Wombatrage Posted January 13, 2012 Share Posted January 13, 2012 Hi guys, i have a 1989 comanche, 2.5L, 2WD, 4 speed. i bought it for $800 expecting to run into some mechanical issues, and sure enough a couple of months into driving it, it became undriveable. It will start, and idle, but when you give it any hint of gas pedal it bogs down and runs REALLY rough, or most of the time stalls out completely. in the condition its in i can't even get it out of the drive way. I thought it was a fuel delivery problem, but ive already replaced the fuel pump and filter. I did notice when i was tinkering one day that if you unhook the hose that goes from the air box into the plastic piece over the throttle body, and cut off some of the air flow with your hand, it would clear up a bit and run strong. Ive taken it to several mechanics (tow bills, parts, labor) And ive heard a million different things. someone said crank / cam sensor, but if those were bad it wouldnt start at all right? I'm thinking it has to be a vaccum leak somewhere, because its so random. sometimes it will rev all the way up no problem, and sometimes it will barely idle. Could it be something as simple as a tune up? (cap, rotor button, ignition wires) or is the problem much larger than that? Any help is greatly appreciated, It is my only mode of transportation and ive tried almost everything! Thanks -Colin Link to comment Share on other sites More sharing options...
jimoshel Posted January 13, 2012 Share Posted January 13, 2012 I had a '89 2.5 do the exact same thing, same symptoms. It was the CPS. Been running great since I replaced it. Also when checked individually, it checked good. Link to comment Share on other sites More sharing options...
Wombatrage Posted January 13, 2012 Author Share Posted January 13, 2012 I already have tune up stuff (distributor cap, rotor button, wires) but i havent installed them yet. the CPS is a relatively cheap fix yes? If so then i may try that next. ive spent about 400$ trying to make this thing work again with no results, so I'm open to anything. the thing is when a mechanic told me that it was the CPS, i went to pick one up and the guy at the auto parts store said that if it starts, its probably not the CPS. Link to comment Share on other sites More sharing options...
ComancheKid45 Posted January 13, 2012 Share Posted January 13, 2012 almost sounds like a MAP sensor problem... Link to comment Share on other sites More sharing options...
jimoshel Posted January 13, 2012 Share Posted January 13, 2012 I already have tune up stuff (distributor cap, rotor button, wires) but i havent installed them yet. the CPS is a relatively cheap fix yes? If so then i may try that next. ive spent about 400$ trying to make this thing work again with no results, so I'm open to anything. the thing is when a mechanic told me that it was the CPS, i went to pick one up and the guy at the auto parts store said that if it starts, its probably not the CPS.[/quote Just off hand, who do you think would know more about cars? A mechanic or a auto parts clerk? I have met some very knowledgeable clerks but they are in the minority, just as there are some mechanics who wouldn't know the difference between a crescent wrench and a screwdriver. It really pays to get to know a mechanic and get on a first name basis with them. :wrench: Link to comment Share on other sites More sharing options...
Wombatrage Posted January 13, 2012 Author Share Posted January 13, 2012 Thats very true, but lately all the mechanics ive been to have sent my MJ back worse than it was to begin with, and i had to pay them for it :mad: Ive been on the hunt for a good reliable person who knows what they are talking about, but they are few and far between. I am going to replace the CPS today and hopefully ill be posting some good news later :cheers: Link to comment Share on other sites More sharing options...
ParadiseMJ Posted January 14, 2012 Share Posted January 14, 2012 I already have tune up stuff (distributor cap, rotor button, wires) but i havent installed them yet. the CPS is a relatively cheap fix yes? If so then i may try that next. ive spent about 400$ trying to make this thing work again with no results, so I'm open to anything. the thing is when a mechanic told me that it was the CPS, i went to pick one up and the guy at the auto parts store said that if it starts, its probably not the CPS. You MAY need to spend even more. I've spent thousands on my two "free" Jeeps Start with the easy stuff, or the obvious first. Replace the CPS, read up on how to do it yourself. MAP sensor not likely (if it's hooked up and there is vacuum, that is). Fuel, Air, Spark is the path to follow. You're missing at least one. Make sure your grounds are clean and secure, battery fully charged etc., gas in tank. Remember most mechanics charge $80 to $100 an hour. So you gotta be %&k'n sure they know what they're doing and will communicate (the truth) with you!! Link to comment Share on other sites More sharing options...
carnuck Posted January 15, 2012 Share Posted January 15, 2012 Check the vacuum hose between the MAP sensor and intake. Then get a can of electronic cleaner spray and spray the TPS (if it improves immediately, it's going bad but mine worked better for a year after I did that), Check the CPS connector and use the spray on that too (do all the underhood connectors and try it one at a time till you get the one that makes it better) Link to comment Share on other sites More sharing options...
Pete M Posted January 15, 2012 Share Posted January 15, 2012 usually (but not always) a bad CPS causes random no-starts or instant-stalls (like you turned the engine off). I would start by cleaning out the throttle body with a toothbrush and some 02-safe throttle body cleaner. it's essentially free, so why not. after that, try spraying that TB cleaner around while the engine is running and look for vacuum leaks, especially around the intake manifold where it bolts to the head. if a leak sucks it in, the idle speed will quickly change. also free. after that I would investigate the TPS. if it's faulty, the computer won't be matching the air coming in with the appropriate amount of fuel. somewhere here is a how-to for checking the TPS with a multimeter, but I usually just throw on a different one from the junkyard and see if anything changes. :D could also be a clogged up cat I guess. or a very weak spark. Link to comment Share on other sites More sharing options...
Wombatrage Posted January 15, 2012 Author Share Posted January 15, 2012 Thanks for you input everyone. i have checked the spark and its fine, not so sure about the cat or TPS. i havent gotten around to putting the new CPS in yet, but once i get it in i will update everyone and hopefully I can go back to loving my Jeep rather than battling it. Link to comment Share on other sites More sharing options...
Wombatrage Posted January 15, 2012 Author Share Posted January 15, 2012 So its not the CPS. i am so baffled by the way it will act perfect one second, and shut off if you give it any gas a few seconds later. Maybe i should take a video to better describe what is happening and the sounds that it makes. when you floor it, the engine dies out completely for a few seconds, but WILL return to idle when you let off of the throttle. and sometimes after about 1.5 seconds of the engine stalling out while full throttle, it will start running really choppy and popping loud for a few seconds before dying out completely. Link to comment Share on other sites More sharing options...
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