Severe Misfiring

voodoochylde · Sep 27, 2010

Hi guys/gals. Got the hesitation problem worked out. Changed the forward-most fuel filter and the fuel pressure regulator. BII's been running OK...well...what little I've run it.

Drove it to work this evening. Been raining off and on for about three days now. This is the first time I've driven it since last weekend. Anywho, started the truck up and it was misfiring pretty badly (which it's been doing). I figure, "Meh, let it idle for a couple of minutes and she'll smooth out as normal." NOPE.

Blasted thing seemed to be running on maybe 3 or 4 cylinders only the entire way home. Had to ride 3rd gear up the mountain to maintain 45mph. Stumbling all over itself, bucking, just horrible in general. Start coasting down the backside of the mountain and OH MY GOD. The smell that entered the cab seemed to be straight from BII hell. It was so bad my eyes were watering.

Just as a rundown on what I've done recently:
Forward fuel filter (Wix)
Fuel pressure Regulator (NAPA)
Plug wires (Freakin' Autolite, all that Advance had)
Plugs (Motorcraft - I set gap at .044")
Rotor Button
Distributor Cap
TFI Ignition Control Module (Duralast, AutoZone's in-house brand)
Seafoamed thru brake booster vacuum line
MAF Sensor Cleaner applied to both the IAC Valve and the throttle body

Other than the rain (which I am absolutely praying isn't the problem as this is supposed to be a winter vehicle) the only thing I can think of is the PCV sits funny in the valve cover. To elaborate, it is quite loose in the grommet. It doesn't snap in or seem to seal. I just hadn't gotten around to it yet...I know, I know...dummy me.

Anything else you wonderful RBV gurus can think of? ANY advice would be appreciated as I'm just plain dumb when it comes to these things. It ain't a Subaru - lol it doesn't make sense to my pea brain sometimes.

Thanks in advance!

kimcrwbr1 · Sep 27, 2010

Motorcraft plugs recommended I prefer autolite single platinum, PCV, reset the computer if you didnt after cleaning the maf. then pull the codes. Always reset the computer when cleaning/changing a sensor by disconnecting the battery for 1/2 an hour.

voodoochylde · Sep 28, 2010

Already reset the ECU by pulling the negative battery cable for about two days.

Thanks for the ideas!

srteach · Sep 28, 2010

I bought now Bosch dual plat plugs and had the misfire problem once. Changed to Autolite plats and the problem went away.

Shran · Sep 28, 2010

kimcrwbr1 said:
Motorcraft plugs recommended I prefer autolite single platinum, PCV, reset the computer if you didnt after cleaning the maf. then pull the codes. Always reset the computer when cleaning/changing a sensor by disconnecting the battery for 1/2 an hour.

'86 2.9 would not have MAF

What smell is it making? Raw fuel I'm assuming? Do you have adequate fuel pressure and are both pumps running?

Make sure you have spark at every plug.

b2rich · Sep 28, 2010

Shran said:
'86 2.9 would not have MAF

What smell is it making? Raw fuel I'm assuming? Do you have adequate fuel pressure and are both pumps running?

Make sure you have spark at every plug.

and that they are connected securely to the wires

voodoochylde · Sep 30, 2010

@ Shran and b2rich, thanks for the ideas. I haven't checked for spark @ all plugs yet (I have next to no free time right now) but I'll get to it when I can. As far as the smell, when it's just sitting there, yes, it smells like it's running horribly rich.

I did discover something a bit weird the other evening by accident - when I tapped a relay next to the air box, the truck cleaned up for a second and then went back to sounding like hell. I think it was the ECU relay - I bought a fuel pump relay at Advance Auto and popped it in there, fit the socket just fine. Didn't seem to make much difference but I've only had it running in the driveway, haven't been able to drive yet.

Shran · Sep 30, 2010

Yeah one relay is for the fuel pumps and the other is for the ECU.

Could be one or more injectors leaking too. That would explain why it is running rich.

voodoochylde · Oct 1, 2010

Any particular way to test for that? Fuel pressure is now great and behaves exactly the way it should. If I let her sit for several hours it'll bleed down. I just figured that was semi-normal for an older-than-dirt truck that sat for the last two years.

kimcrwbr1 · Oct 1, 2010

voodoochylde said:
Any particular way to test for that? Fuel pressure is now great and behaves exactly the way it should. If I let her sit for several hours it'll bleed down. I just figured that was semi-normal for an older-than-dirt truck that sat for the last two years.

You can try a injector cleaning but if you plan on running it for a while new upgraded injectors couldnt hurt. I got mine for my jeep on ebay they have four little holes for atomizing the fuel better gained around 2 mpg. It just depends on what is available for your engine new stock injectors would be a huge improvement just shop around I paid $150 for six of them probably what you would pay to get yours cleaned properly. I would think checking the plugs for color would tell you if they are burning uneven I cant remember did you change the plugs and wires and PCV now would be a good time before winter sets in.

voodoochylde · Oct 2, 2010

kimcrwbr1 said:
You can try a injector cleaning but if you plan on running it for a while new upgraded injectors couldnt hurt. I got mine for my jeep on ebay they have four little holes for atomizing the fuel better gained around 2 mpg. It just depends on what is available for your engine new stock injectors would be a huge improvement just shop around I paid $150 for six of them probably what you would pay to get yours cleaned properly. I would think checking the plugs for color would tell you if they are burning uneven I cant remember did you change the plugs and wires and PCV now would be a good time before winter sets in.

I read the old plugs for color, they looked darn good. Haven't checked the new ones but it is on my to-do list.

Guess I'll be seafoaming the gas tank now lol. That kinda money just doesn't exist right now for new injectors so if it needs them, it'll have to wait.

Yes, I changed plugs and wires. Still need to do PCV valve.

Thanks for the suggestions.

kimcrwbr1 · Oct 2, 2010

Seafoam or just add 4oz of acetone to a full tank of gas to dissolve any varnish that has built up in the system. Three things can cause the drop in fuel pressure the injectors pressure regulator or high pressure fuel pump check valve unlees it is just leaking out somewhere. Put a new PCV in it then check the vacuum pressure it should have close to 20hg in vacuum at an idle low vacuum will make it run rich also.

voodoochylde · Oct 2, 2010

Good information, thank you again!

Severe Misfiring

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