runs poorly in the rain or cold?

[TENGRAM]

if the code was a 95, it may have simply been because previously the inertia switch was tripped...if 96, may have more serious problems. suggest you reset codes by disconnecting the battery for about 15min. then rechecking codes. also next time it rains make sure no moisture is getting into/around the fuel pump connector that should be tucked up on the backside of your fuel tank, and checking for the same around the inertia switch (under the rear trim), and the fuel pump relay (this one should be under your driver seat, or it may be in the engine compartment below the MAF). would also be a good idea to clean the connectors out with electrical contact cleaner, and coat the pins with dialectric grease.


BTW, the ignition module (TFI) is the rectangular plastic thing mounted to the side of your distributor. the pick-up is inside the distributor; you might want to stick a magnetic screwdriver inside the distributor and see if you bring up any metallic dust, or rust. while you're at it, make sure your distributor cap is seated well so that moisture cannot get in.

 

[dragnazz5.0]

has the car always had this problem or did it just start? does it do it once the car warms up or all the time when the weather sucks? that might help us narrow it down a little but im still thinking its a baro sensor

 

[tmoss]

poor running in high humidity or rain has most often been related to the ignition system high voltage circuit for me.........under those conditions, pop the hood in the pitch dark and look for arcing or a blue-purple haze under the hood. I actually had a new rotor have an internal molding cavity that allowed the arc to go to the distributor shaft from the button artea of the rotor - that took a while to find.

 

[OonDeanisS]

when its rainy out, it runs like crap even when its warmed up, when its warm out, it runs crappy only until it warms up. I dont think its arcing anywhere but ill try it.

 

[90mustangGT]

If you look on the distributer, there is a harness that connects to it. That plastic thing that the harness plugs into is the TFI module. The pickup is inside the distributer, it is the electronics under the rotor button. This controlls your spark, and fuel to a point.

 

[OonDeanisS]

thanks everybody, i think the new baro sensor (70 bucks) cleared it up, but it still backfires through the intake before it gets up to temp, which i heard is usually timing, but i know mine is good. At least the bucking is gone.

 

[jrichker]

Backfiring out the intake is either a valve stuck open or a lean mixture or spark plug wire(s) connected to the wrong cylinder(s). Check compression on all cylinders and then look for vacuum hoses loose, cracked, misconnected. Check the line for the vapor recirculation system – it is easy to knock loose and not see it when you connect the air pump plumbing. If the vacuum line for the EGR valve and the air pump are cross connected, some very strange things can happen. Check the mass air flow electrical connection and see that it is tight, the same goes for the fuel injection wiring harness connectors up on top of the manifold near the firewall.

Sticking valves: If a intake valve is bent, has a bad spring or is misadjusted, the engine will sometimes backfire through the intake. Use a vacuum gauge connected to any convenient spot on the intake manifold. Run the engine at 1000 RPM & look for 18-21 inches of vacuum with a steady needle. A problem intake valve will make the vacuum gauge needle sweep 5-10 inches every time that valve opens or closes.

Lean fuel mixture breaks out into several sub categories:
A.). Vacuum leaks
B.) Air entering the intake without passing through the MAF.
C.) Failure of the MAF, BAP/MAP (Baro or Manifold Air Pressure, same sensor, different name), ACT (air charge temp), or ECT (engine coolant temp). These should set a code in the computer.
D.) Leaking exhaust gases from EGR valve at WOT.
E.) Poor fuel delivery due to bad fuel pump, clogged filter or bad fuel pump wiring. Look for low pressure or fluctuating pressure. Standard injector pressure is 39 PSI at idle, with the vacuum line disconnected from the regulator and capped.
F.) Clogged fuel injectors.- see the cylinder balance test below
H.) Fuel injector wiring problems causing injector not to deliver rated flow.
I.) Computer problems: (computer problems are not common like sensor problems)
J.). ROM has bad data in fuel or timing table. This should also set a code in the computer.
K.) Failure of one or more of the computer's driver transistors for the fuel injectors. No code set on this one. Use a noid test light to test the injector wiring & injector drivers,
L.) MAF calibration off or mismatched to injectors.
M.) ACT or ECT bad. Sometimes the sensors will be off calibration, but not bad enough to set a code. If they falsely read too high a temp, the engine will back off fuel delivery.

Cylinder balance test:
Warm the car's engine up to normal operating temperature. Use a jumper wire or paper clip to put the computer into test mode. Start the engine and let it go through the normal diagnostic tests, then quickly press the throttle to the floor. The engine RPM should exceed 2500 RPM's for a brief second. The engine RPM's will increase to about 1450-1600 RPM and hold steady. The engine will shut off power to each injector, one at a time. When it has sequenced through all 8 injectors, it will flash 9 for everything OK, or the number of the failing cylinder such as 2 for cylinder #2. Quickly pressing the throttle again up to 2500 RPM’s will cause the test to re-run with smaller qualifying figures. Do it a third time, and if the same cylinder shows up, the cylinder is weak and isn’t putting out power like it should. See the Chilton’s Shop manual for the complete test procedure

 

[vristang]

thanks everybody, i think the new baro sensor (70 bucks) cleared it up, but it still backfires through the intake before it gets up to temp, which i heard is usually timing, but i know mine is good. At least the bucking is gone.

JR's above comments are excellent.

I would start with the ACT/ECT.
If the output of one of these is out of whack, it will affect the timing.

If the problem goes away when the engine warms up, then I doubt a valve or fuel issue would be the cause.

Remove the ACT and ECT, and test them with a thermometer in some water.
Or you could just hook a voltmeter to the ACT & ECT pins at the computer. This would also show problems in the wiring harness.



good luck,
jason

 

[OonDeanisS]

how do i test them in water with a thermometer? And where are they?

Also, i installed a water temp gauge into the front top of the lower intake, and i dont remember what i replaced. Did i unknowingly remove the ECT?

 

[jrichker]

how do i test them in water with a thermometer? And where are they?

Also, i installed a water temp gauge into the front top of the lower intake, and i dont remember what i replaced. Did i unknowingly remove the ECT?

All the information you need is in my first reply to your current post. See page 1 of this post, about the 8th post down.

Here's a book that will get you started with how the Ford electronic engine control or "computer" works.

Ford Fuel Injection & Electronic Engine Control 1988-1993 by Charles Probst :ISBN 0-8376-0301-3.

It's about $20 from Borders.com see http://www.amazon.com/ . Select boo...very good, and I found it to be very helpful.