86 740 Turbo wagon. 161111 miles. Rebuilt turbo, new catalytic converter. New fuel pressure regulator in the last 2 months. Wrote here a few days ago about my catalytic converter becoming restricted. Ordered a OEM cat and had it replaced yesterday. Since it was a direct fit, I didn't think I needed to go to the dealer for the replacement. The service station mechanic says he test drove the vehicle, driving it about 10 miles after the replacement at 65-70mph and said it ran fine. Yesterday evening when I came to pick up my car, when I first cranked it as I was about to leave the service station, it seemed to have almost no compression but it cranked quickly as expected. Mechanic then sat in the seat and cranked it, and it seemed to be fine. So I drove it home (about 15 miles) and during the last mile or so it seemed to feel almost restricted again, but not nearly as bad as it was with the old catalytic converter in it. Previously when I would disable overdrive there would be an immediate boost, yesterday there was none of the familiar torque "build up". So I called the mechanic when I got home, and he suggested that we check the plugs which may have become fouled from blow-back when the converter blocked up. This is a new mechanic for me, and I don't have a lot of experience with these matters. Does the plug fouling seem a reasonable explanation for the loss of power? To make matters worse, went out to start it this morning to take it back to him, and it wouldn't even crank until I hold the accelerator half-way to the floor and hold it there, and then it runs like it's being starved for air. As soon as I take my foot off of the accelerator, engine cuts off. I looked to see if possibly a vacuum line was off and didn't see any that were not connected. Any ideas on this? Is it reasonable that the plug foul might cause loss of power? Any thing that should have also been cleaned/checked with the swap of the converter? Help. I miss my car already.

If there was a large amount of material missing from your old cat, it may be lodged in and restricting a muffler...disconnect the pipe after the cat and see if things improve(it will be loud)

I have also seen a pluged cat create enough back pressure to force open the EGR(which conceivably could jam open?), burn out the air injection check valves followed by AIR hoses, thten the hot exhaust flowing from the blown hoses melted several injectors and a good part of the wiring harmess. Oil consumption was like 7 qts/hr, and i could not blow a detectable amount of air through the cat! This is on a 460 Ford, but could happen anywhere.

You might want to put a timing light on it to make sure you did not slip a tooth on the timing belt. I know it is probably not your problem, but if it happens you will have a similar loss of power. The only reason I suggest checking the timing is that it won't cost you anything if you have a light, or perhaps you could borrow one from somebody. Mine slipped on time as a result of a slightly loose timing belt and working on the belts (i.e. moving the crank pulley). If you don't have a light you can remove the cover and check the timing marks with a flashlight.

R Duke

"To make matters worse, went out to start it this morning to take it back to him, and it wouldn't even crank until I hold the accelerator half-way to the floor and hold it there, and then it runs like it's being starved for air. As soon as I take my foot off of the accelerator, engine cuts off."

By crank i assume you mean start. So, i had a problem where my car would not start until i had the pedal about half way down. Then when it did start it ran like it was running on 3 cylinders, if you took your foot off the gas a little bit it died. Unplugged the AMM and it started and idled fine. The AMM was the problem. Unplug yours and see if it helps. It only takes a minute to unplug.

I think the plugs are the wrong direction. Did you check for (small,bottom sides) leaks in the turbo hoses? Sounds like a more likely culprit.