Engine Trouble

[Whosondephone]

I’m having some trouble with my 5.0. It won’t start up right. I have to run the starter 3 to 8 times as long as I think I should. It also rumbles at idle. It seems to be misfiring when under stress when going 20-25 MPH in third gear, going up a hill. It behaves similarly when in Overdrive. I also notice it has a strange vibration in the top RPM range. The exhaust smells heavy. (maybe rich?) I can smell raw fuel at startup. I don’t see/feel any exhaust leaks however I smell fumes in the cabin. (Perhaps due to the heaviness of it)

I tried checking the coil impendence however my ohm meter is only accurate up to 0.02±. When I replaced the TFI module the engine died out at times. I then learned how to check for arcing. I noticed arcing on the coil itself. I also noticed arching at the output wire of the coil to some small wires near (I believe connected to) the coil. I replaced the coil. I replaced the wires with Ford racing wires. New cap and rotor. The spark plugs are relatively new Autollite platinums. With the new coil the new TFI module works just as well as the old one does. I have the TFI installed with nothing in-between it and the distributor. Made sure it was clean.

I just checked all of the plugs. They show that the engine is running hot. This could be because I recently used Lucas intake cleaner fuel additive the past 3 fill-ups. I also recently raced it 2 times recently. I have never been able to flush out all of the brown out of the coolant system. I flushed it maybe 4 times last summer using products. Now I’ve begun flushing it once daily.

Some other things that may be related: I’ve replaced the leaking steal fuel supply lines with rubber ones. New Fuel pump and filter. I replaced the PCV Valve. (it looked like it was done recently however it wasn’t sealed) New alternator I have reason to believe the voltage regulation circuit was going.

What I’m considering: The oxygen sensor on the driver side looks new. Looks can be deceiving. Is there one on the passenger side? I think it could be the TFI module because they both were used with the old coil. I feel it is the PIP sensor.

I would appreciate any advice I could get. Thank you in advance.

[sly]

there should be an oxygen sensor on the passenger side (very near the heater plenum at the back of the exhaust manifold). If you put clean water in and it turns brown (like a milky brown) then it's oil getting into the coolant and you may have a blown head gasket. This would explain the rest too. The break in the head gasket is probably very small since you're still able to run at all. But since that's a rather spendy diagnosis (in labor)... should probably wait for a second opinion.

[Whosondephone]

I also forgot to mention that it now has 92,000 miles.

Late Last Summer I made a switch from castrol 10W40, to Moble one synthetic 5W30. I was misled. I didn't realize there was a regular formula and a 15,000 mile formula. So I took a 15 hour drive straight down to Georgia and back. At the time she was leaking oil so I may have put one quart of oil in each way. Than maybe 2 quarts of oil throughout the year. When I changed the oil in the spring I remember seeing copper color waves in the oil. Now I've tightened up the oil pan and calve covers I'm using a Valvoline 10W40 Synthetic blend. No leaks. Doesn't appear to be burning oil.

I flushed and filled the radiator before the trip last year. When I checked it a year later it was down 10%. 90% full.

I was worried that maybe it was the main bearings. I can tell you that I am pleased to think it is the head gasket. It doesn't seem to be getting worse. No more racing.

One other thing. I remember having the hard starting problem in the summer last year. Then it went away in the fall. As I've said now it's back. I think that supports the head gasket theory. The car apparently did a lot of sitting at some point.

I might just adjust the downshift leaver to make it shift sooner as a temporary fix.

[gadget73]

Check the vacuum hose to the MAP sensor. If thats unhooked or damaged, the engine will run horribly rich.

[Whosondephone]

It is interesting how this problem as evolved over the years. Sometimes it runs very smoothly with lots of power. Sometimes it runs very badly and misses with rich smelling exhaust. Since then I've done some head gasket repair treatments, "the complicated kind" that is suposed to be flushed out. I am happy to report green antifreeze for about a year now and still have heat. However I'm certainly putting water out the exhaust.

I've yet to change the oxygen sensor. I was talking with someone who suggested I do it. My question is how does water in the exhaust affect the oxygen sensor? Does it change the results? Does it damage it?

[DerekTheGreat]

You try checking the vacuum line going to the MAP sensor like gadget suggested? How about the MAP sensor itself? ECT sensor?

[Tiggie]

Sound rich and possibly not firing on a cylinder or two. Check that MAP and the vacuum hose. The stock hose gets old and can collapse.

What do your plugs look like? Rich would be black sooty if all are firing. or maybe wet if it's not firing on a cylinder. Hot looks silver.

[Whosondephone]

Whoops I forgot to respond years ago!

When I checked three years ago the map sensor hose was good. The map sensor seemed OK. Perhaps it's worth replacing if possible. Not familiar with the ECT. I'll look into that. The plugs looked slightly white.

I'll recheck everything soon nice weather is coming Thanks for the help!

[Rodentkiller]

Try using regular spark plugs the platnum will not work with a standard street ignition on our old 5.0L cars with the TFI module.

[gadget73]

Boring cheap Motorcraft copper plugs work really good in these motors.

[Whosondephone]

Thanks for all the feedback.

I can't seem to locate the ECT. Could someone tell me whereabouts to look for it? I would also like to replace the hose to the MAP sensor. Do I need to remove the Intake Manifold to replace the hose? I don't think I can get my hands in there. If so I suppose I'll need a gasket for it at least.

[Tiggie]

The ect is near the front of the intake manifold, near the thermostat, but I think it's actually on a pipe coming out of the intake manifold. Heater hose attaches to the same pipe I think. It's easy to get to.

I won't say it's impossible to do the map hose with the upper intake on but difficult. Removing the upper intake isn't that bad of a job.

[sly]

Map hose should be cake to replace. just pull off the map and follow back to the pipe on the back side of the intake. The hose isn't even that long either.

[DerekTheGreat]

You live in Tey-hass where things stay mostly supple. In areas like mine those pull off in pieces and one piece is always fused to the intake's metal tube. Pretty much gotta yank the upper off.

[sly]

Nope. That's when the knife comes out and you cut the crap left on the tube off (I use blade up so as not to scratch the tube).