Idle issue after IM gaskets

[PsYcHo_FrEkE]

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). Seems to run okay going down the road, but tries to (and occasionally does) die when I stop the truck. . 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. My only thoughts are, either the IAC has gone out (again), the new pintle caps are causing an issue with the atomization of the fuel molecules, or 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?

 

[JimMadsen]

I once had a IAC die a few months after I installed it. I was at a gas station with garage when the thing kept stalling unless I gave it some throttle. Checked everything except the IAC since, hey, its new! Ended up leaving it with them for a half day and sure enough, needed a new IAC. Luckily they didn't charge much and it was under warranty.

Could be something else, but check the simple stuff first.

 

[PsYcHo_FrEkE]

That was an event in itself. When I replaced that IAC I bought a BWD. That one wasn't working right, so I replaced it with another BWD. That one worked right, but was howling. I finally got ticked off and special ordered the Hitachi (OE) and it was working fine (prior to changing the gaskets).

Since I didn't take the IAC off when I took the upper intake manifold off I had wondered if maybe I somehow got some trash (carbon) inside of it. Thinking of taking it off and cleaning it out when the rain lets up for a minute. This one has me scratching my head. Really sounds like a vacuum issue or IAC issue to me...

 

[PsYcHo_FrEkE]

Found... of all things... A small piece of a sticker that looked like it came off of the throttle body down inside of the IAC. I pulled it out and cleaned it out real good, stuck it back on and it's still acting like an IAC issue. Is it possible that just that little piece of sticker ruined the IAC?

 

[JimMadsen]

Not sure it would cause a malfunction with the iac, but you think you may have a iac issue and you found a contaminant inside the iac area. Not outside the realm of possibility that the new iac was compromised.

Try this:
http://www.explorerforum.com/forums/showthread.php?t=232262

http://m.wikihow.com/Check-an-Idle-Air-Control-Valve

http://www.ehow.com/how_5560848_check-idle-air-control-valve.html

Ohm meter is your friend....

 

[PsYcHo_FrEkE]

10.6 Ohms... guess the IAC isn't the problem...

Also, it now does it all the time, not only when it's warm...

 

[PsYcHo_FrEkE]

*Bump*


Anyone have any ideas? I'm getting a bit desperate here. Need this truck for work tonight...

 

[PsYcHo_FrEkE]

Just for grins, I tried replacing the IAC.... it wasn't the IAC...

 

[BobbyTang]

Just for grins, I tried replacing the IAC.... it wasn't the IAC...

Definitely not the guy to answer the question but the idle aside sounds like a fuel delivery/alternator issue if the truck is dying out suddenly. I thought IAC too but you've cleaned the carbon build up and replaced it ... The oddity is when you sprayed near the seam of the upper intake and it leveled out the RPM. Just might have to retrace your steps...

 

[BobbyTang]

What do you mean by VC ?? 2am here and my brain isn't connecting the dots..

 

[BobbyTang]

Mines been throwing those codes and I recently took off the air intake to check a few things, cleaned the MAF, throttle body plate and IAC while I was there, and replaced spark plugs... I couldn't visibly find a problem and put it all back together and cleared the codes, CEL has not come back on.... Yet. I know that sometimes the MAF sensor gets dirty and can spring those two codes making you think there's a vacuum leak somewhere... I have had it before where I clean the MAF and p0171+p0174 have gone away for years.. Oddly enough... Anyway you're past that now and I'll get my thinking cap back on..

 

[PsYcHo_FrEkE]

What do you mean by VC ?? 2am here and my brain isn't connecting the dots..

Valve cover

 

[PsYcHo_FrEkE]

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...

 

[PsYcHo_FrEkE]

opinions?

 

[BobbyTang]

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. (

One thing I've learned with torque wrenches is that if you over torque a bolt the threads can stretch or the bolt itself, something among those lines so you would in turn need to keep setting it back to that same setting for a snug fit, now I'm not sure if that can happen very quick or if it has to stay that tight for awhile, I.e. 40ft lbs cannot be set back to 35 without It being loose? If you used the Rtv properly and let it set up a bit before tightening it I'm not sure what to say there..

There's a chance you'd have to redo the gasket but I'm not sure if it is still what's giving you the symptoms above..

 

[BobbyTang]

I am starting to have irratic idle as well, when I took apart the intake hoses I checked my IAC and MAF with a multimeter and they were operating properly, although I've gradually noticed a few oddities when Idling it seems a couple times since, my idle rpm's will drop to 400-500 when it's colder out and I am stopped at a light, usually it ranges at 750-800... When it drops that low it starts to choke and fart a bit but it resumes the proper range and sorts itself out, no CEL since I cleaned the MAF and IAC, so I fear if the CEL does come back on I might be looking at what you did for my next solution, usually the cleaning does the trick for me.. It's been 8 years since Ithe gaskets have been changed

 

[PsYcHo_FrEkE]

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*...

 

[PsYcHo_FrEkE]

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

 

[PsYcHo_FrEkE]

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?

 

[PsYcHo_FrEkE]

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?!