My under hood "bug"

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

 

[Turdle]

Very sweet!

 

[Turdle]

Wooo hooo!!
I just recieved a package all the way from Texas!!Is it a a bill? No, it is an adjustable IAC adapter plate thingy!!

SVO-Stang Girl--Thank you much!!

Now I shall go to the garage and istall this,

In the meantime, What do I do here?

Do I open my IAC screw on throttle body all the way, and adjust from this plate to bring it back down?

Also, about flipping the IAC valve over---A Guru on Stangnet mentioned this,
something about the return on IAC working better with cammed apps if it is backwards???

 

[Dan Whitaker]

No offense taken Jon. Computers are great in some ways & horrible in other ways.

In the old days of non computer cars they were much easier to diognose & cheaper to repair. Now with all the sensors you either have to have a reader or deep pockets to pay a shop to peform the work.

Then if you had a miss it was most likely plug wires or plugs. Now it could be several different things.

What I hate worse than EFI is DIS. Cap & rotar arond $20. Coil Packs $160-200 a set :fire:

 

[410Fortune]

cap and rotor gets replaced every coupld years, coil packs last the life of the engine
plus we have junk yards.
The computer is very good at diagnosing the issue itself if you know how to read it.
Fuel pressure, spark, and compression tests are still basically the same.

But I do understand and get your point for sure, when you have 3 + wires under your hood and 4 vacuum lines it sure was alot easier to eliminate issues!! hahaha
now a broken coil wire or injector can cause you headaches for months....

 

[Turdle]

Well that was fun



First, an upside down IAC valve gives you a really smooth idle, problem is that idle is around 2200 rpms.

Ok on to the good stuff

This adjuster plate lets you completely bypass the IAC, while leaving it plugged in, I guess is the good thing.

I closed the IAC port on Throttle body completely, and used the bypass plate screws to bring idle down to 1100 rpms in neutral.

When shifted into gear, something is still bringing idle up a bit, it hangs at about 1400 for a second when shifted back to park.

Also, the surging still occurs, even when IAC is completey, and rolling idle still hangs at 2000 in neutral, until vehicle stops, at which time it immediately drops to normal. I did notice that the car has to be going at least 60 mph for a while to trigger this. A farmer was going 50 with me behind, didn't surge when we appraoched the curve, as it would do normally if i was going 60
65 mph. cruising 2000+ rpm's seems to set it off.


I know I need a tune, and am budgeting for it. In the meantime, I shall play with collecting data???

That plate looks cool!! I polished it, now I need a throttle body spacer to go with it

 

[410Fortune]

after the throttle body spacer you will have every single bolt on known to man I believe

Wait do you have the intake spacer?

 

[Turdle]

after the throttle body spacer you will have every single bolt on known to man I believe

Wait do you have the intake spacer?

1" Phenolic resin -- it is a good thing.
There are no more bolt on's in the near future.
All effort will be directed toward this problem by pushing buttons. I hope

 

[Turdle]

what to do
dee dee dum

Hey 410
Is that answer from blkmk8 About the pcm a good sign?

 

[Turdle]

Update

I have worked a swap with a gentleman from a mustang forum, he is sending me a set of 30lb injectioners and the matched pro-m maf. He is going s/c so needs this larger stuff. As soon as it arrives, I will swap them and at least take care of that worry.

 

[410Fortune]

I sent BLK MK8 a 96 PCM to fix a problem he was having in a 5.0L conversion into a Miata hahaha the 98 computer he was trying to use wouldnt let them get around the PATS. Apparently it worked!

I plan to buy my tuner from him, if he is still selling them.

 

[Turdle]

Well
I made a larger diameter intake tube today, actually I made it earlier, installed it today. It is quite a bit larger in diameter, I wonder if the previous one was too small. I will road test at high speed tomorrow. Initial in town driving was a bit different. Seems to rev better under load.
I lost about 1/2 inch of vacuum, so the 2.75" was a restriction.it would slide inside the maf and throttle body, wheras this new tube matches the maf, and is a bit larger than Throttle body.

You may wonder why I had such a small tube in the first place.

Hey, I was wanting more vacuum.

 

[Jakee]

Well
I made a larger diameter intake tube today, actually I made it earlier, installed it today. It is quite a bit larger in diameter, I wonder if the previous one was too small. I will road test at high speed tomorrow. Initial in town driving was a bit different. Seems to rev better under load.
I lost about 1/2 inch of vacuum, so the 2.75" was a restriction.it would slide inside the maf and throttle body, wheras this new tube matches the maf, and is a bit larger than Throttle body.

You may wonder why I had such a small tube in the first place.

Hey, I was wanting more vacuum.

JTSmith - Forgive me cuss I haven't read the entire thread but are you sure you don't have a vacuum leak of some sort? I saw the video you had posted on another site and it sure sounds like it. That and when was it that you re-set the computer? 100 miles, 200...ect. ?

 

[Turdle]

JTSmith - Forgive me cuss I haven't read the entire thread but are you sure you don't have a vacuum leak of some sort? I saw the video you had posted on another site and it sure sounds like it. That and when was it that you re-set the computer? 100 miles, 200...ect. ?

Yeah, I am DAMM sure I don't have a vacuum leak.
I do have a x-cam though, and from what I am told, 16-17 lbs of vacuum is pretty darn good.

Just completed a round trip of 334 miles which required no reset, Torque converter remained normal, although I drove very defensively to avoid the situation which causes the surging. ( complete removal of throttle from cruising speed)

Consumed 15.9 gallons of fuel.

 

[Jakee]

Yeah, I am DAMM sure I don't have a vacuum leak.
I do have a x-cam though, and from what I am told, 16-17 lbs of vacuum is pretty darn good.

Just completed a round trip of 334 miles which required no reset, Torque converter remained normal, although I drove very defensively to avoid the situation which causes the surging. ( complete removal of throttle from cruising speed)

Consumed 15.9 gallons of fuel.

Well hell, It actually sounds good! I know that's bugging you but it's really not to bad eh?

Sort of weird little problem.


How about this? (just helping you think here) have you did the throttle action at the TB inself just to make sure it's not binding up just a bit? Maybe help it back after the rev and see if it still does it? If that's not it I'm not sure.

 

[Turdle]

Thanks,
you are thinking for me I can tell
I rode with a voltmeter hooked to it to be sure lol, but good looking out.

here is another hint, watch how my maf-tuner drops to the idle band when idle comes down--which is first, the chicken or the egg?

Adjusting the first knob will cause the surging to stop

http://media.putfile.com/hanging-idle

 

[Jakee]

Thanks,
you are thinking for me I can tell
I rode with a voltmeter hooked to it to be sure lol, but good looking out.

here is another hint, watch how my maf-tuner drops to the idle band when idle comes down--which is first, the chicken or the egg?

Adjusting the first knob will cause the surging to stop

http://media.putfile.com/hanging-idle

I have a solution for you! Add a turbo?

 

[410Fortune]

scantool should be there soon....hopefully it will tell the tale

 

[Turdle]

scantool should be there soon....hopefully it will tell the tale

I am very glad to read that.

Thanks J.

 

[Turdle]

Update
I recieved the Scantool hardware Jaime!!

Thanks
Now--wish me luck here
http://www.explorerforum.com/forums/showthread.php?p=1530881#post1530881

I am on this now

 

[Turdle]

Bad and good news ( I hope)
I am knocking on wood when I say this, but yesterday I cleaned my maf sensor again. Then, I adjusted my TPS , this time to .98v,
Low and behold, after 2 trips to Chanute and back, not 1 surge!!
My wife asked what was wrong, lol, why it didn't surge at the railroad crossing, as it always does.

Her last words about it " I don't think it is fixed" :frustrate

Well, after 10 highway speed to 30 mph decelerations, everything is good.

now about this stupid rev limiter

OK the bad
It is a bad processor in the laptop.
Now I am getting one of those--