My trouble continues....

[Makenzie]

A few months ago I was posting on here about getting help with a '97 GA with a 3.L in it, I have replaced injectors, and fixed a lot of stuff. I feel that I am close but have hit a dead end. I have had a P0305 code, cylinder 5 misfire this entire time, I replaced that injector twice now, I tested the injector before I put it in and it worked fine. But, I still get that P0305 code? I pulled the plugs and it looks as if #5 isn't firing at all, the plug is not showing any sign of burning anything such as the other plugs are??? The plug is sparking though, I pulled it and checked, so what else is left? Is the ECM not sending a signal to it? I don't understand this one, and I am wondering if I put a test light on it will I be able to see if the injector is getting a signal? maybe a grounded or broken wire?

Please help?

Thanks,
J

[carlover626]

I know you tested the injector, but have you tried switching the injector with like #4 and see if the problem then moves to #4 cylinder or stays with #5?

[SE2000]

I think this is a good idea also. Also post a link to your old post

[Makenzie]

Yes, I have swapped injectors, as well as coil packs, different kind of plugs, wire, ICM.

But I always got the P0305.

Here was my last two posts on this.

http://www.gaownersclub.com/forum/showthread.php?s=&postid=940064#post940064


http://www.gaownersclub.com/forum/showthread.php?s=&postid=926752#post926752


Thanks,
J

[carlover626]

Sorry, I can't offer much help here...But here is a bump!

[rixGAphx]

Originally posted by carlover626
I know you tested the injector, but have you tried switching the injector with like #4 and see if the problem then moves to #4 cylinder or stays with #5? Swapping injectors on the 3.1 and 3.4 is the most troublesome way of diagnosing anything.

Step one: Disconnect the intake and throttle body.
Step 2: Remove the Upper Intake Manifold to gain access to the fuel rail.
Step 3: Remove the @#@$%ing fuel rail, which is one unit with three injectors angled left and thre angled right; removing the rail is like wrestling an alligator.
Then use new O-rings and swap injectors.
Step 4: Reverse everything and button-it up.
Step 5: Start engine and see if there's a change.
* * *

No. 5 is still mis-firing, despite a TON of work in every reasonable area.
Time for UN-reasonable. :D

Really, Mak is on the right track: He needs to check the electronic pulse that goes to #5 injector. Either the PCM isn't sending the signal, or there's a wiring problem and it's not getting thru.
Yes, it can be tested, using a digital multimeter.
Sorry, I haven't a clue which wires/pins to test, under what circumstances to test them, or what values they should read.

I *think* just getting to the wiring requires removal of the UIM, but I'm not sure.
And, I don't know why the PCM isn't reporting a problem with that injector's circuitry, as well as a misfire.

I would be more inclined to absolutely rule-out #5's ignition as the cause, before diving under the UIM.
I would assume the plug is good, and:
* Swap the #5 plug wire with the #1, and see if the problem migrates (we both know how much fun it is to work on the rear plugs :roll: ); no joy? then:
* Swap the 2-5 coil with one of the others, and see if the misfire migrates (this is a fairly easy swap).

'Firing' requires: Spark, air-fuel, and compression.
Have you done a compression test?
* If #5 has a bad intake valve train (broken rocker arm or bent pushrod), it won't suck-in any A-F mixture, therefore no fire.
* If it has a broken edge on an exhaust valve (does happen, but it's veeerrry rare), then it won't produce compression, therefore no fire.

Still nothing?
* Closely examine the bundle of wires that serve the injectors. A simple nick or twist could have damaged a wire.
* Attack that injector's circuitry, armed with a DMM and the proper procedure and values.

* * *
Now, for the UNreasonable.

No. 5 has always been the oddball cylinder on this engine; even back in the days of the carb'd 2.8 version.
It's not oval or anything stupid like that :roll: (though Honda experimented with oval cylinders as a way to fit more valves).

Rather, the Exhaust Gas Recirculation, EGR system, has a 1/4" diameter hole in the #5 exhaust port.
There's a passage (and tube, IIRC) that routes the #5 exhaust gases thru the EGR valve, and dumps it into the intake plenum for re-burning.
If/when the EGR fails, the passage becomes caked with sooty unburned exhaust.

I really don't know if, or how, a blocked EGR passage could cause a continual misfire.
But it is an interesting coincidence that the mis-fire is at this 'oddball' cylinder.
(The No. 2 cylinder is identical, headwise, to the #5;
so it also has this passage in its exhaust runner.
But it doesn't go anywhere; just stops at the LIM gasket, no passage in the LIM to receive its exhaust.
The other two cylinders in each head don't have this port.)

Mebbe do some checking on the symptoms of blocked EGR, and troubleshooting/repair.
I know that hunk of metal is crazy expensive, $300 IIRC :eek:

I dunno if any of this helps,
-Rick