I have 93 Aerostar that didn't want to start this morning. Before when I started it the idle woulde lope and had been told it ws the IAC. If the IAC has went totally bad would this cause it not to want to start? I had to crank it and hold throttle to the floor then pump the throttle until it finally started. It had done this once before but then started ok when cold after that. It starts fine once it has been running and the engine is up to temp. Any help would be appreciated !!! Troy

 

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May be you have bad spark plugs.

The other hypotesa - the fuel/air ratio is not the optimal for starting. Sources of these problemes - MAP/MAF, IAT, ECT.

 

welcome neon4x,

cold start is just about the most difficult condition the engine faces...especially below +25dF...

crank speed is slow even with optimum perfect battery, cables and thin oil

spark voltage is low especially when battery voltage is pulled down by small cables, overheated starter or weak battery

fuel does NOT atomize, vaporize and mix well with air, especially these sick weak ethanol mixes, below 40d F....at 0d F, ethanol is worthless

fuel pressure can be low due to low battery voltage and a cold weak slow pump restricted by frozen water in it's intake sock filter

good reliable cold start requires the richest fuel mix the engine runs at....

which engine 3L or 4L?
what is ambient air temps in hard start conditions?
does it always idle well when warm?
when were plugs and wires changed last and brand used=critical?
what is condition of battery and how old?

failing intermittent IAC will affect both cold and hot start conditions plus cold/hot idle

do NOT push the gas pedal to the floor during a start condition until engine fires....pedal to floor and wide open TPS causes ECU to cut off all fuel flow when engine is cranking and not running yet

leave foot off throttle until engine fires...

ECU controls all except turning the key=only driver function necessary

 

Thanks foor the replies...Changed the IAC out with a new one today and it starts like a dream now...Love my 93 Aero with its 3.0L. Now just need to find some rocker panels to undo what the MI winters have done to it. Only place its rusted is under pass. and driver side doors. Troy

 

Troy, unfortunatly aero is OBD-1 and DTC appeares if any sensor is out of range only, but when I see, that something is wronr with engine I use to see OBD-II Actual values and see what is wrong.

To diagnose aero I have to use AVO-meter to check voltages on suspected sensors, o-scope to check frequences.... I have all the tables of the sensor signals and compare what sensor reads to real conditions. For example IAT read what a temperature outdoors. Easy to check.

 

neon4x,

thanks for the followup repair post and glad u got her running well again....lots of satisfaction in successful DIYering...just takes patience and thinking

i know what you mean....Ford broke the GOOD mold when they made these 3L and 4L OHV engine Aeros

go out in the ice cold here at below 15d F, hit the key once, about second revolution, the 4L fires up....runs smooth even cold....just takes forever for the barn inside to heat up even with both heaters going

none of that stick to the flag pole frozen stiff leather seat for this boy....got new space age memory foam seat pad/ backs....my hemmoroiods love 'em