Trouble Codes 53 and 72

[travis_smith25]

Hi,

I am having trouble getting my 91 Explorer running well and an trying to determine cause of trouble codes 53 and 72.

My Haynes Manual decodes these as:

53- Throttle position sensor out of range (high)
72- Insufficient Mass Air Flow change during Dynamic Response Test

The engine has absolutely no power (my old BII with a 2.8 ran much stronger) but doesn't seem to misfire or stumble.

I have cleaned the Mass Air Sensor (and even swapped it with a known good unit from my T-bird) and I have replaced the TPS with a new unit. I've also replaced the ignition coil, plugs (Bosch Platinums), Plug wires (motorcraft), and fuel pressure regulator. All cylinders are making between 120-150 psi of compression. I can floor it and it'll just slowly motor along (I have verified flooring it does bring the throttle to wide open).

Is there something common that will trip these codes together?

 

[MrShorty]

The usual first question I have is, which type of codes are these -- KOEO, CM, or KOER. I expect the 72 is KOER. Normally this would be a result of missing/neglecting the "goose" test.
How I would approach the TPS code would depend on what kind of code it is.

 

[travis_smith25]

53 was during the KOER test.

72- not moving the throttle would explain it- I never did catch the flash of the CEL to move the throttle.

 

[MrShorty]

In that case, did it pass both the KOEO portion and CM portions of the KOEO test?

 

[travis_smith25]

Yes,I believe so anyway, I saw only ones during the KOEO test. However, it looked like it was 111, followed with a 111. (does that sound right?)

When driving or idling the CEL never comes on.

 

[MrShorty]

A 111 followed by a 111 could just be from the KOEO portion, since the system repeats the codes twice. Are you talking about getting one set of 111's followed by a 6 second pause - flash (separator pulse)- another pause and then another set of 111's.

In many ways, I would find it strange that you would get a KOER 53 without an accompanying CM 53 (or other TPS code). It would be nice if the TPS either worked or didn't. If you aren't getting a CM code for the TPS, this suggests the possibility that you have an intermittent fault. does the 53 show up everytime you run the KOER test?

 

[Runnin'OnEmpty]

Travis and Mr Shorty, excuse me for jumping in on this, but here's some thoughts:

The code 53 indicates a constant wide-open throttle. Make sure the TPS is seated correctly, and the TPS tang is turning along with the throttle plate. If it is, then check the wiring and plug-in. You may have a short between the Vref wire (5v), and the signal wire. (I would strongly suspect a bad plug-in). The TPS output is easy to check if you have a multimeter.