1997 Ford Ranger 4.0L EFI.

I just finished replacing VC, IM, TB, Fuel Rail... etc. About all of the gaskets in the upper end to fix a P0171 & P0174. I had to replace the pintle caps on the injectors. I used the generic blue ones from the parts store since they were all that I could find. Put it all back together (all torqued to spec, then upper intake manifold torque re-checked), flushed the engine and the radiator, and it was running great... until it warmed up. I replaced the IAC about 4 or 5 months ago. Warmed up I now have an idle issue that wasn't there before (at least not since I replaced the IAC). IAC checked 10.6 ohms. Seems to run okay going down the road, but tries to (and occasionally does) die when I stop the truck. . I can feel the loss of power as I let off of the accelerator. I'm doubting the problem is fuel related since acceleration seems to be fine. The erratic idle is prominent throughout the full RPM range when sitting in neutral. Currently, there is no CEL. I have posted a youtube video of the problem. In the video I circle the engine to try to isolate the problem if it's a vacuum leak and to double check all of my connections (again).

On a side note when it first started doing it I sprayed some brake cleaner on the upper intake around the seam and the idle straightened out. It only worked one time. I was unable to replicate this. Spraying brake cleaner there now does nothing to change the idle. The only thing I can think of is that perhaps the upper intake manifold is coming apart at the seam or is cracked somewhere underneath. Does anyone else have any opinions on what could be going on here?

 

That does sound bad. Is your power steering ok? Sounds like its low on fluid/

 

Yeah... Right now that little power steering whine is the least of my concerns...

It's been there since I got the truck from my dad's passing... I'll get to that eventually (though I'm not sure what to do about it just yet).

 

I still haven't found the vac leak, but I'm starting to get this sinking feeling that I may have to take the lower intake gasket off and replace it (again). Three reasons:

First, when I was putting it on I accidently over-torqued a couple of bolts and then backed them off because my clicker wasn't working right.

Second, I used the Victor Reinz 2 piece gasket instead of the Ford 1 piece.

Third, because I know it's possible with using a two piece gasket that I may have disturbed the bead of silicone on the area where the lower intake meets the block. With a one piece gasket I wouldn't have needed a bead all the way across.

I really don't look forward to ripping all of that apart again if I don't have to...

 

opinions?

 

I've replaced the IM, Valve Cover Gaskets, and fuel manifold gasket (again). Truck is still doing the same thing. I did hear a rattling that is new, though. Sounded like it was coming from the EGR valve, but I'm having trouble pinpointing it exactly. Still no CEL.

I usually don't throw parts at a vehicle like this. Usually I've got everything researched and have the part narrowed down. This is making me crazy *smh*...

 

Fuel pressure is running at 32psi (42psi with regulator disconnected). Is this right?

 

The problem isn't doing anything but getting worse. I'm to a point now that I'm considering replacing all of the vacuum lines. The problem is that I don't know what to do about the hard lines.

Is there a kit out there somewhere for these?

Are they a dealership part?

They seem rather thin... would trying to rebuild the system throw off the vacuum from the increased inside diameter if I replaced them with all rubber hose?

 

I got ahold of a vacuum tester. The hard lines are good. The only thing I could find was a slow leak in the evap to TB line. I'm not sure how much vacuum the line should hold, but I pumped it up to about 15-20 psi. The guage pulled down to 12-13psi slowly and nearly stopped pulling around 10psi. Would this be enough of a leak to cause this much havok?!

 

Replaced evap canister hoses. They may have been a problem, but definitely not THE problem...


While I'm thinking about it, are the solenoids/sensors in line with the hose that goes between the TB and the evap canister?

 

I'm really thinking about those pintle caps again. I mentioned them in my first post, but nobody commented. Here is (basically) what the originals looked like:



What the aftermarket ones O'Reilly's sold me looked like:

 

I'm not getting anymore feedback from you guys, but I'm going to keep up the thread in case anyone else has this problem.

For anyone following this, according to the seller this repair kit fits my truck:



Ford Mercury 4.0L V6 Fuel Injector Service Repair Kit O-Rings Filters Seals


The kit is said to fit all models 97-98 Ford Explorer. With any luck maybe this will fix the problem. My thoughts are that the pintle cap I used is creating a dead space between the holes for the spray and the pintle cap (something I was concerned with even when I bought them, but at the time couldn't find anything better and needed the truck back together). My theory is that the dead space is building up with fuel and "choking" the engine. Instead of getting a spray, I'm likely getting a stream. My theory goes on that the reason I don't have any issues at 30+ mph while accelerating is because I'm pushing more gas into the system which is forcing all of the fuel through the small hole in the pintle cap and is allowing the fuel to properly disperse into the cylinder. We'll see what happens when the parts come in. I'll keep you guys updated in case anyone is still following this...

 

I've changed the pintle caps and filters. The idle problem is gone now. I guess that was the problem. Now I'm just waiting to be sure that CEL doesn't come back. Thanks for the *ehem* help...

 

Hi, I am having the same problem. I have never changed the pintle caps or injectors. I have replaced the IAC, MAF sensor, EGR pressure sensor, Spark plugs & Wires. And I still have that Idle problem, so did you use that kit you were talking about. Would you think that if I had that seal kit done, it would do the trick. Or do I have to change the Injectors & stuff also? Thanks, Randy

 

I couldn't say for sure. If you've never done anything with the injectors, I would say that your problem isn't the same one I was having. This problem was my own doing from installing the wrong pintle caps when replacing an intake gasket set.

I will say that I don't generally throw parts at the problem, though. If you test a part and it passes then it's on to the next one. Most electronic components can be tested with a multimeter.

I would start by checking for vacuum leaks. If you don't find any, it couldn't hurt to voltage check the DPFE sensor and (although unlikely) the TPS. My problem appeared to be an IAC issue, and I replaced that sensor a couple of times (in spite of it testing good) because I just couldn't figure out what the problem was.

After I had the idle problem under control (after finally settling on an OEM Hitachi IAC), the CEL came on with P0171 and P0174 codes. I discovered also that the 1997 4.0L is bad for fuel manifold gaskets going out. I went through and replaced the VC gaskets, upper and lower IM gaskets, fuel manifold gasket, every gasket and o-ring on the intake side, went through about 8 cans of parts cleaner, cleaned the injectors and replaced the o-rings and retainers (because my retainers were cracked), then put it all back together I finally had it running right again.

One problem with the lower intake on the 4.0L is that the sides tuck up under the valve covers. If the lower IM is taking in air under the valve covers you may never know it because it is undetectable with starter fluid and I would imagine it would be undetectable with a smoke machine as well.


And now... I have a lower end knock I have to figure out... it never ends!!!