96 Formula Won't Start Unless Pedal is Held to the Floor

**Z28pr0jekt** · 05-28-2019, 12:33 PM

Originally Posted by Stormyweather

Does the IAC show vlotage change? I know a bad one won't change. Seen them stuck open just Abit.

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Even on this note, I had a datalog show voltage change on an IAC that was stuck open. I thought the IAC was good until I finally took apart the car. This was causing fuel to load up and a hard time idling. I actually drilled the IAC hole larger before actually checking the IAC like a dummy.

**Stormyweather** · 05-28-2019, 01:02 PM

Yeah. Seen that too. Well hopefully you'll Square it away.

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**Injuneer** · 05-28-2019, 02:03 PM

The IAC value you see in the PCM is how many “steps” it is telling the IAC to open. 0 = closed; 156 = fully open. 20-40 counts at idle is “normal”. There is no feedback as to the actual position of the IAC pintle. And there is no voltage reading in any scans I have ever reviewed. You can test the IAC motor per Shoebox’s instructions:

http://shbox.com/1/iac2.jpg

When you hold the accel pedal to the floor before cranking, it puts the PCM in “clear flood” mode. If the ECT sensor is correct as you indicate, you appear to have something flooding the engine. When you tested the fuel pressure, did you let the pump prime without trying to start the engine? If so, when the pump shut down (hopefully at 40 PSI or above) how fast did the pressure bleed down?

**Stormyweather** · 05-28-2019, 02:27 PM

Well IMD that's what I meant. Does it change? It's been a bit since I trouble shot one. I've got old timers. Carry on. Nothing to see here.

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**Injuneer** · 05-28-2019, 02:36 PM

Sorry about that. I was just trying to help.

**Stormyweather** · 05-28-2019, 02:37 PM

What about me being oder then dirt?

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Older then.

**Stormyweather** · 05-28-2019, 02:40 PM

Your a great asset Mr.

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**Seawolf18** · 05-28-2019, 03:35 PM

I will check the fuel pressure again when I get home tonight. unfortunately, I don't have a scanner that shows IAC counts, I will test the IAC motor . I noticed that it had colder plugs in it. The plugs that were in it have a heat range of two. The plug listing for the same type of plug is a heat range of four. I don't know if that makes a big difference or not. After pondering some more, I may have flooded the engine myself. When it wouldn't start, we did a lot of cranking when we were checking the different parts of the ignition system. So much that we pretty much ran the battery all the way down.

***Fastbird*** · 05-28-2019, 04:25 PM

Might want to just pull the IAC and carb cleaner/scrub it clean good. Can't hurt, and may fix it.

**Seawolf18** · 05-28-2019, 11:24 PM

I checked my fuel pressure. It went to 42 psi when the key was turned on. I let the gauge sit for about 1/2 hour and it only bleed down to 39-38psi. I then pulled the IAC motor. The pentle was retracted all the way and I got 49 ohms on both coils of the IAC. The IAC passage was pretty clean, as well as the sensor. I compression checked the engine. Lowest cylinder was 165 psi and the highest was 185 psi. I then checked the ect on the scanner again. It was at 41 degrees. I pulled the plug off the ECT and there was corrosion in it. I cleaned the contacts, and it now reads 66 degrees, about the same as the garage. I was mistakenly looking at the intake air temp sensor last time. I don't know if this is a clue for not, I noticed that when I was doing the compression check the tac would read about 300-400 rpm while cranking, then it would erratically jump around for about a 1/2 sec, then read normally again.