dwhiskie said:I mounted my aftermarket iac upside down,no more surge
crunchie12268 said:Wow, why would that work?
So,do you mean completely remove the divider between the ports or just make them bigger? My car wont idle below 900 and would like to get it to around 800.Ranchero5.0 said:A little dragon slaying lore here:
99% of the time on a cammed car opening up the divider between the ports on the IAC with a dremel so the motor idles at 1000rpm with the IAC unhooked, the throttle plate shut and the TPS at .98vdc fixes all surge related problems. Found about to do that on my '93 with a very mild cam and good induction it didn't like idling below 900rpm. The IAC can't react quick enough to a lopey cam induced RPM fluctuation so instead of dampening the surge it increases it. Every E cammed car I've ever worked on needed this to keep a stable idle. Similiar to Fords idle bypass plate without the cobbled look.
If that doesn't do it check the 12vdc to the heater on the O2's. One smack of wiring on headers wipes out the fusible link hidden in the wiring on the engine side of the firewall where the main puter harness goes through. This will cause the o2's to slowly go out of tolerance and the puter flips out. check this if the car's running really rich a idle too. Ranchero got nailed when first installed and the '93's done it too. I actually ended up soldering on a stereo inline fusible link and installing a 20a fuse to make the repair quicker.
More to come as I get time...
Jamie
Vacuum is measured in inches of mercury, 30 inces of vacuum = roughly 15 psi. Hose designed for pressure will generally carry vacuum with no problem. Vaccum would try to colapse a hose with no reinforcement by sucking it flat, like a soda straw stuck in the ice cream in the bottom of a milk shake.Funanin said:would replacing the vacuum lines with rubber hose that is rated at 15 psi +/- cause a surge if my vacuum pulls at -17.5 psi at idle?
So basically the 950 or so idle I have is about the lowest Im gonna be able to get it right?Ranchero5.0 said:D, I just dremel out a little at a time till it idles around 1k. In my experience the stock puter doesn't like to idle a cammed car down low.
Jamie
jrichker said:Vacuum is measured in inches of mercury, 30 inces of vacuum = roughly 15 psi. Hose designed for pressure will generally carry vacuum with no problem. Vaccum would try to colapse a hose with no reinforcement by sucking it flat, like a soda straw stuck in the ice cream in the bottom of a milk shake.
With this in mind, the cause of your surge is not the rubber hose.
A healthy engine with a stock cam will pull anywhere from 16"-19" at 675-750 RPM. Changes in spark advance, camshaft timing, and overall engine health will make this figure vary greatly from one engine to another.dvs bullet said:Just wondering how much vac. does a stang pull? by the way this a great idea, I have had this prob. for a long time, and this is giving me a lot of potential solutions.
jrichker said:A healthy engine with a stock cam will pull anywhere from 16"-19" at 675-750 RPM. Changes in spark advance, camshaft timing, and overall engine health will make this figure vary greatly from one engine to another.
Only possible if the hunting idle only happens when the A/C is on.Snake1 said:Low Charge = hunting idle
88GTsocal said:Only possible if the hunting idle only happens when the A/C is on.
I could be wrong, but I'm almost positive that the compressor turns on in the A/C positions and defrost. Not in any of the other positions.Snake1 said:as you probably know Ford heaters are on all the time except when in the off position,doesn't matter is the A/C is on, or heater side is on because your Compressor kicks in on heat side also.
Put your lever on mix on the heat side and go watch your compressor kick in, Trust me i've been thru all of this with my 88GT and R 12. if it doesn't kick in,not enough oil in your system to activate it.
Snake1 said:On the heat side, the compressor kicks on for a bit then kicks off,on the ac side it stays on until you switch over to the heat side,then it starts its on/off cycle again
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