93 5.0LX Studdering at 1000-2000 RPM, RPM Flux, stalling etc

[93ramvert]

O.k. I've got just over 51,000 original miles on this 93, and about I wanna say three weeks ago I started noticing the check engine light coming on intermittenly, no noticeably issues at that time. I then noticed that there was some chugging issues so I figured it was probably the air filter as I have the March Ram Air kit installed and the filter gets clogged pretty easy. Flushed and Refreshed the K&N filter and re-installed, and got nothing. I figured then that I would change out my spark plugs. Well before I had the chance the symptoms changed. I was still getting the intermitten check engine light, and the chugging went away, but I started getting a stutter or hesitation between 1000-2000 RPM, under cruise conditions. Under heavy acceleration would go smoothly through the 1000-2000 range. I changed out the plugs, wires, cap, rotor and changed out the canister filter outside the fuel tank and the stutter got a bit better but it's still very noticeable. Then yesterday a new symptom occured I pulled into Autozone to see if I could have the codes read, and when I parked and and let idle it rev'd from say 900 to like 2,500 and then back down again and back up. Of course Autzone couldn't read the codes. So I read on this site how to do the makeshift code reader thing. I pulled codes for TPS and fuel Pump. The one other thing that I have noticed too over the last three of four weeks is that I am getting the pinging noise when accelerating sometimes in say like 2nd or 3rd gear. I think I've read somehere that this could be a clocking issue with the distrubuter.

I know this is long winded and I'm sorry about that, I'm just trying to give as much info as possible. I'm figuring on cleaning the EAC, MAF, Throttle body and I remember seeing somewhere instructions for setting the TPS. Should that be cleaned as well?

One thing I should also mention is I've got the Ford Motorsports Cobra upper and lower intake (Ya I know cheap China Version) I got boned. But anyway I have had to switch the sizes of some vacuum lines as they were causing the car to sometimes smoke something awful on start-up. Since the change though that has completely gone away. Just thought I'd add that in, just in case that could be a problem as well. But it's been on the car since about 7,000 miles.

Please help if you can, I'm gettin really bummed and the last time I brought it to a mechanic I got screwed hence the upper and lower intake.

[quick5pnt0]

Just for the heck of it the first thing I would do is clean the MAF, TB, and IAC. You don't have anything to really clean on the TPS, but it should be checked for the right voltage and adjusted if necessary. We've got a how to article in our maintenance section on how to do that. It may also point you in the right direction for example if you find that the TPS voltage is really far off from what it should be.
http://www.muscularmustangs.com/tps.php

I'd say considering you came up with a TPS code I'd start with that and see what kind of voltage you get at the TPS. If it's really far off then replace the TPS.

[93ramvert]

Thanks, I picked up on that yesterday, of course after I posted! Why when your looking for something you can't find it. Then right afteryou post the question you find something on it.

I'm going to attack all of that this weekend, it's really starting to get annoying, no actually it started about three weeks ago with the check engine light. I've also noticed that I have horrible gas mileage too. Prior to this issue I was getting 300+ miles a tank I was able to go Thurs. to Thurs. on one tank, now I'm not making it 3 1/2 -4 days. I'll report back after all the cleaning and checking. Thanks quick5pnt0

[Mike23386]

My truck has a 5.0 in it and it also has that surge at the same rpm when cruising. I absolutely know it's the TPS because the voltage was very low when I checked it. I'm too lazy to change it so I can't tell you if a new one worked or not.

[93ramvert]

My truck has a 5.0 in it and it also has that surge at the same rpm when cruising. I absolutely know it's the TPS because the voltage was very low when I checked it. I'm too lazy to change it so I can't tell you if a new one worked or not.

Well set the TPS, could only get it to .94 (was at .075) will not go any higher even notching out the bolt holes. Cleaned everything possible MAF, MAF wires, Throttle body, EAC. Sprayed cleaner on vacuum hoses (no rev of the engine). And the verdict is......................... Same issue, not one of the things I did fixed the problem. But instead of just chirping second I can now actually get the wheels to spin when changing gears. But the stuttering is still there. Would the .04 deficit maked that change, or could it just be that its bad. The only thing I can do now I think is fuel pump filter. I'm getting a bit pissy now

[quick5pnt0]

Try checking the TPS again but this time move the throttle slowly and see if the voltage goes up smoothly as you open the throttle. I believe it should hit 5 volts at WOT. If the numbers jump around or it doesn't go up high enough then that is a good sign the TPS is garbage.

Since it was so low and even with the holes notched you can't get it to proper voltage I'd say there is something wrong with the TPS. If I was in your position I'd probably change the TPS, but to be completely honest it could be many things and there is no guarantee that will fix your problem. Unfortunately with fuel injection it's a big gamble trying to solve a lot of this stuff.

[93ramvert]

Try checking the TPS again but this time move the throttle slowly and see if the voltage goes up smoothly as you open the throttle. I believe it should hit 5 volts at WOT. If the numbers jump around or it doesn't go up high enough then that is a good sign the TPS is garbage.

Since it was so low and even with the holes notched you can't get it to proper voltage I'd say there is something wrong with the TPS. If I was in your position I'd probably change the TPS, but to be completely honest it could be many things and there is no guarantee that will fix your problem. Unfortunately with fuel injection it's a big gamble trying to solve a lot of this stuff.

So I just did the WOT check, Granted the F'n highway was not clear enough for anything more then 100 mph, not that shouldn't have given me the results I needed, I only got 4.27 at the highest point. When I was at full throttle it would go to 4.23 and slowly rise to 4.27. I'll start looking for a TPS.

[93ramvert]

So I dropped the fuel tank, everything look o.k., strainer wasn't clogged or anything. I took off the hose to the pump and blew it out, a couple of decent sized black chunks fell out, don't know what that could be, but I suppose it could be clogging my injectors, but I quess if it was doing that it would be a full time problem and not just a 1000-2000 rom range issue. Well I replace the tank and stuff prob. Wed. night. I'll be purchasing the TPS and putting that in to see if it straigthens out the issue.

[quick5pnt0]

Thats weird about the black stuff in the pump. I guess it's just a bunch of debris it has picked up over the years. Let me know how it goes.

[93ramvert]

So, to add to the list above, I have now changed the TPS, and have gotten absolutely nothing good out of it. Now I've wasted close to about $300 on it and still have nothing to show, except maybe all new parts. I'm going to concede and give it to a mechanic.

[quick5pnt0]

That sucks! sorry to hear that.

[93ramvert]

Well brought her to the shop, they pulled a code for the MAF. And he let me take it so I didn't get hit with his charge for the install. Just changed it about ten minutes ago, haven't run her yet still at work. But something I did find really pissy was the price of used mustang parts as compared to used say Sable or Taurus parts. As some of you may now the MAF on the 5.0 is the same as the MAF on the 3.8, of course I didn't know that till today. I didn't want to blow $100 on a new one if it wasn't the fix so I hit the junk yard. They gave me the 3.8 one and yes it's the same as the 5.0 I double checked. The search I did on ebay lead me to a used MAF for god dang 63-70 plus shipping. I did a search for a Taurus and a buy it now for 10, Un-F'ng believable. Man I hope this works. I've got a deal on a beautiful Jeep Wrangler that I can make if this is the fix.

[93ramvert]

So, for any of you flowing this mess, I decided after all the changes I would check the fuel injectors. Found the problem. Two out of the 8 had completely lost the plastic tips basically heat cracking and material loss. Two others had started heat cracks in the tips, and the black crap I mentioned earlier on in the post was in some of the filter screens of others.

Now I'm going to replace all 8, but my question is has anyone ever had any issues with the Ford Motorsports Cobra upper and lower intakes. They are replica versions made in china (F'ng chinese), prob. made of lead. Anyway I'm wondering if the poor manufacture of the intake may be playing a role in this whole thing. I may have to look into purchasing another intake.

[quick5pnt0]

I've never heard anything bad about the cobra knock offs. I know that they aren't made to the same standards as the real cobra intakes (flashing not ground off, different finish, etc) but never anything bad.

[93ramvert]

I've never heard anything bad about the cobra knock offs. I know that they aren't made to the same standards as the real cobra intakes (flashing not ground off, different finish, etc) but never anything bad.

Well thats good to know. I didn't know any better when I bought it and it's what I got. Oh well live and learn. While I'm waiting for the injectors I'm going to grind down the upper intake.