I HAVE A 95 F-150 302 AUTOMATIC 4X4 IT SHUTTERS WHEN DOWNSHIFTING AT LOW SPEEDS AND AT AN IDOL , IT SPARK KNOCKS AND LOOSES POWER WHEN PULLING HILLS, I HAVE CHANGED THE TORQUE CONVERTER, COMPLETE T

Asked by Feb 07, 2011 at 09:04 PM about the 1995 Ford F-150

Question type: Maintenance & Repair

TUNE UP, DISTRIBUTER, COIL, MASS AIR FLOW SENSOR, IDLE SENSOR,FUEL FILTER,AND CLEANED THE THROTTLE BODY. CAN NOT FIGURE IT OUT . HAS ANYONE HAD THE SAME PROBLEM AND ANY ADVICE ON POSSIBILITIES ? I WOULD REALLY APPRICIATE IT

20 Answers

clean or replace the IAC,Idle Air Control,is located on TB.

1 out of 1 people think this is helpful.

THE IA C IS ACCTUALLY WHAT I MENT WHEN I SAID I REPLACED THE IDOL SENSOR, THANKS FOR REPLYING , DO YOU HAVE ANY OTHER SUGGESTIONS?

bad knock sensor for spark knock,your cat converter could be cloged up.try the drill test.on down pipe befor cat drill a 1/8 hole in pipe drive it see how it does,put a metal screw in hole to seal it back up.most muffler shopes well do this test for free.

thanks for the suggestions, i will try that this week end ,i know this problem is really baffleing me, thanks again

235

I had very similar symptoms in a 93 F-150. It turned out to be a burned valve. The cylinder was basicly dead . On hills and when shifting the loss of the cylinder caused the engine to shake and become unbalanced. Power and fuel mileage went down. If you feel this is a possibility in your truck, a simply cylinder compression check should tell you what is ging on.

A burned valve will not cause his problem,all it will do is skip like a fouled out spark plug,where do you people come from.

235

How did I know that you would make a comment about that post? When a spark plug fouls the cylinder does not fire, therefore there is no force exerted on the piston. The system is balanced only when all cylinders fire as it is a mass and force balanced system, the lack of force from combustion coupled with friction forces in the cylinder leads to a vibration in the system. At certain rpms the system will be operating at a natural frequency causing the shuttering when he downshifts. When the system was designed the natural frequencies would have been outside of the operating range of the engine but with the dead cylinder it could be causing the problem. I didn't say this was what was happening, I said it happened in my truck and that was the problem. I do not have as much experience working on vehicles according to all the times you have posted your acheivments, but I did work at a restoration shop, oh, and I also study mechanical engineering with a specialty in machine systems. He asked for a reason and I gave him a possible one and I assure you a dead cylinder can cause the issues he is having. Learn to think outside the box.

i appreciate the input, i am not machanically inclined , i am shade tree , please if anyone thinks of anything else , please reply .

is there another name for the knock sensor? my local oreilly's can not find it in thier parts listings.

no ,knock sensor is it,have you had the timeing checked,its possable it has jumped time..you can check it,1 pull num 1 spark plug,2 get piston up to top on compression stroke,3 take dist cap off,see if end of rotor button is pointing at num 1 piston.

thanks, i'll try napa on the knock sensor. the timing is good.

MY TRUCK DOES NOT HAVE A KNOCK SENSOR, THE CAT CONVERTER IS NOT BLOCKED. WOULD THE IGNITION MODUAL POSSIBLY CAUSE THIS PROBLEM??? I WOULD ASSUME THE IG MODL WOULD ETHER BE GOOD OR BAD , NO IN BETWEEM????

yes,even when bad they will still work,not right tho,it could be the problem,also it could have sheared a gear on distributer,pull it out ,take a look at it.

i put a new distributer in already , thought that might be the problem but wasn't. this was my oldest son's truck, i lost him in 06 to a motorcycle , so the truck has a lot of sentamental value to me and i just want you to know that i do appreciate your time trying to solve this problem with it.

sorry about your son,did he have any mods done that you know of.

NO NOTHING BESIDES ABOUT A FOUR INCH LIFT, OTHER THAN THAT TRUCK IS ORIGINAL DRIVE TRAIN , JUST HOPE IT IS NOTHING INTERAL WITH ENGINE , I REALLY DON'T THINK IT IS BUT I MAY BE WRONG AND THANKS,,JUST WANT TO GET HIS TRUCK STAIGHTEND OUT. I HAVE BEEN LEANING TOWARD FIRING , WHAT ABOUT FUEL PROBLEMS, CHANGED TPS , IDOL VALVE , FUEL FILTER. WHAT ABOUT FUEL PRESSURE REGULATOR OR FUEL PUMP ????

If it runs good going down the road at speed,dont think fuel problem.you should have the cylenders checked for compression,check tranny mount at back of it they made of rubber,see if you can push up on tail of tranny,check for up movement,you should check motor mounts also. check all lift kit parts for loose ,broke bolts also check U bolts on rearend for loosness,I feel it is a drive line problem.

IT FEELS TO MUCH LIKE A SKIP TO ME ???

JUST NOTICED SOMETHING ABOUT MY PROBLEM ,, TRUCK RUNS GREAT UNTIL IT WARMS UP , SEEMS TO BE WORSE AFTER IT IS TURNED OFF AND THEN CRANKED AGAIN AFTER IT IS WARM . HAVE ALSO INSTALLED NEW TPS, EGR AND EGR SENSOR, ENGINE COOLANT TEMP SENSEOR, FUEL PUMP RELAY , IGNITION MODULE, AND FUEL PRESSURE REGULATOR , I KNOW THIS SOUNDS ODD , BUT IT RUNS GREAT WHEN IT IS NOT ACTING UP , EVEN AFTER IT ACTS UP , IT WILL GO RIGHT BACK TO RUNNING GOOD EVEN THOUGH IT IS STILL HOT

85

i have an 05 f150, that spark nocked. but its got some mods. you might have to big or to small of a gap in your plugs. try lookin up plug gap specs for it. then pull and check each plug. maybe a full tune up is needed. i just started running 91 octane fuel in mine and it fixed the problem.

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