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injector info. The injector info. is contained in the link below. Many Thanks to Gale for putting all this info on his site. BTW, I love my Stang injectors. However, yours are probably OK so don't feel the need to replace them. I have a set of good BMW injectors that were cleaned and tested within the past two years. If you feel like you need injectors adn can't find the mustang injectors, let me know and I'll make you a deal on my injectors.
Air Flow Meter Testing:
I'm feeling pretty sure you are running too lean from the dessription of your spark plugs. It is not uncommon for our cars to eventually evolve into this state. My 535is was the same way until I adjusted the AFM. However, before you test the AFM, you need to make sure you have NO AIR leaks anywhere. Check and double check!
A simple way to determine if you NEED to ajust the AFM is as follows:
- Remove the air filter housing and elbow leading up to the AFM.
- You will probably have to put a small piece of wood or rubber under the AFM to support it on the Valve Cover.
- With the engine idling, gently push on the AFM flapper-door. If the idle rpm increases and the engine smooths out, then your AFM needs adjustment.
- An additional test. Repeat the above step, but hold the throttle as steady as possible at 3,000 rpm. If the highest rpm and smoothest operation occur only when you advance the door position, then you need an AFM adjustment.
This information was originally posted by Bob on April 28, 2000 at 15:08:12 from the E24 board and I find it very close to the way I've performed this task. Thanks BOB!
Several things I NEED to point out. The toothed wheel mentioned below MUST be held firmly as you loosen the retaining. If you let this wheel slip uncontrolled or rotate freely, you will be SO SCREWED! Also, I found that I only had to adjust my wheel by two cogs, i.e. VERY little. What this did, was loosened the resistance of the flapper door and hence enriched my fuel mixture slightly. You will be tempted to adjust it much more, but you shouldn't even think about doing this. Small increments are better. I would try only one cog first and you can always increase another cog or two if you feel the need. Also, you will want to rotate the wheel in a clockwise manner. This will loosen (or enrich you fuel mixture) the flapper door. IMPORTANT: Be sure to use some type of bright paint to make a mark on both the wheel and the reference hole, so you will know where you started, in case you want to return to the original wheel position. I've scanned and posted a diagram of what you'll see under the black cover.
Also, I chose to not reseal the black plastic cap on the bottom of the AFM. Rather, I secured it temporarily with a couple of linked zip ties wrapped around the AFM in such a way to hold the cap on. I then ran the car for a few days to see how it perfomed. If I like it, I took the zip ties off and resealed with silicone sealant. I've done several this way and it is pretty straight forward.
Additionally, I used the idle method Bob menioned below. I'm a KISS guy and this approach worked well for me. Seemed much Simpler!
Finally, If you have any problems, shoot me an email.
Calibrating the AFM
Theory:
The amount of fuel fed to the engine is determined by the 1)FUEL PRES and 2)PULSE WIDTH (length time wise) to the injector.
The pulse width is affected by several factors (inc. but not limited to PROM, Temp Sensor, O2 Sensor, AFM Flap Position*...)
*Up to about 3500 rpm only
We are going to modify the Flap Pos'n Sensor by making LESS air open the flap WIDER (Wider=More Fuel). Usually these engines are set at the edge of leanness when new, and as they age, they go leaner, making for poor performance and idle. By "calibrating" we are simply maximizing the engine output for the other parameters using the AFM to "tune" the system.
Doing the Job:
1)Unhook the air cleaner elbow from the AFM.
2) Rotate the AFM 180 deg (M30) so the black plastic rounded-corner plastic cap is on the top (watch the wires).While the AFM is upside down, center the idle CO screw (count turns) in its range.
3) CAREFULLY cut the sealant (RTV) and pry the cap off.
4) Notice the screw holding pressure on the toothed wheel (looks like a gear).
5) Paint a mark on the wheel and the post as a reference mark for future re-setting if desired.
6) Disconnect O2 Sensor at firewall, start car and warm to operating temp.
7) Set RPM to above idle (1500-1800 rpm is fine)and hold it there mechanically.
8) Loosen clamp screw and rotate to maximize rpm.
9) Tighten screw.
10)Check idle smoothness. If it is rough, note present toothed wheel position and try moving 1 to 2 teeth either direction until idle smoothes out.
11)Adjust idle CO screw for edge-of-lean smooth idle. (remember screw works backwards from carb idle adj.) (i.e. CW=Richer)
As an alternative, you can simply adjust the toothed wheel for the smoothest idle (at idle rpm of course) in step "8" above and have done with it. You probably won't notice a big difference at running speeds anyway.
Hope this is fairly clear. If not, ask and I'll modify or try again.
Bob
P.S. You'll notice I didn't mention the O2 sensor again. You can reconnect it, but remember it may TRY to drive the system leaner than you just set. Most "enthusiasts" run open loop w/o the sensor (see disclaimer below).
Another way of doing it to retain closed loop system would be to
1)Replace O2 sensor with a new one (just to be sure)and run it 100 miles (burn it in)before step "2" below
2)Perform steps above (1-11) (except do not disconnect O2 sensor). This will maximize calibration using the Closed Loop mode for emissions. If the engine runs poorly after this method, check ALL the other sensors in the system. If they check good, and you have no air leaks, you may have a computer that is out of calibration. Buy a new $$$ computer (Or run the open loop method above).
Disclaimer: Understand that you MAY be in violation of Federal Law by operating open loop on the street.
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