Hey, guys, I’m new here and I’m having a lot of engine troubles with my 1990 F250 with the EFI 460 and e4od trans, which I bought little over a year ago and haven’t driven it much due to running poorly. Just wondering if anyone has run into this problem.


Symptoms:

Running really rich (extremely bad gas mileage, heavy unburnt fuel smell for exhaust)

Runs almost like its missing on one or two cylinders (seems to clear up at high rpms)

Really bad engine shakes under load at low rpms

New Parts:

Cap and Rotor, spark plugs and wires, map sensor, tps sensor, iac value, ignition control module, new intake gasket, ecu, ignition pickup, ignition coil, o2 sensor, intake air temperature sensor, coolant temperature sensor, new pcv valve, new vacuum lines, fuel filter and air filter, cleaned injectors, new battery cables



I have checked all vacuum ports and intake gaskets using smoke and carb cleaner. I also checked all fuel injectors with a mechanics stethoscope to make sure their pulsating when the engine is running. No engine codes both KOER and KOEO except for the EGR code since I have removed it and blocked off the port on the intake. I have checked the fuel pressure in the rails, and they are in specs. Checked the cat to make sure it wasn’t clogged. Checked compression and that’s good, clean most of the connectors and grounds. There probably a few other things that I tested but forgot.

If you guys have any thoughts or recommendations that would be great it, if not my last resort is converting it to carb.

 

Welcome to the forum, We need more information in order to help.
What year and what vehicle is this 460 in. Did you test each component when you installed it or did you replace a bunch of components at one time?
Does the code number on your new PCM match the code on the sticker inside the door? How did you clean the injectors?
Hook up your EGR valve to vacuum and the electrical connection. You can either reinstall it or tie it to something but you don't want any codes being generated.
The PCM only looks at the position of the pintle and the ref voltage which is controlled by vacuum.
Something is telling the PCM that your fuel mixture is running lean and is compensating for it. Did you pull the SPOUT connector when you set the timing to 10 deg BTDC ?
A broken or frayed wire is sometimes a problem when trucks get this old which is why each part or component needs to be tested for proper operation. I have the factory manuals and I can assist you with information for testing.

 

What does that mean? Do you have numbers?

 

Its a 1990 F250 and when I bought it the guy said the long block was replaced 80,000 miles ago not sure if that changes anything. I did try to test each component before I replaced them one at a time (over the course of this year) by using the method that I found on this forum. The PCM matched the one that was previously in the truck but I didn't know how to match it with the door sticker.
I "cleaned" the injectors by using a tire stem value and placed it over the top and sprayed carb cleaner through the injector. Then activating the injector using a 9v battery and did that a few times then used the air compressor and placed around 50 psi on the injector while it was in a bucket of water to check if they were leaking. I know this is not the correct way hahaha
For my egr value, it would still give me an error code (at highway speeds) when it was hooked up and doesn't that just active at highway speed and once the engine is warm and shouldn't affect it an idle since it wouldn't throw a code?
I did pull the spout and timed it to 10 BTDC and the fuel pressure was around 32 psi at idle and high 30s at higher rpms.
I did bring this to my mechanic that used to work on these older fords and he couldn't find anything and said it is probably is in the wiring harness. Which sounds like a needle in the haystack.
Also, i did hear that the old distributor shafts could become magnetized after awhile. Not sure if this is true or how much it would the distributor pickup.

 

I will pretend this is my truck and explain what I would do. Double check me as I may be wrong about some things. I have the complete set of factory manuals for 1988 F250 XLT Lariat 7.5l 2wd 5 speed manual trans. I don't know what the differences are from 88 -90 there may be none or there may be a few. The first thing is to check the sticker on the driver side door jam and see if the PCM is the right one. The fact that the truck ran rough from the purchase date makes me think the previous owner sold the truck because he couldn't figure out what was wrong with it. In my factory manual it mentions that there is a two minute window to pull the spout, set the base timing and put the spout back in. I don't know why but I didn't write the book. I would locate and clean the grounds I could locate. (I have the list and locations) Since my mechanic said it was probably a wiring issue I would find an engine wiring diagram. (Which I have) Starting at the battery I would start testing voltages at the component level to verify correct readings. Only the ends or termination points of a wire need to be checked which will determine if the middle of the wire is suspect. If I find a suspect wire I will just run a new wire since messing with an old crusty wire harness is asking for trouble. Due to my previous jobs I am good at finding electrical and electronic problems but I do it in a methodical fashion.

Your EGR valve is non functioning which is why you were always getting a code. Stop by your local Target parking lot Pic-A-Part and get another one.

I can try to give you any information you request (sometimes I'm an upload retard) but I will figure it out. Or I will just post it in this thread.

 

Alright, I fixed the EGR so it is working now and I tested the continuity from the PCM harness side to all the eec-iv components and they appear to check-out. So my next step would be making sure all the components are giving a good signal/voltage to the computer, so I went and bought a Thexton 126 breakout box from eBay since it would be much easier to do it this way and it was only $50. However, they do not come with a manual. Does anyone know where I can get one or are there values in the Haynes manual for each component that I need to measure?

 

This morning I am looking through my factory manuals and getting the information you will need. I also have a break out box and you really don't need a manual, it is just a tool allowing you to access your wiring harness and components for checking. I will give you the test procedures and the BOB terminals to check. Have patience this may take me a few hours to put together.

 

Awesome, thank you so much and no rush, I won't be able to work on my truck until Thursday anyways.

 

Is the reluctor tight on the distributor shaft?

 

Yep the reluctor is tight and I also checked the timing chain wear and I was only 2 degrees and the Haynes manual said it should be less than 5 degrees so we're good there too.

 

have you checked the spark plug wire routing, if wrong could crossfire, that way you can also check firing order, is correct

460 routing, and firing order

 

Hey wil, Ive got nothing to contribute. Just wanted to see if you've gotten to the bottom of this. Im going through the same.

 

To answer your question, yes i did get it to run better and that was by swapping a 6.9 into it. In the end, I think I did figure out why it was running rich, when I hooked up the oscilloscope to the fuel injectors. It appeared that one of the banks was firing continuously (no deadtime compared to the other bank) however I never figured what cause this if it was a bad wire somewhere or the new computer was bad etc causing that bank to fire all the time. At this time I was pissed off that I just swapped a 6.9, sorry I couldn't be any more help. Hope you figure it out.

 

try pulling your PCM, look for burnt capacitors, if you have done everything he has and its still rich, and your O2 is not 10yr ld, check for codes?

 

I recently had the injectors rebuilt and tested, probably less than 1000 miles ago. I started another post to see if anyone else can throw some ideas at me. Link