Hi all,

I wanted to give you fine folks a crack at this one, since it's the same engine that the aeros share...

I have 96 Explorer with the older style 4.0L, which I would think is the same engine Ford used in the mid 90's Aeros...

When I start the engine, it runs really rough until it gets warmed up... and lacks power... almost like it's running too rich or something.

I noticed I'm getting a P0401 code now of late - which is an EGR code... if the pressure sensor is bad, which is what many think it is, would this cause the engine to run like crap until it's warm? or is EGR unrelated to engine performance?

Thanks to all on this - and sorry that I'm budding in here - but I do also own an 89 Aero :-)

any ideas? stuff to check out?

Bob

 

Bob,
clean EGR valve also, they do carbon up....if it is running rich on cold start/run modes then EGR may be stuck open which dumps rich unburned fuel/air back into intake from cold rich exhaust...rich on rich condition

IAC may be carboned up and not opening full wide open which is mandatory for cold start/run modes

check IAT sensor and ECT sensor...if they fail or wiring fails will cause rough cold idle/run....ECU doesn't know to go into cold run rich mode....Aero's have reached the age where we are seeing many of the original IATs and ECTs fail

http://fordfuelinjection.com/?p=64

disconnect batt. neg lead for 10 minutes to reset ECU KAM and force relearn after service changes

 

hi 96,

this is an exp, not the aero - but same advice? Can I use TB cleaner to clean the EGR Valve? (that's the round thing with the plunger, right?)

IAT and ECT? where are they? on intake? or TB?

Can I spray TB cleaner into the EGR hoses to help de-carbon - or how should I handle those?

Thanks,
Bob

 

same engine same system, Ford is CHEAPO...used on Ranger, Explorer and Aero....all fit the same EPA testing criteria

remove EGR to clean it....soak in carb cleaner...needs strong cleaner to remove hot cooked carbon....blow out with compressed air....also clean port where it mounts and tube from exh. manif...also fitting in exh. manifold
if all won't clean>then replace...tubes do burn/corrode thru

IAT is usually on air tube from MAF to TB or on TB, haven't looked at an older 4L Explorer engine layout in years....check Explorer forum....Ford did move the IAT sensor around depending on MAF/air tube mounting/routing

ECT is on front top of engine on passenger side to passenger side of thermostat coolant outlet, 2 wire plug....

one wire sender is the idiot temp gauge

one EGR valve is working and clear of carbon and still getting EGR codes....time for DPFE sensor replacement...they are expensive so i would save for last for replacement

 

This may sound silly, but Easy-Off oven cleaner does a pretty good job of baked-on crud, even on exhaust systems.

 

well, worst case, the EGR valves are $60 at AutoZone, if I have to replace it... but that's a good idea, as long as it won't damage anything...

If I spray PAM on the top of the engine, can I fry eggs on it too? :-) that would be cool for camping :-)

 

hey 96,

if I had a cracked head, or something like that, would the engine run poorly all the time? not just when cold, right? The coolant level is still at the top after driving it 100 miles - but I swear I smell coolant before the engine is warm - however, the previous owner had a leak at the heater contol valve, and that is fixed, so maybe it's just the remains of that disipating... The exhaust does smell like coolant at all.

The coolant looks good, and the oil looks like it should on the dip stick... did the 4.0L's have a Head Gasket problem?

I guess I'd know for sure, if I pulled the plugs, and see if any coolant was wet there?

Bob

 

If you pull the plugs, check for any of them being wetter than the others. THe center insulator should have a light brown powdery coating on them. If any of them looks wet, it indicates that that those plugs were not firing well. That could be from many things, including weak spark, too big of gap, leaking head gaskets, or cracked heads.

Yes, the 4 liter engine has a weak head gasket that is very susceptible to overheating. But I hear the 3 liter engine also had this problem.

If your fluids look OK, and none of it dissappearing, then you probably don't have leaks.

There is a book called "Manifold Destiny" that describes how to cook foods on your car engine. It's an amusing read, and maybe useful if you were actually going to take a liesurely trip somewhere anyway. But it's an expensive way to cook food.

 

Really? I heard that the 3.0L, which is what I have in my Aero, is not as bad with this problem...

My other thought, is that I might Have a bad wire that only starts working once it gets warmer... I had this problem with my Aero, whenever it rained, and the engine was cold, one of the wires wouldn't fire... I think he had it tuned up a year or so ago, but not MC wires, which I know from experience makes all the difference...

I'll update with what I find after I pull the plugs... hope they are all dry :-) The engine doesn't smoke or anything, so I don't think it's burning oil...

Runs great after it's warmed up - that goes for my Aero too - Must be a ford thing :-)

Bob

 

Had the exact same problem. Replaced most sensors, EGR, Throttle Air Idle, etc. etc...Finally determined it was cracked heads, NOT blown head gaskets.

The 4.0 heads are notorious for cracking not blown head gaskets. My heads had two big cracks in each one. All four between the cylinders. Ford took a 2 litre engine and bored the hell out of it until it was a 4.0. Too thin in places. There are quite a few head and piston designs they played with including the double domed ones in my 4.0 OPD II version. Most failed.

Are you having to put ANY water in the overflow container? Water vapor coming from the exhaust pipe. Check your heads for seekage down the block. Water can leak into the cylinders causing misfires. When the heads heat up they expand and seal. Eventually the cracks will get so large it will start bucking going down the road from misfires.

I bought new heads at National Cylinder for $199 each. They have new heads they designed for Ford to correct the cracking problem by casting more metal between the cylinders and porting more water through the sleeves. Had them installed with new head bolts and a high end gasket kit. My engine has 160 psi of compression across all cylinders, never misses, and no water had to be added to the overflow container for over a year. Runs like new.

Hope this helps...

 

Hi,

I guess I will have to see... right now, it looks like there is still the same amount of water in the overflow as there was 100 miles ago, but again, it may be just the beginning of the problem?

Did you smell antifreeze for the first 4-5 mins until the engine came up to temp?

I noticed that if I punch it, before it's warm, I do get some smoke in the back, but I figured that was because it was running so rich? didn't smell like antifreeze... smelled like exhaust, but... could be...??

Did you put the new heads on yourself? How much would it run me to have that done? (ball park) I guess even if I need to do that, did I still do ok for $500 for the truck? how many miles have you put on it since you did that?

What year was/is your exp? Mine has 115K on it...

How can I check to see if I have seepage? would I see it on the outside of the head/block?

Would a compression test on all the cylinders proove this also? or would I see the result of this on the plugs too if I pull them?

Thanks for all the help on this... I won't panic - yet :-)

 

Note All Engines Made After 1995 Have The Sensors For The Computer That The Ones In 95 And Before Dont.

 

mediaman,

compression test generally is not helpful in deciding if there is a head gasket leak or cracked head
a leak down test is more definitive....look for air bubbles in coolant at radiator fill hole and listen for air leaks into exhaust ports

you're right, engine computer in cold start cold run mode has everything set to extra rich condition....like an old choke system on 3/4 choke

check and compare the spark plugs...will show white powder residue from silicates and other chemicals in antifreeze....also causes missfire in leaking cylinder....plug may be black from misfire

head gasket/cracked head coolant leak will usually cause more performance poor run issues hot than cold startup

4.0L Ford OHV early pre '95 heads usually crack between the intake/exhaust valves....they also have head gasket issues....Ford came out with an improved head gasket in later years....torque to yield stretch head bolts, one time use, always use new

Ford changed from OBDI engine management computer system to OBDII in late '95 model year Aero's....only sensor count difference was the addition of an after cat. converter O2 sensor to monitor performance of fuel mix control front O2 sensor
Ford had to go to an EGR valve system in later 4.0L setups to make the EPA and Calif smog haters happy

 

I replaced the DPFE Sensor, and the EGR Filter (not the diaphram) - and it runs great now... what causing most of the problem for sure, but it's still not 100% perfect...

what happens now, is the same thing, but instead of taking until it's warmed up to run smooth, say 2-3 minutes, it only takes about 10-20 seconds... but it still happens, just gets to good idle a lot sooner, but the inital rough idle is still there... no where near like it was as far as time it takes to get right, but it's still something that seems wrong. I could live with it the way it is now, but it's just one of those "bug me" things.

If you start the truck, put it into R, pull out of the parking space, and then put it into drive, by the time it takes to do that, it idles fine. usually, just giving it some gas cures it right away.

there are no more codes now, no more p0401 anyways...

before I got the P0401, I got a P1442, which is an evac code - the other day, my OBDII reader shows 0 codes, but is still showing a yellow ? mark for the evac system, which still flashes... Maybe this system takes a while and a few drive cycles before it knows if it's ok?

I replaced the Gas Cap - as most have said.

Could a componet of the evac system be causing the rough idle at all? or is that impossible? how do I diagnose this system?

Also, for "96" Do you know exactly when Ford switched to a better head design? be nice to know that my 96 Sport has the better heads in it's 4.0L

Also, I get no bubbles when looking at the overflow while it's idling, etc - I guess the only way to really look at this, is to pull the plugs to know for sure, but now that the EGR stuff made a big difference, I don't think it was a cracked head.

 

Actually I was once taught how to cook a steak on the exhaust manifold, while dring. But trust me, it doesn't taste too good