but still just feels rough when in the cab. I can feel a little stumble every once in awhile, but not too bad, and just running a little rough. The other symptom is when it's cold, it's kinda hard to crank. The few second delay is the renix system, but I have to let it crank for a few additional seconds and then it will turn over, a pump of the gas helps it out. If it was an older car I'm use too I would say the choke was not working correctly and/or the high idle cam was not properly set, but I don't think this vehicle has either of those. It cranks right up when it's warm. With the rough idle if it was one of my older cars I would say I just need to tweak the idle/mixture and curb idle, double check timing, and triple check I have no vacuum leaks and I would smooth it out just fine. It's not that far off, but I don't really have fine adjustments like I'm use too... Another clue is it was idling very high, like 1k RPM, and fluctuating a bunch. A friend tried another IAC he had on another Comanche, no change, then tried the MAP sensor from the other Comanche, no change, then checked the vacuum line to the MAP sensor and blew it out with air and it was clogged, unclogged it, plugged it back in, unplugged battery to do a reset, and then the idle came down and it started running much better. I feel it can run even better though... Compression is good on all cylinders. Another clue, once you are off idle, it runs great, accelerates fine, no dead spots, no sputtering, nothing, runs great... I will add, the idle isn't bad, it runs, never feels like it's going to die or anything, isn't surging, just feels a little rough. I plan to do all the "renix tips" from cruiser, but was curious what people thought it might be? I was going to do #1 and check the ground this weekend by the dipstick and try to adjust the TPS. I was also thinking about just getting new vacuum hoses, but so far I can only find a Dorman aftermarket one with mixed reviews... The other thing I was thinking was a leaking EGR, those suckers are $150 Thanks! Link to comment Share on other sites More sharing options...
wutangwisdom Posted July 16, 2015 Share Posted July 16, 2015 yeah My 89 I6 does the same thing EGR are expensive but if yours still has vacuum while accelerating then I would just take it off and clean all the carbon build up on it. also the 2 inch hose that goes from the side of the airbox to under the headers shouldnt have any holes in it and if it does should be replaced. Other than that I believe most rough idle issues that arent IAC related are TPS related.... So dick with the tps and clean egr before you replace the egr. Link to comment Share on other sites More sharing options...
dkmcgowan Posted July 17, 2015 Author Share Posted July 17, 2015 I went looking tonight for some bad hoses and I found one really bad one, broke apart in my hand. It is the one that goes from line from the throttle bottle to the air box, it's a rubber hose on that connection right before the air box. It goes all the way around to the vapor canister on the passenger side. The plastic was still good but both rubber ends were in terrible shape... I rigged some fuel line I had, it doesn't fit well but close enough, and it seems to idle better. I wouldn't think this could effect idle at all, just a vapor vent and not even a vacuum line right? I was have my hands all around the passenger side to get the hose on, so maybe I wiggled around those wires near the main sensor ground and made something work better, unless someone says the crankcase vent to the canister having a huge leak can effect idle somehow. Link to comment Share on other sites More sharing options...
Megadan Posted July 17, 2015 Share Posted July 17, 2015 Definitely refresh the lines and hoses. They are probably as old as the truck and need it anyway. Do as many of the Renix tips as you can and see where you end up. When I first got my truck it was a nightmare, and aside from a couple of non-renix related mechanical fixes, most of my improvements came from doing Cruisers tips. Have you compression tested that engine? My truck runs a little rough too, but after everything I have done, including a rebuilt head (done for different reasons) the only thing left to really attribute to my rough running is the lack of, and very uneven, compression. My motor was rode hard and not taken care of well before I got it... At least it doesn't burn any oil. Link to comment Share on other sites More sharing options...
dkmcgowan Posted July 17, 2015 Author Share Posted July 17, 2015 I ordered new lines and hoses last night, so will start with that... I also plan to start the renix tips this weekend... My compression is pretty good... I didn't do a leak down test, but I did a compression test. 1 - 130 psi 2 - 135 psi 3 - 135 psi 4 - 140 psi 5 - 125 psi 6 - 125 psi Link to comment Share on other sites More sharing options...
dkmcgowan Posted July 18, 2015 Author Share Posted July 18, 2015 I discovered a vacuum leak today... It was related to the vent vacuum canister. The idle got better for sure, but not perfect... Do I need to unplug anything, battery, sensor, to have it reset? I ordered all new lines so I might have other leaks as well. http://comancheclub.com/topic/47713-help-fixing-vacuum-canister-for-vents/ Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now