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Discussion Starter #1
99 3.0 DOHC. AX4N. No codes via FORScan. No lights. Battery is good. AC off, no electrical accessories on. Same issue in P or N. Same issue with foot on brake or off brake.

I searched, and I found that others have a high idle at start up. Seems some of it is normal, and a few suggestions for others.

Mine has sort of a double issue. When cold starting (not cold climate) the car requires two turns of the ignition switch. I’ve tried holding it, it won’t start. I’ve turned the switch for just a second or two, let it spring back, then turn it again and it starts right up. It then jumps to 2200 or so RPM and slowly lowers. When warm it does not require it. The car starts almost instantly on the first turn and it will go up to about 1100 RPM until it’s completely warm, lowering to about 800 RPM.

Sensor? Cleaning? Adjustment? Testing? Any info would be great (and maybe a keyword to search for if you know something is posted here).

I appreciate the help. Would love to get some feedback on some appearance questions I posted (wagon-air dam, rear spoiler, etc). I’ve posted a bunch in the last few days but I figure I want this thing to last. It’ll be getting a decent undercoating, treatment for all the door seals, and grease where ever that goes soon as I’ll be moving to New England.

Thanks all,
Marc


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Discussion Starter #3
I would guess coolant temp sensor or air intake temperature. I know those two can cause no start when temps are cold. Both are cheap.


Just want to be sure - it does start right up, but if the engine is cold it takes two turns of the key. The first one can be for just 1/2 a second. But I can hold it on first turn (cold) and it won’t start.


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Both those sensors can cause that and not cause a check engine light. Im not 100% sure thats the problem but thats what i would change first. I also get sensors from the junkyard for free so it would take about an hr to get them from the junkyard and swap em.
 

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Fuel pump pressure and ability to pressurize the fuel rail could be your issue. On one of my 2001s it took four key turns to build pressure to design PSI. Easy to see since 2001s have a place to hook up a pressure gauge. Gauge took a jump up every key turn. Replaced pump and it fired up on one turn. On my 2006 it was the battery that caused a to key turn start, no slow crank just took two turns. Replace battery fixed the issue. My 2006 is starting to have the issue again after a couple of years and thinking it is the fuel pump which has 205k miles on it.


High idle at start is usually caused by aftermarket IAC valve. If it is original then remove and clean plus a drop of oil on valve shaft. Could be sticking on first start.
 

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I Agree with AutoMender12345. Sounds like a fuel pressure issue.

Try cycling the key, not to the start position, just to the on position, 3-5 times before starting, letting it sit in the on position 3-4 secs each time. Than try to start. If it starts imediately, than you know the system is not holding is fuel pressure, and is also not building it fast enough for the system to be happy.
 

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If it was a fuel pressure issue how do you explain the high idle? A false temp reading from a faulty sensor like the iat sensor or coolant temp sensor would cause delayed starts when cold and high idle. Clogged fuel filter or dying fuel pump wouldnt cause a high idle like that. Just sayin.
 

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If it was a fuel pressure issue how do you explain the high idle? A false temp reading from a faulty sensor like the iat sensor or coolant temp sensor would cause delayed starts when cold and high idle. Clogged fuel filter or dying fuel pump wouldnt cause a high idle like that. Just sayin.

DOHC high idles are usually a vacuum leak or faulty IAC. Since the idle recovers it could be a sticking IAC valve or aftermarket one. Fuel pressure is easy to check with the multiple key cycles. Once pressure builds it doesn't take much gas to idle the engine. I have never had a fuel pump fail to run a taurus at any speed once it started. I have had three pumps that made starting difficult but never had issue driving the car.


I have also had a issue with my 2006 that low battery voltage on cranking made fuel pressure low but as soon as the alternator starts to charge the system voltage jumps and pump runs fine.


Also a person on this forum had no start but crank issue and by jumping the car the fired up just fine.



Not sure why a faulty sensor wouldn't throw a code or be just an issue on a cold start. I guess it could if there was a certain offset in accuracy that wasn't bad enough once the engine warmed.
 

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Discussion Starter #10
Marc, please update if you solve the 1st/cold start prolonged high idle. Youngest son has the same issue.


Have gone the winter, same issue was continuing. I had replaced air filter and did basic spray clean of TB. No change.

Mechanic tested battery (good) and fuel pressure (good). He said he checked the IAT was good. Vacuum is good - no apparent leaks. He then pulled air tube, resprayed TB and used toothbrush to remove every little bit of buildup, including cleaned inside surface of flap.

It seems to have cured the 2x issue. It still idles around 2200 for the first few seconds (<10), then drops to 1700 for another 5-10, then 1050 until warm.


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Strange fix because the throttle body has very little to do with idle that two key turns would fix. Maybe the idle air port on the throttle body was partially blocked. up. If he cleaned the IAC then I could possibly believe a sticking or slow IAC valve. I had a similar issue on my 2001 Vulcan recently and I swapped in a known good IAC valve and it solved the issue.
 

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Discussion Starter #12
Strange fix because the throttle body has very little to do with idle that two key turns would fix. Maybe the idle air port on the throttle body was partially blocked. up. If he cleaned the IAC then I could possibly believe a sticking or slow IAC valve. I had a similar issue on my 2001 Vulcan recently and I swapped in a known good IAC valve and it solved the issue.


I was thinking blockage / sticking somewhere.


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Strange fix because the throttle body has very little to do with idle that two key turns would fix. Maybe the idle air port on the throttle body was partially blocked. up. If he cleaned the IAC then I could possibly believe a sticking or slow IAC valve. I had a similar issue on my 2001 Vulcan recently and I swapped in a known good IAC valve and it solved the issue.

Agree 100%
 
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