Bucking, driveability & CE light...

[91 SHOplus]

Hey SHOwners,

Recently, my plus has had some driveability issues. sometimes while accelerating from a stop, it will buck, hesitiate, and feel as if it's about to staul. It bucks hard. My CEL will come on, and blink off intermittently.

So I went to my tool cabinet and got my trusty code reader (paperclip ) and got some info.

KOEO showed 11, 63.
KOER showed 21, 74
Cylinder balance was a 9

I went to Mike's site and found out that these codes are...

11 - System checks OK
21 - Engine Coolant Temperature (ECT) sensor out of range
63 - Throttle Position Sensor (TPS) signal too low
74 - Was brake depressed after engine ID was received ? Brake On Off (BOO) signal open or short to ground (Weird, I didn't touch the brake )

These codes don't sound consistant with my plus' symptoms, do they?

 

[Ishodu]

Was the engine warmed up fully? This may cause the ETC code. When doing the KOER you have to have the ECC off and turn the wheel and press the brakes as part of the test as well as a little goose in the throttle. Ignore the brake code if you didn't press them during the test. Now the TPS is something you may want to look into. If you have a electrical test meter you can test it I am sure if you tried a search you can find out how to rather than me try to remember and not be 100% right on the numbers you are looking for.

 

[91 SHOplus]

Thanks Marcel,

Now that you mention it, I remember reading about a test with a digital voltmeter to check the TPS.

I didn't know about having to hit the brake. I thought I only had to turn the wheel side to side & goose the throttle.

Time to start digging.....

 

[91 SHOplus]

OK, I did some searching and came across a post by RangerJ in this thread....

http://www.shoforum.com/newreply.php?do=newreply&p=232177

masho95,

sorry about the delay. I got busy working on my daughters Explorer. I think they put that engine in with a shoehorn! My hands are all cut up.

Ok, the connector at the TPS is a three wire connector. The wires are;
1. Signal Return (Sig RTN) Gray/red tracer(stripe), 2. TP signal(TP Sig) Gray/white tracer, and 3. Voltage Reference (VREF) Brown/white tracer.

With the key off for at least 15 seconds disconnect the TPS connector probe between VREF and Sig RTN at the TPS vehicle harness connector with the KOEO.

You should get between 4 and 6 volts. If NOT Check VREF circuitry and wiring.

Next.Connect the TPS connector and backprobe the TPsig and Sig RTN with the KOEO. Move the throttle through its entire range(closed throttle to wide open throttle. Do this slowly and make sure your probes make good contact at all times. You should get variable voltage between 0 volts and 5 volts. You should see a starting voltage at about .4V to .6V and a wide open throttle voltage at about 4.5V to 4.7V.

If not - Faulty TPS. Watch closely for a momentary drop off in voltage if your TPS has a "flat spot". rangerj

What I don't understand is in the first few lines...

With the key off for at least 15 seconds disconnect the TPS connector probe between VREF and Sig RTN at the TPS vehicle harness connector with the KOEO.

So do I do this test with the key on or off?

 

[Ishodu]

You turn the key off then after 15 seconds remove the plug then use your meter to probe the wire in the harness and where it should plug into the TPS then turn on the key with out starting the engine.

 

[91 SHOplus]

Cool, got it. Thanks again.

 

[91 SHOplus]

I just bought a new TPS from Josh @ Shonut. For $20, It's affordable enough, even for me!