The particulars.

2004 D2 HSE. 161K miles. Previous owner slipped sleeve at 128K miles, gave it to my son, who rebuilt it (total engine tear-down and rebuild with flanged sleeves) and drove it 4+ years and 35K+ miles thru high school and college.

Over the years, we have had to replace all the usual "minor" stuff: purge valve (with Hyundai version), thermostat, coil packs (moved to front of engine -- very worthwhile mod), ignition cables, MAF, O2 sensors, etc.

A 4-6 weeks ago, it started "pinging" (not sure how to describe it exactly) intermittently. Right after a pinging event, it would throw IAC, purge flow and bank 2 knock sensor codes, plus misfire and maybe an O2 code. At first, the codes didn't affect anything, then it started to intermittently lose power under throttle acceleration.

At time, it felt like a fuel delivery or maybe even a bad gas issue: I would press accelerator to the floor, and nothing would happen -- no revs, it wouldn't die but would struggle to stay 250-750rpm -- after feathering/nursing the throttle for a while, power/revs would eventually come back, and it would run fine.

Two weeks ago, I bought used IAC, new knock sensor. Replaced the IAC, discovered under vehicle that one of the knock sensor wires had broken, got a good knock sensor pigtail off a junkyard D2, crimped it onto harness, installed new knock sensor.

Ran for about a 10-14 days really well (mpg went from 14-15 to17-19).

Then yesterday (taking wife to airport at 4:30am), it went into a complete meltdown. Again, not power/revs, but even after nursing/feathering the throttle, I couldn't get it back to normal, limped home, switched cars.

It threw 14 codes plus a blinking SES.

P1884 - unknown
P0332 - knock sensor bank 2
P0102 - MAF
P1300 - unknown
P0308 (x2) - misfire cyl 8
P0303 (x2) - misfire cyl 8
P0305 (x2) - misfire cyl 8
P0302 (x2) - misfire cyl 8
P0300 - misfire multiple cyl
P0441- purge valve flow?

The new element in the equation seems to be the MAF code.

The MAF was replaced 3.5ish years ago at about 135K miles with a high quality genuine Bosch. We run a paper filter forward of the MAF (no K&N).

I really need this vehicle running right to loan to some German friends that are coming in for a visit next week.

Thoughts? MAF? Big air leak? TPS? Fuel pressure regulator, fuel filter (it has a filter, right), fuel pump?

 

Unplug the maf see if it improves and no fuel filter on the D2 aside from the sock on the fuel pump pick up

 

SAI fuel pumps are like 50.00 so that’s not bad at all. Purge Control valve wise the OEM Hyundai replacement is excellent and it can be found online (Ebay) for like 15.00.

I have had a D2 almost completely die at idle from a bad Purge Control Valve. I’d have never believed it, but I saw it for my own eyes. It finally set a fault & once I swapped it out the near complete stalling never happened again.

 

You may know this already but the knock sensor is a coaxial cable and cant just be spliced in. You have to maintain the shield around the center conductor or it won't work. When I had that happen my shop pulled a complete knock sensor cable out of a used harness and made a home run out of it, rather than splicing into the existing harness.

 

Found problem.

Cleared codes, started again, this time only got the misfire codes. Exact same ones

2,3,5,8 - those cylinders are all on one of the 2 coil packs.

Replaced it -- I moved the coil packs to the front of the engine way back when, so 5 minute fix -- and no more power loss.

Guess it wasn't meant to run on 4 cylinders.

Regarding the knock sensor connector repair, I cut the one from the donor harness back at the coax. However, I spliced it post-coax at the orange and black wire, which is where it had broken (at the black wire). Not sure why they used coax as they don't transition the coax to the two wires using an impedance balancing balun -- they just solder the two wires to the coax center wire and the shield.