idle problems

[boosted mustang]

looking for some help. Ive got a surging problem and ive went through so many surge check lists and nothing has fixed it. I have no codes affect anything. koeo and koer both clear. ive replaced iac and maf. its a c+l blowthrou and ive clocked to around about 20 times. no help. anybody have any ideas they can throw out there i can check. Any help would be awsome im running out of ideas.
my car is a 1989 with a a9l
stock bottem end
gt 40 upper and lower
anderson cam
canfield heads
75 mm tb
44lb inj
75 mm c+l maf

 

[HISSIN50]

Ive got a surging problem and ive went through so many surge check lists and nothing has fixed it.

The best list is the one in the Tech Thread Sticky.

You don't give much info on the conditions in which it surges or what you have already done on the checklist.

Did this combo ever run without surging?

 

[boosted mustang]

sorry. car starts cold or warm and instantly surges from 600 or so to 1400 or so rpms and will not stop. This has been doing it for about 4 month now and i put it away for a while got sick of working on it and now i want to get her goin.
this is the check list i used. went over it many times

http://www.stangnet.com/mustang-forums/698148-help-me-create-surging-idle-checklist.html

 

[boosted mustang]

just to add to befor is that even when i unplug the iac it has no change still surges when it is started an whenever i rev it up

 

[HISSIN50]

Are you sure there are no vac leaks? Surging upon start-up with no IAC should not occur.

Assuming this is a forced induction vehicle, did the combo ever run without surging? Or has it done this since the blower and accompanying components were installed?

 

[Tanus]

I had tons of idle problems, surging too. this little plate fixed everything, got it from ford for like 15 bucks, this guy is chaging a sh itload for some reason.

http://cgi.ebay.com/ebaymotors/86-8...r_Truck_Parts_Accessories?hash=item27ada4cb98

 

[boosted mustang]

sorry. this car is not boosted yet. it has not always ideal like this. If i can remember i think it started when i did the maf and inj swap. I have done some reading on the adj iac plate. and you recommend it, i have tryed cutting the iac gasket between the ports and all it did was make the idle go to a high rpm?

 

[boosted mustang]

let me start over. went out and started car cold its like 16deg. in my garage. car did not surge when i started it. i let it warm up and reved it up and it started searching for idle and shut it off and started it warm and started searching for idle right away. heres allittle run down of what i checked went and did it again and wrote everything down.

KOEO-31,81,82,85,84
KOER-31,94,44
car started suging 400ish rpm to 1400ish rpms when koer was complete was not surging when i started test?

Check iac (brand new)
red wire-14.26v
red wire/lt blue between-1.6 to1.7v

tps-.98v (brand new)

check all vac areas and nothing changed can find no leaks. put a vac guage on line and it sits at about 14"hgs

O2's
pin 29 at ecu-varies between .3 and .9
pin 43 at ecu-varies between .3 and .9
dvom grounded next to com.

alt voltage-14.34v

Mass air meter- 75mm c/l 42lb tube
red wire-14.4v
blue-orng-.673v or so
boxed in air filter to avoid air turbulance.

new fuel pump and filter and have cleaned all grounds many times. does anyone see anything that is missing everything seems in spec right.
heres my cam specs.

Anderson ford motorsport cam

intake exaust
advertise duration .006 280 288
duration at .50 228 236
timing events at .050 8/40 52/4
lobe lift @ cam .340 0.355
gross valve lift with 1.6 rockers 0.544 0.568
degree intake lobe to 106
valve lash full turn after zero lash


this is the spec sheet i got and this is what it tells me
i did change valve lash tho 1/4 turn thou

 

[Tanus]

sorry. this car is not boosted yet. it has not always ideal like this. If i can remember i think it started when i did the maf and inj swap. I have done some reading on the adj iac plate. and you recommend it, i have tryed cutting the iac gasket between the ports and all it did was make the idle go to a high rpm?

without that thing I have to turn the idle up with that 10mm bolt on the TB, thats when I get surging and the idle not wanting to drop normally, it hangs up at like 2k for like 10 seconds then drops almost dies then suges til it finally rests at 1k.

with it it idles a 800, no hang-ups no surge.


edit- but I do think the plate just covers up some other problem

 

[boosted mustang]

pretty much sounds like what my car does. but if you think this is just a bandaid i would really like to fix what is acually causing the prob. maybe i will just buy one and see what it does