Lately my car has been hesitating and running extremely rich at idle and part throttle. When I slam down the gas I would get a slight miss as well. I also noticed in my rearview that after a few hard runs I would get blue smoke coming from the exhaust. I have a crankcase evac system and noticed the hoses are soaked in oil. Are the Mr. Gasket valvecover fittings supposed to filter out oil in any way? I'm thinking maybe those are bad and the oil is getting onto my O2 sensor causing my hesitation and running rich problem. If those aren't, how can I prevent oil from getting sucked into the exhaust so I don't have a smokeshow after every few runs.

-fuel injected 406, evac system, dfi for tuning.

 

Anyone??? I'm trying to sell this car, but I need to figure this out before I do!

 

If the VCs arent baffled, you can suck up alot of oil. Also, it sounds as though the engine is just way rich all around.

 

The VCs are baffled. Yea, it's running a bit rich, but I think that's mainly because the oil is coating the O2 sensor and throwing it off. I need to figure out how to keep the oil from getting sucked through and then deal with the running rich. I may just block off the evac system altogether for now, although I'd like to keep it.

 

For the oil, maybe you want to get an external seperator to pull the oil out.

Also, how does it run under WOT? If the O2 isnt heated, then it can be fouled out with carbon. This can cause the AFRs to swing excessivly as the ECM tries to get the desired output out of the O2.

 

Well the point is that it didn't used to do it, so obviously something went or broke causing it to go into the exhaust and smoke now. Under wot it runs fine, but it is putting out less power than it used to. It just feels a bit weaker, and the car seems rich just from smelling it. I thought the O2 plays no role in wot?

 

Still haven't figured this out!

 

Dynoed the car and it only made 403 rwhp .... about 60 less than in the past. I was only able to run a compression test on a few cylinders due to header clearance, but I haven't been able to figure this out. It's definitly running rich seeing that all the plugs are equally very black. I pulled off the cap and the cap and rotor were in prety bad shape so I replaced those today. Having a weak spark could contribute to the missing issue, but I still don't understand where the smoke comes into play.

I was thinking possibly a headgasket issue at first, hence the reason I was doing a compression check, but once I saw all the plugs and they all looked te exact same I find it unlikely that there is a problem in just 1-2 cylinders. There was also no oil / coolant mixing.

I also tested my map sensor and tps sensors as well as checked for vacuum leaks to try and figure out the hesitation / rich issue and everything checked out great. Any other ideas?

 

My 305 has a simular problem. I did a compression test and 2 of the cylinders had 70psi. The blowby was so bad even with a PCV valve it would blow the breathers off. I ended up cutting the bottom off of it and removing the guts so it would releave the pressure better. At idle they dont fire right but when the rpm get to around 2k they start fireing. If i stomped it off idle it would spin for a few feet then bog horribly. Ended up changing the silipping transmission and put the 3k converter in it and now it will spin the tires for a good 30ft

 

Did you end up having a bad headgasket? That's what I was thinking my problem is, but I have no oil / coolant mixing or other obvious signs. Like I said I'm only able to get the compression tester to a few cylinders because of how the headers are. Is there a special tester available that allows me to test with the headers on?

 

No, the motor is just plain worn out. Somewhere around 230k on it. Cutting the pcv valve helped my problem, all i had to do after that is ritchen the carb so the motor wouldent lean out. It is just a bandaid tho, i dont want to rebuild the motor.

Still running great, i drive it everyday and take it to the track every friday. When i first cut the pcv valve and got it running ok i got a 15.9 out of it. after the trany, stall, and roller rockers i got a 14.7.

I dont know if there is a special tool for getting the compression tester around the headers. I needed to change my gaskets so i just unbolted them when i did the compression test on mine.