Kia Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
2001 Kia Sportage Limited Edition

The check engine light on my Sportage has been on now for two years. The same code comes up each time I take it in to be hooked up to the computer - Cylinder 1 Misfire. The engine always ran fine, no rough idling or anything. Just the check engine light on.

Recently however, the engine is noticeably misfiring and now the check engine light will flash and the engine is obviously misfiring. Took it in for computer hook up.... these are the codes I received:

P0301 - Cylinder 1 Misfire
P0141 - o2 Sensor Heater Circuit Malfunction - Sensor 2
P0135 - o2 Sensor Heater Circuit Malfunction - Sensor 1

So to knock out as much as possible - I replaced the following:

All 4 Spark Plugs
Both Coils
Both Wire Sets
Both o2 Sensors

The car was still misfiring. Re-did everything - same codes.

Saw somewhere that the fuel pump relay may be the issue. It was said that the Main Engine Relay and the Fuel Pump relay were the same part # - I confirmed this physically by looking at the numbers on the relays. So I swapped out the relays - fuel pump in main, main in fuel pump -the engine would NOT start. So I thought logically, hey this tip was correct - the fuel pump relay was bad, so I replaced it. It worked for 5 minutes - the engine was noticeably better, however it started to misfire yet again - noticeably.

I went to get the codes again - same codes.

On a whim I decided that since I had two good relays in, that I would swap them out just to see what would happen - well the swapping them out - led to a no start situation. swapped them back - starts fine, but still has misfire.

So I think something is destroying the fuel pump relay.

Does anyone have any suggestions?
 

·
Registered
Joined
·
2,216 Posts
A (dead) to-ground short from the fuel pump relay socket -> the O2 sensor heater circuit wiring (and connectors) would be a possible cause of burning the relay out,

And would also be physically inspecting the condition of the wiring in the engine compartment fuse box (underneath from where the relay plugs in) also,

--

And as a sanity check, with the fuel pump relay out, would be confirming good trigger voltage at the relay socket, and (+12) v on the relay power feed, to start.

--
If the major ground points in the engine compartment have not been checked / cleaned / QA'd, I would be doing that also,

If the fuel pump ground ring (under carpet flap / back cargo area) has not been cleaned, I would be cleaning that also .. (Also energized by the fuel pump relay..)
 

·
Super Moderator
2008 SpectraSX, 2014 Optima LX,2006 Jeep Liberty, Linux Mint Mate
Joined
·
6,922 Posts
You might want to check the voltage at the fuel pump...A corroded relay socket could cause a voltage drop and a reduction in the amount of fuel pressure being supplied to the engine...

Like GottaCruise said "
And (I) would also be physically inspecting the condition of the wiring in the engine compartment fuse box (underneath from where the relay plugs in) also".
Dave
 

·
Registered
Joined
·
2,216 Posts
That's a good point Dave, would be checking voltage and connectors at the fuel pump also .. the fuel pump wiring harness is grommeted and goes through a cover plate / is a potential wear area, the connectors at the fuel pump are exposed outside the vehicle ..
 

·
Registered
Joined
·
2 Posts
Discussion Starter #5
I will measure the voltage tonight and take a quick look at the fuel pump grounding ring you described and get back to you on the results.
 
1 - 5 of 5 Posts
Top