stalling on a 1990 4.0L
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stalling on a 1990 4.0L
I have a 1990 Ford Ranger with a 4.0L engine that has 206,000 miles on it. For three weeks my truck has refused to idle unless I keep my foot on the gas and keep it at around 750-1000 RPM.
If I take my foot off of the gas, it will fall down to something like 500 RPM, then stall. Sometimes it will run very rough at these low RPMs especially when I first start it, other times it just stalls without shaking the vehicle too much.
The check engine light comes on but error is number 22: Manifold Absolute Pressure (MAP)/Barometric Pressure (BP) out of Self-Test range.
So far I have tried a different MAF, cleaned my current MAF, tried a different barometric pressure sensor, and cleaned my IAC.
If I take my foot off of the gas, it will fall down to something like 500 RPM, then stall. Sometimes it will run very rough at these low RPMs especially when I first start it, other times it just stalls without shaking the vehicle too much.
The check engine light comes on but error is number 22: Manifold Absolute Pressure (MAP)/Barometric Pressure (BP) out of Self-Test range.
So far I have tried a different MAF, cleaned my current MAF, tried a different barometric pressure sensor, and cleaned my IAC.
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The air and fuel filter were replaced 15,000 miles ago. The spark plugs and wires were replaced 25,000 miles ago. The truck runs fine other than the stalling problem, its still getting the same gas as it normally does.
The confusing thing is the BP sensor error. Is it just a red herring? Is there a way to test the BP sensor? Would a failing BP sensor cause stalling like I'm having?
The confusing thing is the BP sensor error. Is it just a red herring? Is there a way to test the BP sensor? Would a failing BP sensor cause stalling like I'm having?
5th Wheeling
Joined: Feb 2008
Posts: 26
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From: Omaha, NE
Had a similar problem several years ago. Went through all kinds of troubleshooting and sensor swaps without a fix. A few questions - is the exhaust burning excessively black (almost wet),can you smell fuel and does it seem like you're truck is sucking down fuel? May be your fuel pressure regulator. If the FPR fails, it's dumping too much gas into the manifold and the sensors can't calculate the mixture. It's fairly easy to access & change but pricy if you have a garage do it.
If this is the problem and you have the quick disconnect hose and regulator assembly, I strongly suggest you get the screw-on fitting type FPR at a parts store (or junkyard), but the hose will probably have to come off an old Explorer (couldn't get one at a parts store). My QD fitting started to leak after a year from replacing the pressure regulator - not good when it leaks onto a hot engine. I took the whole FPR and hose assembly off an Explorer out of a junkyard and haven't had a problem since.
If this is the problem and you have the quick disconnect hose and regulator assembly, I strongly suggest you get the screw-on fitting type FPR at a parts store (or junkyard), but the hose will probably have to come off an old Explorer (couldn't get one at a parts store). My QD fitting started to leak after a year from replacing the pressure regulator - not good when it leaks onto a hot engine. I took the whole FPR and hose assembly off an Explorer out of a junkyard and haven't had a problem since.
Senior User
Joined: Aug 2003
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From: Huntsville, AL
It seems that your map sensor is bad. It is located on the firewall on the passenger side. And unlike the name leads you to believe, it is not plumbed into the engine. All that connects to it is an electrical connector.
5th Wheeling
Joined: Feb 2008
Posts: 26
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From: Omaha, NE
Commonbrick, I re-read your post, I thought you changed the MAP already. Johncfox is right, IF you have one, that's probably it. I say "if" because my '90 4.0 never had a MAP sensor, although the wiring harness has a connector where it would plug into a MAP (factory cap still installed). Not saying you don't have one, I'm just going by my truck's setup. Maybe I have the misfit - AutoZone's Component Location page says the 4.0 doesn't have a MAF (although I've changed it twice in it's life), but it says I have a MAP (not)!
As far as the Barometric Pressure sensor goes, I'm guessing you read the diagnosis out of the Actron Code Scanner manual - it lists both the MAP and the BP under Code 22, but the BP serves the same function as the MAP, although it may be called the BP in a different model vehicle; so if you pulled a Code 22, don't be concerned about the BP, but focus on the MAP (again, if you have one). Anyway, because of my truck's setup, that's why I suggested the Fuel Press Regulator - that threw all kinds of codes at me and unfortunately, I threw parts at each code without fixing the problem. Testing with a Fuel Pressure Gage only takes 5 minutes just to eliminate that anyhow.
As far as the Barometric Pressure sensor goes, I'm guessing you read the diagnosis out of the Actron Code Scanner manual - it lists both the MAP and the BP under Code 22, but the BP serves the same function as the MAP, although it may be called the BP in a different model vehicle; so if you pulled a Code 22, don't be concerned about the BP, but focus on the MAP (again, if you have one). Anyway, because of my truck's setup, that's why I suggested the Fuel Press Regulator - that threw all kinds of codes at me and unfortunately, I threw parts at each code without fixing the problem. Testing with a Fuel Pressure Gage only takes 5 minutes just to eliminate that anyhow.
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