I'M FRUSTRATED!!!! (kinda long, sorry)

[OMAR]

My '93 has:
4.10’s, FORD “B” springs, rebuilt AOD w/ shift kit, Flowmaster 3 chamber catback, off-road H, equal length shorties, adj. FPR, fender well CAI, pulleys, MSD 6al, MSD wires & coil, MSD in-car timing control knob, NOS kit currently jetted at 125hp.
In this form, (not spraying off the line) the car ran a 13.19 ET. On street tires.

These parts added a few months ago:
TwistedWedge heads, E cam, new timing set, new lifters, new 6.75” pushrods, CRANE 1.6 stud mount rollers, StreeHeat intake, 24lb. injectors, C&L 76mm MAM. T-Body & EGR plate are still stock.
After these mods, I can’t get the car to run properly. It’s overly rich, bogging and backfiring. It seemed fine for a lil while and then something went bad. With the stock H-pipe on(for emissions test), the first cat on drivers side seemed to be getting a dull red glow, so I put on the off- road. Suggestions made are: 1. dist. off 180 deg. (I don't think so because the car runs, just very poorly. Plus it ran decently for awhile after mods). 2. Air pump not working causing O2s to read incorrect. (I checked the discharge tube that goes into the exhaust, and it's blowing air). 3. I can't find any vacuum leaks. After I shut it off, it won't start for awhile (I'm assuming it gets flooded). What else can cause this? I'm desperate! If I can't fix it, it's going to be for sale!

[b055]

whats your timing at?

whats your fuel pressure at?

changed plugs lately?

what heat range are they?

[BLACK85GT]

Last time I had a glowing cat converter, it was a vacum leak.
Did you plug all the holes in the back of the heads?

[OMAR]

All holes are plugged; new, stock-range plugs installed with parts; FP was at 42 psi w/line off, timing at 14deg. I've been playing with both in infinite combos to no avail.

[420nitro]

Originally posted by OMAR
All holes are plugged; new, stock-range plugs installed with parts; FP was at 42 psi w/line off, timing at 14deg. I've been playing with both in infinite combos to no avail.

Now you say it just went bad all of a sudden, or was it kind-a-bad and just got alot worse all of a sudden?

What size injector?
What mass air flow sensor?
Is it calibrated for your injectors?
42psi....it should be 36-38 psi with no vacuum signal.
Did you check your idle air control valve?
Check engine light on?
Whats you T.P.S volt at idle?
Does it miss with or with out a load.
Let me know.

[420nitro]

Ohh.ohh,
Does it make a screech sound from the back of the engine then rpms jump up and down?

[OMAR]

After assembling everything, it ran okay. Actually stronger on the top end than before, but it felt like it should've had more power. I figured it needed fine tuning. Then it started bucking and popping after about a week or so and gradually got to the point where I can't even drive it.

24lb injjectors w/ corresponding tube in C&L MAM.
F.P. at 42psi. w/ no vacuum signal( a lil high maybe, but when I turn it down now, the car wants to die out).
How do I check the IAC valve?
Check engine light comes on sometimes.
TPS was set at .99v a long time ago. Do I need to recheck it?
Before, it would only run bad under load,and off idle til about 2800 rpm. Now it does it even while idling.

I haven't noticed any screech sound, but when I rev it, it seems to take a while to wind back down to idle. Kind of a "rev-on" type deal.

[420nitro]

Originally posted by OMAR
After assembling everything, it ran okay. Actually stronger on the top end than before, but it felt like it should've had more power. I figured it needed fine tuning. Then it started bucking and popping after about a week or so and gradually got to the point where I can't even drive it.

24lb injjectors w/ corresponding tube in C&L MAM.
F.P. at 42psi. w/ no vacuum signal( a lil high maybe, but when I turn it down now, the car wants to die out).
How do I check the IAC valve?
Check engine light comes on sometimes.
TPS was set at .99v a long time ago. Do I need to recheck it?
Before, it would only run bad under load,and off idle til about 2800 rpm. Now it does it even while idling.

I haven't noticed any screech sound, but when I rev it, it seems to take a while to wind back down to idle. Kind of a "rev-on" type deal.

Yes, check your tps volts again, and take off your iac valve and clean it with carb cleaner or something.
Your engine is not making any noises right?
Your timing is set with the spout connector off right?
If your tps volt is at 1.0 volt or higher the computer will think your at part throttle and cause havoc.
Double check for vacuum leaks.

[420nitro]

Hey you said if you drop the fuel pressure below 42 pounds...it wanted to die out?
If true, your guage might be bad...crank it up some more to see if it likes it...If it does then most likley your guage is bad.

[OMAR]

FP gauge is new, I cleaned the IAC valve out w/carb cleaner before reassembly, and timing was set with spout plug out. I'll check TPS voltage tommorow and maybe disonnect the MSD timing control knob. Maybe it went bad

[tmoss]

If you used a freshly oile K&N filter you may have a contaminated MAF wire, or it may just need cleaning. Take alchohol and a q-tip and gently clean the sensor wires. It's cheap or free and it may cure your problem.

[LX5liter]

I agree with tmoss, sounds like a mass air problem to me.

[bottlebaby91]

Get a Pro-m mass air and your problems will be solved. I had this same problem this spring, got a new maf after trying everything else and it fixed the problem.

[Coupe50h]

420nitro, what would that screetch sound be? i kind of hear that in mine. (not loud though)
also i like the last reply, the pro-m is a good part, i chunked my c&l for a pro-m and my car runs better than ever.

[OMAR]

I rechecked the TPS, and it was reading 1+ volts with the key on. I guess it moved a bit upon reinstallation of everything. I reset it to .99. The MAM was still clean with no oil on it, but I think it may be malfunctioning. I checked the voltage with the car idling, and it varied constantly between .7 and 1+ volts. It should not swing that much at idle right?

[420nitro]

Originally posted by Coupe50h
420nitro, what would that screetch sound be? i kind of hear that in mine. (not loud though)

That sound came from thre throttle body. It would make that sound then kick up the idle too about 1500-2000 rpms. At that time I disconnected the egr valve. Then no more noises.

[tmoss]

If the car was surging during the .7-1+v readings, then that is about right. If it was not surging, then that variance does not sound right and could indicate a sensor problem. Don't just look at the sensor wire to see if it "looks" clean or not, a quick alchohol cleaning will tell you for sure if it's dirty or not.

Here is the stock transfer curve to look at regarding the .7-1+v readings - shows flow variance of about 15-20kg. Your may be similar.

[OMAR]

Alcohol and Q-Tip revealed a lil dirt. While I have the MAM apart, I'm reconsidering the sampling tube sizes. I bought it used from a guy on-line w/ 19 & 24 lb inj. tubes. I assumed the larger one was for the larger inj. Could it be that I should be using the smaller tube?

[USMC302]

Generally the tube increases in size as you go up in the calibration. Here is one point to pay close attention to though, make sure the tubes you bought were for your year models and not the 94-95 model and that they are C&L tubes. The 24lb tube for the 1995 76mm C&L is different than the 1988-1993 76mm C&L mass air, even though they are both 302 5.0's. Call C&L and they have them specifically color coded for the tube you should be using in relation to the size you are running and the year car you have. Call with the color you have.

Another thing to check is your O2 sensors, and pull those plugs again, could have fouled out, I've had plugs do that brand new. We can always tell alot from the plugs.

[OMAR]

Thanx guys for all of your help, but I've given up. My 'Stang is being sold and I'm buying a FOCUS as a daily driver( I WILL NOT RICE IT OUT EITHER!!!). Maybe someday I'll have another Stang. Until then, Goodbye.