Exhaust Loading Up And Dying.

[jamestaylor47]

I bought this car a last night and I drove it 200 miles and it ran fine no problems at all it's the 96' 5speed 3.8 and guy I bought it from said when it gets into triple digit weather it loads up and does bc they took the whole pipe off and there isn't any pipe right after the cats. And sure enough it gets to 100 degrees and it loads up and dies...do you think putting the stock pipe back on would fix it or was she just pulling my leg and something else is wrong with the car?

 

[g96v6-250k]

i would not remove any 02 sensors. see if all 4 are in use or missing.

 

[jrod2423]

you definately want the full pipe system especially on a v6 because a motor needs a little bit of back pressure to keep the valves warm because if there is no back pressure then the valaves may get warm then cold then warm and that will cause them to warp, you can take the muffler off and have pipes all the way back, so yeah it sounds logically.

 

[g96v6-250k]

could very well be a sensor failure like the crank/cam position sensor. i dont think a failed coil would make it stop firing all pistons out of nowhere. fuel pump might be another culprit for it dieing. what makes you think its is "loading up"?

 

[Killian Korth]

That doesn't sound too good. Take it from me, valve-warp is a biznitch. Back-pressure good. No exhaust system, bad.

Even if that isn't the problem you still should get that taken care of.

 

[jamestaylor47]

Not really loading up but it will start when it does this the whole car shakes for a few then dies and if you give it has. It dies. I put the stock pipe back on but of coarse it's cut off right after the muffler but at least it's a little longer. But it still died today but it started right back up after about a minute instead of 20 like last time

 

[jrod2423]

it could be a sensor falirue because electronics do fail, but with the circumstances and the information given its more likely that his valves are either warped or pretty close to it and then, he'll just need a new motor because thats just about as easy as tearin his apart to fix it.

 

[fiveohwblow]

I thought this was a thread about too much coke.

I have nothing to offer.

 

[jrod2423]

if it keeps dieing within the next few weeks then the valves are probably gone, and u dont need the muffler just the small factory pipe will due

 

[g96v6-250k]

so you say its run quite fine untill it starts to miss-fire and then it dies? figure out what codes the pcm might have stored.

 

[Killian Korth]

I thought this was a thread about too much coke.

I have nothing to offer.

I laff'd

 

[kramer]

you definately want the full pipe system especially on a v6 because a motor needs a little bit of back pressure to keep the valves warm because if there is no back pressure then the valaves may get warm then cold then warm and that will cause them to warp, you can take the muffler off and have pipes all the way back, so yeah it sounds logically.

ive never heard this , can u tell me where you got this info?

 

[jrod2423]

my dad and uncle told me about this when i was experimenting with my exhaust system, and they warned me that if the valves didn't have a constant heat or pressure and they were aloud to warm and cool on and off then they would warp and ruin the motor

 

[kramer]

well i dont know about it having to have pressure though , back pressure is bad on an engine no matter what , mostly because it pushes spent exaust gasses back into the cylinder and thats just not good in any situation and thats all backpressure does , but as for heat , ya has to be a certain length of pipe or else it will cool to fast when being shutoff and that is what will cause it to warp , as long as you have pipe thats at least long enough to reach the backseat you should be fine , and of course mufflers will help slow the cool down and so will cats , warping doesnt happen while you drive , it happens after you drive and have shut down the engine

 

[wmburns]

This is silly to think that cutting off the exhaust pipe after the cats will cause it to run poor in hot weather due to "back pressure". Of course this assumes that the exhausted isn't blocked.

To me a plausible theory might be the hot exhaust gases are heating up the fuel line causing vapor lock.

What has been done to CONFIRM:

• the fuel rail pressure intake vacuum reference line is connected and leak free?
• the Input air temperature (IAT) is giving accurate information to the PCM
• The engine coolant temperature sensor (ECT) is giving accurate information to the PCM.
• There are no exhaust leaks ahead of the front O2 sensors.
• That the cooling system is in good repair and most importantly there isn't ANY air trapped inside the motor.

An ODB2 scanner is likely to make short work of this problem.

 

[Mustang5L5]

The exhaust isn't the issue. Chopping off the exhaust will cause you to lose a TON of torque, but not cause the car to stall like this. When i was young and dumb, i used to drive around with open headers on my 5.0. Car ran the same, just didn't have torque.

Still, i'd recommend getting a full exhaust. Your powerband will shift downwards slightly giving you the feeling that you gained low end torque. On a street car, you want torque.

is the check engine light on? Any other symptoms or potential causes not related to the exhaust?

 

[blacksheep-1]

I've actually started an engine without any exhaust on it to see if it would at least start. then shut it off immediately to prevent exhaust valve warpage. I don't think that you have to worry about an aftermarket exhaust (or a shorter exhaust, or an exhaust with no muffler) warping the exhaust valves, because IMO it's just not going to happen.

 

[kramer]

here we go again with the back pressure myth , dont feel bad we all believed it at one time or another

http://www.gomog.com/allmorgan/exhaustbackpressure.html

 

[kramer]

oops sorry thats the wrong one

http://mechdb.com/index.php/Exhaust_back_pressure_myth

 

[jrod2423]

neither of these covered the issue of back pressure that im talking about, what im talking about is if hot exhaust fumes are pulled away to quick then you get colder air then what the engine is running at being pulled in instead and this is where the warping can also happen, but most deffinetly when the motor is shut off also, as stated above