neurotic

So, I've got a 2000 AP1 with a pending P1399 code. It sets the code ~2 minutes after start-up, simply idling. I can feel the car missing at idle, with a noticeable exhaust burble noise. The car seems to run fine with some load, but misses a bit at idle and occasionally stalls (which may be a dirty IACV).

Full blown CELs were once set for P1399 and P1304 while someone else was driving the car. Although, I haven't been able to replicate the CELs, or see a pending specific cylinder code.

Things I've tried:
- Replaced the plugs with used, but known good ones, no difference
- Moved the #4 coil pack to cylinder #2, no specific cylinder code since
- Swapped in known good coil packs from a properly running '06 CR-V (same as '04-05 S2k's), no difference
- Removed E-manage, no difference
- Verified valve lash adjustment; it's ~0.0005" looser than set when adjusted two months ago (25 degF ambient for adjustment, ~72 degF ambient for check)
- Voltage checked with engine running due to a thread about alternator issues. The dash does change brightness, but the car's voltage measured ~14.1 Vdc with <40 mVac while running
- Checked fuel trims, at cold to warm idle STFT ranges from 5 to 20% while LTFT is 0%; does this indicate a fueling issue?

Work recently performed:
- New intake installed
- E-manage installed
- Header installed
- Valve lash adjustment
- P0410 & P0411 set when first removed from winter storage; these no longer set pending codes and the pump is actually pumping

I'm thinking about the following:
- Having the injectors tested/cleaned
- Cleaning the IACV
- Replacing the MAP sensor
- Separate the header and cat to inspect the catalyst brick (70mm Berk HFC)

What should be my next step? Thanks.

windhund116

Check compression?

neurotic

I'll likely perform compression and leak down tests again.

I performed these last fall, less than 1,000 miles ago. Off the top of my head, all cylinders had 240-245 psig compression and 3-6.5% leak down rates; no real change from the prior year's tests.

Soviet

I don't want to be that guy but the Misfire Thread has a pretty comprehensive step by step process to diagnosing your misfire.

Anyways, I've solved a P1399 on a customer's car and it came down to faulty injectors. That was on a 2004 w/125k miles. I would try to find someone locally that would lend you some injectors because they are a pretty penny new. As windhund said, compression would be another logical next step as the misfire isn't targeted at just one cylinder.

neurotic

Yeah, I'm going through that list, just in a different order. I think I can also rule out TPS and fuel quality. I've observed TPS voltage increase linearly with pedal input, and it doesn't seem to detonate or miss under load.

So, that leaves injectors and compression. I found a local shop to test and clean the injectors, and I'll perform a compression test tonight. At this point I'm guessing I have an injector that leaks or has a very poor spray pattern.

neurotic

So, compression is fine, now to pull the injectors and perform a leak down for S&G's.

Today (cold):
Cyl 1 225 psig
Cyl 2 229 psig
Cyl 3 221 psig
Cyl 4 223 psig

9/20/13 (hot):
Cyl 1 229 psig
Cyl 2 234 psig
Cyl 3 227 psig
Cyl 4 227 psig

neurotic

The problem seems resolved with a combination of injector and IACV cleaning. The cylinder #4 injector was slightly down on flow (~4%); so perhaps it had more issues at low flows. Also with the IACV cleaning the idle quality is greatly improved.

chickenstar

I've been battling the SAME THING, but 3 days so far, no CEL or pending codes (crossing fingers) and what did the trick?? Injector cleaner and seafoam!

Chuck S

From my understanding the P1399 is a pending misfire. Run the car until the ECU figures out which cylinder is misfiring and tags it with P1301, 2, 3, or 4 (for a 4 cylinder car).

-- Chuck

neurotic

After the initial codes, I drove the car for three days and it never set another CEL; just the pending P1399. So, I attacked the problem.