Wierd problem '90 Ranger

[rusty93xlt]

Coworker has a '90 Ranger(Could be a '91, looks like a 1st gen Explorer from the front) with the 4 cylinder OHC engine, looks like a 2.5 like the Mustangs use but could be a 2.3 or 2.4. Anyway he just had a brand new motor put in and says that when the truck is at operating temperature there's an intermittent power loss from time to time and it's not there every time he drives it.

Looked for the EEC module and test plug but didn't see it, should be on the driver side IIRC. Anyway he said that before the engine was replaced there was a constant check engine light for an 02 sensor but he hasn't seen it since the engine swap. Also, when the key is in the on position w/o the truck running there is no check engine light, should be getting one when it's not running.

Any ideas? Sounds like a sensor related issue. CPS maybe?

Thanks for the help!

 

[dmac0923]

you should see the CEL go through its tests when you first start the truck, based on the year of the truck the bulb could just be burned out. but if not then id say its computer related