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1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

302 missing under low rpm pull

 
  #16  
Old 01-31-2002, 06:38 PM
UncBob
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302 missing under low rpm pull

My EGR problem was crud build up on the INTAKE MANIFOLD SIDE where the EGR dumps not the Exaust side
 
  #17  
Old 02-01-2002, 07:21 AM
MrPleasant
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302 missing under low rpm pull

Retarding the timing to about 7 degrees did not help at all...made things worse I think. I currently have the ACDelco Rapid Fire plugs in the truck...bought some cheap Autolite 25's to see if that helps. Guess I will have to do some vacuum checking this weekend too....

Can you say frustrated?


:-X11
 
  #18  
Old 02-01-2002, 09:23 AM
cwmerc88
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302 missing under low rpm pull

Well at least I am not the only one that is very frustrted with these trucks. I have tried all suggestions no luck. I just do not get it I have even put a new motor in because before I leaned about the pcv valve I had burnt a hole in the #8 piston. Every thing is new except for the upper and lower intake, but they were checked for leaks under pressure, and the computer is orginal. I am waiting to change the computer because I want to go with mass air. I am reading and trying to get the best suggestion and sultion, bafore I have to pay $700.00 for the conversion kit. I also want to change my cluster to one with a tach. I canot find one around here(Bristol TN),any suggestions. I want to thank everyone again for all the help. Keep me up to date if any think else becomes known about these trucks.
 
  #19  
Old 02-06-2002, 02:58 AM
cwmerc88
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302 missing under low rpm pull

I was wondering if anyone had anymore ideas. Still no luck with the truck. Thanks again.
 
  #20  
Old 02-06-2002, 10:26 AM
MrPleasant
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302 missing under low rpm pull

Make sure your plugs are gapped according to the underhood sticker. I have a 1991 f150 5.0 and my Chilton's manual, the spark plug book, and the Wal Mart computer all tell me to gap them at 0.054". The underhood sticker says to gap them at 0.044". Trust only the underhood sticker.....


 
  #21  
Old 02-06-2002, 02:37 PM
kwing
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302 missing under low rpm pull

Well, I was just in the Tri-Cities region in January. Nice country. Drove my 92 F-150 there and back. Try doing a diagnostic test on your M.A.P. sensor for proper (RPM or voltage) feedback. It directly affects fuel delivery to your injectors and can make your engine run extremely rich under load (or even lean) if it is worn out or malfunctioning. Another thing to try as well is injecting throttle body cleaner (oxygen sensor safe) into one of the openings in your vacuum tee, to clean out the accumulated gunk and carbon from the exhaust and pcv emissions. Use the whole can. Then reset your emission sensor fault codes (as per instructions in your Chilton or Haynes manual) and then reset the Keep Alive Memory by detaching the negative terminal of your battery for at least 5 minutes. Then hook it back up and run the truck for about 20 miles (with some steady hiway speed as well) so the computer can relearn the adaptive parameters for all the sensors. Hope that helps. If not, there are lots more things to play with on a 302!!! I also have a 78 F-150 with a 300-6 and I would go back to one in a flash. Never had a problem. Cheers.
 
  #22  
Old 02-07-2002, 07:08 PM
jmccoy
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Post 302 missing under low rpm pull

93 F150 5.0L 165K mi.
The hesitation I experience matches this almost exactly. If I put the truck in D, not OD, then I have no problems at all. Once in OD and at cruising speeds where the truck shifts into OD, it hesitates badly with slight throttle, until you step on it to downshift..then all is good. Other than this post, Is this the same hesitation symptom experienced by all, or is this different than what is discussed in most of these other responses? If this was your symptom, did you check/replace the plenum gasket...and did that do it for you?

I plan on hitting the easy fixes (moving pcv hose and separating #7,#8 wires)

>My 92 with a 302 had similar symtoms at two different times
>and were two different problems. It would run fine until I
>would get to cruising speed and in overdrive, if I would lug
>the engine down enough like pulling a hill it would start
>missing. The more I put my foot into it the worse it would
>miss until I would downshift then it seemed to clear up.
>That time it ended up being a bad gasket under the plenum.
>It was sucking air between the top of the intake and the
>bottom of the intake plenum. NAPA sells this gasket for
>about $5.00.
 
  #23  
Old 02-13-2002, 01:06 PM
fiddy
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302 missing under low rpm pull

>Retarding the timing to about 7 degrees did not help at
>all...made things worse I think. I currently have the
>ACDelco Rapid Fire plugs in the truck...bought some cheap
>Autolite 25's to see if that helps. Guess I will have to do
>some vacuum checking this weekend too....
>
>Can you say frustrated?
>
>
>:-X11

I had a set of those rapid fires in my 94 w/302. ran like crap with them - put a set on champions in and it has run great for a couple of years now. those gimmick plugs are just that - a gimmick.

 
  #24  
Old 02-26-2002, 09:47 AM
MikeS
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302 missing under low rpm pull

Well did you ever get this problem fixed? I am having same problem now on my 93 5.0 with E4OD. It showed a week or so sfter I installed Bassani equal length headers. Most noticeable when pulling my boat. Under light pedal up a hill or speeding up without gearing down it will ping and miss. I messed with timing and fuel pressure and made little difference. Timing was at 6BTC and still pinging. Unhooked battery for 10 minutes and reset timing to 10-11 and fuel pressure to 44 or so and when I restarted and drove it ran perfectly for a few trips. Then it readjusted itself to run poorly again. What is up with this????!!! I guess I will pull EGR off and clean intake holes out. Maybe replace upper intake gasket while I am at it. Lets figure this one out before we melt them down.
 
  #25  
Old 02-26-2002, 10:43 AM
uy7v
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302 missing under low rpm pull

i too have a rough idle that starts when the truck is not stone cold i have had it scope checked, no codes present still replacing parts and hoping to find this problem .hoping someone will give me another thing to check..
 
  #26  
Old 02-26-2002, 04:17 PM
cwmerc88
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302 missing under low rpm pull

I just received a little insight to our problem. Most of us that have installed headers or any air modifaction. I have had my truck on a dyno testing and testing and testing. Most of it comes down to even though we have anough fuel pressure timing correct (moved up and down no help 10 is best). I have found that it still runs lean. installing an adjustable fuel pressure regulator, or a FMU unit will help. This is after you make sure you move your PCV valve to the top port of intake. I changed to 24 lbs Bosch injectors 155 LPH fuel pump, 110 reccomend by most if doing any air mods to the engine. Even adding the K&N changed it dramticaly. So far it is great but I am not through on the dyno. Also if you have an ignition upgrade try on step colder plug. I have a Jacobs unit and went to a ASF32C. Hope this helps. Anyone find any more info let me know please. THANKS
 
  #27  
Old 02-26-2002, 05:07 PM
Mike Lewis
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302 missing under low rpm pull

[updated:LAST EDITED ON 26-Feb-02 AT 06:07 PM (EST)]
Are the 24 lb/hr injectors really necessary? What is the difference between universal fit and the ones specifically for the 302?

What rate injector is stock, and will larger injectors truly help a truck with K&N FIPK and exhaust only? What about adding a higher rated fuel pump?
 
  #28  
Old 02-27-2002, 08:26 PM
cwmerc88
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302 missing under low rpm pull

I cannot say for sure that the bigger injectors will help but the adjustable fuel pressure regulator might. Svo sells 24 lbs and so does Bosch
 
  #29  
Old 02-28-2002, 08:03 AM
xekimx
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Post 302 missing under low rpm pull

Just joined the forum to see if anyone else has this problem and that appears affirmative. I first started having problems while pulling a trailer with an E-150 with EEC-IV. It suddenly started misfiring badly at low rpm and upon inspection I heard the pcv valve making noise so I replaced it and that improved things to a point where I could get on down the road but it's never ran the same since. My symptoms are identical to what I hear from you all. Since it ran good when cold I excluded the ignition as a problem but I have heard more than one input about cross firing between #7 & #8 wires. I recently installed a cooler thermostat and new coolant sensor which didn't help. I've tried disabling the egr system which helps but doesn't totally eliminate the problem. I keep getting a code 31 (with everything back to stock) although all components check good. I've read on two other forums where these symptoms were attributed to the egr passages in the intake manifold being plugged up. Also a vacuum leak possibility between the plenum and manifold. A hard to detect leak would only show up after warmup when the system has leaned out. In conclusion I'm to the point of removing the plenum and cleaning everything out to see if that is the problem. Good luck to all my fearless frustrated Ford fanatics.
 
  #30  
Old 02-28-2002, 08:17 AM
xekimx
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Post 302 missing under low rpm pull

 

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