Sluggish past 4500rpm - 93 LX need help

Have you changed the fuel filter? 5spd,or AOD?

Top End Power

Things that I have done that made a big difference to the feel at high rpm -
Under Drive Pullies
Remove mechanical fan
Advance Timing (the previous owner had it way off)

Basic stuff, but it really effected the willingness to rev to 5500 - before it just died after 4500.

Most any hci (heads, cam, induction - also exhaust) type modification will net more in the high rpm range. Ultimate top end benefit - stick a BIG turbo on.

maybe your tfi
maybe need tune up cap plugs rotor wires.

could be several things.
if its a mass air car clean the meter with throttle body cleaner or break cleaner.

I seem to have a similar problem w/ my 92. It cant be any of those things the guys said cuz all of mine are new/replaced. It seems w/ my car when I get up around that RPM neighborhood the engine just stops increasing in power and there is a shuttering from the drive train. It's not a severe shutter though, just one that kinda says "I'm not going any faster". I have 117,000 miles on mine, but have been very responsibly maintaining it w/ synthetic oil. Let me know if you hear anything.

I have a accel billetech dizzy, Its made for the manual tranny mustang. I ordered a tfi moduel for the auto tranny mustang thinking it wouldnt make a differnce because they didnt have the manual tfi on hand. Well my car would pull hard all way to 4500 rpm and then start cutting out like it was hitting a rev limiter. I put the wells tfi mod on from my old dizzy and the problem went away, thats why I suggested the TFI mod. apparently there is a diffence between the auto and manual ones.

rseifert, if your car is 5 speed it could be your clutch slipping a bit at high rpms. 5.0droptop, I converted my car for auto to T5 and sometimes my car cuts out. Are the Ford Motorcraft auto/manual specific too?

need to give us more info. if you can let us know what your fuel pressure is at the problem RPM's. the TFI suggestion is a good one - though more troubleshooting is in order (unless you have deep pockets).

what flavor of plugs do you run (copper or platinum)?

good luck.

I have a 91 5.0 LX auto with 2.73 gears only owner, purley stock,i just putt around in. Last weekend i decided to run it hard on this lonely strip. Held in 1st gear to 5500 then in 2nd gear to 5500. Runs great with know sputtering.

However slow off the start with the gears but runs strong once i get to 3000 rpm.

Check or replace:

Cap, rotor, wires, plugs, fuel filter, air filter, PCV valve/screen. Clean out the TB and intake.

Well, I'm going to go out on a limb here and say take it to your local Ford dealership where they actually have the equipment to diagnose the problem. They will have oscilloscopes, breakout boxes, so on and so forth.

They don't have to fix it...you can do that if you choose. However, it may prevent you from "hunting and pecking" around the engine for something that "might" be wrong. Maybe it's just worn valve springs...who knows.

stylin - pull the diagnostic codes before you start replacing anything. The computer is designed to let you know through the codes if bits/pieces are malfunctioning.

If things need replacing - do so, then see what you think. The stock engine's power peak occurs right in the 4500 rpm range, so it's completely normal for a stock one to feel like it's running out of steam above that, especially in the higher gears.

If you simply want more power higher in the rpm range, you'll have to alter major engine components to achieve that - exhaust systems, intake components (maf size, throttle body size, intake manifold), heads, cam, etc. Or you can add boost via a supercharger or turbocharger - the latter is more involved. But be careful - the verts are heavier than the non-verts, and you need good low end torque to move them - especially in street driving. It's possible to mod the naturally aspirated motor in a way where your peak power is much greater and occurs much higher in the rpm range, but doing so usually significantly reduces torque production in the low rpm range - which makes one even less fun to drive on the street.

If I were in your shoes, I'd take these steps. First, pull the codes and fix anything necessary to be sure the car's running right. Second - pull the stock silencer out of the inlet to the air cleaner box, and put a flat panel K&N filter in. Third - set the initial ignition timing to about 14 degrees btdc. Fourth, have a different set of rear gears installed in the car - 3.73's are a good compromise. Fifth, put on a set of long tube headers and a free-er flowing exhaust system. Those changes should make a big difference in the way the car feels/drives without significantly harming drivability or efficiency. If you still want more umph, then you can move on to other mods.

BTW - the folks at AutoZone will usually pull the diagnostic codes for free.

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.dalidesign.com/hbook/eectest.html for more descriptive help
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.