1998 S70 Runs fine cold, misfire when hot at low revs bad KAE fuel relay Topic is solved

[scot850]

It is possible, but If the wiring is not damaged, I can't see it being an issue unless it managed to get into the joint some how.

I know I have had problems getting the ABS module connector apart when it has not been disturbed for a long time. Wish I could actually get my hands on the connector to tackle it.

Those wires from NGK are possibly part of the issue. We only ever recommend OE brand or OEM Bougicord due to so many issues with other branded part just not working.

Other parts should be good.

Neil.

[abscate]

An OXS won't cause a huge misfire like this. Are you getting codes? The Short term fuel trim will run out of limit if the OXS is totally bad, which will pop a P0171 code.

Start at the coil and look for battery voltage, and then fault trace the ignition system all the way to the plugs. You just can't assume parts are good, you have to remove them, look at the wear surfaces, and correct.A bad rms is probably from crankcase over pressure, which will blow oil in the distributor cap.

[WhatAmIDoing]

Pulled distributor, very little moisture/oil around the edges where it mates with the block. Inside looks good, no arcing, maybe the slightest trace of moisture. Would think there would be some kind of rubber seal to keep dirt/water/oil out. What do some people do to keep moisture out of the distributor?

[WhatAmIDoing]

An OXS won't cause a huge misfire like this. Are you getting codes? The Short term fuel trim will run out of limit if the OXS is totally bad, which will pop a P0171 code.

Start at the coil and look for battery voltage, and then fault trace the ignition system all the way to the plugs. You just can't assume parts are good, you have to remove them, look at the wear surfaces, and correct.A bad rms is probably from crankcase over pressure, which will blow oil in the distributor cap.

Missed your post somehow. I misplaced my good code reader, and my spare took a dump (so did my multimeter). Going to limp the car to an auto parts store this evening. Car had PCV done when I bought it. Passes glove test. Theory is the seal just deteriorated.

[WhatAmIDoing]

Borrowed a code reader. 5 Stored codes, 0 Pending, in order: P0141, P0136, P0440, P0410, P0108. Don't know how I didn't get a P0300, which is what I was expecting. I know P0141 and P0136 is from the downstream O2 sensor being disconnected. P0440 is evap system malfunction, this one comes and goes. P0410 is for secondary air pump, comes and goes, need to do SAS delete. P0108 - MAP Pressure Circuit High Input is new. My money is on this one, which means I'm looking for a vacuum leak or a short due to water.

[abscate]

Clear codes, see what comes back. That P0108 could be a ghost.

[WhatAmIDoing]

Cleared codes. P0141, P0136, P0440 came back. Knocked some debris out of the air filter, resat the MAF connector. No change, misfiring and stumbling when hot. Decided to pull the fuel pump relay and pop apart the housing before pulling all the plugs and wires. PCB was fried and several solder joints were touching. Not sure how the engine was even able to start. Plugged in a spare Volvo relay. Initial start was a bit rough, then it evened out and all is good now. KAE relay failed in 4000 miles, bought itself a one way ticket back to FCP.

[abscate]

If you talk to FCP, without using the internet, you might get the KaE piece of poop upgraded to a Decent relay for a nominal charge

Thanks for closing up the report!

[WhatAmIDoing]

If you talk to FCP, without using the internet, you might get the KaE piece of poop upgraded to a Decent relay for a nominal charge

Thanks for closing up the report!

Just did. Genuine Volvo on the way. Let this topic be a warning to anyone thinking about buying a "cheap" fuel pump relay. This was the 3rd KAE I've burned through. Fortunately, the first 2 came with the car.

[scot850]

Glad the lateral thinking on your part found the root cause. Well done and hopefully plain sailing for a while!

Neil.