98 Cobra trouble, need some advice

[phinhead34]

I have a 98 Cobra which I took to get painted at my friends body shop. He had the car there for about a month, anyways when I got the car back it had a bad battery, vacuum leak, and was stalling on me on deceleration. Battery was replaced, vacuum leak was fixed, but I still have issues with it stalling on me on deceleration and when I accelerate hard on it, it loses power at like 4k rpm and starts to hesitate and/or sputter. I cant get my rpms above that or it takes forever. Im kinda at a loss and need some advice from you guys. Could it have lost its tune? I have long tubes, RAI, 4.10s, off road H-pipe, flow masters, pro 5.0 shifter, 255lph fuel pump. Any advice would be grateful. :beer:

 

[96SVTKB]

Did they paint the engine bay? I would start by making sure all electrical connections are plugged in ( to include plugs and coils and egr). As for the tune, it shouldn't matter at 4k rpm, stock or otherwise it should still pull at 4k.

 

[crazycarlo]

well if the battery went dead it could have messed the tune up. I know its not suppose to but I have had it happen to me before I thought it was just a glitch. However id take the alt off and have it tested. It could be bad as well which I have heard will cause problems if its not charging all the way.

 

[Wynn]

Should still run fine even if it reverted back to.the stock tune. Check for more vacuum leaks to start.

 

[SVT Pille]

This may sound a little obv but check the MAF, TPS and IAC connections and make sure they're all good.

 

[phinhead34]

I've checked the MAF, IAC, & TPS connections.The engine bay was untouched other than them detailing it. I havent checked the alternator, and im going to swap out the spark plugs and wires and see what happens. Its driving me nucking futs!!!!!

 

[Shake&Bake]

My question would be why did it have a vacuum leak? Was something disconnected? Maybe bad gas?

 

[phinhead34]

My question would be why did it have a vacuum leak? Was something disconnected? Maybe bad gas?

The vacuum leaks were one by the pcv valve and another on a hose that was worn and showed up after the detailing. Which that was not the problem. I have dropped my tank to make sure strainer was clean and nothing dirty in the tank.

 

[cummins96cobra]

Thats weird i just got my cobra like last week and it feels like it stops pullin and takes forever after 5500 or 6 i wonder if this is normal

 

[phinhead34]

Thats weird i just got my cobra like last week and it feels like it stops pullin and takes forever after 5500 or 6 i wonder if this is normal

I never had that problem before, my car would pull pretty hard. Mine now stops pulling at around 4000 and if its hotter outside its even worse. :cuss:

 

[BraMas]

are you throwing codes? ie IMRC stuck closed code? A few years ago I plugged one of the coil packs in wrong yes I understand you are not supposed to be able to do this but my plug is broken and will plug into the coil either way. And my car did exactly what you are describing. I started throwing parts at it and nothing and for some reason unplugged the coil and turned it over and all problems went away

 

[phinhead34]

are you throwing codes? ie IMRC stuck closed code? A few years ago I plugged one of the coil packs in wrong yes I understand you are not supposed to be able to do this but my plug is broken and will plug into the coil either way. And my car did exactly what you are describing. I started throwing parts at it and nothing and for some reason unplugged the coil and turned it over and all problems went away

I did have a code with the imrc, I'm going to look into that, thanks

 

[carkrazy]

You mentioned that they detailed the engine bay which means they probably used degreaser and hosed it off with water via hose or pressure cleaner. I would definately check the plugs as water could have gotten down where the plugs are and puddled up some water.

 

[cpSTACK]

I would try using a spare spark plug and pulling wires one at a time, plugging it in a make sure your getting a good spark. Sounds like a coil pack or a wire acting up to me. I'd check everything else out prior to pulling plugs just to avoid the possibility of stripping any threads.

 

[Salmonsnake]

My car did this when i first got it and i put plugs and wires on it, cleaned the MAF, seafoamed the engine, put a new fuel and air filter in it and one of those things fixed it. Good luck !

 

[mwolson]

Is your speedometer working?

 

[noslow50]

I would look at the IMRC plates too, they should open around 3200 rpm to let more air in the intake. I have seen people on other forums that have had a promblem similar to the one you describe, and alot of times it will be a carbon deposit that builds up and doesnt allow the butterflies to open.

 

[phinhead34]

My speedometer has been acting eratic, i have one ordered to replace the one i have. I will keep you guys updated, I appreciate your help!

 

[crazycarlo]

well one way to see if its the imrc's is to seafoam the car. I know its not anywhere near as good as taking them off to clean them but maybe itll loosen something up if it is them and give you an idea that they are the culprit.

 

[mwolson]

The VSS signal from the tranny goes to both the speedometer and the PCM.

The PCM handles going closed throttle differently when you are moving than it does when you are stopped. This is so the load from the power steering and power brakes will not cause the engine to die. That extra load is not on the engine when you are stopped, so it drops the RPMs faster. If your PCM doesn't see the VSS signal, it assumes you are stopped and it drops the RPMs too fast, and the load from the steering and brakes will kill the engine.

So you probably need to fix your VSS or the VSS wiring rather than the speedometer.