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89 F-150 302 running bad

My 89 F-150 302 starts great, idles fine, and drives around town great but when you accelerate at full throttle it misses bad and falls flat on its face. The only mods are the elimination of the cat with true duals and a open type K&N air filter. I am an old school gear head so where do I start ?
 

Fellro

Moderator
Staff member
A good tune up can't hurt, plugs, wires, cap, rotor and fuel filter.
 
Well I had the Ford dealer change fuel filters, fuel pumps throttle position sensor, map sensor, distributor timing, and with 45 lbs fuel pressure at all throttle positions it still falls flat on its face at full throttle. Now I know why it was traded in. Needs a Chevy engine I guess.
 

Beach66Bum

Moderator
Top Poster Of Month
Well I had the Ford dealer change fuel filters, fuel pumps throttle position sensor, map sensor, distributor timing, and with 45 lbs fuel pressure at all throttle positions it still falls flat on its face at full throttle. Now I know why it was traded in. Needs a Chevy engine I guess.

I'd be taking it back to the shop if I paid for all that work done and it still had the issue you brought it in for. Doesn't matter what engine you have, if there is a problem, it needs to be addressed.

What RPM does it start to fall flat?
 
As noted from idle to half throttle its great. Push the accelerator to full throttle beyond that point and it begins to miss severely and loses power. The Ford dealer has given up and says that they have no clue. Timing was off and adjusted to spec with no change in performance. A recip engine runs on fuel, air, and spark but the dealer has found nothing . It has 45 pounds fuel pressure, the fuel filters are new, the tanks are new, the TPS is new,the MAP sensor is new and the Ford dealer has no idea. They are only charging for parts and no labor. I am totally out of the Ford engine loop and especially the EFI stuff. I love the truck but it needs fixed. Maybe I should pull the injection and put an intake and carb on it. I know it would require a pressure regulator. What else?
 

Fellro

Moderator
Staff member
So here's a little check to do... If it runs good to a point, back off the pedal and then lightly step back in. If it feels like you can get a little more out of it doing that, it is the cats plugging up. I have had that happen plenty of times. step in, get it going, then it falls down, back off and lightly step back in and it picks up. Step hard, fall on its face. I learned that behavior on a Chevy engine by the way.... My 83 Trans Am. Also on my sisters old late 80's Ford van.
 

dustybumpers

don't play well w others
Have you or anyone checked the codes before throwing parts at it?
 
So here's a little check to do... If it runs good to a point, back off the pedal and then lightly step back in. If it feels like you can get a little more out of it doing that, it is the cats plugging up. I have had that happen plenty of times. step in, get it going, then it falls down, back off and lightly step back in and it picks up. Step hard, fall on its face. I learned that behavior on a Chevy engine by the way.... My 83 Trans Am. Also on my sisters old late 80's Ford van.

I almost suggested that too ,but he said that the cats. were eliminated!...:cooldude:
 
The dealer tells me that there is no OBD on that year truck and there are no check engine lights showing. I guess that is the reason that they can't fix it. Everything is based on the vehicle telling the mechanic what to change and my truck won't do that. I am intent upon getting all of the performance expected even if I have to go old school with an aluminum intake and carb. Its too nice of a truck to throw away. Any tips on that conversion would be appreciated by you Ford experts.
 

fatherdoug

Tonto Papadapolous
I think the dealer is incorrect. There IS OBD for the 89 model year, albeit OBD1. OBD1 would have started in 1985 for Ford.
 
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dustybumpers

don't play well w others
The dealer tells me that there is no OBD on that year truck and there are no check engine lights showing. I guess that is the reason that they can't fix it. Everything is based on the vehicle telling the mechanic what to change and my truck won't do that. I am intent upon getting all of the performance expected even if I have to go old school with an aluminum intake and carb. Its too nice of a truck to throw away. Any tips on that conversion would be appreciated by you Ford experts.

Does the check engine light come on when you first turn on the key?
Your bulb is probably burnd out. Your truck has a port to check codes right beside the air cleaner box.
You can check codes with a test light if you don't have a scanner, BUT the check engine light in the dash has to work

That Ford dealer lied to you.
 

Fellro

Moderator
Staff member
If it has electronic fuel injection, it has a computer, and since it has a computer, it will have codes. They just can't plug in the 96 and newer style diagnostic computer is all.

I seem to recall my diagnostic port being back by the driver fender near the master cylinder on the fender.

I missed the part about the cats...
 

dustybumpers

don't play well w others
I sent some stuff to Smokey to help with this issue.
 

smokey

Hitech hillbilly
Staff member
This is from Dustybumpers Thanks charlie


This is how you can retrieve your KOEO codes

open your hood, and look at the firewall/drivers fender for this

attachment.php



Pull the plugs from the cap
attachment.php



put your test light into the small plug, and onto a good ground
attachment.php


Sit in the seat, and put your key in the ignition.
Be sure to turn off all accessories
Turn key on
Watch check engine light
attachment.php



Codes on obd 1 are in 2's obd2 are in 3's
It will flash. first will be flash,,,,,,,, flash. that will be 11 ( 3obd2 will be 111)
That code is system pass,
then you will start getting the codes.
All codes are repeated twice

I forgot to mention that was the location for 92-96. this is the location for 85-91, same side of the truck, right behind the air cleaner
attachment.php
 

Attachments

  • 85-91.JPG
  • Check codes 001.JPG
  • Check codes 002.JPG
  • Check codes 003.JPG
  • Check codes 005.JPG
The dealer tells me that there is no OBD on that year truck and there are no check engine lights showing. I guess that is the reason that they can't fix it. Everything is based on the vehicle telling the mechanic what to change and my truck won't do that. I am intent upon getting all of the performance expected even if I have to go old school with an aluminum intake and carb. Its too nice of a truck to throw away. Any tips on that conversion would be appreciated by you Ford experts.

Seriously Bruce don't ever go back to that mechanic you are using ....... these trucks use an obd1 protocol and the procedure that has been put up will certainly do the job or you can buy one of these for under $25 https://www.amazon.com/INNOVA-3145-Ford-Digital-Reader/dp/B000EW0KHW
Very easy to use and the book that comes with it will really help you to diagnose problems.

Check to make sure that the "spout" connector has been plugged back in after they set the base timing too.
 

fatherdoug

Tonto Papadapolous
^^^^True Dat! I found an OBD2 diagnostic tool on Amazon for $30. It was VERY intuitive. I didn't even have to read the instruction manual. I discovered I needed a new gas cap on the not ford. The code cleared when I put on the new cap.
 
Thanks to all you guys for the recommendations. I ordered the diagnostic tool as recommended. I will check it out and see what the codes are. I do not think my check engine light comes on when you turn on the ignition. (I am really disappointed in the dealer.) I will post results. Again much thanks.
 

dustybumpers

don't play well w others
If the CEL don't light up, you need to put a bulb in it. The one on the 89 is in a different spot than the photo posted, that is a 95
If you can't find you'rs let me know, I have an 89 here, I can post a picture of the location of it. If I can't, Smokey can..... :)
 

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