Valve Cover Gaskets

My valve cover gaskets are starting to leak now. Not too bad, just a little bit.

My question is does this cause a vacuum leak? My intake manifold was recently done; it is dry as a bone and does not leak.

Will leaky valve cover gaskets create a vacuum leak causing vehicle to lose power?

I get no codes or check engine light. The Ford dealership says everything looks great.

The problem I have is vehicle has loss of power (especially when cold). When its cold it takes about a full minute to get up to 60mph! As it warms up, however, power gets better, but never reaches its full potential.

Everything in the world has been done to no avail.

1. New VSS (vehicle speed sensor)
2. New tranny
3. New intake manifold gasket replace
4. New radiator / hoses / water pump / thermostat
5. New injectors (about a year ago)
6. New MAF
7. New brakes
8. New Electronic ignition system
9. New FPR (Fuel Pressure Regulator)
10. New fuel pump
11. New O2's
12. New Catalytic Converter
13. New battery
14. New battery cables
15. New plugs and wires
16. New TPS (throttle Position Sensor)
17. New ECT (Engine Coolant Temp Sensor)
18. New Idle Control Valve
19. New Fuel Filter
20. New Air Temp Sensor


I am beginning to lose faith in FORD

Am I missing something... Do I have dirty injectors? I used to run fuel injector cleaner through the tank quite regularly.

I have a 1993 Ford Explorer Sport V6 with auto trans with auto 4x4 engage

It basically drives as if its pulling a load

Any suggestions.... By the way, Ive checked the timming.. it's dead on and have also done a compression test... All cylinders are within 3 PSI of each other. Can't find any leaks anywhere other than the valve cover gaskets. And they aren't leaking bad, only a little.

Suggestions?

By the way my rig does not have an EGR !!! And I don not beleive it has a camshaft position sensor. I have looked repeatedly (Rear of engine on manifold?) But do not see anything...

Thanks everyone!


Steve

Nope.... V/C gaskets will not cause a vacuum leak. If you do want to replace them however, the latest offering from Ford is a great (if a tadspendy) gasket.

On your list of parts, I don't see a fuel filter. This little puppy can cause all kinds of grief if it's not replaced regularly. I recommend at least once a year.

It sounds like you are right on track with all of your testing and replacing.

If the injectors are only a year old they shouldnt be dirty, and since you have already replaced the fuel filter and the fuel pump they shouldnt be a problem.

If it isnt pinging I wouldnt worry too much about vacuum leaks, the two normally go hand in hand and I have had an engine ping in 50 degree outside air temps with a bad vacuum leak, so it's not always heat related.

How are things on the intake side? I didnt notice if you are running any type of aftermarket intake setup but if you have the stock setup you may want to check for blockages in the intake tube that runs from next to the passenger side headlight to the airbox, there is a rubber flap in the area that I have heard can get sucked back into tube, also I have found all types of stuff inside of this tube ranging from paper towels to plastic bags and other interesting things that can get picked up on the highway.

That is about all I think of right now, if it isn't pinging it sounds like it just isn't getting enough air. Good luck.

Tim

Oops.... I guess I got cross-eyed and didn't see the fuel filter (bad me!!).

This almost sounds like what you could get with a bad torque convertor. Not very often we see this problem but if the sprague in the TC is bad there wont be any torque multiplication and acceleration will be painfully slow.

To diagnose a torque convertor malfunction such as this you need to perform a "stall test" (fancy name for brake stand). This test can be very hard on your equipment and I'd seriously suggest having a good transmission mechanic perform the test sequence for you.

Good point Jim, would such a problem also cause the engine speed to flare way up without a lot of vehicle movement?

Steve,

Here is dumb one that I didn't think of on my first reply and probably isn't worth mentioning other than the fact that it happend to me once. I have found that aftermarket floor mats can get jammed up under the accelerator pedal and cause it not to go down very far, you also might want to take a look down the throttle body while someone steps on the accelerator just to make sure you are getting a full range of movement, there is a slight chance it could be a linkage problem.

Tim

Yep.... checking for WOT (wide open throttle) is something I overlooked and a very good point, Tim.

For the TC sprague, it's been almost 20 years since I've had the need to perform a stall test. The stator impeller mounts to the sprague which in turn slides on the stator support section of the transmissio pump. It can fail in one of two ways...... lock up or free wheel both directions. Either way will have very different effects on the performance of the vehicle. Unfortunately, the ol' brain matter just ain't remembering at this moment, but I don't recall engine flare being any more than an indication of slipping bands/clutches.

Just so's everyone realizes that stall testing (nad brake stands for that matter) create an amazing amount of heat in the convertor in very short order.

Guess im not sure what u mean by testing the torque converter....

As I've mentioned previously, the transmission was done about 10 months ago. New torque converter and all.

The problem is like this.....


My RPM gauge goes up to 5 K before redlining///

If on the freeway say doing 55 mph, and I go to accelerate to pass someone, the RPM needle will not even rise, it will stay right around 2 K and that is it. I will not hear the engine come alive or anything. It's as if there is no fuel or air.

I have checked the air passages / all is good


Sometimes, however, just out of the blue, for no reason at all.... vehicle will run like it is brand new. This will only last approximately a day at most and then back to ****...

Suggestions....

How do I perform the torque converter test you mentioned>>>>


Thanks again..

Steven

hmmm... you say its spuratic, kind of off agian on again. i would check for loose wires and other dirty connections. check all the wiring going to the TPS, and possibly the MAF, which i assume is clean. How does it rev with no load in park and in neutral? also when you ran the compression test did you happen to notice what the spark plugs looked like? they can tell a tale.


im betting on the TPS, but im not sure if the IAC motor has any effect on WOT. sounds like a weird gremlin.

This is a toughy, complicated by the fact that you have already relplaced just about every sensor and run just about every test you can to verify the itegrity of the engine, that along with the fact that every once in a while it runs great makes it sound like a major electrical gremlin.

Here is another stupid question, do you get a Key On check engine light? (Just want to make sure that the CEL is working)

It's a bit fuzzy right now but I think I read a thread a few years ago about someone frying an EEC (computer) in such a manner that it slipped into a limp home mode. Have you had any major electrical problems such as bad voltage regulators cause voltage spikes? or any other weird electrical problems?

My next step at this point if it hasnt been done already would be to run it on the highway with an AutoXray (niffty little $150 code scanner that has some other tricks built in to it) hooked to the EEC in real time DCL capture mode to see if the fuel injector pulse width is rising with throttle opening. It is posible that the EEC may not be responding properly to sensor inputs thus creating the lack of fuel/air feeling you have. Since you have replaced the battery and cables I think we can consider the EEC to have been reset several times. Oh yeah BTW I don't trust anything that ford says when it comes to troubleshooting.

When you say that the RPM will rise to 5k before redlining is this on the highway or in neutral? I would think that a lot of throttle at 2k@55 would cause a downshift, I know my engine doesnt do much at 2k on the highway but I have 3.08 gears and that is about 75 for me, however if I step into enough it will drop into 2nd and come "alive!" I'm not sure what triggers the downshift on the A4LD but if it's not downshifting that could also be a problem. I'm assuming that the problem existed before the tranmission/TC swap so we can probably rule out the TC as a problem. (Unless you just have bad luck with TCs)

Anyway those are my latest ideas, maybe when I sleep/sober up I'll have a few more. On the bright side when you fix it you will an almost brand new truck.

Tim

>Sometimes, however, just out of the blue, for no reason at all.... vehicle will run like it is brand new. This will only last approximately a day at most and then back to ****... <

Ahhh.... it helps to start getting ALL the information. Intermittents can be very hard to diagnose sometimes. Are there any other symptoms or abnormalities? Any engine modifications?

I understand that you can rev the motor to 5000 rpm and it just stays there without going higher? Does this happen in neutral?

What were the compression numbers (I wish I could afford a guage that accurate)?

It would be interesting to see what you have for fuel pressure during a full throttle acceleration and to be sure that the timing is advancing.

Torque convertor problems are generally not intermittent.

Another cool feature of the AutoXray is that you can watch the timing advance as seen by the EEC, but not at the crank.

Not sure how to do a good fuel pressure test under load (the EEC doesn't monitor fuel pressure) without running a lot of tubing or putting the truck on a dyno which costs a few $$ but can provide invalueable information regarding the fuel air mixture and timing at various loads.

Yeah compression numbers would help too. +/- 3 psi on all cylinders at a low compression could mean a lot of bad things.

Tim

With a hood that fits as tightly as the Explorers fuel pressure would require some lengthy tubing. Need to be a little careful here since the presuure on these isn't what you'd call low.

I always tie in at the Schrader valve and duct tape the guage to the windshield (no way I want that kind of fuel pressure sitting in my lap).

Just out of curiosity and since I've never done an under load fuel pressure test, what kind of numbers are you getting? Ever had an oil pressure line to an oil pressure gauge break? Messy.

Doesn't someone make an electric fuel pressure gauge? I'm pretty sure I've seen one but I think it cost a few more $$$ than I wanted to spend at the time.

Tim

Memory tells me fuel pressure should be 32 to 41 PSI - specs might be different for this particular application but still retty close. The fuel pressure varies with manifold vacuum since the injector is designed to give it's best spray pattern at a specific pressure drop across the injector nozzle.

At idle, when manifold vacuum is high, fuel pressure will be low. Unplug the vacuum line from the fuel pressure regulator and you shoud see the fuel pressure climb immediately.

When your diagnosing suspected fuel delivery problems, its important to check the pressure while the problem is happening since we now bring volume into play.

For test purposes, you just can't beat the accuracy of a good mechanical guage. There are electric fuel pressure guages available, but these are more for show on the dashboard since even the best "affordable" electric guages are still a slave to the vagaries of the system voltage. I would never consider mounting a mechanical fuel pressure guage in the passenger cabin - just too scary to think about...

If you're gettin' a boner for a fuel pressure guage, check out Stewart Warner or AutoMeter - I'm pretty sure they both have them. For a mechanical test guage, check your local tool monger and you should be able to find one that's reasonbly priced if you don't go gung-ho on test adapters.

Let's Try This Again!

Well I must say, you have both been helpful...

It is nice to get fedback from people with intelligence!

<<<<I understand that you can rev the motor to 5000 rpm and it just stays there without going higher? Does this happen in neutral?>>>>

Perhaps you misunderstood the above statement. In nuetral and/or park .... I can bring the RPM's clear in the red. While freeway driving, however, this is where I notice the most power loss. Like I said, sometimes she'll drive like new (Hit the gas she goes smoothly and fluidly without a hint of lag). Most of the time, however, it is difficult to accelerate above 60/65 without literally flooring it. And when the RPM's do finally rise (enough to enable the tranny to downshift ... hence RPM's rise) it will shift quite hard and then immediately up-shift. It's as if it doesn't have enough fuel delivery to compensate for the load. I have checked for any air flow restrictions... NONE!

Compression is 185 +/- 3 PSI on all cylinders..

I agree>>> Torque convertor problems are generally not intermittent. If it's bad.... it's always bad!

It's almost as if one of my sensors has a short / maybe one of the wires. But visually inspecting everything that I can / I see nothing out of the norm. Wires are not kinked, burnt, frayed (Nothing Obvious).

I wonder if perhaps my computer is bad, however, Ford says it is good. What R your thoughts on this?

Also / I've never bothered replacing my ECC Relay or Fuel Pump Relay. Can these be bad or intermitently bad? Perhaps they aren't supplying full voltage 100% of the time?

I appreciate your input and any further ideas you may have!

One last thought.... my transmission has an aftermarket modulator. Not sure who makes it, but it is one that appears to be adjustable. I have checked with Ford. They apparently make two modulators for this tranny. Neither of which are adjustable (Obviously the one i have is after-market). Ford manufactures two... High Altitude and Non-Altitude. Non altitude is about $40 and High Altitude is around $170 I am told, however, that without the original modulator/ they have no way of knowing what modulator I had. Is this bullshit or what. Surely there has to be a way of finding out.

Anyway, my question is would the modulator affect the way the truck drives. On again off again power. RPM's not rising etc?

Thanks again!!!


Steven

A bad modulator will "usually" either make ATF disappear or raise the trans shift points.

Next time it runs good, notice if anything else is different (weather, accessory usage, road surface). This is called grasping at straws while I continue to scratch my head.....

I had a similar problem w/ acceleration on a 91 sport. It seemed it was starved for fuel. Chased out fuel/air/ sensor systems for a week or so. Problem was eventually solved by replacing the ignition module (about $135) mounted on the firewall in front of the battery case. Also clean the contacts if you replace it.
Let us know what eventually works.

Sounds almost like you got a partially clogged exhaust system, but that would cause the tranny to kick down and stay there a while. Try disconnecting the exhaust between the muffler and the cat and see if that makes a difference, other than being somewhat louder.

My '76 Chevelle had a 305 in it and would scream if I floored it usually but it started having a hard time keeping 70mph, turns out the original converter had failed at 160,000 miles and the muffler was partially clogged as well.

Hmmmmm...

I had a similar prob with my 91 but with CEL and MPG loss. After replacing O2's, MAF, and FPR turned out to be clogged cats. I know you replaced them. I didn't really notice a difference after I replaced mine until I reset the computer. I don't mean to sound disrespectful of the intelligence of the board but when was the last time the Comp was reset?

BTW---Whatever the fix is, at least you'll have anicely rebuilt ride!!

Oahrens
Gosh - you replaced your 91 Explorer's cats or catalytic converters! I thought the 91 Explorer only has one "cat" ?? And pardon my ignorance, but what is a "Comp"? or is this merely shorthand for the computer.
Steve
As I hope someone has already said, just because it is new does not mean the new part works OK. Great set of comments in this thread. Nice going to all. Mike 91 XLT, Seattle