Constant Miss on #2 and Piss Poor Idle
 

Just bought this truck last week, and I like to start from scratch so when I gave it an oil change I also did a tune up. Since then I have a miss on #2 and it has fouled 2 plugs. I replaced the cap and rotor on the distru, wires and plugs etc. Since then I get a miss at idle when warm. I replaced the wires again, had a warrenty on them and exchanged them, instaled the new ones and within 10mins I have the miss again and I pull the plug and they look like they have seen 100k. WTF is going on here? I have worked on several 302's in my old Stangs, but never had a problem carry over like this. And I must have done something because the tune up she didn't miss. Just a slightly rough idle, nothing bad.

btw: It's an auto 302 4x4.

Thanks,
John

What does a wet/dry compression check show on #2 vs. the other cylinders?

haven't run wet/dry. But this has carried over now to the new parts as well. I am about to give up and see a dealer. I never thought I would say that but I am very busy. Argh I am going nuts with this! :mad: Damn it it was fine the day before I did it. argh!

John

oh yeah, it's not just the idle, under light throotle she stumbles abit and under hard highway power she still hesitates abit too.

You really need to do the compression check. The reason you're getting a miss is most likely that you're not getting enough compression to give you decent combustion. The reason that throwing more ignition parts at it hasn't solved it is because it's NOT an ignition related problem; it's mechanical. Your dry compression on #2 is probably going to be something south of 100 PSI, not good. If youre very, very lucky, you're wet compression will be low as well. That means all you need is a valve job (I'd bet on a burned exhaust valve but I've been wrong before.) If your wet compression is good, you need to either re-ring the engine or get rid of the truck.

Theres still other possibilities such as a bad fuel injector. Also just double check that all the wires are run correctly and are going to the right cylinders. and inspect all the other parts you installed, make sure there isn't a crack in the distributor cap for instance.

-Jon

I did run some injector cleaner threw it but I also know tat stuff is not exactly the strongest stuff. As for it needing a valve job, I've never had one just stick after a simple job like a tune up, graned I've know what has been done to the old engines before and this is like a stranger in the bed but still. When I can I am going to get on it and do alittle more digging.

John

Alright turning in my wrenches...

I have replaced...

-cap and rotor for the distru
-plugs
-wires
-intake temp sensor
-thermo
-timing chains and gears

I still have the miss and the aweful idle. This didn't happen till I did the plugsand wires in the first place. The rest is tracking down the issue afterwards. WTF.

John

and thanks in advance.

Humor me. Do a compression check.
Look at the bright side. If it comes back OK you can tell me I'm a dumba$$ and that I nag worse than your wife. On the other hand, if I'm right you'll stop throwing good parts away trying to fix the wrong thing.

Or you can sell me the truck for $100 :)

-Jon

I would if I had the tools to do it up here. I may just bring it in for service, but I prefer to look for oher options. argh.

same problem
 

i've got the same problem. trucks runs rough. i've mentioned it before. mine is a 93 also so i have the obd1. i get the two codes: "fuel runs rich" and "fuel runs lean." i've been told

1.) check for vacuum leaks
2.) check for bad fuel injectors.

the fuel injectors were apparently kinda easily broken on these models. mine "might" be stuck open on the #1 cylinder on my 300 I-6 because that plug looks way fouled.

i've checked plugs, firing order, distributor cap, timing, and plug wires. i've exchanged an oxygen sensor and the coolant temperature sensors (because they were both bad too). i've actually also changed out the plugs. (i put truck plugs in from champion....don't do that! they were horrible). it runs way better than it did, but it's still rough. i think the engine is getting too much fuel because there's an odd fuel-like smell. so i'm kinda giving creedance to the bad fuel-injector idea.

i don't own the fuel pressure guage to check for a bad fuel pump. otherwise i'd do that. i dn't know how much they cost. is there a way to test for a bad fuel injector without removing it?

Not without a fuel pressure gage. You need the one that screws into the Schrader valve port on the fuel rail.

If you know that the #1 cylinder is causing the problem you could try swapping the injector with another cylinder and see if the problem moves.

-Jon