Hey gang - 88 TPI; to my dismay I haven't driven my car much this year. When I do, he runs like a champ. Starts right up, no issues while cruisin. Occasionally though, he's idled a bit ''rough'. When I initially start it up, the car seems to run fine. After sitting in the driveway warming up a few minutes it sometimes does a very minor surge....like it almost wants to stall but doesn't. The surge doesn't last more than a minute or two, and eventually goes away...usually never coming back again during that ride.

Sometimes when I come to a light or stop sign, and let my foot of the brake to get moving, the car will again do that minor surge where the engine comes somewhat close to stalling. But even this is very random, and almost never happens.

And again let me stress - this "surge" that I'm describing is extremely minor. I don't need to press hard on the gas pedal to get rid of it, and it usually corrects itself if I just sit there. It's been happening on a few occasions the past 9 months, and when it does happen, the car never officially stalls. But it's almost like it's the early stages of symptoms that will worsen over time, and I'm wondering what it could be. Any suggestions?

 

ANYONE? I've replaced plugs, cap, rotor, and wires. The "roughness" keeps happening when i start the car and let it idle for a few minutes...and while it's still not major, it almost seems like it's getting closer to stalling. And as usual, the rough idle magically disappears after a few minutes and doesn't come back until I start the car again after a drive. Don't want to end up stuck somewhere! PLEASE HELP!

 

Over time, your engine will develop a gun in the throttle body and plenum. This is caused by splash back when you cut the engine. Check that first. The throttle body will naturally be silver and the gunk that builds up is black. You'll know if it looks dirty. A bottle of throttle body cleaner costs $5. Check that first. All you do is spray the throttle body cleaner in to break the crap up and then wipe the gunk out. It took most of the roughness out of mine the first time I did it.

edit: Also check for the same gunk in the Idle Air Control valve (IAC). It's right below the throttle body. Just be careful if you take the throttle linkage off to make cleaning easier.

 

I would also recomend starting with that because its so cheap and easy to do.

I do NOT recommend putting it off because thats when it gets worse and turns into a real problem.

My first guess is the IAC is gunked up. Get the cleaner and a clean rag (not one that will leave little ***** of cotton all over!) and wipe the throttle body and both sides of the throttle blade clean the best you can. If you know where the IACV is, spray some of the cleaner down into its hole and let it sit. I usually let it sit for 15min (I use and highly recommend Seafoam, always worked great for me but is slightly more expensive). After the 15 min or howeveer long you feel it should sit to clean up the iacv, start the car and run it for a few minutes, maybe take it for a test drive while your at it to see if it still happens.

Now, even if that fixes your problem, you are still stuck with a can of seafoam laying around! The stuff is great because it can be used for just about anything. You can run it thru vacuum lines, thru the gas tank thru the intake, even the oil. If it hasnt been done in a while, i would do it to clean it real well.

The best method for running it thru the vac system is thru the PCV line, because it is high pressure. I always run quite a bit thru here, just to make sure its all as clean as possible.

If you want to run it thru the tank, put the racommend amount for how many gallons your tank holds in it. Its recommended that you have a full tank when doing this. Its possible one of your injectors is gunked up or the fuel filter needs replacing, but if it was it would be more of a constant problem rather than an intermittant one like your having.

Have you even looked thru the through your throttle body and into the plenum? Go ahead and do it, then youl understand why I suggest cleaning the H*ll out of it! Spray into it and clean it the best you can, maybe use a toothbrush to reach back a little further and scrub.

Another great thing you can do with it is clean the combustion chamber. Put a bunch into the intake manifold/plenum (make sure its enough to adequetly feed all 8 cyl.!) and start it for about 5 seconds, then turn it off. Let it sit for at least 15min. If you use enough, what your doing here is letting the seafoam sit inside the intake manifold, intake/exhaust valves, and combustion chamber so it eats up all the varnish/crud so that its cleaner when you start it up again. If its done right and the car is high miles/oil leak into cumbustion chambers (like bad valve seals which these cars are notorious for) or hasnt had this done in a long time, you will notice a nice, crisp throttle response, slightly better power and maybe even slightly better mpgs.

Sorry for the long message, but if you try this and still have the problem we will go from there!

 

Thanks for the great detail guys. I will try this today and let you how it goes after a few drives.

 

you can do the full seafoam treatment also. helped my old jeep out a lot