Hey All,

My 93 F150 has been acting up like crazy lately. First problem turned out to be the throttle position sensor, got that fixed and things went well...for a day. The next day I found myself stranded in a parking lot with a busted post on my battery. It couldn't maintain a solid connection so I got that replaced and it started up perfect.

Driving it today, i'm not sure if it's getting the proper power still. I can watch the battery gauge jump up a down when i'm at idle and whenever i let off of the gas. It's very visible when I slow down to turn because the turn signal actually slows down because of the power drop. Could this be an alternator problem?

I also have a squeel whenever I turn but only when giving it gas. This morning it started even without turning but coming off of a light or stop sign. Any ideas?

I'm the first to admit that i'm no mechanic, but I'm trying to learn. Can anyone help me out with where I should start on either of these problems?

Let me know,
93candycane a.k.a. Big Mike

 

I should also mention that the squeal is similar to the one I had when the AC went. I disconnected the wiring to the compressor and it hadn't made the noise in the past 6 months since. When I had the truck in recently, I had the serpentine belt changed as well. Is there any chance that the battery problem and the squeal are somehow related? Any help that anyone might be able to provide would be great. Thanks.

Big Mike w/ the 93candycane

 

Just curious how did your truck act when it needed the throttle position sensor replaced?

 

It was shifting late and then it wouldn't shift down when I was slowing down...i'd sit at half throttle with the brake on at a stop light. I took it into a Transmission shop because like I said, i'm no mechanic. According to the computer, even at idle it was registering that I was at half throttle so based on word of mouth with this garage, i told him to go ahead and change the TPS. Do you think it could be something screwed up with that installation?

 

I doubt your current problems are related to that installation. I am just wondering because my truck is acting up and I can't figure out what is wrong with it. It looses power on the highway and won't go above 2k rpms. If I restart it goes back to normal.

 

squeel
Squeels under the hood 90% of the time are belt and pulley related, so you may have a worn belt, a worn pulley on the alternator, maybe the water pump bearing, but probably the belt and/or the pulley tensioner.

Easy to replace both for the non-mechanic in you, the tensioner holds on with one large bolt and the belt slips on an off if you move the tensioner with a socket and a breaker bar. 10 minutes for the belt, 15 minutes for the pulley. The belt requires 140-160 ft/lbs of tension in order to not slip, which means if you push on it in the longest span between pulleys, you should not be able to move it more than 1/8" or thereabouts. Any play, it or the tensionor is toast.

voltage gauge
What RPM is your idle? The correct setting should be on your radiator support bar or on the underside of the hood, and is typically about 750-800 RPM or so with the AC off, and 50-100 higher with the AC compressor on. When you flip on the AC the idle should increase slightly to compensate for the additional load. Does yours? If not, then your IAC solenoid is probably gunked and stuck, and/or dead. That too is easy to replace, its just a gasket, a connector, and two bolts. If thats not the case, you might have some other issues with the EFI and we can get into that later if needbe.

It could be your battery is partially shorted, or your alternator/regulator is dying, but before you buy and replace anything, verify your idle RPMs and see if the idle is just too low. If its set correctly, then explore the battery and the alternator/regulator.

 

Can't really tell the RPM's to the best of my knowledge as I don't have a Tack on the dash. It's a 93 dash with large speedo in the center and 4 little guages on the side. I just had the belt replaced so "in theory" there shouldn't be anything wrong with the tension etc. on that. AC has been disconnected for a couple of months so I'm not sure if there is anything in that area, though the belt does still run over the pully at the compressor.

Is a pully on the altenator possibly messing with the voltage etc.? ie. when the engine idles down in a turn or a stop sign, the battery gauge drops 3 or 4 volts as well? If so, this might be something I could get checked out as I'm not sure any work has been done to the alternator on this truck. Let me know what you think. thanks.

 

The pulley on the alternator is held to the alternator shaft with three bolts, so the alternator is at least spinning.

Take the truck for a ride so it gets to operating temperature, then let it idle in the driveway. Put a voltmeter across the battery, and you should have 13.5V or close to that. If you have 11, 12, etc, you probably have either a bad alternator or a bad regulator (part of the alternator in later model trucks).

Shut the truck off, and measure the voltage across the battery. Should be almost 13V or so, and if not, you have a bad battery or something is shorted thus draining the battery.

When I suggested a tach, I didn't mean the in-cluster tach, those things are only approximate anyway. You can buy a test tach that you can clip onto your distributor and your battery and measure your rpms that way. its a good tool to have, often part of a tach/dwell meter.

Some auto stores even sell a tach/dwell/timing light as a combination kit which is very useful for troubleshooting ignition timing, performance, etc.

 

I appreciate the help Frederic...i'll try the meter on the battery tonight after work to see what I can find out. I don't think it's the battery as it is only 4 days old, but there could be a short somewhere; i hope there isn't, that could get costly. for some reason i'm betting on the alternator, not really sure why though. If it was a short, would that not have been picked up by the computer last week when I had it in for a new TPS? Let me know.

 

Nope, your ECM wouldn't find a short, unless one of the sensors shorted and the earlier trucks (like my 93, and yours) often doesn't set codes for such "unimportant" thing.

In fact, I've found that my truck doesn't spit out many codes at all unless the failure is catastrophic.

Though, it did notice the o2 sensor went bad, maybe there is hope

 

I'll do some testing tonight or tomorrow and see what I can come up with. thanks for the help.