My under hood "bug"

[Turdle]

OK
I am really hoping for some technical help here.
Jamie, you were right, it still does it

Since I installed this ( nothing stock) engine, I have been plagued with a small drivability issue.
Everything is going great, no CEL, good gas mileage, great performence etc.
However, when driving at highway speed, then needing to slow down, upon deceleration my engine wants to surge. Lifting from throttle, when engine speed slows to 1000 rpm's, it will rev to about 1700, back down, back up, until either transmission is shifted to neutral, or vehicle is slowed to below 10 mph in drive, at which time the idle will stabilize.
vroom, vroom, vroom vroom, when I slow from speed---get it?

So, I first thought IAC
disconnected it, CEL on and still vroom vroom when slowing

new TPS installed
vroom vrooom vrooom

I then drilled 1/8" hole in throttle butterfly to facilitate lower TPS voltage at idle
vrooom vrooom vroom


so to be sure I installed a new intake manifold gasket and fuel injector o rings
vroom
T/M headers to fix the ticking ( maybe a leak getting in?)
vroom

I conferenced with Jamie on vacuum diagram, to double check.
I did find a few things " reversed"
vrooom

When the Rpm's rise, vacuum goes down, and vice versa.
both needles bounce opposite of each other, until it stops revving

This tells me something is opening to allow vacuum pressure loss
EGR!!!!!!
I installed a 1 way vacuum valve to the EGR valve. I was hoping to lessen the vacuum pulse to it. It seemed to help momentarily, however, being a 1 way valve, it builds a vacuum. It ended up holding the egr valve open.

When I removed it I could hear the valve close as the presure was released--

Could it be my EGR vacuum solenoid freaking out?


My next step---remove vacuum line from EGR valve- plug it and road test???

HELP

Once, due to the revving, my wife slowing for a curve, the engine died because of it.
Not good when my woman looses power accessories,
other than this issue, it is woman tame


BTW
I am in no way interested in bypassing the EGR circuit.

[SVO]

You have PM








Jeff -

[dman726749]

if no one here can figure it out, but my money is on svo knowing a solution, you might try a mustang forum, as they have much more knowledge of the 302 and 347

[Turdle]

Originally Posted by dman726749

if no one here can figure it out, but my money is on svo knowing a solution, you might try a mustang forum, as they have much more knowledge of the 302 and 347

I agree
If it comes down to it, I will have to drive to Texas. He is the only person I would trust to wrench on this.

[Turdle]

I will post here my engine stuff
In case anybody has an idea

new sportsman block
bored .030
billet crank
h beams
10.1 cr probe PRS Pistons
Edelbrock performer efi head stage 2
58 cc Combustion chamber
180 cc intake runner

X cam
typhoon intake
75mm Tb
Prom Big mouth 80mm maf and maf tuner
aeromotive fuel rails-regulator
42lb FMS flow matched injectors
High volume in tank pump

[dreamr]

HMM I too am betting on SVO solving this issue.

However here's a thought. I have seen this issue pop up on various Mustang boards. Seemingly most common with the 331 and 347 strokers. Many have been able to solve their idle woes (including what you describe) with a bit of tuning and this little bugger from Ford Racing. Obviously you want to rule out any other mechanical concerns first, but this may help.

http://www.latemodelrestoration.com/...0%201&comp=LRS

[Turdle]

Originally Posted by dreamr

HMM I too am betting on SVO solving this issue.

However here's a thought. I have seen this issue pop up on various Mustang boards. Seemingly most common with the 331 and 347 strokers. Many have been able to solve their idle woes (including what you describe) with a bit of tuning and this little bugger from Ford Racing. Obviously you want to rule out any other mechanical concerns first, but this may help.

http://www.latemodelrestoration.com/...0%201&comp=LRS

That looks like an egr gasket

Is it a restictor?

No
It is in the IAC circuit

WTF is it
please tell

[ssmith]

I can't believe Jon is finally asking for help after two going on three years for help with this surging problem. It makes me crazy.

[dreamr]

It is basically a little spacer that goes between the IAC and TB. It has two bolts which can be adjusted to partially close up the IAC opening.

With many of the stroked Mustangs they run into atrocious idle issues including surging during deceleration. In turn this helps to fake out the IAC and allow more normal idle parameters.

In your case though I am unsure if it is the cure or not. I have read a couple threads on the Mustang Forums that are very very similar to what you are dealing with. One was solved with this part. The other had vacuum issues.

[Turdle]

Thanks dreamr
I did just that, I have been a member on one for awhile

Hey
I just thought

Sticking pcv valve?
I did install a new one, can't say it was explorer specific, it seems to rattle good.
At this point I am brainstorming what it is that is opening to let air in

[BrooklynBay]

Did you examine the check valve on the power brake booster?

[Turdle]

Originally Posted by BrooklynBay

Did you examine the check valve on the power brake booster?

Hmmm
This was new with new engine also.

I will check this. Thanks

[Turdle]

Originally Posted by dreamr

It is basically a little spacer that goes between the IAC and TB. It has two bolts which can be adjusted to partially close up the IAC opening.

With many of the stroked Mustangs they run into atrocious idle issues including surging during deceleration. In turn this helps to fake out the IAC and allow more normal idle parameters.

In your case though I am unsure if it is the cure or not. I have read a couple threads on the Mustang Forums that are very very similar to what you are dealing with. One was solved with this part. The other had vacuum issues.

Dreamr
I have a BBK power plus throttle body. It has a idle speed adjuster, and a adjustment screw in the IAC path, for adjusting idle in gear ( iac on).
Isn't this accomplshing the same thing as the adjuster plate?

asking, not disagreeing

[dreamr]

Originally Posted by jtsmith

Dreamr
I have a BBK power plus throttle body. It has a idle speed adjuster, and a adjustment screw in the IAC path, for adjusting idle in gear ( iac on).
Isn't this accomplshing the same thing as the adjuster plate?

asking, not disagreeing

From what I understand on BBK's website it does have an adjustment that is similar in nature, though the spacer is still a recommended part according to FRPP

Looking at the diagrams though I am not sure that the adjustment on the throttle body does the same thing. I know on the BBK 66 mm on my Explorer it does not, nor does the Pro Products 70 mm on the Mustang. I am not sure if there is a difference between the units for the 5.0 stangs and the 5.0 X's.

If it is the same part then no it does not do what the spacer does....at least it offers less adjustment to be more accurate in my statement.

Like I said though this very well may not help you at all, just what popped in to my head thanks to a lot of research into the future stroking of my old tired 5.0 Mustang

[SVO]

The IAC adjusting plate was the first thing that popped into my head when I read this but, before I was going to pop off with the mouth I wanted to cover some bases first.

In therory that should eliminate this but he needs a soild answer to the probem, with a soild fix.

Note he has a MAF adjuster but he doesn't have a chip/tune burned for his set-up, although he fudging the MAF signal, the compliance with the stock programming might not be enough.

Gonna do some checking with some parameters on All Data (No Data) and then cross reference with some other stuff.

JT you did set the TPS votage (.89v)??

What CC's are the cylinder heads?


Jeff -

[Turdle]

Jeff
edelbrock lists the combustion chamber as 60 cc, it is actually 58cc

intake runner 170cc ( after the massaging I think they are closer to 180cc?)
exhaust 60cc

[410Fortune]

X cam = stock PCM = ???????
I think you need to get a dyno session and tune with somebody who really knows stang pushrod small blocks.

I have a low vacuum situation with my setup, I have sealed up the block tight (dipstick, all vacuum connections, PCV, intake spacer and gaskets, etc.

In the Ford Racing catalog, right next to the E and X cam it says:
*will not work with explorer 5.0L"

Why do you think this is?
My guess is the PCM is freaked out by your setup OR low manifold vacuum, too low for allt he vacuum controlled explorer emissions and truck junk.
Do you have a chip right now?

I noticed that with my E cam and roller valvetrain it likes a low idle, like 5-700 and if I turn the AC on it can die. I also found that when I turn on the blend door (when you put the HVAC controls into any mode and it sucks some vacuum, to move the blend door or whatever) the idle drops even more and it can die, not often but it does happen. it will cause a surging as well, like if I am at idle in slow traffic not pressing the gas, it will surge to move forward, turn the heater to off and it smooths out.
(so a vacuum load on my 5.0L = worse)
I figure its a combo of:
stock torque converter
intake spacer
headers
E cam
lack of 02 in Colorado causing a low maifold vacuum

OR:
stock PCM program with modded engine, in your truck 10 fold


I thought about looking into ways to keep the manifold vacuum higher, dont they make a vacuum controller for race engines? but then I have not even tested my manifold vacuum yet.
I would like to know what a stock 5.0L psi would be at diuring idle then see yours (and mine)
A vacuum test is also a good idea I think to detect any leaks, the factory setup does ot exactly seal up well, especially the PCV valve

Thoughts?

[dreamr]

Originally Posted by SVO

Note he has a MAF adjuster but he doesn't have a chip/tune burned for his set-up, although he fudging the MAF signal, the compliance with the stock programming might not be enough.

That I did not know, there is likely at least part if not most of the issue. On my Mustang maybe I could trick the sensors enough being the EEC IV set-up, though I won't try. But I highly doubt you can fool an OBDII Explorer 5.0 that really has a built 347 under the hood. That computer has got to be going nuts.

In my 4.0 X just the TB MAF and FIPK were enough to throw 4-5 error codes, a CEL, and minor runability issues. Bamachips was able to cure this, but I still want it Dyno tuned one day (likely when I do the stang after it's upcoming top end rebuild).

Sorry if I wasted your time with the IAC adjuster JT.........It may still prove useful, but you need to look at that tune first

[Dan Whitaker]

I have a solutuon for you Jon.
Rip all the computer junk out & carb that that bad boy! You don't have emission inspections.

I had thought about a stroker for my Mountaineer but not now. I'll leave that to my '92 Cougar. It will be carbed. ###### the computer garbage.

I hope Lindsay knows what she is getting into.

[410Fortune]

well the factory PCM is capable of adjusting for ALOT and with no codes it may be just fie the way he has it set up. the computer has nothing to do with how much vacuum is in the manifold however, if the vacuum is too low it could cause this, with it getting worse when you use vacuum related accessories on the engine it leads me to believe that it may fix the surging/low idle issue if we address the manifold vacuum.

First thing to do is test the psi with a gage and then compare it to stock numbers,, then hopefully find a way to get back to stock numbers and see what happens.
Then a dyno tune would be bonus time to take advantage of all the power possible but I am not convinced it is cuasig this surging, because Section (E cam) and myself have similar issues.