Having issues with the car, can't figure it out. please help.

[astronut1885]

Hey guys. For the last few weeks, my car has been running poorly. It has cut it's gas mileage by almost a 1/4, from 200 miles per tank down to 160. It is very hesitant to accelerate and rev up. When driving it, it almost feels like driving a supercharged car when it comes into boost (but with less power obviously). The car is sluggish when I first hit WOT, but then when I get to 3000 RPM it comes alive and starts to pull. Even then, it still feels like it's missing power, and alot of torque. It doesn't pull hard enough to make me think it's running right, as it's barely over stock IMO.
One possible thing I can think of is my MAF meter. It's a PRO-M 76mm unit with a calibration code for a 93 Cobra. To my knowledge, and after alot of homework, the same MAF that came on all mass air GTs was equipped on the Cobra, so if this ProM cna replace it on a Cobra, it should replace it on a GT. I know Cobras came with 24# injectors, but the computer in the cobra was equipped with different programming, which reinterpreted the signal from a 19#MAF into 24# language.
My mechanic said to look for vacuum leaks, but I can't find any. The motor was torn down three months ago, and the only stock pieces are the block, pistons, rods, rings, fuel rails, and injectors. Everything else is what you see in the sig. I just can't figure out why the car is running like crap and getting bad mileage. I am going to pull my plugs tomorrow, and see what they look like. Also, I am getting a full MSD ignition setup (6AL, coil, wires, cap, rotor) within the next week or so, so maybe my stock ignition could be tired or not able to keep up. Timing is set at 15* BTDC, TPS is .99 volts, fuel pressure is 40 PSI, cylinder compression was 175 when I tested it a few weeks ago, and I run 93 octane gas. Please give me suggestions.

 

[astronut1885]

Another thought- I have no idea what the condition of my 02 sensors are. I know one is maybe a year old, because I broke the old one taking my stock H pipe off, the other one is anyone's guess. Maybe I should replace them both with matching O2s. Could that help?

 

[proxses]

Hmmm
You might want to look at the plugs and o2 sensors like you said. This might help diagnose the problem.
Did anything happen before the car started behaving bad?
Also, the MAF sensor could be dirty. Not likely, but still possible.
Not sure what else to look at.

 

[astronut1885]

Nothing happened before the car just started acting bitchy. Before I put the MAF on, I went to a dyno event and made 258 RWHP and 281 RWTQ. Those numbers are pretty low for my setup. The car was timed at 22* BTDC and running really rich. I brought the car home, and bought the MAF off a friend. We installed it, and were able to time the car down to 15* and we backed the fuel pressure off a turn (maybe 1-2 PSI, it was originally 42*). Before the MAF, the car would die if we turned the timing below 20*. Once the meter was on and we retuned, the car ran like a demon, pulling hard as all hell, and getting good gas mileage as long as I stayed out of the pedal. Now it's back to running how it was before we got it tuned with the MAF. it's pretty aggrivating. I am going to check the plugs tomorrow, but I'm not sure how to check the o2s. Maybe I should get new ones just for peace of mind.

 

[proxses]

Hmmm
The car would die if it had below 20* timing....
What kind of shape is the harmonic balancer in? Are you sure the timing is accurate? The balancer may have slipped. 20* is way too much.
How are you setting timing, just to be sure?
Also, o2 sensors are not too expensive, better to be sure in that aspect.

 

[astronut1885]

The balancer is fine, and we were using a timing gun. When we had the stock MAF meter on it, the car ran at 22* BTDC. When we bumped it to 24, it pinged. Once we put the larger MAF on it, it pinged until we backed it down to about 16, and we put it at 15 to be safe. I think that the stock MAF was messed up, and was restricting air to the motor, so it ran so rich with 93 octane that I could run high timing. Once I opened up the air path, and backed off the fuel pressure to balance out the a/f ratio, it pinged until I brought it back to normal timing.

 

[astronut1885]

One other thing- the car started having a surging idle at startup once this all started. I had one before, but got one of those idle adjuster plates and that fixed it. Now it surges unless I hit the gas and balance it out.

 

[proxses]

Yeah, this does sound like a vacuum leak. How are you looking for the leak?
Are you spraying carb cleaner or starting fluid around vacuum lines?
I'm not sure what the problem is. Hopefully someone else will step in and help as well.

 

[astronut1885]

Well, I was looking for a leak with my eyes and ears, I'm going to try carb cleaner in a little while. I replaced my coil, distributor cap and rotor, and plug wires with MSD pieces today, and it got alot better. My old cap and rotor were so pitted that it looked as if rocks got in there. It was bad. I put some Lucas fuel treatment in with my tank when I filled up today, so I'm hoping that'll clear up any issues there. I'm installing new Denso O2 sensors in an hour, and I'm hoping that'll help a little too. The little buggers were 45.00 a piece. In addition to all of that, I put my new 2 1/2" MAC catback in today, and I think it helped a little over the cobbled Flowmaster thing I had going on (2 1/4 tailpipes ). I just feel like the car doesn't pull enough still. I almost bought a code reader at autozone, just to see if the computer will tell me anything.

 

[95stocker]

Try resetting your computer and replacing the pcv valve. I replaced a bad pcv in my 95 and I get anywhere from 50 to 80 miles more per tank of gas.
You're definately going to want to reset the computer anyhow if you're putting new O2 sensors in. (I'm sure you know that, but just thought I'd mention it)

 

[proxses]

I have a code reader, and am happy I got it. It stays with the truck at all times. Very helpful tool.
The cap and rotor thing I never thought about.
Try the new o2 sensors, and let me know how things go.
Also, I have noticed this with my truck, the car may pull close to the same, but you are just used to it. So it feels slow.
Like Mario Andretti says: If everything seems under control, you are not going fast enough.

 

[astronut1885]

Well, the O2 sensors that came off were ugly, mismatched, old POS units, and the Densos that went in work great. The car idles better, surges less, and feels all around better. Also, I guess earlier I left the coil wire half plugged in, but now it's fully connected. The car revs up and pulls alot better than before, but I still think something's amiss. I'm going to keep playing with it till I get it right, but I'm getting there. Hopefully when my MSD 6AL gets here it'll help a little more. I also pulled some plugs, and they looked good. some were a little black in some spots, but for the most part looked pretty normal.

 

[Michael Yount]

Have you pulled codes yet? That's the first place to start. The transfer function (voltage vs. flow) for the Cobra maf is set for the Cobra ecu - it's definitely different than for the HO's. So you have a mismatch there - how much it's affecting things is difficult to predict. But it sounds like a non-issue here if the car used to be running fine set up the way it is now.

 

[astronut1885]

No, I haven't pulled codes. I don't know how to be honest. There was a code reader at Autozone, but the chart for which vehicles it worked on was weird so I didn't buy it on the chance that it didn't work.

 

[Michael Yount]

At the AutoZone here, they'll pull the codes for you for free. Did you ask them? There's a good chance you'll buy something from them if it's id'd by the reader. I wouldn't mess with much else until you can pull the codes. You're pretty much just guessing otherwise.

 

[astronut1885]

This is from my newer thread. I was having a sticking idle after I installed the O2s, and some MSD stuff (wires, cap, rotor, coil.) I messed with it for three days, until I figured it out:
Well, I think I finally got it. I swapped back in the stock MAF, and that stopped the surging at startup and during idle. The RPMs still stuck around 2k, so I disassembled my IAC and cleaned it out good, and lubed it, but that didn't help. Then it dawned on me. I now have working O2 sensors monitoring the emissions. I have the FRPP idle adjuster plate that goes on the IAC, and I had it wide open , allowing more air into the motor than it wanted . It was essentially like the IAC being stuck open. I screwed it closed, and boom, no more sticky idle. It revs good, and has more power, which I attribute to having the right MAF directing the fuel flow. I might be buying a Tweecer off a friend, so when i get that I can reprogram the computer and put the Pro-M back on with the 19s. Isn't technology cool? I'll never have to buy a MAF again if it works. Until then, I'm stuck with the shrimpy stock MAF.

 

[Michael Yount]

......and you can probably take that idle plate out completely now and sell it to someone else. Way to go!

 

[astronut1885]

I'm going to hang on to it, because God knows eventually I'll need it to help with something, and if I got rid of it I'd be S.O.L. (****e outta luck). For now it's going to stay put. Better safe than sorry.

 

[jrichker]

No, I haven't pulled codes. I don't know how to be honest. There was a code reader at Autozone, but the chart for which vehicles it worked on was weird so I didn't buy it on the chance that it didn't work.

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.dalidesign.com/hbook/eectest.html for more descriptive help
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

 

[astronut1885]

Well, I did't fix it. I took it out this morning and the idle kept climbing up and sticking. If I unplug my IAC and just use my adjuster plate, it idles fine, but if I plug in the IAC, it shoots the idle way up. What a pain in the butt.