cold start stall......?
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Senior User
Joined: Nov 2004
Posts: 234
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From: Mount Tremper, New York
cold start stall......?
ok, so since i got my lightning, i havent been paying the bronco as much attention, mostly just driving it weekeds running errands, and goin to work.
anyway, the last couple weeks i have been having a problem on cold starts, where it fires right up like normal, but the the rpms drop, and it stalls out, unless i hit the gas a little, or if i let it stall it fires right back up. thennnnn, on the first couple minutes of operation, it hesitates harshly untill it gets a littlw temperature. so im wondering if anyone could shead a little light on this for me, i have yet to pull the codes, but ill do that tomarrow.
BTW for those who dont know...'91 302/E4OD
anyway, the last couple weeks i have been having a problem on cold starts, where it fires right up like normal, but the the rpms drop, and it stalls out, unless i hit the gas a little, or if i let it stall it fires right back up. thennnnn, on the first couple minutes of operation, it hesitates harshly untill it gets a littlw temperature. so im wondering if anyone could shead a little light on this for me, i have yet to pull the codes, but ill do that tomarrow.
BTW for those who dont know...'91 302/E4OD
Lead Driver
Joined: Feb 2003
Posts: 8,140
Likes: 4
From: Oak Harbor, OH
Ok, that's kinda normal for an older 302efi. Go out and start it 5 to 10 minutes earlier than you need to leave would be my fix. If it really bugs you, you'll need to clean the IAC, and the throttle body. Also you should check the TPS for correct function. If it reads within spec (.7v to 4.9v) then the computer will give it a clean bill of health. Even if it's giving sporadic readings as long as they are within spec it'll give an OK code.
Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
Stalling out is not common and should NOT be something to just accept. If a good cleaning of the induction system or tune up doesn't help and you get no fault codes, you may have an ECT sensor that is stuck "open" causing the computer to "think" the truck is warmer than it really is. It won't necessarily trigger a faut code because the truck CAN BE that warm. In other words the reading the computer is getting from the sensor is not beyond the normal operational range of the sensor but becasue the sensor is failing or stuck, its giving the computer the WRONG temp reading for the actual temp of the engine. Contrived and less likely than a cruddy IAC I know, but it is possible.
Last edited by greystreak92; Oct 8, 2006 at 08:03 PM.
Lead Driver
Joined: Feb 2003
Posts: 8,140
Likes: 4
From: Oak Harbor, OH
Greystreak, every EFI 302 I've ever owned did that, it would stall the first time you started it and then have a slight hesistation until it was warmed up a little. There wasn 't really anything wrong with the engine, and it never got any worse.
Lead Driver
Joined: Sep 2002
Posts: 9,182
Likes: 12
From: Gateway to the West
Well its case-by-case thing then because all ...lemme think.... all 14 of the various 302's I have owned/worked on have had various hesitation issues (including the type described here) from time to time but never dealt any particular issue that coudn't be recitified.
New User
Joined: Oct 2006
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I am having the exact same problem. I own a 95 full sized bronco with the 5.8.
Upon first startup it runs very rough can't get above 2300 RPM. If I turn of the ignition it will occasionally correct the problem, though its getting worse. i also get no codes or check engine light.
I am replacing the ECT tonight. I will post the outcome tomorrow.
Upon first startup it runs very rough can't get above 2300 RPM. If I turn of the ignition it will occasionally correct the problem, though its getting worse. i also get no codes or check engine light.
I am replacing the ECT tonight. I will post the outcome tomorrow.
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Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
If I owned a vehicle that displayed those symptoms, I would certainly think that something's wrong. I would start with a tune-up, then clean the throttle body and IAC, and check/replace the TPS like Joe suggested.
In fact, I did that, and it fixed the hard starting and stumbling problem on the Bronco.
In fact, I did that, and it fixed the hard starting and stumbling problem on the Bronco.
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Lead Driver
Joined: Feb 2003
Posts: 8,140
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From: Oak Harbor, OH
Come to think about it, all the ones I've owned were WORE out.... The '88 E150 has well over 350k miles on it, the '87 F150 was driven hard and put away wet, and the '89 E150 never ran right to begin with.
I think I'd start at the fuel pressure regulator, and it's vacuum line.
I think I'd start at the fuel pressure regulator, and it's vacuum line.
