I know that this engine is kinda weak from the factory, but it's getting worse. I'll give you a little history on this engine.

Everything was pretty good untill an upper intake manifold gasket blew, dumped coolant into the #1 cylinder, and took out the head gasket. I drove it burning coolant for probably at least 6 months because 1) I didn't have the ability to take it off the roa because I use the truck for business and 2) I didn't have the extra cash then.

So I finally got it fixed. Basicly rebuild the engine w/o messing with the short block. Heads were trued, all new gaskets, cylinder walls checked, new plugs, boots, etc. 2500 dollars worth of Ford F-up.

It now seems like it's low on power. It takes a lot more pedal to maintain speed and its downshifting a lot more. It feels like something is holding the truck back. The engine revs, but there is nothing there. The valley right after the 1-2 shift is the worst. Add AC and a trailer and it's terrible.

There is no smoke, no oil consumption, no coolant consumption, fuel economy isn't any worse than normal and might actually be better.

I don't think that anything like brakes are dragging as it coasts fine in neutral.

I'm going to replace the fuel filter as it's been a while.

What else should I check? I was thinking fuel pressure. What's it supposed to be?

How about the cats? Could coolant have screwed them up?

The air filter is new and the engine just got its internals cleaned.

The truck only has 87K on it now.

Thanks,

Mike

 

I would look at the cats having a problem especially after drinking that much coolant I had a Dodge come in the shop that wouldn't run 55 mph. And showed not other signs took the exhaust loose from the mainfolds and it ran like a scalded dog replaced cat and everything was fine. A vacuum gauge will tell you if there is to much back pressure.

 

After all of that engine work, you may want to get a compression check to make sure everything is good and tight.

A backpressure test for your cats is cheap and easy as well.

 

I'll look into all that. I have a lot of faith in the shop that did the work. I'm mainly concerned with the cats. I thought I read that coolant is really bad for them.

It feels like a restriction issue. Or a not enough fuel issue.

It hasn't had a CEL since the engine was fixed. I haven't pulled any codes yet though.

Can anywhere do a cat back pressure test for the most part?

Mike

Edit: I have a vacuum gauge at my house. How do I run that test?

 

Most exhaust shops will check for free.

 

Ok I did the vacuum test and it read 20mmHg pretty much the whole time. The only drops were with increases in throttle.

I changed the fuel filter, changed the air filter, cleaned the TB and MAF sensor, and Seafoamed the engine through the brake booster line.

It still feels like I'm towing a bobcat all the time. Even the wife noticed that it has no power.

BTW-The truck is pretty much stock. The only things non stock are a SCMT running 87 octane program and stock size (265/70-17) BFG ATs.

I haven't done the back pressure test yet.

But what I did find with the Seafoam treatment was a good amount of smoke leaking between the connection of the passinger exhaust manifold and the down pipe to the cats. That is the same side that the coolant was leaking into.

There are no codes in the ECU. I'm thinking cats are clogged on at least the passinger side.

I'm still going to try to have it tested, but I think I've pretty much ruled everything out except for an exhaust restriction.

So I'm thinking bilateral cat replacements. I looked quickly at Summit and direct fits are around 250. Universals are much cheaper and I can weld them in myself.

Does anyone know what size in/out I need and if I need the air injection stuff? I plan on using one high flow cat per side instead of the stock 2. Will this keep the o2 sensors and computer happy?

While I'm under there I'll go ahead and do a cat back as well. I'm thinking 3 inch single Summit system with stock exit location.

Mike

 

Be carefull if your state does emmission inspections they are some times pickey about replacement cats. I would probably drop the exhaust pipes from the manifolds and take it for a spin to see if it improved before I spent the money for the cats. your vacuum test would indicate there is no exhaust restriction.

 

No E check here. Just don't want the CEL to be going crazy.

I'll have to wait until the weekend when I'm out in the country to drop the pipes. I don't think that the neighbors would appreciate the noise.

If one side was clogged and the other wasn't, should I still get reduced vacuum? What else could it be if not an exhaust restriction?

Mike

 

Even if only one cat is bad you would see it in the vacuum test at idle it might read ok and you expect it to drop when you open the throttle but when the engine rpm comes up the vacuum will come back up some and stay level. With a bad cat the vacuum will stay low or continue to drop.

 

I just don't know what else it might be. I still haven't done a fuel pressure test, so I'll be sure to do that. I'm also going to redo the vacuum test and try to schedule a back pressure test.

When I'm in the country this weekend, I'll try to disconnect the cats and drive it.

The only other thing I could think of is bad o2 sensors, but I figured that they would throw a code.

Mike

 

Unbolt the front O2 sensors from the exhaust and take it for a spin See if it frees up a bunch. Just leave them plugged in to the wiring.
I think the coolant may have wasted the converters.

 

Awesome idea. I'll try that out tomarrow as I'm at the firehouse today. I'm thinking that the converters are wasted as well.

Does anyone know the in/out pipe size and if I need the air injection port so that I can start pricing things out.

Mike

 

Should be 2.5" and it has no air injection/smog pump.