98 F-150 dies when decelerating!
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98 F-150 dies when decelerating!
Thanks in advance for any help you can give me:
Here is the scoop. Several weeks ago I cranked up my truck, and it sputtered a little bit cold, which is unusual. A few more weeks go by with everything fine, then I get in and start heading down the road, and the truck starts to buck intermittently. When I came to a stop sign and took it out of gear and braked, the RPMs dropped out and the truck died. No coughing, sputtering, anything else......it just died. No CEL related to this. Of course my first thought was bad fuel. I bought some STP, ran it through the gas, and no change. Then I replaced the fuel filter, fuel PUMP, cleaned the IAC, cleaned the MAF. Still no change. I gave up and took it in for diagnostics. $130 and 2 days later, the shop calls and says they can't find anything on their computers wrong. They said they changed out some wires and it was running fine. I pick it up, and surprise surprise, its still running like crap. I would think if this was an EGR problem I would be getting a code. Very odd. Anyone have any other things I can try? Thanks again.
Here is the scoop. Several weeks ago I cranked up my truck, and it sputtered a little bit cold, which is unusual. A few more weeks go by with everything fine, then I get in and start heading down the road, and the truck starts to buck intermittently. When I came to a stop sign and took it out of gear and braked, the RPMs dropped out and the truck died. No coughing, sputtering, anything else......it just died. No CEL related to this. Of course my first thought was bad fuel. I bought some STP, ran it through the gas, and no change. Then I replaced the fuel filter, fuel PUMP, cleaned the IAC, cleaned the MAF. Still no change. I gave up and took it in for diagnostics. $130 and 2 days later, the shop calls and says they can't find anything on their computers wrong. They said they changed out some wires and it was running fine. I pick it up, and surprise surprise, its still running like crap. I would think if this was an EGR problem I would be getting a code. Very odd. Anyone have any other things I can try? Thanks again.
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had the exact same problem with my 70 chevelle last year with a 400sbc. we could not figure it out until we tried measuring the voltage on my distributor. turns out the gear on the end of the shaft was worn and not functioning properly and did not provide enough spark at low idle. took a long time to figure this one out. changed the distributor shaft and gear and it fixed the problem instantly.
maybe you will have the same luck.
maybe you will have the same luck.
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The IAC is nice and clean, not sure if its "going out". And just to update, I when ahead and put a half tank of premium grade gasoline. Truck is running like its old self now, at least so far today. Maybe I overrated STP's ability to stabilize bad, watery fuel? I hope its something this simple....but if it is I will feel like a total dope.
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Update:
Truck is running like shiat again. Here are my next options. What do you guys think?
-replace IAC
-Throttle position sensor?
-Fuel pressure regulator?
-EGR valve?
As I said, the truck will cut out a little bit every so often driving, then when I come to a stop the RPMs will drop to 200 or 300, sometimes recover and sometimes just die. Starts right back up. Runs fine for half a day or so, then back to crap, then fine again for a while. Thanks again...I am out of ideas.
Truck is running like shiat again. Here are my next options. What do you guys think?
-replace IAC
-Throttle position sensor?
-Fuel pressure regulator?
-EGR valve?
As I said, the truck will cut out a little bit every so often driving, then when I come to a stop the RPMs will drop to 200 or 300, sometimes recover and sometimes just die. Starts right back up. Runs fine for half a day or so, then back to crap, then fine again for a while. Thanks again...I am out of ideas.
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From: DIXIE
I would have to say it's either the EGR valve stuck open, the DPFE sensor holding the EGR open, A bad coil pack or a bad CPS.
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From: SE Michigan
Originally Posted by roperjoe
the truck starts to buck intermittently. When I came to a stop sign and took it out of gear and braked, the RPMs dropped out and the truck died. No coughing, sputtering, anything else......it just died. No CEL related to this.
What engine? Miles since last plug change? Miles on COPS/wires? Sure sounds ignition related to me...
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Update!!!!
Thanks for everyones help thus far. I replaced the pcv (just for good measure) and replaced the IAC. Still no luck. Truck is running rough intermittently, and occasionally when I engage the clutch the rpms drop out and the truck dies completely. Sometimes it will run fine for 2 or 3 days, then it just has a crappy day. I am getting some new codes though, P0401 which is the EGR, and P0172 running too rich. Any thoughts on my next replacement? Wow, these costs are adding up fast. Thanks.
