High RPM Miss

[dangerranger83]

The 4 speed was standard. The 5-speed was an option. It wasn't until later the 5-speed was standard and the 4-speed was chucked, I think when the 2.9 came out.

 

[fastpakr]

Right, I understand that. Just never heard any reference to the 5 speed not being an available option from the beginning.

 

[dangerranger83]

So any up-dates?

 

[Eric Kropp]

So back on the tranny subject. Mine is an '83 according to the registration and could/should be an '84 according to the date it was built, 10-1984. And it has a five speed. I wish I had more time on my hands to come to Sacramento and get my hands dirty on the Nicky's truck and help make it pass but the last two months have really been bad.

 

[TheNicky]

Ok guys sorry i had been busy...

Dropped the tank... cleaned out the rust...
Took it again with the following modifications

Inline fuel filter (becuase the fuel sender filter was trash)
Can of restore
Fresh oil change
New air filter and carb fuel filter
Can of HEET
New gas
And added a MSD ignition to prevent misfires
New fuel cap

And after all that i drove to smog left it running the whole time
AND STILL FAILED

i guess it had a miss at the 25 mph but me and tim are stumped...
ill get numbers up soon but the only fail was HC's at 25mph im thinking because of the miss...

So since i failed i can only go to test onlys now...

 

[dangerranger83]

Okay time to go over everything in the ignition system. What hasn't been changed? I'm going to be doing one question at a time. Its time to dig a little deeper. I'm probably going to be doing research to help you out.

 

[TheNicky]

Lets see im sure ill forget something but here goes

Ignition Module
Thoroughly CLeaned the dizzy
Cap
Rotor
New plugs (gapped properly)
Wires
Coil

I think thats it...

 

[dangerranger83]

There are parts in the dizzy that can go bad but I dont know what they are.

I know everything that you have done to the fuel system including the carb. not being tuned but. The hydrocarbons are from unburnt fuel. I wanna ask if you have replaced the CAT on it. It has to do alot with the hydrocarbons it might not be doing its job good enough if it needs to be replaced. I know they are expencive. Also the air pump too. I dont see where it introduces the exhaust gases back into the system. All I see is it allowing outside air to be pumped into the exhaust system, kinda wierd in my opinion. And ya they arent cheap either.

I just cant think of what would be making it miss like it is. Try to get those numbers up so that I can see how bad you failed. I think its pretty stupid that the spout conector is unplugged during the test. Its more or less missing because the timing cant advance. Has it been missing for you when you have been driving it?

 

[TheNicky]

Yes every once in a while still...

ummm newer cat...
and carb is tuned... and it doesnt make a difference becuase its tuning for idle in which it isnt testing... it only failed at 25 mph HC's i think it was a 172 and max was like 125-150 or something... in that area

 

[dangerranger83]

Well something got worse. Your last run was 142. The max is 126 from what you said.

 

[enginepaul]

I think I'd be looking in the air pump department. The air is fed to the catalytic converter and helps burn off those hydrocarbons. Test were done showing Ford cats perform better than after market ones and those vary too.
Start with air valves and hoses and the vacuum line that control the valves.

You're almost there.

 

[dangerranger83]

I've heard of a guy that hooked his air pump to a constant vaccum sorce and made it run at all times. I dont think it would be good on the pump though or legal. Its weird how you go from 142 to 172 on the HC. What was different from then to now that you might have changed?

Like enginepaul said you're almost there.

 

[TheNicky]

Sorry i havent been on... A) I havent been at my truck in a couple days...

The city is hating on me and tired of seeing my truck in my buddies driveway so i had to move it for a couple days... B) i had some things to get done... but i promise to post the numbers...

Last run i ran sea foam on a semi warm engine

this time i had

New Oil
New filters
Restore
And HEET

so i dont know... i should check the air pump!
But whats to check?

 

[Big Jim M]

Are we all aware of the fact that the idle jets in the carb are metering fuel at all rpm? So in effect a VERY rich idle mixture can cause the entire metering system to be rich at all rpm?
Another point to make about the carb is the float setting.. Just a small (1/8") setting too high will cause a slightly rich mixture at all rpm.
I think I'd be looking into the carb settings.
Big JIm

 

[dangerranger83]

Im aware that that idle jets effect metering fuel at all rpms. After adjusting those screws on my dads 2.8 hes getting much better fuel mileage and they weren't adjusted that much either.

As for the air pump I know of no ways it can be checked. I think its a hit or miss kind of thing when knowing its working right or not. I would try to emission the truck with just gasoline and no additives. They might not be helping you out, they may be hurting you.