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Justin Hearn (aka Swb360) [ View ] [ Jus10rh@yahoo.com ] [ Car Ads ] [ Blogs ] San Antonio, Texas

Well as a few of you may know me from a while back, i had a problem with this truck making a "sporatic knocking noise." that seemed to be the flex plate, as it is no longer a problem. .. Although, i have another issue that needs to be addressed, and im not even sure where to start. This truck is a 1986 dodge D-150, came with a stock 318 when i bought it, no mods.. from what i could see. i put on an after market dual plane intake, a 4bbl holley (600cfm), and headers. 8mm wires, OEM distributor, cap, rotor, and new plugs. since ive done this to the truck, its been running/idling really rough. revving it causes a popping out of the exhaust, bad misfiring under acceleration, and overall bad engine performance. i set the timing to 12 degrees BTC as the placard on the underside of the hood states. Considering I'm trying to INCREASE the horsepower... it seems as though im only making it worse. Could i have possibly missed something in the Ignition system thats making it misfire like this? there is an ECU on the firewall thats never been replaced... a coil thats never been replaced.. and some sort of computer box? in the left hand fender well. i didnt even think this truck had a computer. could that not be keeping up or not recognizing the aftermarket parts? the truck came stock with a 2bbl carb and intake. I have no idea what else to do, i hate to replace parts to find the problem still existing. ANY help to this problem would really be appreciated. Thanks =)

Comments

Posted by reneg8d  -  12/07/2007 02:21 AM hmm, since I'm a mopar nut... I'll jump in... Is the engine original? Mileage? The box on the fender is the ignition module. If the truck idles fine, then I doubt if it is an ignition problem. Its possible, but not likely. I would start with a vacuum gauge and see what you have at idle. If the gauge bounces a lot at idle, it's time for a valve job. If it is really low, it's also possible that you have a vacuum leak at the intake... As basic and silly as it sounds, recheck the rotor position against the TDC mark... Rock the crank back and forth and see how much slack is in the timing chain too.. Let me know what you find Steve ASE Master Auto Tech [ View ] [ Email ] [ Blogs ] [ Car Ads ] Thoreau, New Mexico Charter Member since July 2005   Posted by Red's Place Custom & Restoration  -  12/07/2007 02:23 AM check to make sure none of the plug wires are crossed and that the plug gap is set correctly sounds like ignition problem maybe some of the plugs were dropped before you got them and the gaps are wrong. They don't usually come pregapped at all. check a good tune up manual to get all the correct settings. hope this helps RED Red's Place Custom & Restoration [ View ] [ Email ] [ Blogs ] [ Car Ads ] Charlotte, North Carolina   Posted by REBORN55  -  12/07/2007 04:08 AM Check that the distributor is not loose internally--bushing could be bad causing shaft to wobbl- Seen it a couple of times here lately. Ken [ View ] [ Email ] [ Blogs ] [ Car Ads ] De soto, Illinois   Posted by cruiser63  -  12/07/2007 08:28 AM If it ran okay before the changes,i would think it has something to do with the parts installed.I am kinda thinking like Red said plug wire crossed, hell, i have changed them one at a time and got them crossed,and like reneg8d said you may have a vacuum leak. Check the wires to make sure your not getting them into the header tubes.. cruiser63 [ View ] [ Email ] [ Blogs ] [ Car Ads ] Plain City, Ohio Charter Member since March 2005   Posted by Swb360  -  12/08/2007 01:56 AM Thanks for the quick responses. here are answers to the questions asked : the engine has 174,000 miles on it. i just got a valve job done. after running a compression check before, i found to have one burnt exhaust valve, thats fixed now. however, i checked for vacuum leaks by having the engine idle and covering the carburetor with the aircleaner off.. and also by spraying WD40 at the intake where it meets the block and heads.. not to find an increase in rpm, which leads me away from a vacuum leak. the crank does have some play though, with the dist cap off, i can turn the crank about 1/2 before the rotor moves... slop in the chain? i checked and double checked the wires , none were crossed. i set the gap on all 8 plugs to 0.035 as per the chiltons book before i installed them. whether or not they were dropped before i bought them.. is another thing. i installed an OEM distributor recently thinking the old one had up and down slack on the shaft, but that didnt change anything. if the #1 cylinder is at TDC and the rotor isnt pointing right to the cylinder... could that be causing the problem? if so.. how can i go about fixing that ? thanks again for all the help. =) Swb360 [ View ] [ Email ] [ Blogs ] [ Car Ads ] San Antonio, Texas   Posted by ol bear  -  12/08/2007 02:13 AM hell id start it up in the dark and see if ya have a leak ,,ol bear OL BEAR [ View ] [ Email ] [ Blogs ] [ Car Ads ] crown point, Indiana   Posted by whipsold39  -  12/08/2007 03:25 AM One tooth off on the distributor. whipsold39 [ View ] [ Email ] [ Blogs ] [ Car Ads ] 400 9th ave silvis 61282, Illinois Charter Member since January 2006   Posted by reneg8d  -  12/08/2007 04:16 PM "i can turn the crank about 1/2 before the rotor moves."... 1/2 what? If you can turn the crank 180 deg before the rotor moves, it shouldn't run at all! Rotor position isn't relevant as long as it points to the #1 wire location with the cap on... By tradition on sb mopars at TDC, the rotor points to the front intake manifold bolt on the drivers side of the engine..If the rotor is not in that position, you can "adjust" all of the wires one position on the cap to compensate. All things considered that you have checked, you might actually have either a bad plug, or a bad wire, or both... And we know that isn't possible because everything we buy new is perfect, right? NOT! Up and down movement on the dist shaft is ok as long as in isn't more than a few thousandths... The movement to be worried about is side to side on the shaft. This leads me to another possible problem.... The slotted shaft in the block that drives the distributor has a bushing that can wear out and this will kill distributors. Take the distributor out and stick a long screwdriver down in the slot and see if the shaft has any major side to side play... Hope these help some... Steve Another possibility although rare for mopars, is slippage on the harmonic balancer. If the outer ring has slipped, the timing marks are gonna be way off where they should be... You can check this by pulling #1 plug, bump the engine til you're close to TDC, the with a long screw driver inserted into the #1 plug hole, turn the crank by Hand(Don't use the starter!!!)and watch for the screwdriver to rise out of the hole til it stops(an extra pair of hands really helps). Then look at the timing marks and see if they are off. If they are off a lot, just remark the balancer. If they're close, just subtract or add degrees to your timing to adjust. And plan on replacing the balancer soon too ASE Master Auto Tech [ View ] [ Email ] [ Blogs ] [ Car Ads ] Thoreau, New Mexico Charter Member since July 2005

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