94 cobra without the punch

cyclonemercury · Sep 8, 2007

I recently purchased a beautiful 94 SVT cobra that is all stock and runs great...as long as it is driven normally. if you punch it and try and get her to take off it feels like the captain threw out the anchor. Nothing seems to be there on the power band. the car has 130,000 miles Idles perfect starts fine. I have done a complete tune-up with fuel filter. the engine light comes on intermittently but I had the codes scanned and nothing showed up. I don’t want to just blindly throw in mass air flow sensors or new cats hoping the problem goes away, I’m on a tight budget. any one experienced this problem?
Allan

Pokageek · Sep 8, 2007

Yes. Clean the MAF sensor with alcohol and a cotton swab, VERY CAREFULLY. Try this first, it has solved a lot of folks issues. And congrats, sounds like a nice car. Got any pics?

Yobi1Kanobi · Sep 8, 2007

welcome to the club

cyclonemercury · Sep 8, 2007

cool

Thanks- Im mostly into 60's early 70's fords, troubleshooting this emmissins stuff is beyond my comprehention. I know enough to follow your advice though, Great stuff! pics attaced?

reddy351 · Sep 8, 2007

cyclonemercury said:
I know enough to follow your advice though

All you need to know. There are some really helpful people here. Stay tuned! Welcome!

earleys94gt · Sep 8, 2007

Sounds like you might have a clogged catalytic convertor. Mine was having a similar problem, when I punched it it would not go anywhere. I went with a catted x-pipe and the problem went away. It would also not hurt to clean you MAF, just be VERY careful not to break the sensors. And a tune up might not hurt either.

Good Luck.

WHITE94COBRA · Sep 8, 2007

Have you done any engine testing? Compression check can do wonders, it lets you know a couple things, 1. good or bad cylinder pressure, 2. good or worn rings. I would do that first, also note the color and smell of your sparkplugs, again it lets you know a few things, A/F, rich (black and gas smell), or lean (white and chalky no real smell), you want them to be a brown color.
while the car is started have somebody hold the gas at a constant 2500 to 3k rpm's until the car is to operating temp, note the exhaust temp and smell, just put you hand behind an exhaust pipe, if it's really hot check the cats, if it stays consistently warm to hot it may be something else.

Imho it sounds like clogged cat's, but buying a used car (especially a sports car) you never know the history, someone could have beat the piss out of it, or did a forced induction of some sort causing the rings to wear prematurely, or worse.
Dont be too scared, these motors are very resilient.

RAD · Sep 9, 2007

Cleaning the MAF: http://www.muscularmustangs.com/maf.php

cyclonemercury · Sep 9, 2007

Wow

Hey guys, thanks for the levelheaded advice and the link! This makes working on these things rewarding instead of frustrating.
Maf is Polished up - Power is Back...95.5% I am pleased. I still have an intermittent engine light. Plugs were brown. Acceleration is strong and steady. Still not sure if its all 240 hp though? I can check compression. Cats may be somewhat restricted? I believe they are original with Flowmaster exhaust any thoughts going forward are appreciated.

Thanks again!
Allan

No picks yet, Im still dial up.

SQUEEZE&STROKE · Sep 9, 2007

Sounds to me like 02 sensors...my Check engine light would come on every now and then...Does it not runvery well until it is warm? If you have both these, check the O2 sensors...I replaced mine and it ran MUCH better!

The Green GT · Sep 9, 2007

SQUEEZE&STROKE said:
Sounds to me like 02 sensors...my Check engine light would come on every now and then...Does it not runvery well until it is warm? If you have both these, check the O2 sensors...I replaced mine and it ran MUCH better!

Same here.

and if you do change the O2 sensors, remember this. THERE ARE 2. NO MATTER WHAT THE PARTS STORES SAY.

For some reason all of their computers say there are 4, like on the 4.6 cars.

fastgtfairlane · Sep 9, 2007

the 02 sensors sound like they are indeed going bad. however i would still invest in new mid pipe. if you dont have to pass an emissions test where you live, you can get an off road pipe. either an x-pipe or h-pipe. on a stock car the power increase will be about the same. the main difference between the 2 would be sound. x-pipes will have a higher pitched sound and a little raspier and h-pipe will be a little deeper rumble. i have an off road x-pipe with flowmasters and it sounds pretty good. suprisingly theres not much drone inside the car. when i changed my stock pipe and put the x-pipe on it, it was a nice power increase throughout the rpm range. well worth it.

BlownFiveLiter · Sep 10, 2007

It's probably in need of some O2 sensors with 130K miles. Remember to disconnect the negative battery cable when you replace them, so you can reset the EEC and the adaptive strategy will relearn all of the sensors. IIRC, most intermittent check engine lights are caused by EGR issues. I know mine is, but I have a couple of other codes to take care of as well.

94-302-vert · Sep 10, 2007

I'll second the new H-pipe and O2 sensors...

I had horrid drivability, but after a full iginition tune up, some good fuel system cleaner (a couple of times), changing out the H-pipe, and New O2 sensors it was probably running as strong as at the factory.. (with 125k miles on it at the time)...

SVT32VDOHC · Sep 10, 2007

Cleaning the sensor might help. I wouldn't use a swap because the wires are fragile and thin like a human hair. I just sprayed mine with brake clean and my stumble went away.

Other things to check: Timing, fuel pressure, TPS voltage.

Engel · Sep 11, 2007

i had the same problem, it was the 02 sensors for me...

the way it was explained to me an o2 sensor can be worn , and throw no trouble codes.. They really have to be shot to throw a code

cyclonemercury · Sep 11, 2007

into the sunset.

Car runs good cold and hot. I will do the o2's and front pipes in the near future. Info much appreciated. To be continued...

Voice of Reason · Sep 12, 2007

If the Check Engine light is coming on there's got to be codes somewhere. You said you had it scanned. You didn't have someone hook up a scanner to the port under the steering wheel did you? On our cars those things aren't used. For us you have to jump a couple wires in the engine compartment and then count how many times the CEL light flashes. Do a search on something like "Check CEL*" or maybe just "CEL*" to get the procedure.

5spd GT · Sep 12, 2007

Glad you are working things out...

I wonder if the plugs should be brown though...

94 cobra without the punch

cyclonemercury

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Pokageek

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Yobi1Kanobi

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cyclonemercury

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earleys94gt

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WHITE94COBRA

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RAD

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94-302-vert

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