need help, 94 cobra started runnig rough all the sudden

tizzle0469 · Mar 7, 2015

Ok so my cobra isnt my daily, I went out to start it (hasnt run in a week or so) car started and ran great for 20 minutes or so. I shut the car off and put a new belt on it. Went to start it back up and it had a real hard time starting, sounded almost like the battery was low. I finally got it to start and now its running like total crap. The belt is installed correctly. Sounds almost like a vacuum leak or a bad sensor. Its just really weird that it started all the sudden after the belt change. any help would be awesome. Car has 113k and is bone stock.

CC'S95GT · Mar 7, 2015

Welcome to the asylum.
Have you pulled codes?
When was the last time the plugs, wires, cap, rotor, and fuel filter were changed?

tizzle0469 · Mar 8, 2015

I just recently got the car about a month ago, I got it from an inheritance. I don't know what was done last maintenance wise. I bought new plugs, wires, oil change, PCV, belt pretty much all basic PM stuff and I just made it to installing the belt before the problem started...I'm telling you it ran like a friggin top for the last month up until yesterday. I went outside this morning and fired it up for a second, it started and ran GREAT for a few minutes and then started surging again. I have basic mechanical knowledge so I can most likely fix whatever is wrong, just looking for ideas on where to start. The car did sit for awhile before I got it so I kind of expected to have stuff start to break after I started driving it...i guess I can start with the fuel filter and plugs and wires and see where that takes me.

tizzle0469 · Mar 8, 2015

Also it didn't throw any codes

CC'S95GT · Mar 8, 2015

You can have a code without the CEL being on.
You can pull codes with a paperclip if you don't have a OBD1 reader. directions are in the haynes/chilton manual.
The OBD2 port under the dash doesn't work on 94/95 GT's and Cobras.
Clean the MAF and IAC vlv too. maf spray works well.

Did you replace the screen under the PCV vlv. It's hard to see and a pain to remove without needle nose pliers.

Surging usually means a vacuum leak. Ck the clamps on the intake tube at the throttlebody and MAF.

tykempster · Mar 8, 2015

You're SURE the belt is on correct? Odd it would act up after only a belt change.

tizzle0469 · Mar 8, 2015

Yes, triple checked. That's what I thought too...I'm gonna pick up a stethoscope tomorrow and get to searching for a vacuum leak..where's the PCV at? I can't find that dumb thing anywhere

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toyman · Mar 9, 2015

In the block at the firewall. The hose goes to the upper intake. Replace the PCV, grommet, screen and hose.

tizzle0469 · Mar 9, 2015

Awesome thanks

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tizzle0469 · Apr 14, 2015

Changed all plugs, wires, cap and rotor and fuel pump. I removed and cleaned the throttle body, egr and idle air regulator and pulled the upper intake to check the vacuum hoses. Found the problem. Busted vacuum hose on the bottom side. Replaced all intake PCV hoses and she runs pretty damn good now. Still has a little hiccup hear and there so I'm gonna run a couple bottles if injector cleaner through it then probably pull and rebuild the injectors if that doesn't work.