I have an 88 E-250 with a 460 motor and a C-6 tranny. In the last few days it has been hard to start and when it does, black smoke comes out the exhaust for a few seconds until it stumbles up to idling speed. It is now stalling and exhausting a few puffs of black smoke every time I accelerate. Have learned to step on the gas very slowly which sort of works OK. Runs good otherwise but will hesitate at the start of every acceleration. At each hesitation, vacuum gauge will drop 10 points or better then go back to a normal reading which I do not ever remember it doing before.

Also after driving it for a while then stopping, the idle runs medium fast for several minutes before slowly dropping down to normal.

Have changed out the tranny vacuum modulator with an adjustable unit and the coil with a MSD blaster. Runs a little better but did not solve the problem.

Would appreciate any help.

Have you checked the timing? If the engine is gettin' up there in age, the chain may have jumped. Just an option... :confused:

fuel injected ,carbed ?

seems like it could be fouled plugs and stuck choke.

Thankx for your interest.

Have checked timing and it looks good. I am willing to put in a new timing chain but do not know what to measure to see if this is needed at this time, or if there is a better chain than OEM.

It is fuel injected. I just took out the injectors for cleaning. Engine ran great for about a week. The job seemed straight forward enough. Didn’t adjust anything but it does act like a stuck choke. Also it has new spark plugs and the oxygen sensor is only about a month old.

Hmm, bad fuel pressure regulator perhaps?

This may sound dumb, but mine did that and it was a plug wire that was not fully seated. If yours are old, go get a new set.

Fuel pressure reads 38 pounds. I have an ajustable regulator the injector cleaning guy recomended. He said to ajust it to 42-44 pounds. Obviously need to wait on that until this sputtering problem is solved.

Dosen't sound dumb to me. I wll check. Will also check to see if the choke is stuck or not working. Thankx

This is going to be vague as hell, but here goes....I have heard that it is common for the 460 to develop a leak in one particular spot at the head or intake. I saw some posts about it 2 years ago and several people mentioned the same thing. Could explain a cold start that gets better as it warms. Again, this was just something that caught my eye since I have a 97 F250 with the injected 460. Try pulling codes??

Anyone...Anyone????

KOEO test reads code 21. Engine coolant temp (ECT) out of self test range. What the hell does this mean? The temp gauge shows that the therostat opens when the engine is warm. It usually runs just over 200 degrees. After this problen started I installed a new temp sender which I assume is what the computer reads. The new temp sender did not change anything.

KOER

Test 1 reads codes 21 / 42 / 73

Test 2 reads 'engine not responding' Turned off engine and restarted.

Test 3 reads codes 21 / 72 / 73

Sure would appreciate advise on where to go from here.

Sounds like the sensor is toast and the EEC is defaulting to the cold, fuel rich, mode.

Test the sensor stand alone if you can, or just replace it.

JP

You mean the temp sending unit? That's easy enough.

Also I recall having disconnected the throtle positioning senser. later, when I read about it in the manual, the book said to make a score mark so that it can be put back exactly how it was taken off. I didn't do this (oops) but there did not seem to be any way to adjust anything anyway.

No matter cold or hot, if I give it gas too fast the engine stutters. Could this be related to a mis-aligned throtle positioning sensor?

Thankx

I have a 89 460 EFI from a F-350...and yes you cannot adjust the TPS. However you can ream the bolt holes out a bit and adjust it a LITTLE bit.
I would retest for your codes because it sounds like you misunderstood the 2nd code...make sure you get it right.
I also have a rich problem, but all the time...not just certain times. Horrible rich problem....5 miles per gallon rich problem. Choking exhaust in the cab rich problem. Black smoke rich problem. Changing your fuel pressure regulator will not help that problem either...yours is fine. Keep us updated, your problem might help me. I'll do the same.
-Will
89 XLT 460
Daytona Beach

The coolant temp sensor I had earlier replaced was for the stock dashboard temp gauge.

Ford told me there was a second coolant sensor for the computer.

Found out that the previous owner or mechanic screwed an Air Charge sensor into the Engine Coolant sensor hole (both sensors have the same thread size).

They apparently did this because page 34-02-24 (Wiring Light Truck) of the official shop manual tells them to. It shows the Air Charge sensor to be next to the distributor and the Engine Coolant sensor to be at about the middle of the intake manifold.

The correct placement is that the Engine Coolant sensor is next to the distributor and the Air Charge sensor is in the middle of the intake manifold. Bought new sensors and placed them where they belong. All of the problems disappeared. The engine now has that beautiful lub-blub sound I had always heard in RV’s with 460 motors but never in mine.

Will do driving tests tomorrow.

Thankx for all your help.