I appreciate your responses and encouragement. As rovers get older I hope that someone will find this thread helpful.

 

I've found this thread useful and it's nice to know that others have misfire problems...however mine aren't due to vacuum leaks or anything simple to fix sadly.

 

I think I may have figured it out. Now to test my theory...

Recall that I have replaced plugs and wires in the last week. Today, I removed the intake and replaced the o rings on the injectors. I also replaced the coil with one I already had. In fact, I have an entire, spare, toasted engine. When I pulled the injectors, most of the o rings looked like crap. Replaced all of them. Had my very detail oriented wife check my wiring to the coil and cylinders. Put it all together and... IMMEDIATE cylinder 8 misfire. Worse than before. Erasing codes did nothing and it drive like utter crap. That's significant because I am positive that I swapped the #8 injector for one of my others. I also swapped the coil. So just to be sure I had spark I pulled the number 8 plug, put it in the boot, and started it long enough to see a really awesome spark. While I was doing that (of course I got shocked and hit my funny bone, rendering my left arm useless for a bit) I did not smell gas coming from the 8 spark plug hole.

So I turned it off and swapped the 8 and 1 plugs... Just to be sure it wasn't plug related.

Hopped in and drove. Now I get p0308 and p0208. Wow! Tell me that doesn't mean the wiring to my #8 injector is fried.

Not a cause for celebration on the whole, but maybe I am Narrowing this down. It got much worse when all I had done is pull the injectors, put new o rings on them, and put it all back together (with swapped coil). And I didn't smell gas from the open spark plug hole for 8. To me, an idiot, it seems natural that the number 8 injector is not doing its job. And since that is a different injector, the probability that the injector is bad is astronomically low. Ergo, wiring.

Does anyone agree or disagree? How can I test this theory? I do have a complete wiring setup from my other engine, but surely there is a way to test this before replacing all of the wires.

Will a noid tester do it? I don't have one but I could use a test light. Or can I? And if I do so, how do I test that connector? Can I start the engine with the intake off?

Best,

Charlie V

 

To be fair and honest and for any others with similar problems, I determined that my anomalous 3/5 misfires resulted from me crossing the connectors to those injectors. Discovered that tonight. I always work with a flashlight at night, and have poor close-up vision. The wires were also bent at a crazy angle that made it appear that their respective injectors were obvious. When I worked on it tonight I made sure that the wires went to respective injectors in the order that they exited the loom.

This is what It looked like before I changed it up...



I noted before that a lot of these problems occur after HG jobs..
And HG jobs require removing the injector connectors to remove the intake. I wonder if those wires aren't just getting pinched or bent or whatever. Or mixed up, as I did.

 

So to catch up, you have narrowed it down to only one misfire (now only #8) and a #8 injector circuit fault?
You are making progress. I believe you are correct in that P0208 does point to the problem being the injector or injector plug/wire.


The mixed up injector wires explains the clearing the codes and it immediately running better. In my opinion the computer was taking a second to recognize that the injectors were on the wrong cylinders and when you cleared the codes it would immediately reset and think the injectors were back on the right cylinders.


Now for the problem with #8. It could be a few things.
1) the injector is completely clogged or bad
2) You pinched the wire or have a short in the wire somewhere
3) You may have got a piece of dirt or some water in the injector plug or bent the 2 connections in the injectors.


I hate to say it but I think you need to tear the thing back down one more time. Take a really close look at the injector plug and wires for anything bent, cut, pinched..... If you don't find anything take the #8 injector and move it to one on the opposite side with a known good injector (or if you have 8 good spares on the other engine, just replace it with a good one).

 

Well the old engine died. Ex drove it with broken radiator hose until it spewed antifreeze arterially. I guess that could affect the injectors so I might have grabbed a bad one. I'm definitely going to have to tear it down again, though I won't be putting new coils on or removing the injectors so it should go faster.

Can I just use a test light and look for a pulse on the number 8 wire? And how does one do that when the injectors are buried in the intake manifold? To move the intake manifold I have to remove vacuum, a water line, and a bunch of other things. Can I turn it over long enough to look for a pusle with the intake to the side?

 

Injector pulse width too narrow for a bulb filament to heat up.
An LED could work.

An oscilloscope is the best tool if you have one.
Put the O-scope on DC 15V and you'll see the square wave if the injector circuit is working..

Thinking the injectors all have one side wired to +12
and
the ECU just grounds the other side with open collector power transistor.

So on the injector plug - two wires.
Betting that one is hot - with the key on. That voltage is fed into the injector and
the injector fires when the other side is grounded via the ECU.

To simulate this, you may try a 100 ohm or even a 10 ohm resistor on the plug and put a scope across the resistor.

The voltage across the resistor will only occur when the injector circuit fires and tries to ground that one side.

Or - just get an old injector from the old engine and put it in your hand.
Attach the wire.
You will feel it clicking in your hand.
That is easier.

 

I would pull the wire from both injectors and get an ohm meter and put it on X10.
See if the injectors are at the same ohms reading.

yeah, if the wires were switched, you have that figured out.
Now just #8.

Don't mess with the head bolts.
You did a good job on those, so leave them alone.

 

And yes the number 8 is the only one throwing a code now. I failed to mention that I re attached all of the injector loom to the rail pretty carefully and, more importantly, replaced the number 4 injector with one from my old engine after I boogered it removing the lower o ring.

If the next tear down reveals the wiring as the culprit I'll be sure and post that. In any case I will be much more careful with injector wires in the unlikely event that I ever do another head gasket job.

 

I doubt that the engine will run with the intake off because it won't have vacuum. Also, if there are open coolant line they will pump coolant if the engine belt is on the water pump so you my need to take off the engine belt. I'll need to do a little bit of research on how to test the injector, but I'm thinking that you might be able to remove the fuel pump fuse or relay (fuse #10 under the hood I believe) so that the engine wont fire up but you can still crank it. The computer might still send signal to the injector even though the fuel pump has no power (don't hold me to that, they may be tied in together and if the pump has no power the injector may not also). You may be able to put a test light in the injector plug while a helper cranks the engine a few times. .