[boss102371]

ok i have a 94 sc. the car is really acting up lately. at a stop light the car will come off idle at around 750 rpm then click and drop to about 500rpm. when it hits the 500 range the car will act like its a diesal, just surgging.(sorry if the spelling is bad, its been a long night in MA) when i take off from the light it radomly misfires and when its on the highway it will jerk too. this problem happens at random, but will last most of the ride. sometime out of noware i will hear a click and the car will run great, but only for a short moment. I have done plug, wires, and barmetric pressure sensor. passange side of the exhaust has no cat on it due to rutted cat but the passange side has one(but will be remove on sunday with another test pipe). i am throwing a check engine light but its for the tranns, but nothing else. tomorrow i will set up my camera and try show you what im talking about. ill try to download the video to this post.
thanks
dave

 

[ZeroRain]

cam and crank sensor done yet? how about the DIS module? maybe even a coil pack. i dont know if its the same but when i had my 89sc i had a weak spark until i did the DIS module. could be why your getting the misfire/ low idle.

 

[007_SuperCoupe]

The surging idle is usually indicative of a vacuum leak. They are easy to form and hard to find! Best way to find it is to pressurize the entire intake system and spray spoapy water on each joint. There's a lot of info on it over on SCCoA.

The random miss sounds like your DIS is going bad. It's not very common on the '94-'95 SCs since they relocated it from the accessory bracket. When was the last time that you changed your plugs and wires? Stock gap on the plugs is .054" and when I changed mine for the first time, the gap had widened to an average of .073"...that can cause a miss pretty quickly too.

Best thing to do is get a code reader and find out for sure what the CE light is for. 99% of the time, a CE light means there's something wrong with the emissions (most common being O2 sensors or EGR). I've never heard of a CE light for a tranny issue...but I could be wrong too.

Unfortunately with the SC, a lot of the problems that are encountered have the same symptoms. It's really hard to diagnos on the internet like this. You do have a couple areas to start looking at now though. Good luck to you.

 

[CougarXR/7]

Dis

Sounds one problem is the DIS..................changed mine and the miss/stumble was gone.

 

[TampaBear67]

Just My Opinnion

Hey Guys, I'm kinda new here, but I have looked in several times since I have Owned a number of Thunderbirds. Even though I'm only 39 I've had 8 Thunderbirds in my life, a 64 Coupe, 65 Coupe, 66 Town Landau, 84 Fila 5.0, 87 and 88 5 Speed Turbo Coupes, an 89 SC Auto, and my 97 LX 4.6.

My 89 SC is doing the same thing. It Ran fine untill the Transmission went out at 100k. I had the transmission rebuilt and when I got it back it started acting this way. Since I have my 97 Thunderbird LX 4.6. I haven't really fooled with the SC but now I'm going to have to go check this out.

I recently had an issue with my 97 after replacing the P.O.S. Intake manifold that cracked on me at the Heater Hose Outlet. It started running really crappy, and missfiring on Cylinder #1. Everyone told me the same thing, Plugs, Wires, Coil Packs, and Vacuum Leaks.

Well I did the Plugs, No Change! I found a Vacuum Leak and fixed it, No Change! So I did the Plug Wires, even though I had replaced them less than 30k miles ago, and I am Happy to say that it's Running Great! Better than the day I Bought it!

So needless to say, I'd tell you to Start with what i'm planning to do. I'm gonna do the same with the SC I did with my LX. Plugs, Wires, and Check for Leaks, and Hopefully get The SC back on the Road!

 

[boss102371]

do you guys know where the DIS module is located on a 94 sc?

 

[007_SuperCoupe]

It's on the passenger side fender well. I'm skeptical that the DIS would be your cause. Those don't go out on '94-'95s like they do on earlier models. Earlier models the DIS was mounted on the accessory bracket. You can have it tested, and I would for sure, to see if it is ok. Testing is free and a quick way to isolate the problem if that is the problem. If it is okay, then you've got to start looking at things like the O2 sensors, plugs, wires, etc. There's way too many things that have the same symptoms when they go bad on these cars!

 

[boss102371]

thanks for all the info. i just removed the other cat but it still runs like crap. the thing i dont get is why its not throwing a code. I'll test the DIS and see where the gets me.

 

[007_SuperCoupe]

Codes are emission related...if it's not directly related to the emissions, it generally won't throw a code. Sometimes you'll get one for a coil failure (which really means the DIS). I've had several sensors go out on me...no code for the sensor, and sometimes a code for a symptom.

I think it still sounds like your DIS is failing you. It's unusual in a '94+ but not unheard of. One thing you might also check is the plug wires...make sure they are seated completely on the plugs. I've had it happen where I thought it was on there, and wasn't... That caused similar issues as well.

 

[4.3Lcougar]

Codes are emission related...if it's not directly related to the emissions, it generally won't throw a code. Sometimes you'll get one for a coil failure (which really means the DIS). I've had several sensors go out on me...no code for the sensor, and sometimes a code for a symptom.

I think it still sounds like your DIS is failing you. It's unusual in a '94+ but not unheard of. One thing you might also check is the plug wires...make sure they are seated completely on the plugs. I've had it happen where I thought it was on there, and wasn't... That caused similar issues as well.

this might sound dumb, but check your plugs again and make sure they are all the way on. that could contribute to the clicking...IE spark jumping. and possibley with the misfire.....IMOP thats where id start...just my 2 cents..

 

[boss102371]

well i replaced the coil pack and now it runs like a champ. thanks for all the info guys.

 

[boss102371]

ok car still runs like crap. i had the computer read again and its telling me that bank 1 o2 sensor is reading lean and also reading rich. i also just swapped to s 5 speed from an auto and i got all kinds of trans codes but the computer hasnt been flashed yet. so anybody got any ideas????

 

[Midgetchaser]

did u swap in the 5 speed computer?

 

[boss102371]

no i couldnt find a computer to swap it with. im going to get the computer flashed when i move to florida. i had the problem before i did the swap and its worst now cause of the 5 speed, direct drive and all that.

 

[boss102371]

i just replaced the idle air control valve and it wont idle less the 1500. the it revese to 2500 and wont go down. any ideas?

 

[007_SuperCoupe]

Did you get the IAC from the dealership or a parts store? If you got it from a parts store, it's not the right one, no matter what they tell you. The SC version is a dealer only item. It's cataloged wrong in all the electronic systems the parts stores use...I learned that lesson the hard way...

Also sounds like you've got a O2 sensor going out or already gone. Replace them all and be done with it. Not sure if the '94s had a third sensor or not...

It also sounds like you need to get it tuned pretty soon. SCT has the best option for tuning a SC...there's a few people who are capable of that (Dave Dalke is my recommendation) and can get it running smooth. But you definitely have to have all the mechanical and sensor issues worked out first.

 

[boss102371]

ill replace the o2s when i get to orlando. do you know anyone who tunes down in the FL area?