P0306 and all that fun (1 Viewer)

[george_tlc]

So, had a P0401 come on for a few weeks now, reset, comes back (unlike before), so definitely 'for real this time'.

I've had a VSV sitting in the garage for a few years now for when P0401 would become permanent, but been waiting for nice weather before bothering to get into it.

Fast forward a few days ago... on a short drive to pick up my oldest son and then head to another place and I'm at the lights so figure ok, plug in my ultragauge to reset the CEL, do that and drive off. Next light and the 80 starts stumbling - definite feel of a misfire. Talk about coincidence...

Anyhow, drive a mile or two, still stumbling and CEL back on and flashing, check the ultragauge and P0306 and a P0171. Drive back home still stumbling at low idle. Leave it till today, fire it up, stumble still there. Ok, it's 'for real'

Time to tackle a bunch of jobs. The valve cover has been leaking a bit of oil, P0401 stuck, now P0306 for good measure.... Weather is good enough, time to get into it.

So, first job is to pull spark plugs which is reasonably easy on a s/c vehicle. Also remove the heater valve/lines to gain some decent access for the rest of the saga.

First I pulled the spark plug leads and ohm-ed them out, #6 highest at 20k ohms and within the 25k max spec of Toyota. #5 was about 17k and less and less moving to #1 the shortest. These are the 2nd set and OEM so I'm pretty confident that they're good. Pull the distributor cap, all looks good, no cracks etc (it's the 2nd one replaced when I replaced the spark plug leads), so no problems there.

Next I pulled all 6 plugs, all look identical, no surprises on #6, no steam clean... Coolant level still correct in the radiator and the overflow (right on the line). Dipstick check and oil looks like oil... Oil filler cap clean underneath, no build up etc. So, assuming no HG issue (at least crossing fingers).

Next pull glove box and look at wiring loom routing to ECU, all looks good, pristine and no sign of any wiring rubbing etc.

Next pull the upper intake manifold since I planned to fix the VSV anyway and to get access to the loom and check EGR stuff.

With the help of my 15yr old we removed all the bolts/nuts and yanked out the EGR and then the upper intake. With a vacuum pump I tested the EGR valve and it's all happy. Blew through the intake EGR path way and not clogged, but definitely needs a clean along with the rest of the intake runners.

Unwrapped the heat wrap around the loom near the EGR valve and all the wires look new and no sign of heat stress etc. Will have to re-wrap it with new material.

Now I'm starting to get a little worried about the #6 misfire issue.... But one more thing to check...

Next, removed the fuel rail which is pretty easy with the upper intake out of the way. Removed the banjo from the fuel filter outlet, also reasonably easy to access with a 3/8 ratchet from above.

Bit of fuel spilled as the system depressurized - basically a few tablespoons of fuel (had already released any pressure in the fuel tanks by opening AND leaving loosely open the fuel cap.

Pulled off the fuel rail and then unplugged each of the injector connectors.

Out with the multimeter and ohm out injector #6 (varies from 20k to 30k). Hmm, so, what's good? Buzz out #1, 13.8 ohms, but #2, 13.8 ohms, buzz the rest, 13.8 ohms. Buzz #6 again, (20k - 30k). Check FSM and 13.4 - 14.2 at nominal 20C is the correct value. So, #6 injector is dead, time to order a new one and send the other 5 for cleaning/testing. So, that explains the P0306 and confirms it's not HG time for me (yet).

So, with that success it was time to check the VSV for EGR since it's always been a likely candidate. Took out the new one that's been waiting for the 'right time'. Pulled out the meter again, ohmed it out and around 32 ohms. FSM says 30 - 34 ohm at 20C, so all good. Measured the old one - open circuit and obviously totally dead.

Come Monday I'll be ordering new gaskets for the manifold, valve cover, spark plug tubes, EGR valve, throttle body and a new injector and new vacuum lines and and and ...

Waiting for parts will give me a chance to send the other 5 injectors in for service and also to clean the upper intake manifold and valve cover etc.

At least I know my loom/harness is in good condition and all it needs is some new heat wrap around the EGR area. I did find the plastic clamp that holds the loom away from the EGR valve had disintegrated so I'll need to provide an improved restraint to keep the loom away and locked in place.

It's also an opportunity to run a new single piece of hose to to the throttle body - since with the s/c they provide a brass barb to extend the hose but I've found that area invariably dribbles over a few years. A single piece hose will resolve that issue.

cheers,
george.

 

[george_tlc]

So, this is what a good harness looks like next to the EGR:

The 'guts' of the VSV (blown/open circuit coil):

And the hose I'll replace with a single piece instead of the barb. There's also a bunch of cleaning I need to do before it all goes back together again. Still need to remove the valve cover to clean it and replace the gaskets/plug tube seals etc.

cheers,
george.

 

[SierraMtns]

Good write up. What you going to use to cover the wires?

 

[george_tlc]

Thanks. I'll use some heat wrap - various products available at auto shops, I'll just pick one I like and nicely re-wrap cover the harness and then make sure to fix in place as far from the EGR valve as possible.

cheers,
george.

 

[george_tlc]

Still working on finishing up the job. Since our 80 isn't a DD anymore, I can take it easy.

This is my write up so far, not finished yet since I have to re-install the injectors and upper manifold.

Spent a couple of hours this morning with the throttle bypass hose - which is not quite as a pain as the PHH but is also in a stupid location (maybe even more stupid than the PHH...). Anyhow, got it done no thanks to the stupid orientation of the toyota OEM clamp.

Now I have a single hose (quality gates green stripe) running from the relocated (due to the S/C) throttle body to the block. No more weeping from the joiner that came as part of the S/C kit.

http://www.george4wd.taskled.com/injectors.html

and a couple of pics from my writeup since mud folk like pics

and

cheers,
george.

 

[blkprj80]

Nice work George!
Could you do me a favor and measure that big nut for the EGR tube? I'd like to buy or make a wrench for the next time I have to spin one of those off. My Knipex pliers did the trick, but there must be a better way.
Thanks, and have fun putting it all back together!

 

[george_tlc]

It's all back together, just finished a couple of hours ago. Took a bunch (a lot more than I thought) of cranking to get fuel back into the fuel rail and have it fire over. Runs nice and smooth now, misfire is now missing

My http://www.george4wd.taskled.com/injectors.html writeup has the EGR nut size, it's metric (32mm), but a 1 1/4" fits very nicely (and is cheaper).

I'll update my writeup with the last of the install info, nothing major left to describe though.

cheers,
george.

 

[blkprj80]

Thanks George!
Nothing more satisfying than when it starts up smooth. I had two injectors that gummed up. Once that was fixed it sounded soooo much better!
I cranked probably 30 seconds to fill up the filter and get it to fire the first time. I did a few key on/off cycles in hopes the pump would run. I don't think it has to get oil pressure on start to run the fuel pump a few seconds each cycle?

 

[george_tlc]

Yeah, I cranked for maybe 7 seconds the first time and it sounded like it wanted to do something (likely whatever solvent/fuel was in the cleaned 5 injectors (in hindsight). After that is sounded like the starter was spinning freely, but on observation the motor was turning over, just zero fuel.

The next cranks were probably around 5 seconds each (which seems like a long time when you're actually cranking and wondering why nothing is happening...). After a couple of such cycles I went and checked that we hadn't miss-connected something but all looked good. Figured I'd try another few times and then on the last cycle it sounded like it wanted to start. Tried a final time and it kicked over - lot's of fuel smell out the exhaust for a little while and then it cleared up. Let it run a couple of minutes and shut it down for a while. Heard some liquid noises and spotted a little dribble/splutter on one clamp near the heater valve. I have mostly breeze constant tension clamps, but on the hose that was dibbling it's standard clamp, so gave it a few more turns of the screw and topped up the radiator.

Fired it up again and it started immediately. Nice and smooth, no fuel smell and let it run while checking for leaks and all looked good. Let it run until the temp gauge was at normal and ultragauge showed no new errors (I cleared the old ones) etc and temp up around 165F. No leaks and all looked good and engine nice and smooth running. As you say, the cleaned (and one new) injectors make it purr like a kitten.

I had initially left the key in the on position (looking for fuel rail leaks prior to putting the upper intake back on), but I'm wondering if the fuel pump does anything (since it is ECU controlled) without the engine cranking/running? If it does, maybe with air in the filter/fuel rail, it just pressurises the air and then sits happily. In hindsight maybe using a vacuum pump on the pressure regulator vacuum line will open up the pressure regulator to allow fuel to circulate freely? Anyhow, all moot at this point since all is running happily. I'll be checking leaks and topping up the radiator over the next few days as it purges any remaining air out of the cooling system.

cheers,
george.