When its cold, it runs great in forward and reverse, but once it warms up it stalls at red lights and as soon as I put it into reverse. I just got this truck over the summer and have changed the plugs, plug wires, fuel filter, air filter, oil, etc. I read in one of the posts to check the IAC. I took that off and cleaned it good a couple of times already and it is still doing it. I am at a loss now. Any ideas?
Not yet. I read in one of the forums that auto zone doesnt carry the code reader for this year truck, so I printed out the instructions on how to rig it to read without the code reader. The holidays put a hold on it.
The best code reader you're going to get for a '92 is a paper clip. Jumper the STI pin on the DCL to ground, climb in the driver's seat with your favorite beverage close by, turn on the switch and count the flashes of the CEL (Check Engine Light). Works wonderfully. You guys with the E4OD probably have 3 digit codes (PCM instead of ECM). My M5OD has 2 digit codes (No tranny to control, that's my job). Check out www.fordfuelinjection.com for the details on doing this. Keep the money you would have spent on a reader for replacement parts, if you need them. Or, use it to by a good vacuum gauge instead. Stalling on throttle chop or when IAC closes off, is generally a good sign of vacuum leak, or ailing parts near the throttle body (IAC or TPS). NOTHING from the ECM is going to tell you if it's sucking extra air, unless it's bad enough to cause a lean mix to that triggers an O2 code. (Mine never did trigger a code unless I disconnected something, but look at my gallery for what I found). The ECM only checks to see if the sensors are sending appropriate signals, and even then, seems to have a pretty wide tolerance. Been there, done that, and 2 dealerships couldn't find it, because it required a little more effort than a mouse and keyboard, and the mechanics didn't want to get their hands dirty. I didn't have stalling issues, but SEVERE lean-misfire and pinging when climbing hills. One dealer retarded the timing all the way back to 10 deg. ATDC to hide the pinging and proudly announced he'd fixed the problem. You think a 5.0 SO is gutless when it's running good, try it with the timing 20 degrees retard. Depending on where a vacuum leak is, it can cause a lot of weird symptoms, but normally is associated with fast (above 800 RPM) idle.
Certainly, check the codes FIRST, to see if a sensor is failing. If you get 11, or 111, then you're going to have to dig a little deeper. A good arsenal of old fashioned gauges can tell you a lot more than the ECM will sometimes, and WON'T lie to you.
Sorry it took so long to get back, I had back surgery on 12/28 and havent had the chance to do anything with the truck. The reverse and red lights part should have ben two seperate sentences, the truck stalls out during both. I printed the paper clip instructions out and will try that this weekend.
The PSOM (programmable speedometer odometer module) could be the culprit. I believe that year had them? Anyway, this would be a quick check. Go to the rearend and unplug the VSS sensor. They call it the AntiLock brake sensor but it also functions as a VSS.
What could be happening is the PSOM is bad, it basically takes the signal from the
VSS and not only does it take care of your speedo reading and odometer but it also will apply correction and conditioning to the signal and passes it on to the EEC.
If the EEC sees a signal that is greater than something like 45 mph it will LOCK the torque converter as soon as it is placed in gear. If it sees a signal that it thinks is above 100+ mph it will not only lock the converter as it is above the 45 but it will also shut off fuel to the engine, Speed Governor.
So it could be the PSOM, VSS, or the wiring between. So by unplugging the VSS connector then the PSOM will hopefully be telling the EEC that you are not moving an will then go into a sort of Limp mode. It will shift very hard, based off TPS and RPM's instead of MPH.
This is just a thought,
hope it helps.
I went through this whole thing about two years ago.
Have you noticed that your SPEEDO will bounce at certain MPH?
No speed limiter on the 92 model (see my sig). Trust me, I know. Speed limiting wasn't put on the full size trucks until after the roll-over scandal with the Exploders and Rangers. (Thank you Firestone). I had a '98 Ranger, though, and you could go 96 mph in 4th, or 96 mph in 5th, and MAYBE get it up to 100 going down a steep hill on the interstate. I dunno how fast the '92 F-150 will go, but I know it's a lot more than 100 mph with the 5.0, M5OD, and 3.08 dif combo, and a lot faster than I want to be going in something with the aerodynamics of an outhouse.
Normally, when the VSS goes bad, there's NO signal at all from it, which is the cause for the hard shifting on E4OD tranny's. I'm thinking the 92's all had AOD's anyway. Don't think the E4OD was available in these trucks until '94, but someone that has a better Ford History Book will have to answer that one. VSS on the '92 was more for the RABS operation.
The stalling when stopping, or shifting into gear after the engine warms suggests a sticky IAC. Sounds like it's binding after the throttle body warms up. Try removing it and cleaning it thoroughly. Another test would be to turn the steering fully to one side to put pressure on the power steering pump, and see if it maintains idle speed. If it droops, then the IAC isn't opening to keep the idle up. Try the A/C as well, with the tranny in Neutral to see if the engine speed varies with the A/C clutch engaging. That will prove if something isn't idling the engine up when it should. There's also a possibility of an intake leak or an EGR valve sticking open, allowing lean miss and ultilmately a stall because of lean mix at idle.
Pull the codes, and let us know what you find. Normally if the IAC is binding, that will trigger a CEL latched fault.
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