when van is started theres a gas odor. motor shakes and is worse when in gear.while driving the van seems to backfire/pop(sounds like its coming from the exhaust).theres no smoke from the exhaust.missing like crazy while driving and i can seem to figure it out.can any one help/suggest something to try?

first code was lean,cleared it and drive it then i got a cyl 1 4 and gen. mis fire.
van has a new fuel pump,ff, coil(changed twice), omni wires, motorcraft plugs. changed the intake gasket, cleaned all fuel injectors, checked for vacuum leaks.fuel pressure at idle is 34 and with regulator unplugged it rises to 40.compresion for 1 2 3 4 5 is 170 and 6 is 160. used a scope and all injectors are pulsating. cleaned maf. cats were suposably gutted. has no codes coming up.

 

If your cats are gutted, the oxy sensor readings will be screwed up unless you have oxy sensor simulators after the missing catalytic converter(s).

Seems to me that the post-cat oxy sensors will be getting messed up readings and leaning out your mixture to try to compensate. Gutting cats is pretty illegal and if your van is a long term keeper, I'd get some cats on the thing. In the old days I have removed and gutted cats myself (and removed air pumps, etc) so I could run regular leaded gas but these days I like the idea of preserving the world for future generations. But these were vehicles without oxy sensors and computers.

Good luck,
George

 

Can't be the cats George, the mixture is only adjusted with the front sensors. The downstream sensors only exist to make sure the cats are working.

 

Thanks for the info--would the downstream sensors just trigger a check engine light and corresponding OBD II reading if the cats were not there?

I get paranoid about the idea of messing with any kind of emissions equipment in this day and age because everything is so interrelated.

Regards,
George

 

Yup, that's exactly what would happen. One of the big purposes of the OBD-II system was to make emissions checks easier. The idea is that if the check engine light isn't on the car should pass emissions. So the downstream sensors were implemented to ensure that the emissions equipment was working properly.

Yeah it certainly is. Unfortunately lots of folks remove or gut catalytic conversions for what I think are pretty silly reasons. I haven't heard of anyone having issues with how the truck runs after that though.

 

Did all this bucking, odor etc suddenly start or has it been one of those "slowly getting worse...." situations?

From your description possibly you have an ignition and/or firing order issue, sounds like motors with timing chains where its "jumped time" and not firing properly.

Has anything in that realm been checked yet?

 

its a companys van i work on.they told me it started while driving down a dirt road.when i picked up the van there was only a lean code.i cleared it and drove it for about 7 miles(my shop)and codes came up as cyl 1 and 4 and gen mis fire so i replaced the coil again, wires and plugs cleaned the injectors did the compression test.it ran alittle better but still skips bad and when in idle i turn the ac on and put it in gear and itll stall.
could it be a bent valve or push rod?

 

The popping is diffidently a misfire, gases are firing in the exhaust manifold.

After you replace all the above listed 'basic' parts, did you check the major components?

Have you checked the distribute for "looseness"?

Have you checked the timing chain for "Slack"?

I was fighting this same problem on my '92 5.8, found the dist was wobbling, replaced with new, could get the timing on at idle, but rev'ed up, the timing was bouncing all over +/-. Did the chain test, and ended up replacing the timing chain and gears, and on the way into that, found that the chain was not OE.

All that helped, but still not running right.

Conclusion = cam shaft is shot. Yes, this is the pre- '94 roller cam engine.

Next step - engine replacement, cause I don't thing it's worth just doing the heads and cam, next thing to go, the lower end?
And this engine only has 126K on the clock, but I'm not the original owner.