HELP WITH MY CAR LOOSEING POWER BACKFIRES

How long has it been doing this and what your current battery voltage. With such little information so far, it sounds like classic symptoms of a dead alternator.

At the top of this forum is a thread index. Look in that index at Jrichkers thread for surging idle.

There are lots of diagnostics within that thread. Things that you can go through and check for fuel, vacuum, and electrical issues.

With no idea where to start; doing some looking into individual systems may help.

There are no cluses to your current configuration, You could be carb or EFI. That's why it is a good idea to use the sig under the user control panel (User CP) option. It allows you to post your car year & mods, which help greatly when troubleshooting things. No, it is not there for us to snoop and see any "Secrets" you have hidden away under the hood. Be a good stangnetter and update you sig for future reference & don't keep us guessing.

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.

Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.

Check the firing order to make sure that the spark plug wires aren’t crossed.

The HO firing order is 1-3-7-2-6-5-4-8.
Non HO firing order is 1-5-4-2-6-3-7-8

Just in case you aren’t sure, here’s the way to know if it is an HO or non HO engine. Remove the #1 & #3 spark plugs. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Slowly turn the engine until the TDC mark and the timing pointer line up. Mark TDC on the balancer with chalk or paint. Put your finger in #3 spark plug hole and crank the engine 90 degrees. You should feel pressure trying to blow past your finger. If you do not feel pressure, repeat the process again. If you feel pressure, it is a HO engine.

No pressure the second time, remove spark plug #5. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Put your finger in #5 spark plug hole and crank the engine 90 degrees. If you feel pressure now, the engine is not a HO model, no matter what it says on the engine.

Using a small carpenter or machinist square to mark the harmonic balancer off into 90 degree sections may be helpful here.

A 15/16 deep socket & breaker bar or ratchet may be used to turn the engine.

Sticking valves. A valve stuck open will cause a reduction in vacuum at 1000 RPM. You should see 18"-20" of vacuum at 1000 RPM. With the vacuum gauge hooked up, look for the needle to sweep regularly. This is because the valve is open when the cylinder starts to make compression. That reduces the vacuum and makes the needle sweep every time the bad cylinder comes up on compression stroke.

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.) Clogged fuel injectors.
F.)Fuel injector wiring problems causing injector not to deliver rated flow.
G.) Computer problems: (computer problems are not common like sensor problems)
H.). ROM has bad data in fuel or timing table. This should also set a code in the computer.
I.) Failure of one or more of the computer's driver transistors for the fuel injectors. No code set on this one.
J.) EGR not opening at cruse power. The computer adds timing advance to compensate for the slower burning speed of the EGR diluted intake charge.
K.) MAF calibration off or mismatched to injectors.

87notchback said:

well thanks its not a mass air car its a 87 and do you have anywhere i can get a picture of the vacuum route in detail i got rid of the smog and ac so there are some vac lines that go to nothing

Click to expand...

Mass Air and Speed Density engines backfire for the same reasons, so don't disregard the comments I posted.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/

Diagram courtesy of Tmoss & Stang&2birds



ttp://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif