Trans Revisited

Sam from WA · Feb 20, 2011

I pulled codes off the computer in my '89 F150, it shows 21 and 24 codes. 21 is Engine Coolant Temperature sensor out of range - ECT. 24 is Intake Air Temperature (IAT) or Vane Air Temperature (VAT) sensor out of range - IAT VAT. There are no misfire codes. So does this confirm that I do have a transmission problem, or still an engine problem? I talked to a auto mechanic friend, he thinks its probably the overdrive band going bad. I crawled under the truck and looked over the bottom pretty well, there is a small amount of ATF on the bottom of the bell housing, so the pump is leaking too. Could the pump be leaking internally (through hard, dry seals) enough that its not making enough pressure to keep everything happy? Fluid level is ok.

Bob · Feb 20, 2011

"So does this confirm that I do have a transmission problem, or still an engine problem?"

Wasn't one of your complaints poor mileage?

The temp sensors "out of range" sure won't help with that!

As far a not seeing any misfire codes, that old 'puter is nowhere near as touchy as the newer OBDII stuff, and I'm not sure what misfire codes (if any) you could expect to find.

ANYHOW, the rule is, starting with the lower code # first, fix what is causing THOSE problems.

Once the engine control system is free of codes move on to the transmission problems.

You CANNOT accurately diagnose the tranny while the engine is throwing codes.

Bob · Feb 20, 2011

"Could the pump be leaking internally (through hard, dry seals) enough that its not making enough pressure to keep everything happy?"

Simple answer is NO as there's NO seals INSIDE the pump to get "hard or dry".

Seals in/on various clutch or band apply pistons COULD be leaking, though.

You CAN'T get anywhere blindly guessing like this. If you are wondering about tranny oil pressures you need to get a service manual with the "specs" and a gauge to check them out!

mmidlam · Feb 20, 2011

I can't ofter much help, but on a cold engine, the 2 temperatures should read about the same with a scanner.

Sam from WA · Feb 20, 2011

Where do they hide the Air Charge Temp sensor? Coolant sensor is under the air plenum at the base of a heater hose.

Bryan inIowa · Feb 20, 2011

IAT should be screwed into the pass side of the upper intake plenum . As Bob said ,,you can still have a miss and no code . I doubt they have a missfire counter on the system ,,least not till 94 OBDII systems . Even then miss won't always set a code .

Sam from WA · Feb 20, 2011

After a little more poking around I found it, its in the intake manifold between #5&6 injectors. I found that the engine will NOT run with it unplugged, which verifies that is does work, but doesn't confirm that its good or bad.

ASEguy · Feb 20, 2011

If your ECT is out of range it could very well explain poor fuel economy. If the engine controller "see's" a colder temp. they will add more fuel to obtain the same combustion event. This is what's reffered to as open loop. Closed loop means the controller see's normal operating temp. On some older vehicles the IAT is simply a double check. The codes, if cold enough, which probably isn't the case, could inhibit overdrive. So they probably aren't related to transmission concerns. Gerard

Sam from WA · Feb 20, 2011

So what you're saying is that the codes its throwing are probably unrelated to a possible misfire? Is there something with the ignition wires/plugs I'm missing? I haven't been able to get very far with the TSB 94410. Is there something important to know about the way the wires are routed? Like to kind of keep them apart from each other? I've gone around and around this thing trying to figure out where to start with it, I think its the trans going because it ONLY acts funny in overdrive at 70+mph. But I'm not sure now with all the angry replies I'm getting.

ASEguy · Feb 21, 2011

ECT will make a truck run rough if the information given to the controller is way out of wack so yes it can PROVIDED it's not isolated to a single cylinder. The only issues I have ever seen with plug wire routing makes reference to electrical interference with another component not necessarily other wires. Overdrive in your trans. engages well before 70mph so this is the reason to the reference to secondary ignition by some. If you load the secondary side of your ignition (plugs, wires, coil, cap and rotor), and a component is defective, that is when it will show up. Overdrive loads the secondary side the most of all your speeds which is why you MAY be experiencing the problem you have especially when going up a slight incline in overdrive. Hope this helps. Gerard

Trans Revisited

Sam from WA

Member

Bob

Well-known Member

Bob

Well-known Member

mmidlam

Member

Sam from WA

Member

Bryan inIowa

Member

Sam from WA

Member

ASEguy

Well-known Member

Sam from WA

Member

ASEguy

Well-known Member

Similar threads