Hello,
History: 1991 Ford F-250, 5.8L, EFI, 5 Spd MT, 4X4, 185K ( 30K on rebuild)
I just bought this truck. Motor was rebuilt 21 months ago. Before, engine was blowing so much oil, aircleaner housing was full ( I can tell because garage never cleaned the dual intake tubes) Starts/runs perfect cold. At random times it will start missing and flood out, unless you can get you foot down on the throttle and hold it open until it cleans out; (black smoke pouring out of exhaust), but after that it will not idle. Sometimes it cleans out and runs great for a spell. I ran the codes, came back EGR and coolant temp sensor. Replaced both ( also the EGR sensor on top was replaced) I also had a hesitation of idle, figured that was a bad TPS, sure enough, when I pulled the old TPS the wires were bare and twisted. I have since replaced the Idle Air Control motor, ran codes again, only code stored is 111, I believe that is okay. Has anyone heard of this before? Could the EFI computer have been damaged by the twisted TPS wires?
Thank you
I forgot to mention, I have receipts for engine and the guy paid $500.00 to have injectors rebuilt. I can buy new ones from NAPA for $48.00 each

 

Which coolant sensor did you replace. One tells the computer what temp the air charge is in the manifold and sets the fuel accordingly and the other just makes the gauge work. On the 5.8L I'm not sure where it is but if you had a 4.9L I could tell ya.

Sounds like the Fuel regulator might be bad. Pull the vacuum line off and check for fuel on the vacuum side. If so then replacethe regulator.

 

I replaced the Temp Sensor, NAPA told me that there was a sensor and a switch, the switch was for the gauge. I will check the vacuum line, I didn't think of that. The problem is so intermittent, no pattern at all, just a real pain on a hill with a clutch and have to share the right foot with the brake and throttle to get it running. Fancy foot work..ehhh

 

One thing I forgot to mention, the garage that did the work did NOT clean the intake assembly. When I took off the EGR valve, the port in the intake was plugged solid with old oil and carbon had to use a screwdriver to clean it out. Think something could be plugged further in?

 

yes need to clean egr and check it with vacuum make sure it holds open with vacuum applyed. make sure the tps is set should be .96 just not over 1.00 at idle. also idle control valve passage way needs to be clean. you may want to check your valves settings maybe to tight on couple of cyl.s dave

 

five-o motor sports has Bosch Design III 19 lb. injectors for about $268 a set of (8), which is about $33.50 each. If the injectors were rebuilt such a short time ago they should be o.k. I don't know if the 5.8 uses the same injectors as a 5.0, but you might check out five-o's website if you think you might need injectors.



guzzler96

 

Thanks Guzzler and Shane. Today I ran the codes again and found the temp sensor kicking and screaming again. I traced the two wires from it and found another bare section of wire against the block. Repaired the harness, and drove to work this am, all seems fine now? Still don't trust it. On the EGR valve, I replaced it with a new one, but the prot in the intake was completely blocked. Cleaned it out and sprayed a bunch of carb cleaner in there. Let it set for a few to soften the gunk. Will run codes in a couple days to make sure all is better. Thanks to all that answered me..

 

For the Temp sensors (ECT or ACT) to pass the tests, the engine must be warmed up. Get a Fuel pressure gauge and put it on the shrader valve on the fuel rail. Watch the PSI. At idle the PSI should be around 35.