DTC codes, at a major loss before a long roadtrip

[lurch03]

I have a 94 Ford Explorer with the 4.0l, standard and I am having some problems. Sometimes when it's cold it won't start, or it'll start and run very poorly, coughing and sputtering. Most of the time it'll warm up and run fine, but now it attempted to leave my wife on the side of the road. It finally gave a code, but it didn't store it... So, I did a KOEO scan that retrieved nothing, then I did an KOER and it said:

Cyl: 6
DTC: 116 (Engine coolant temperature higher or lower than expected)
DTC: 411 (Cannot control RPM during KOER low RPM check)
DTC: 538 (Invalid cylinder balance test due to throttle movement during test)

I have read everywhere I can find information about these codes. Supposedly it's the IAC, it brand new. Supposedly it's the TPS, it's brand new. I'm at a loss with only one vehicle, and it's on the fritz.

Any help it much apprecited, and thank you for your time.

 

[Iron Weasel]

First off...

Hi Lurch, always nice to meet a local.

Second, DTC 116 usually happens when you run the KOEO or KOER self-test without the engine being at operating temperature. However, it can also be caused by a defective coolant temperature sending unit.

DTC 411 is generally caused by a dirty or non-working Idle Air Control motor, but it can also be caused by a high base idle or incorrect engine timing.

DTC 538 usually occurs if you don't goose the throttle at the specific point during the KOER self-test that the ECM requests it.

Do you have a scanner or are you using the CEL and counting the flashes?

 

[lurch03]

Born in Alb, currently in MS. Going to Englad!!!

My wife's military, can you tell? Thanks for your speedy reply.

About the DTC 116, my wife drove it home and I tested it like 5 minutes after, and the temp sensors are brand new BWD sensore, for the gauge and the computer...

I am assuming that DTC 411 isn't the IAC, because it is also new... How can I tell if it's the engine timing, I have no owners manual. Define high base idle too please. I have a decent knowledge, but not enough on some stuff.

I swear I gunned the thing when it said, I just floored it and released it as it requested.

I have an Innova 3140 scanner.

I read it one here that one person was having similar problems and it was the spark plugs, could Motorcraft cause this? I forgot to mention that when I want to jut out across traffic I will romp on it and the engine doesn't do anything.

 

[Iron Weasel]

If the sending unit (gauge) and temp sensor (computer) are new, check to make sure the upper radiator hose is hot.

To check the base timing, you'll need a timing light, which can be rented at most parts stores, to check the timing. Once you have a timing light, disconnect the SPOUT jumper. It's a gray plug looking thing that's plugged into a 2-wire connector which is located near the Ignition module. The ignition module is on the radiator support behind the passenger headlight. It's kind of a pain to actually remove though. Once you have the SPOUT jumper removed, hook the timing light up and aim it at the crankshaft pulley from the passenger side..you'll probably have to crank your head around to see.

There's a pointer bolted to the timing cover and as cylinder #1 fires, the timing light turns on for a very short duration...less than half a second, but every time it flashes you should see a mark on the crankshaft pulley in line with the timing pointer. That mark indicated 10 degrees BTDC (Below To Dead Center). That's the factory timing and can't be adjusted, you just want to make sure the timing is correct. If it isn't then that's usually a good indication of a more severe mechanical problem.

High base idle is how many RPM's the engine is doing with the IAC connector disconnected. If the base idle is too high then the IAC motor won't be able to control the idle speed within the limits its designed to.

During the "goose test" the engine needs to hit at least 2000 RPM, if it doesn't then DTC 538 is set.

As for the spark plugs, it may be worthwhile to take them out one by one and see what kind of condition they're in. Motorcraft plugs are of course OE and should work very well with the engine. Personally, I run NGK plugs in mine and they work fine, but I have heard that plugs other than Motorcraft & NGK don't always play nice with the OHV 4.0.

 

[lurch03]

Alrighty...

If the timing were off, wouldn't the engine be running poorly on a more regular basis, rather than intermitent?

Can you give me a range the "high base idle" should be and I'll check that?

I swear, it almost seems like when I took Autolite out and put in Motorcraft, this crap started.

P.S. I went to Belen High and was class of '03.

 

[Iron Weasel]

If the timing were off, wouldn't the engine be running poorly on a more regular basis, rather than intermitent?

Yes, but it's one of those things that is always at the top of the list of things to check.

Can you give me a range the "high base idle" should be and I'll check that?

There isn't a defined absolute idle speed that I can find. The idle speed is controlled by the various sensors and the IAC. "High Idle" would be anything over 1000 RPM with the IAC motor disconnected though.

I swear, it almost seems like when I took Autolite out and put in Motorcraft, this crap started.

P.S. I went to Belen High and was class of '03.

Were the plugs gapped properly?
Did you disconnect a vacuum line by accident when you were replacing the plugs?