1990 Festiva Idle/Stall Problem

[theleetbeagle]

Hello, this is kind of a repost of this thread:

http://www.fordfestiva.com/forum/viewtopic.php?t=9693

Here's the body of that message:

So I just bought my first Festiva! 1990 automatic for $800 here in NE Ohio. 108k on the car, 70k on the engine. Looks fantastic, in 9/10 condition, great buy!

Anyhow, one of the problems I've found is this.

After the engine warms up, I cannot sit at intersections w/o dropping the trans into neutral. If I don't, the car will fluctuate from 100 rpm to 1000 rpm and will most likely stall. If I have the headlights on, it's almost guaranteed to stall.

Headlights off, in neutral, it idles perfectly.

When the engine is cold, or just starting to warm up, it idles fine no matter what.

I've replaced plugs, wires, distro cap and rotor. No change. I am thinking maybe alternator or battery problem, but the alt looks okay (visual inspection) and the previous owner just put a new battery in it.

Thoughts?

Thanks!
-Nick.

Now then, six months later, I have the same problem, but it's a little better. I am now shifting into neutral at all intersections/going down large hills/or when I am anticipating a red light in the name of fuel efficiency. So it's not a big deal that it stalls in Drive, because it's always in Neutral, but I'd still like to know what's going on.

It's not the charging system, the battery it top notch.

I strongly think it's vacuum related, esp since the engine has been swapped and I don't know how competent the mechanic was. Problem is, I don't know anything about vacuum checking. I do have a Haynes on the way, so maybe it will help.

But what can I check vacuum-wise that could be causing a stall at idle?

Thanks for reading this ultra-long post.

-Nick.

[freshtiva]

Have you ever noticed that when you take your foot off of the accelerator just a little like to adjust for going down hill that the car seems to fall on its face like you took your foot off the accelerator completely ?

[miami man]

my 91 has had an ideling problem for years now i have traced it to the vaf meter wiring. i shake it and it idles better. just a thought

[theleetbeagle]

fresh, nah I don't have that problem at all.

[FestYboy]

*!&^#$*@!#^*&^ computer!!!!!!!! logged in, wrote long message to pinpoint problem, hit send.... "please log in to post message" *&^$*!&^ :evil: :x :x

:rant over:

ok, try this... engine warmed up and idling in nutral. tap (firmly) the VAF and IAC w/ back of screwdriver or the like. note changes. have friend apply e-brake and pedal brakes and engage drive. repeat tap test. can also perform wiggle test on injector harness for each condition. biggest change in opperation = most likely culprit.

edit: had to post three times for the server to accept message

[theleetbeagle]

I will do this tonight... just as soon as I learn what a VAF and IAC are...

[FestYboy]

vaf=vane air flow, the funky looking box after the air filter box.

iac=idle air control, stepper motor that controls air past the throtle body to maintain desired idle. its right after the throtle, small ROUND metal thing with 2 wire plug.

[freshtiva]

# 1 and #3

[packrat427]

I have taken the hose off for #7 poured some Seafoam in there while the engine was off and also running , then put my thumb over the hose and revved it a bit , to let it suck thru the IAC .

I just kept loading it up and would take my thumb off the cover it , the Seafoam helped dissolve the junk that was making the IAC not adjust in mine.


I was having similar issues , with the car dying

[FestYboy]

# 1 and #3

correction, #1 and #7

[freshtiva]

^ ops: thank you !

[rdrangr]

theleetbeagle,

Did you ever find a solution to this problem??? I am having the same problem and it is driving me crazy!! What I find really odd is that it idles rough in drive, but idles fine in reverse. It definately seems like a vacuum problem, since vacuum drops to almost nothing when it is acting up.

I am very interested to read any information you can provide.

[jglutz]

It definately seems like a vacuum problem, since vacuum drops to almost nothing when it is acting up.

Be careful...that's a what came first scenario...the chicken or the egg.
Bad idle causes bad vacuum....and....bad vacuum causes bad idle

How about the idle mixture screw....between 4 and 6...maybe it's clogged or gummed up or something....turn it all the way in counting the number of turns (not to tight) then take it all the way out. Spray the screw and port with gum-out. Put the screw all the way in and then back it out the number of turns previously counted.

Also...something I never seen posted before....What about the dashpot!?!? Do they ever go bad on Festivas?

[rdrangr]

FINALLY!! I found the problem. I tried everything suggested, but there was no problem with the idle screw. I also flushed the IAC with carb cleaner. None of that worked. I have talked with a couple master mechanics and tried several things they suggested with no luck. They were stumped too.

I discovered I was able to make it act up just by pushing on the engine; rocking it back like it does under acceleration. After about a half hour of wiggling harnesses and examining every vacuum attachment, I discovered the flexible section of the rubber air inlet, the part that look like an accordion, had cracks down inside the grooves where air was getting in. The cracks only opened up when the engine rolled back.

I patched the cracks with RTV and voila! No more problems.

[25Horseplay]

Long term you might want to replace the hose.