running rough out of no-where

B

bryantaylor

Registered
95 mark, put new plugs, MSD wires, air filter, fuel filter, etc when i bought the car a few months ago. always ran perfect. well today i was going about 25-30mph and i punched it to get by a car. let off when it shifted to 2nd because the light turned red. as i hit the brakes, the car felt a little rough slowing down and the idle got really rough. continued like that all the way home.

now at first, i was thinking the coilpacks were going out, but after searching it is more likely a bad cam sensor. the roughness is only at idle, and slowing down. idles high, then settles down, you can see a little jumpyness in the tach, and you can really hear it in the exhuast. as soon as you hit the gas, it smoothes out as far as i can tell, but i babied it home too.

so any ideas, suggestions, or anything else before i start testing and doing some diag?
 
Any check engine lights?

The high idle would suggest a bad IAC sensor but it wouldn't make it rough.

Sounds like you have a miss somewhere also. Make sure all the plugs are still in and tight.
 
started it this morning to go to work, idle was a tad high, but i am only talking about a 100rpm or so. ran ok for the first couple of miles. stoped at a red light and the idle got worse than yesterday. at about 500rpm and VERY rough. actually sounds and feels like a pushrod motor with a HUGE cam. you can see 100-200 rpm jumps on the tach. but as soon as you hit the gas, smoothes out.

i have a CEL than comes and goes from my EGR tube being disconected, but thats it. no cel when it has the rough idle.
 
jamies98lsc said:
bad gas maybe?
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filled up the other day, it was running fine untill mid-day yesterday. and only idle is bad. i think i am going to change the cam sensor and mabee the crank sensor too just because they are both cheap and easy. and they both have almost 130k on them.
 
wgr2112 said:
It may also be a good time for a Seafoam treatment or two. There may be some carbon buildup somewhere.
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no carbon. i pulled the intake and cleaned and gasket matched it a few months ago, there was a TON of carbon in it. put all new gaskets on it and copper sprayed them, so they are good.
 
I'd read for codes anyway...not all codes will throw a CEL. I had one (even tho it's a '97), turned out to be a bad COP.... never did light up the CEL, but it sure showed up when I hooked up my code reader. Told me exactly which COP to change...# 7
 
I'd start looking for a vacuum leak or air bypassing the MAF as well as possibly the IACV. Seems odd the IACV would start acting up under those driving circumstances though. I know my 93 had a vacuum leak that puzzled me for quite a while. It would run down the highway OK but idled like crap, sometimes with a high idle as if it were the IACV.
 
sprayed down the intake and vac lines with WD-40, no change in idle. i am starting to think its a coilpack. put my timing light on each wire to see how they were sparking, the two wires nearest the center of the car on the pass side where not sparking evenly. all the wires were tight on the plugs and all of the plugs still looked great.
 
bryantaylor said:
i have a CEL than comes and goes from my EGR tube being disconected, but thats it. no cel when it has the rough idle.
Click to expand...

You say your EGR Tube is disconnected....whats plugging the EGR side...and whats plugging the DPFE sensor tubes?

Sounds to me like a bad vacuum leak and considering it was idling bad and high when you're braking, you could have a bad power booster. Do you hear a "hiss" when you apply the brakes or does the engine idle/run different when applying the brakes?

When I disconnected my EGR tube with my Kooks headers, I had to use a metal plug or else my car would idle like junk and throw a CE light. Almost sounds like you lost whatever you capped off your open ports with.
 
good point there J, the exhuast side is welded shut, but i mught have lost my plug in my EGR tube. i also ordered a set of MSD coils, should be in tomrow i hope. i dont hear any his while on the brakes, and the pedal feels fine. also sprayed the booster with WD and didn't change idle either.
 
WD40 isn't "that" flammable, I usually use light sprays of brake parts cleaner or ether. Probably why you can't get any reaction. 5 bucks says you take some brake cleaner and spray back by the EGR when its running rough and you'll hear the idle kick up.

Also, to properly "lose" the EGR, you'll have to get a Tune and program it out.
 
the EGR system is still there, just no tube. i was hoping not to get a CEL, but still have one that comes and goes, usually at cruise. i will cap off the tube again and install my new MSD coils when i get off of work here in a little while. i hope thats it.
 
DAMNMIT!! still no help. but it was turned in to a more regualr miss now. need to test the wires now.

drove it, heavy low end problems. CEL was on for a few minutes, then went off. ran the codes, still just getting 111.
 
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Just for info.....try to diag which cylinder it is. My MSD wires gave me a wierd rumble, but when I got on it, it was a dead miss (running on 7 cylinders) so I knew it was a wire.
 
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