I have been chasing a recent misfire and, longer term, witnessing declining performance and increasing smoke since I built the 408. The smoke is a bluish-white, and is now just steadily coming out and giving a throttle creates a cloud. Picture any of the early Caravans you see, they all do this, and triple it. I was out there warming it up trying to find out why my scan tool says it stays in open loop, I went behind the car, looked at the smoke and figured I was wasting my time.

This is what happens when you run a new motor with 36# injectors and a blocked off return line, probably 70+psi. I have only myself to blame, all that work and one stupid mistake....

I'm hoping I can get away with a simple hone, it's already .040 oversized. I will be using this as an opportunity to go solid roller, up compression and maybe some new heads.

 

You can always do a compression check and a leak down test to make sure it's the rings that are causing the problem before tearing into the engine.]

You might be pleasantly surprised if it turns out to be nothing more than a sticking regulator or some other easily repaired problem.

The 02 is probably fouled from the excess fuel in the exhaust.

Jake

 

Say it ain't so Steve! I sure feel your pain! I chased that problem all last season!

 

Sorry to hear

 

Yeah, I need to do a little more homework. My compression readings vary by about 10%, with more being on the low side. This is sort of within range for many motors but I don't think it looks good for a professionaly built motor with less than 5,000 miles. These readings are 6-8 months old and the smoke is worse now. I am currently searching for leakage tester, we had a shop one but I no longer work there.

I'm thinking you're right on the O2 sensor. When I first started this quest I thought it was running rich due to the smell, but as the smoke has increased, it is not black. Certainly nothing like the first couple days of running 70+psi. (the previous owner installed a shut off valve on the return line which i used while the car sat with no motor. I forgot to open it up prior to starting it. The smoke was unbelievable.)

I recently changed plugs, that were less than 1 yr old themselves. I could remove a chunk of carbon from them, not just scrape, but a chunk on the backside of the electrode.

I will wait to do a leak down test, mostly because I was unable to hear air escaping the intake/exhaust or breather when I introduced compressed air after the compression check. Because I could not verify air in the crankcase, I held off doing anything at that time.

Dave,
Yeah, I remember talkin about it with you. It just runs worse and worse, everytime out to the track it was slower and slower and the smoke now is terrible. I wish I could resolve the problem the way you are with an "upgrade".

Thanks Agent. on the bright side, my only interruption to the build this spring will be a class to satisfy my Phys Ed requirement, every Thursday evening....Golf 101 for two credits. I love being a student again.