Slow SHO when in warmer temps: Any idea about this?

[DJ SHO]

Now I know the SHO runs better (faster) when the air temp is cooler but my car is ridiculous. When we had nice 80 degree, average humidity days, my car was slower than crap. Throttle response was lousy, pickup sucked, and overall ran under-average. Barely get a chirp from the tires off the line. Now when it's damp out, like after a heavy rain, or when the air is nice and cool (like under 55 degrees) my car runs great. Everything responds like it should. Tranny shifts are smooth, car has a lot more a$$ to it, the throttle response is good. Now in either case, the motor isn't running hot. The gauge indicates normal temp range, usually no more than 3/8 of the way up on the gauge after it's warmed up. O2 sensors are new, K&N is clean, t-stat is working fine, water pump is fairly new. I'm clueless here. Does the SHO use a Barometric Air Pressure Sensor? If it does don't you think it could be bad? I need to run these codes to see what I come up with. What about a bad EGR? If it was bad would it cause these symptoms?

Like I said, I realize that the SHO runs better in lower temps, but I don't think there should be this much of a change from warm air to cool air. It never was this bad last year. Any Ideas?

<small>[ October 10, 2002, 12:33 AM: Message edited by: DJ SHO ]</small>

 

[projectSHO89]

The SHO uses a MAP (Manifold Absolute Pressure) sensor which does the same thing as the BAP. It is mounted top dead center on the firewall.

The SHO also uses a ACT (Air Charge Temperature) sensor that tells the EEC-IV the temp of the incoming air. It is mounted on the stock air box.

You can disable the EGR completely for diagnostic purposes by removing the valve from the intake, inserting a blocking plate, and re-installing the valve.

Over-oiling a K&N has been known to cause some goofy problems with oil contamination of the MAF sensor and the ACT sensor in other Ford vehicles that I have experience with. You might try cleaning both of them with some cleaner. FWIW, I use brake parts cleaner to clean the sensing wires in the MAF. A gentle spray usually cleans them nicely.

Steve

 

[V6&V8SHO]

My 1993 atx sho does the same crap, slow as **** in the hot weather, once it cools down its a friggen bear.

 

[sdpatt]

The SHO engine has a barometric absolute pressure (BAP) sensor. It measures the pressure of the atmosphere from its location on the firewall. A manifold pressure sensor must be attached to the manifold to measure that space.

Regarding the loss of performance in the warmer temperatures, I must ask what grade of gasoline are you running. The warmer, drier air will more quickly challenge the spark advance and result in greater ignition retard and the subsequent loss of power if the octane is not sufficient to prevent knock at the ignition advance settings the ECC dials in for optimum performance.

Even a new SHO engine requires 91 octane for optimum performance under all conditions. Older engines may require an even greater octane rating to prevent ignition retarding due to knock. Especially at the warm and dry conditions at which you are experiencing the power loss.

 

[DJ SHO]

Thanks SDPatt for the info. I've never run anything less than 93 in my SHO.

So what can be done to help the situation other than higher octane?

<small>[ October 10, 2002, 02:55 PM: Message edited by: DJ SHO ]</small>

 

[projectSHO89]

Actually, from what I've been able to infer from the 89 EVTM, is that the SHO version uses a MAP sensor (same sensor as the other Taurus engines) but has no connection to the intake manifold. This leaves the sensor (while still a MAP sensor from its design and manufacture) functioning as a barometric pressure sensor only. In fact, the emissions decal on my 89 does refer to it as a BAP, while the EVTM calls it a MAP.

Confusing, eh....?

In the versions of the Taurus where it is connected to the intake, it measures barometric presure during the Key On, Engine Off timeframe, then measures the manifold pressure (vacuum) once the engine is running.

See page 69 of the 89 EVTM for this reference.

The nomenclature was probably updated for later model years...I hope.

Steve

 

[shojuan]

DJ SHO:
Thanks SDPatt for the info. I've never run anything less than 93 in my SHO.

So what can be done to help the situation other than higher octane?

Put a bottle of water wetter into your cooling system. Improving the heat transfer can lower your head temperatures and thus lower octane demand. Using a greater proportion of water to coolant would help too but I wouldn't recommend this in New York unless you are willing to adjust your ratios for spring/summer and fall/winter plus you need to make sure you have enough corrosion inhibitors for the lower coolant ratio (the bottle of water wetter will do this).

Put in a bottle of Redline complete fuel system cleaner (used to be called redline SI-1. It still has SI-1 on the label in small print at the upper left corner). After that keep your car on a steady diet of 1.5 oz SI-1 to 10 gallons fuel. Keep an empty bottle of SI-1 and pour up to the first "G" from the bottom of the bottle to get a dose for 15 gallons of fuel. I used to use 1/5 a bottle in every tank in my old camry to keep octane requirement down, injectors and valves clean. Now I'm a cheap skate so I stick to the 1 bottle per 100 gallons dosing in my SHO ever since I did the 60K.

Every SHOwner should be using this product at the maintenance dosing schedule in every tank. Especially after getting the intake clean during a 60K. Just shop around to get the best price. It really is that good of a product.

Another thing DJ SHO: You might want to try the decarbon procedure. Excess carbon will increase octane demand.

Rick

 

[projectSHO89]

Every SHOwner should be using this product at the maintenance dosing schedule in every tank. Especially after getting the intake clean during a 60K.

FWIW, a fuel-based cleaner will only keep a very short section of the HEAD's intake ports clean. The injectors are located only an inche or so from the intake valves so there is very little cleaning of the "intake" possible with these particular products.

The intake cleaning procedures that rely on a vacuum line port near the throttle body will actually do something for more of the intake.

BTW, where do you guys find the "Sea Foam" product I've seen mentioned?

Steve

 

[shojuan]

Ah ha! You do not know the power of SI-1! It is not a fuel based product! It's composed of polyol ester based synthetic oils and detergents. The detergents will actually survive the combustion process. Blowby gases laced with this stuff will recirculate though the PCV system and exhaust gases through the EGR (if you have EGR). Should help keep stuff from baking on the inside of the intake. Lubricates upper cylinders too.

RE: The seafoam. You can find it at NAPA. They might have similar containers of different stuff. Look carefully at the bottle and there will be a list from top to bottom (injector cleaner, carburetor cleaner, carbon cleaner, fuel stabilizer, de-icer anti gel, upper cylinder ****, frees lifters - rings, dries oil and fuel). Make sure to pick the bottle that has the "carbon cleaner" part of the list highlighted in red.

Rick (the Red Line Devil!)

 

[AutoSHO]

shojuan:
Ah ha! You do not know the power of SI-1! It is not a fuel based product! It's composed of polyol ester based synthetic oils and detergents. The detergents will actually survive the combustion process. Blowby gases laced with this stuff will recirculate though the PCV system and exhaust gases through the EGR (if you have EGR). Should help keep stuff from baking on the inside of the intake. Lubricates upper cylinders too.

RE: The seafoam. You can find it at NAPA. They might have similar containers of different stuff. Look carefully at the bottle and there will be a list from top to bottom (injector cleaner, carburetor cleaner, carbon cleaner, fuel stabilizer, de-icer anti gel, upper cylinder ****, frees lifters - rings, dries oil and fuel). Make sure to pick the bottle that has the "carbon cleaner" part of the list highlighted in red.

Eh... My car had SL-1 used in it every tank before I got it. I pulled the intake off for other reasons right after I got it, and all that the cleaner had done was kept the spray area of the injector clean. The intake was still dirty, and it does not work miracles. Sorry to burst anyone's bubble... Its a fuel system cleaner.

 

[shojuan]

I didn't say it would keep the intake clean, just that it would help keep it clean. I guess I should have said it might help keep the intake clean Guess I got carried away, sorry folks!

I love the stuff, it is a good product to use on a regular basis. Should at least keep the injectors and valves clean. I still look forward to doing a complete intake cleaning my next 60K.

Rick

 

[Fine89]

Are you sucking air from the fender with the stock box or from the engine area with a K&N cone?

 

[DJ SHO]

Stock box with K&N drop-in.

 

[Slo-Sho]

My car is sloooooow too.