Driveablilty problem

Greetings all
I normally hang out on another ford enthusiast site, they recommended I come here with my problem. Several are mustang owners, and as I have more of a mustang engine than the stock explorer engine in my Mountaineer, it makes sense
here goes

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 on vacuum diagram, to double check.
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.
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 4 degrees advanced
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

At idle, 1000-1100 rpms, she pulls 16 inches of vacuum
__________________
The sound of Torquemonster headers
Yes it is an X Cam
http://media.putfile.com/Torquemonster-exhaust



__________________

NFGTragedy said:

I know some stangs, especially the cruise control ponys and autos, came with a sensor that was mounted on the speedo cable right where the speedo gear enters the tranny. Does your have this sensor or atleast the harness for it? That could explain the surges possibly. I have the harness but no sensor right now as I have the wrong speedo cable in it. When I stop quickly my cars rpm will drop down to 350-400rpm range (almost stall) and then surge up to like 1400 then drop back to idle. Kinda annoying and the quicker the stop the lower the drop and higher the surge. Just a suggestion to look into...

Click to expand...

Thanks for the quick response
I am running the stock 98 explorer OBDII pcm
It controls and monitors the transmission completely, Speed is sensed by the VSS , no speedometer cable
The transmission is a 4R70W, with a divorced AWD transfer case

My ENGINE is exactly like a 94-95 mustang, with 98 mustang electronics, It is DIS ignition

86bluecobra said:

why do you have such big injectors seems over kill unless this thing has a S\C.

Click to expand...

It is going to, or most likely a remote mount turbo

heh heh

Fuel pressure doesn't effect this issue, runs at 33 psi now ( at 1:1) 23 psi at idle

This setup seems to like lower pressures with these huge injectors.

HISSIN50 said:

Does it only happen if you are rolling?

If so, your thoughts were the same as mine - disco' the IAC to remove the rolling idle strategy. If it only happens during a rolling idle however, I'd read up on the EEC strategies to see what other sensors and solenoids (that don't use the IAC as their slave) have input in said circumstances. The list should be small.

If you're going to get a handheld for the F/I, you could do it now and tune the issue away probably.

Good luck.

EDIT: I'd also check the mod motor sub-forum as this sounds more like an EEC issue than a mechanical issue. They probably deal with issues we've never heard of.

Good luck.

Click to expand...

Ok
Check this
I have eliminated the IAC 2 ways, both with no effect on the rolling surge

My BBK throttle body has an IAC circuit adjuster, which I have closed off completely trying to eliminate this

also, as I said I did disconnect the iac, This time I got a CEL ( 1406) i think
idles speed control circuit error,
any way

So
Upon further experimenting, I read the mafs voltage has something to do with the EGR solenoid signal, which leads me to the EGR.
To verify, while the rolling surge is occuring, I can adjust the lowest band of my MAF tuner, just a bit towrd the richer side, and the surge stops.
However, leaving it in this tune will triggger a cel Bank 1 and 2 rich.
This coinicides with the reading on my air fuel ratio gauge.

I would bet a good handheld scanner-tuner would be my fix for sure, and get rid of my 5400 rpm limiter also hahaha

Oh wow

HISSIN50 said:

i would add that some IAC's need to be installed upside down to function properly (it should say so in the instructions).

does the idle drop when you have it running (warm motor) and disconnect the ISC connector? if so, i would really hit that EGR. even if this does not happen, i would jump the code. if you are introducing EGR gasses at idle, the car will likely not idle or idle terribly.

good luck.

:OT: hey, Id, how ya been?

Click to expand...

old quote

Are you familiar with a spacer between the IAC and Throttle body, with flow adjustment? This might allow me to mount mine reversed from it's current position

http://www.latemodelrestoration.com/iwwida.pvx?;item?item_no=LRS-9939A 1&comp=LRS

Me also
Pick up later on this?
I'll post more after I try a thing or two.

BTW
Yes, my BBK throttle body has a iac adjustment screw, and an idle set screw.

I have even closed the iac screw all the way, surge still occurs

Thank you very much for the help

Bump for opinions from the day crew

This is a video showing my guages at idle, and after a few throttle blips.

Notice the air fuel ratio---looks good
Vacuum --good

also notice the hanging idle toward end

Thanks for looking, it may help troubleshoot this.

Still waiting on the spacer, however I think this is going to require a good tuner.

http://media.putfile.com/hostingpit-video