2002 Protege Occasional Rough Idle

[salguod]

2002 Protege, 160K miles.

The other day the upper radiator hose split at the engine side clamp, ran hot but I think it was shut down before any damage. I fixed the hose, refilled with coolant but then had a CEL. Pulled the following codes:

P0117 - Coolant temp circuit low input
P1250 - Fuel Pressure control circuit malfunction
P0304 - (Pending) cyl 4 misfire.

Since the first anyway seemed related to the low coolant situation that was fixed, I reset the codes and drove it a few miles. No new CEL, but I've got an occasional rough idle / stumble like it's going to stall. It only is rough in gear and not always. It may stumble when accelerating but only at first, it smooths out pretty quickly. During driving, it's fine until you stop, then the rough idle may return.

Came home and check the codes and the pending P0304 was there again.

The misfire I've dealt with before (I've owned 3 Proteges) and a coil pack usually fixes it, but that code was pending, never active. I'm wondering if I'm dealing with a different issue that is causing the misfire. Plus, I replaced the 1/4 coil 2 years ago.

I'm going to inspect the vacuum lines to the PRC solenoid valve and see if I can't test it to make sure it's working. That seems to be what the P1250 leads to, even thought that code hasn't come back.

Any other ideas?

 

[salguod]

The coil had a lifetime warranty and it's stupid easy to change, so I swapped in a new one. Seems to have cured it, I'll know better when my youngest drives it a bit more tomorrow.

 

[pcb]

Keep in mind that the IAC needs to relearn how to idle the car after the battery is disconnected.
It takes about 100 miles of driving for it to settle down.

P5 rough idle... Help!

My DD is an awesome automatic P5 with 183k miles, just barely broke in! The car has been great! I drive 62 miles each way to work 4 days a week and it's been a perfect commuter for a long time! Here's the backstory... I've been having a CEL code p0455 for awhile now. (Code is a common EVAP...

mazdas247.com

 

[salguod]

Good to know, but I never disconnected the battery for either the hose repair or the coil. Maybe I should have, but I didn't.

 

[katapaltes]

If "lifetime warranty" implies Autozone coils, I'm shuddering more than your car. I bought one of their coil packs once and even though they had free replacements, for me it just wasn't worth the risk to emissions equipment. Hitachi coils are the OEM part and will last for 75k miles or longer.

 

[salguod]

A new coil fixed it.

These were Autozone. I've had similar experience with Advance Auto coils too.

For me, taking an hour (including driving to the parts store) every couple of years isn't a big deal. This is a 20 year old $2K car with 160K+ miles, it's not likely to see more than a few more years on the road and almost certainly not another 75K.

 

[katapaltes]

Good point... The reality of my car being 20 years old is only now sinking in with me as both it and I show definite signs of aging. I've been fighting it on both our behalves, but at some point I will just give up.

 

[salguod]

The irony is that this 165K 2002 Protege is my kid's and my dailies are older - a 299K 2001 Tundra and a 146K 1998 Boxster. But that's because I like to drive old stuff, not because I have to.