302 problem
Thread Starter
|
Freshman User
Joined: Mar 2007
Posts: 25
Likes: 0
302 problem
1986 f150 with 302 EFI I think the pcm is bad but not sure put new timming chain on it was worn but had not jumped. The motor runs like the wires are crossed but they have not been off and they are wright. It misses and back fires like it is try to fire on wrong cylinder. Put new control module on the dist. don't know what else could be wrong unless its the pcm put a new one on about 5 years ago need help.
Moderator
Joined: Jan 2001
Posts: 56,992
Likes: 2,741
From: Virginia
Everything was fine till you did the timing chain correct? Strange coincidences happen sometimes, but rarely.
If someone had timed the engine to compensate for the worn chain, then the timing on the engine may now be way off with the new chain.
Disconnect the spout connector and time the engine according to the specs on the sticker in the engine compartment. Then hook the spout back up.
If someone had timed the engine to compensate for the worn chain, then the timing on the engine may now be way off with the new chain.
Disconnect the spout connector and time the engine according to the specs on the sticker in the engine compartment. Then hook the spout back up.
Thread Starter
|
Freshman User
Joined: Mar 2007
Posts: 25
Likes: 0
I had the problem before I put the new chain on the new chain didn't help at all I took the spout loose and moved the timing but no help it won't idle long enough for me to put a light on it. Its that bad try and race the motor and it misses like it is cross wired but its not.
Moderator
Joined: Jan 2001
Posts: 56,992
Likes: 2,741
From: Virginia
I would pull the sparkplugs and see if you can tell what's going on. Some that are wet indicate a leaky injector. This would also cause it to backfire in the exhaust if raw fuel gets in the manifold.
Junior User
Joined: Feb 2007
Posts: 71
Likes: 0
From: Florida
Check the stator and make sure none of the stator arms are bumping the pick up inside the distrubitor. sounds EXACTLY like what my 86 f150 was doing. You should have an air gap on both sides of the stator between the pickup.
Trending Topics
Posting Guru
Joined: Sep 2003
Posts: 1,002
Likes: 1
From: Right Next to U
According to some Tech Facts, among manufacturers...50% of PCMs have nothing wrong with them when they are returned under warrenty....this isn't to say that yours isn't defected now...they were talking about those PCMs that were NEW while under warrenty were returned. Throwing parts at a engine without doing a proper code read is useless and expensive. Read the codes! Buy a code reader, that useless computer has the codes that will give you an idea where to start with your problem (s). Even if it won't start for long, there is something there that got you misguilded to the point your ready to throw a new computer at it. There are many posts here that have your problem someplace and a solution to your problem. If you don't have a code reader, there are other ways to count the needle flash on a Analog meter. The posts are here...the people to help you are here...but if you want to learn about your truck and work on it, and be satisied that you fixed it...ask the questions. Don't just throw parts at it.....it will only make the parts man happy with that new boat.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Posting Guru
Joined: Sep 2003
Posts: 1,002
Likes: 1
From: Right Next to U
Things to look for... vaccum leaks, on an EFI engine, this little stuff will not make it run. The computer uses all the info from the sensors from the LAST time it ran. Pull the codes. Post them. If you have already disconnected the battery, there will be no codes after 30 min. Or the quickest way if you didn't want to wait is to put the code reader on TEST and while the key is on, turn the code reader tester to off...this will clear the codes in the computer AND the code tester, no waiting the 30 min time limit...instant clearing of the codes.
If the codes are no longer in the computer, the computer is now in learn mode. You HAVE to start it, run it for 10 miles or 30 mins if it won't move. Pull the codes and post them. Don't disconnect the battery or clear the codes UNTIL you fix something that the computer senses. (" new control module on the dist") would mean to me that its a computer sensor idem.....perhaps the computer sense's that SOMETHING is different among the sensors....(distributor is a major feedback to the computer).
If the codes are no longer in the computer, the computer is now in learn mode. You HAVE to start it, run it for 10 miles or 30 mins if it won't move. Pull the codes and post them. Don't disconnect the battery or clear the codes UNTIL you fix something that the computer senses. (" new control module on the dist") would mean to me that its a computer sensor idem.....perhaps the computer sense's that SOMETHING is different among the sensors....(distributor is a major feedback to the computer).
Thread Starter
|
Freshman User
Joined: Mar 2007
Posts: 25
Likes: 0
checked the ref. volts had 5.0 volts checked the center wire and had 5.0 volts on it with the map unpluged. with it pluged up had 2.5 volts on the center wire my book said it should have 5.0 with no vacuum i put 20 inch vacuum on it and my reading didn't change If i under stand it wright it should drop to about 1.0 volt with 20 inchs
vacuum. So I go buy a new map and get same reading on it. now what is it bad too?
vacuum. So I go buy a new map and get same reading on it. now what is it bad too?