New Member Help!

[Jimnlynn908]

This is my first explorer. Got it from a mechanics shop. Im the 3rd owner. It belonged to an elderly couple who couldn't afford the repairs.
Rebuilt tranny aamco, new radiator, thermostat with new housing and sensors, valve cover gaskets brakes and battery.

Truck runs beautifully when it reaches operating temperature. However, when its cold it idles fine but if i press the gas pedal it will try to stall at 1/4 throttle and the check engine light will flicker on and off during the warm up. I replaced the IACV cause it would have sporatic idles... fixed. I cant figure out why it tries to stall at 1/4 throttle... after warm up. No check engine light and runs fine.
Anyone have suggestions?

 

[arco777]

Welcome to the forum!

If the CEL is flickering, check for codes. If there are no codes it may just indicate a misfire, but more likely there will be something stored in memory. I would recommend running a KOER test, as part of the test checks dynamic engine response to throttle input. The PCM should see the fault then and output results.

 

[Jimnlynn908]

Welcome to the forum!

If the CEL is flickering, check for codes. If there are no codes it may just indicate a misfire, but more likely there will be something stored in memory. I would recommend running a KOER test, as part of the test checks dynamic engine response to throttle input. The PCM should see the fault then and output results.

Ok.... I did the test per Mr. Shorty's how to.

KOEO test read 15, so I assumed no codes in memory

KOER test i got a 177 and a 217. 177 o2 sensor. 217 ignition coil 3 primary circuit failure. but theres no miss fire. what else could a 217 mean? I read the trouble code link.

 

[arco777]

KOEO gave a 15? 11 is a pass. 15 in KOEO is "EEC permanent Read Only Memory (ROM) test failed." Seems an unlikely failure though, unless maybe you have an aftermarket chip installed or there is ECM damage. Perhaps a typo?

177 doesn't mean the O2 sensor is bad. It just means the system is showing rich on the left side. There are a lot of possible reasons.

217 code does indicate a coil failure detected. Usually the coil packs on these models are pretty robust but if yours has a fault, you might try swapping in a known good coil and see if it makes a difference. Maybe you have weak spark and the unburned fuel is showing up as a rich mixture on one side.

 

[awood]

I had a similar problem with a Ranger (same engine/tranny). It had no CEL and no KOEO or CM codes. KOER pointed to a TPS. You could do a simple resistance test (search the forum or go online). It's fast and easy, and you just might find a flat or dead spot on the sensor.

https://www.youtube.com/watch?v=svh5VsWIEkQ

With something like this, I'd rather use an old analog ohm meter than a digital meter. It's easier to see the needle fall off if you hit a dead spot.