could bad dis, iac cause this?

G

GREATWHITE666

Registered User
Hey guys, searched a lot but cant find an exact answer--
Only on a COLD start up, the car will idle fine for about 5 seconds and then rpms drop off and try to stall, i will tap the gas and it will either rev back up and then do the same thign again or just stall. If i immeadiately put it into drive or reverse before the rpms drop, and start to roll, if i hit the gas the car will just boggle and boggle for about 3 seconds like it's starving for gas or air... then it will just turn normal and everythign is fine. it will never do this again unless i start up from it being cold. tonight it took extra long for it to get going, it kept boggling longer than normal and this is the first night i started it from cold in 65 degrees, the air temp is usually hotter. car runs fine after this happens, the engine has less than 30K on it, and the whole car has 85K on it, it does have EGR too.. i thought maybe somethign with that could be it, it used to not be this bad, it used to boggle for a split second and then go, but now, it does it for a little longer, and recently if i went to turn on the AC right after starting up, the rpms would drop right away and the car would struggle to stay alive and i would have to rev it a little... im stumped- any help? thanks guys-
Damon
 
dude thats how mine started and mines messed up now
get it fixed before it turns out like mine shutting off on you at every stop
 
Mine did something very similar and turned out to be a vac leak at the SC Collar nut. A HIGH idle is usally a sign of a bad IAC Valve, followed by goose honking, and howling in cold temps.
A LOW idle is a good sign of a vac leak, but not always. Try and see if your collar nut came loose as they should be torqued over 100 Ft lbs, think it is 150ish, but you should check that. It may be more noticable when cold because when it warms up, maybe the tolerances between the seal are sealed but as it cools down the gap increases making the vac leak worse. Also if it feels like it is starving for fuel, look at your fuel filter. Might also look at your MAF sensor, you can GENTLY clean the small wires with rubbing alcohol and Q-tip, but I'd still double check your IC Tube connections.
 
Have you scanned the EEC for any stored codes (assume you have not noticed any "check engine light" during the rough idle?). This way you can try to eliminate the DIS, Cam Sensor, etc from being a possible culprit.
Good Luck.
 
no ce

yea there is no CE light, cam sensor replaced about a year ago, i also did replace the fuel filter too. I thought about vac leak, as i did put in a raised top but i have tbird88's gasket set and i have the same about of vac at idle as i did when the car was stock. also today it didnt do it nearly as bad as last night... i ran codes a while ago and it passed but im going to do it again when i get chance, and unplug the battery and see where that gets me. thanks for the replies guys, ill letu know what happens-- meanwhile anyone have any other experiences on thigns to check please post, thanks--
Damon
 
If the driveability around town is fine and it only acts up at idle then I'd bet a little heavier on a vacuum leak. Does it sound like it has a slight cam in it at idle? Mine did the same thing yours is and also searched for idle, wound up a vacuum hose on the backside of the inlet plenum was leakin'.

Try wigglin' some of the connections under the hood. Plug wires okay?

'bird
 
leak

actually 2days ago, i did wiggle a few connections, the dis, the connector on the IAC and a little tube around the EGR then the next day it didnt do anything nearly as bad, i had a little boggle for a split second after pressing the gas in drive, but that was all. maybe it is a vac leak, im gonna go wiggle some more stuff althought i am pressing 15 psi with my 5% pulley, -- what do u mean by "is there a slight cam at idle"? idle feels ok though-- thanks for the help-
Damon
 
GREATWHITE666 said:
....what do u mean by "is there a slight cam at idle"?..
Click to expand...
When your in a built V-8, you know that "lumpy" idle it would have? Like a Whuump whuump whuump (That is hard to spell a noise :p ) as opposed to our cars that idle fairly smooth idle without the engine shaking all over the place like the V-8 would. Understand?
 
got it

oh i see what u mean, well i do have a little thump thump at idle, but it's very slight you can barely feel it, it happens every few seconds or so and the car did that even before i had this problem, so i dont know... a built v-8... ahhhh, sometimes i wonder why all put so much money into a car when we could spend half as much on another car and have it twice as fast.. but then i think how great this car was for it's time, and even now, never give them up...
Damon
 
Damon, with the weekend coming up and all, I'd try and pull the plastic cowl off and take a propane??? torch WITHOUT it being lit, start car, and wave the gas around your:
IC joints including the Collar nut;
TB including the IAC Valve;
Intake Manifold;
Vacuum hoses.

That will make yer car rev/idle higher as the gas gets sucked into engine via a leak. Go to the FAQ Forum and look for "Boost Leaks and how to seal them" as it has some great ideas on how to find them. You will at least be able to rule this out and go from there.
 
hell yea

awesome man--- sucks i wont be in town this weekend, but good damn idea-- Thanks a lot for that-- im gonna go read FAQ again and see what i can find-- thanks again
Damon
 
if the battery was unhooked mine took about 3 days and about 200 miles before it learned to idle right again it would idle low or stall till the computer learned how to idle and to run it again, at first i thoght something was wrong but i knew all i did was change battery
 
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