OneBadTurboCRV

Unfortunately, the only way a timing light will show you that mechanical timing is off is if you can't get in spec. They are simple devices and only light up when the distributor sends a spark pulse. I am only starting to nit-pick because if everything is OK - then why is there a problem, haha. The engine seems to check out mechanically - the onlything that would somewhat make sense is a sensor, mechanical timing, fueling, or ignition timing. We can somewhat rule out sensors due to the fact it was previously working and no CEL is thrown (unless the ECU is at fault). You say everythig else is spot on - so if you could double check everything that would clear all that.

How did you set the ignition timing?

crxsirg

Something else I just noticed, I had gapped and put in the old spark plugs from the other D16a6 I have sitting out (the one that didn't have hesitation issues) thinking maybe my new plugs were an issue. Well I pulled one out to check it (I've only driven about 1000ft from my house and just went WOT to test) and I noticed it's a grayish-whitish color whereas the plugs were originally a nice golden brown. I would think this indicates a lean condition which would seem to validate the possibility that not enough fuel is flowing at the WOT state. Given the fuel pressure is OK and assuming it really is a fuel issue, I would guess injectors as the culprit?

What do you think?

crxsirg

Oh I understand the nitpicking since I'm doing it as well.

For ignition timing, I jumped the 2P connector and used the timing light to line up the pointers on the lower timing belt cover with the middle red notch on the crankshaft pulley.

Oh, I also ohmed the plug wires and they're fine.

OneBadTurboCRV

Injectors could be a possibility - since you have them it would be a "freebie". I must have missed that in your previous post. Unless you recently ran your vehicle out of gas? Could be a clogged sock/fuel filter. Providing enough pressure but not flow.

Being that you say your plugs are "ashy" that could be from the oil of fuel additives you may be using. It can also be from worn valve guides... Although you would have to do a more in depth vacuum test to confirm that. Too much of that build up would cause misfiring...

crxsirg

Hmm...well I'm not using fuel additives. I sure hope the valve guides aren't worn; the motor was supposed to have no more than 50K miles on it. The build-up is very minimal but it's more on the whitish side.

crxsirg

Well...PROBLEM SOLVED!

I'm pretty sure it was the ECU. The one I had in it was bought from a member on here and it was chipped. The owner had no idea it was chipped and I ignored it since the car fired up and seemed to run alright. Well I put in the ECU from my dead CRX and the hesitation is gone.

So, maybe someone overheated something when installing the chip socket or maybe the fuel map isn't quite stock...I don't know. I'm just glad the hesitation is gone. Unfortunately I think the motor is still burning a little oil. I'm hoping it's just stuck oil rings, but I've soaked them in marvel mystery oil and seafoam for a total of 4 whole days.

Anyway, thanks to all those who gave advice and suggestions.

OneBadTurboCRV

Well if its minimal then I would suspect those look like a "normal" plug... The only part that concerns me is it happened quickly... Read up on how to "read" plugs - that way you can be sure what you are seeing/explaining is OK.

OneBadTurboCRV

... Hah - you should have said it was socketed from the begining!!! Oh well, congratulations! I knew something just wasn't adding up right at all...

Hexakis

Hi, all. I, too, have a high-load, low RPM random misfire (codes 300-304, usually 301 and 303 -- 1st and 3rd cylinder), but in a CR-V 1998. I've Sea Foamed it three times, and now I don't get any more smoke out the back. All the carbon than can be reached by Sea Foam (via the brake vacuum line) is gone. I still have the misfires, but they are slightly improved. If I load it hard and get the misfires, I get the blinking MIL, always the same thing (P0300 codes).

Here is the most interesting thing: I've figured out that I can drive to work and back (35 minutes on the Fwy) without ANY engine light by simply starting out gently in 1st (automatic), then upshifting when the RPM are around 4-5k, and keeping the RPM high at all speeds. If I keep the RPM up and don't load it too hard, no misfire at all -- perfectly smooth. I can even tap the pedal and get bursts of power without misfiring. BUT, if I load it moderately hard for more than a split second, it WILL misfire, even at high RPM. If I do it enough, it will keep misfiring even at high RPM and low load (cylinder walls heated up?). If I then drive at low load/high RPM for a few minutes, the misfire goes away (hence, my thought about heating, cooling).

Not sure what is going on. Plenty of spark. New plugs didn't do anything. Wires seem to work fine; no jumping. Compression was a little variable before I Sea Foamed, but I haven't checked again. Oil is full synthetic, at ~3500 miles. Up for a change, but shouldn't cause misfire. Air filter isn't too old and I don't drive in dust, so that's not likely the problem.

My plan: replace the fuel filter (it's been a long time), check the fuel rail pressure and make sure no leaks, check under the valve cover. Also, I bought an ohmeter, but haven't ever used it. I could start checking some resistances, but checking voltages is kinda freaky. Also, I'll Sea Foam the fuel when I fill up (today). Not expecting that to work any miracles, though.

Any other thoughts? I don't want to just replace stuff and "hope." What should I do next?

OneBadTurboCRV

You should make your own thread and post it in the correct Forum. This is an OBD-0 EF Forum not a OBD-2a RD2 Forum...

Hexakis

Will do. Thanks.