anyone know about a pre heat system mod

Topic: anyone know about a pre heat system mod (Read 1162 times) previous topic - next topic

anyone know about a pre heat system mod

December 21, 2005, 01:00:14 PM

I have a 86 cougar with a 3.8 L CFI. I've removed the emissions system. Does anyone know about a work around for the air cleaner system that takes in exhaust gases when the car is cold. I would like to connect the exhaust back into the air cleaner throat but I need a system that will turn the valve open in the air cleaner throat to let exhaust gases into the air cleaner when cold and close it after the car is warm. Any ideas ?

anyone know about a pre heat system mod

Reply #1 – December 21, 2005, 01:52:25 PM

Quote from: mpd86

I have a 86 cougar with a 3.8 L CFI. I've removed the emissions system.

What all did this entail? The O2 sensors are considered part of the emissions system, but I bet you didn't remove those.

Quote

Does anyone know about a work around for the air cleaner system that takes in exhaust gases when the car is cold. I would like to connect the exhaust back into the air cleaner throat but I need a system that will turn the valve open in the air cleaner throat to let exhaust gases into the air cleaner when cold and close it after the car is warm. Any ideas ?

I forget the official name of the system, but it doesn't intake exhaust air into the engine. It imbibes warm air that has passed over the exhaust manifold to heat up the intake faster. I'm not really sure how you've disabled this in the first place. Your air cleaner comes with a temperature sensor and vacuum lines to run to the valve.

anyone know about a pre heat system mod

Reply #2 – December 21, 2005, 03:37:22 PM

Dosen't a CFI 3.8 have a "heat stove" over the passenger side exhaust manifold and a tube conected to the air cleaner? If so just put that back together and vola intake air is heated:D

anyone know about a pre heat system mod

Reply #3 – December 21, 2005, 06:44:28 PM

I kept the oxygen sensor part of the emissions system in place.

The 3.8L CFI has a pipe that comes from the passenger exhaust into the throat of the air cleaner. Unfortunately, the device on the throat that controls whether hot air or outside air passes through to the air cleaner works on vacuum that is tied to the air cleaner, vacuum pump and a pre heat device on the driver's side intake manifold.

I'm debating on whether to partially force open the swinging mechanism that is in the air cleaner throat so that it can always take some hot air into the air cleaner at all times during the winter.

Any ideas ?

anyone know about a pre heat system mod

Reply #4 – December 21, 2005, 08:42:14 PM

hook up the heat stove and then run you a choke cable to it so you can open and close it as you see fit. Best set up I can think of for what you want on the cheap.

anyone know about a pre heat system mod

Reply #5 – December 21, 2005, 09:34:22 PM

I'm still not sure what your problem is, so I slapped together a PowerPoint to see where the gap of understanding lies.

1 - Vacuum line that tees into vacuum source
2 - Vacuum distribution [full vacuum]
3 - Line that runs into the temperature sensor [full vacuum]
4 - Temperature sensor [varies vacuum to motor depending on temperature]
5 - Line running to vacuum motor [zero to full vacuum]
6 - Vacuum motor
7 - Warm air inlet

It sounds like you've got no place to run #1 to. If that is the problem, just run it to any vacuum source.

thanks for info

Reply #6 – December 22, 2005, 09:36:29 AM

Your right about the vacuum source. I don't have a vacuum source plus my plan since I've removed almost all of the emissions system is to next remove my vacuum pump and shorten my main belt.

Do you know if the air cleaner throat system and vacuum motor operates in the winter time more as an on or off mechanism or in a variable mode adjusting the valve opening slightly.

I suspect more in an on or off so if so my plan was to jury rig the vacuum motor partially open all the time for Winter in Michigan.

anyone know about a pre heat system mod

Reply #7 – December 22, 2005, 09:43:38 AM

vacuum pump?? are you referring to the "air pump?" that has nothing to do with your engines vacuum.If your vacuum block is full, just tee off one of the lines.:D

anyone know about a pre heat system mod

Reply #8 – December 22, 2005, 11:13:45 AM

Quote from: mpd86

Do you know if the air cleaner throat system and vacuum motor operates in the winter time more as an on or off mechanism or in a variable mode adjusting the valve opening slightly.

It is variable. It tries to keep the incoming at 70 deg. F

As cougarman said, just tee off of another vacuum line.

Added edit:

The vacuum pump you are referring to is the Thermactor AIR pump. On start-up, it pumps air into the exhaust manifolds until the ECT (Engine Coolant Temperature) sensor reads warm enough or the timer runs out [pumping air into the manifolds while the oxygen sensors are operating will give a false lean signal and make the car drive poorly]. This air (and the rich mixture that the computer is already commanding) help to light off the catalytic converters quicker to give you lower emissions. Once the engine is up to temperature, the Thermactor system directs air into the catalytic converter. The extra air is needed due to the coarseness our EECs fuel/air control. On WOT, deceleration, or after a certain time spent idling, the Thermactor system dumps the air to atmosphere.

mpd86, I recommend you pick up this book from Charles Probst. It gives a good overview of our vehicle's fuel injection system.

thanks

Reply #9 – December 22, 2005, 11:41:19 AM

Thanks for the info. Appreciate your time.

anyone know about a pre heat system mod

Reply #10 – December 23, 2005, 12:47:19 PM

Quote from: mpd86

Unfortunately, the device on the throat that controls whether hot air or outside air passes through to the air cleaner works on vacuum that is tied to the air cleaner, vacuum pump and a pre heat device on the driver's side intake manifold.

The pre-heat device you mentioned is the EHC (Exhaust Heat Control). When the ECT is below a certain temperature, the EHC valve actuates and lets warm exhaust gasses pass under the manifold. This acts to warm the manifold up quicker for better drivability/mpg in the cold. The valve doesn't actuate at WOT or when the coolant is warm.

Now, I can see why you want to eliminate the Thermactor system as it gets in the way and doesn't help drivability too much...but why the EHC? Eliminating it only serves to hurt your fuel mileage and drivability. (Same reasoning goes for the EGR)