88 4.9 cutting out
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5th Wheeling
Joined: Aug 2024
Posts: 33
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88 4.9 cutting out
Hello I have a 88 f150 4.9 w t18 4 speed. Having a cutting out / hesitation / misfire issue, when cold it will idle at 1k rpm n climb to 1.5k then back to 1k and misfires a good bit until it starts to get warm, then it will idle around 700ish and doesn’t miss as much. When revving while parked it will miss around 1-1.5k rpm. When trying to drive it doesn’t miss much in 1st gear but it’s starts to misfire like crazy in 2nd and 3rd, can’t even think about putting it in 4th. Driving downhill isnt as bad since there ain’t much load on the engine. Only code I was getting from the truck was tps low voltage. Truck has new distributor, spark plugs, tps, map sensor, upper intake gasket, and all injectors. All the smog/egr stuff has been deleted. Pulled all the plugs and surprisingly they all look like the have been burning good and weren’t wet with fuel.(fuel pressure is around 55psi, and 65ish psi with fpr vac line disconnected) all vacuum lines are good/new. Only other thing I could think of is coil or the computer? Any help would be greatly appreciated thank you
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5th Wheeling
Joined: Aug 2024
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too high? From what I’m seeing it should be within 50-60 psi. If not please let me know what it should be
Last edited by Bricked88; Sep 11, 2024 at 06:47 PM.
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5th Wheeling
Joined: Aug 2024
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thanks for the reply! I have the timing set at 10°btdc. I assume the possible leaking capacitors would be fairly easy to spot when taking it apart? Will definitely look into that in the morning. Thanks again
Logistics Pro
Joined: Nov 2013
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From: Mojave, Ca
Yes. Leaking capacitors leave a corrosive stain under them.
Hotshot
Joined: Jul 2020
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From: Near Salt Lake City
Mine (caps) were no good with no visual evidence of the electrolyte leaking out
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Thread Starter
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5th Wheeling
Joined: Aug 2024
Posts: 33
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Pulled the ecm today, found one capacitor is leaking. Going to pick up a new soldering iron and new capacitors today, going to replace all 3. Any tips? Have soldered wires together before but have never done anything on circuit boards lol. I really appreciate the help guys y’all are awesome
Hotshot
Joined: Jul 2020
Posts: 10,453
Likes: 2,630
From: Near Salt Lake City
The caps are polarity sensitive
The line on the top designates minus and or current flow with an arrow
Make sure you get that right
Take a picture of your processor before you remove the caps
Use a soldering suction gun, they work amazing
Spring loaded syringe device
Radio Shack has them
The line on the top designates minus and or current flow with an arrow
Make sure you get that right
Take a picture of your processor before you remove the caps
Use a soldering suction gun, they work amazing
Spring loaded syringe device
Radio Shack has them
Thread Starter
|
5th Wheeling
Joined: Aug 2024
Posts: 33
Likes: 1
The caps are polarity sensitive
The line on the top designates minus and or current flow with an arrow
Make sure you get that right
Take a picture of your processor before you remove the caps
Use a soldering suction gun, they work amazing
Spring loaded syringe device
Radio Shack has them
The line on the top designates minus and or current flow with an arrow
Make sure you get that right
Take a picture of your processor before you remove the caps
Use a soldering suction gun, they work amazing
Spring loaded syringe device
Radio Shack has them
Thread Starter
|
5th Wheeling
Joined: Aug 2024
Posts: 33
Likes: 1
Checked codes again, get a 12 and 13 for idle speed controller (iac I assume)
tested/cleaned the iac, 10ohms between the 2 prongs and OL Between progs and iac body. So I’m assuming it’s still good and doesn’t need replacement, but it is the oe from 88 according to the tag on it
tested/cleaned the iac, 10ohms between the 2 prongs and OL Between progs and iac body. So I’m assuming it’s still good and doesn’t need replacement, but it is the oe from 88 according to the tag on it
Thread Starter
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5th Wheeling
Joined: Aug 2024
Posts: 33
Likes: 1
Seems to idle ok after its warmed up, random miss but not too bad. 1st gear she’s smooth, 2nd is ok with minimal throttle anything more and it’s just starts cutting out. Not sure what else could be causing this issue, it’s driving me nuts