warthogdriver

95 3.8l man.......sorry lots of info here.

i have replaced the plugs, plug wires, fuel filter, oil change, pcv valve, and all vac lines that i could find. my usual welcome to the family treatment for used car buy.

i also just replaced cam pos sensor...only thing that came up on the c.e.l scan

i have two issues, first rough idle engine will shake and stall when coming to a stop, at higher rpms and normal driving all is great.

i dont know if it is related but i am noticing a gas smell at passenger fender. i took a look behind it when changing vac lines and noticed some sort of black box..guessing part of fuel system...one of the lines running from that box that goes towards front of car and winds down by radiator is the source of gas smell.

big question (mustang newb..be gentle) is that an issue related to my idle problem? is something in fuel system plugged up causing a vapor lock?

coil pack maybe...that is the other thing i have come up with after some searching.

oh and no check engine light.

RedFire281

You might want to try the throttle position sensor before the EDIS coil pack.

Hope you resolve the issue.

warthogdriver

thanks for the lead, i will take all the help i can get at this point.

this problem is starting to hold up my other work on the car purely from an aggravation point i have, with starting work when first problem is still out there.

i hate hide and seek engine issues!!!!!
edit: looks like i also need to check and clean the maf

Fink

idle air control valve is also another thing to check before the coil pack.

JKs95stang

Usually when it's an IAC problem, the idle goes up higher than normal(mine went to like 2600 rpms at idle). If you have a friend with a stang(or a 3.8 around the same yr), you could swap the coil pack real quick to test. It sux throwing parts at a car and not solving the issue. GL

m3bluegsr

When u rev it in neutral when it drops back down, does it die? That can be too small of a gap on the plugs. How did they look when you took them out? How many miles on the car? Id try the coil pack, cause its pretty easy, plus you can always take it back. No leaks from the maf to TB? When it tries to settle at idle, does it idle low? or does it hang for a sec at 1k then try to drop down and gets rough?

warthogdriver

here are some more symptoms:

right after starting the car the idle is norm for a very short couple sec. (rough) then drops. to 500-1000. sometimes it will idle for quite some time. one thing i did check when replacing vac lines was leaving a "sensor" disconnected from the vac lines. it looked like a small cylinder about 2 inch long. only things on it where two vac lines and the plug. when off the vac line it idled for a long time. but back fired a couple times...so i reconnected that and kept replacing the lines...(trial and error??..sorry dont know correct name for part.)

if i rev it the car will more often die, i can drive it and it runs smooth no issues till i sit still, the engine also will shake sometimes to the point i can feel it in the stick and steering wheel while it idles.
from dead stop i have to baby it to get going..if i step on it the car will die.

i have not checked for leaks from maf to tb...didnt think of that one.

i will be doing the carb cleaner hunt on vac lines again...maybe i missed something.
i have been looking for vac diagram to double check, found alot of 5.0l ones with google.

as far as plugs, the ones i took out were def. way over do...but they were dry looking, just very blackened. the new plugs are gapped correctly, double checked them before installing. car has 190,000 on the clock.
work that was done by prior owner, new clutch and new heads/gaskets caused rebuild at 135,000 (go figure)
so i guess 60,000 give take.

i drove the car home when i bought it, 45 min trip. still had same issues so it will happen if the engine is hot or cold.

cant think of anything else to add.
also when i changed oil and flushed antifreeze i couldnt see any signs of cross contamination.

m3bluegsr

I think your talking about the diff. pressure sensor (not sure the exact name) but im pretty sure it hooks up and controls the egr. I'd clean both of them with brake clean. On a 2000 mustang it has a filter in it, so clean that too by removing the top of it, if it has one.(the top just pops off) Here's some info on the egr stuff. http://www.bullittarchive.com/7003.htm Also check the IAC, it sounds like it maybe starving for air, if the plugs are really black. If none of that works, i'd say go back to basics and do a compression/ leakdown test, and if thats fine, you know its in the fuel or ignition systems.

warthogdriver

ok, i looked up that sensor ...it is the " canister purge solenoid" i noticed that it was closed = no vac/air movement and when i reconnected while car was running it stalled out.
i know that if i hook up the vac line from engine it will not pull on other side.
i dont know exactly how this solenoid works..so maybe it is doing its job and opens when needed to control emissions..dont know.
i went and got some elec. cleaner for maf.
i am hoping to do some detective work this weekend.
checking/cleaning maf and connection to throttle body
iac clean and inspect (again)
egr valve check.
vac line - carb cleaner check...missed one??

when i solve this (fingers crossed) i will report back.
i have read alot of threads on this site and others...seems like a p.i.t.a problem with waaaaayyy to many causes.

thanks for all the leads.
now the fun part.

warthogdriver

ok, well i can report back now a happy camper.

the culprit was the maf, bought some maf cleaner
(thought it was funny can said..4-10 hp improvement..really?)
put it all back together and presto, a run up and down the road and all is good.
well almost, i still have to clean/replace iac...the idle is smooth but now is going up and down ever so slightly. man double whamee.

is maf routine maintenance on these cars? i have a 99 blazer ( i know long way from mustang) and have never cleaned the maf...let alone look at it.

still happy though, thanks for all the help