Missfire under heavy load. Please help!!!!!!!!!!!
04-23-2006 | 09:57 AM
#1
Missfire under heavy load. Please help!!!!!!!!!!! I did a cam swap and valve springs, push rods, timing chain ect. in March. Car was running fine. Ran about 3 tanks of gas. The other day it sounded like I blew up the motor. It backfired and shut off at around 4000 RPMs Started back up and drove ok untill I hamer down and it backfires and sputters and shuts off sometimes. I have no SES lights. So I am assuming it is a misfire. I checked all the plug wires, valve terain, 4 of the spark plugs, (they were just changed 1000 milse ago). Every thing looks ok. Could I have a bad coil pack or fuel injecter? If so shouldnt I get a SES light? How do you check a coil pack or fuel injector? What the hell is wrong with this car? Please help.
Car has SLP headers and y pipe, MAF, lid, and custom tune by Texas speed. Cam is 228,228 on 112LSA. Cheap Flowmaster exhaust. I aslo get codes for the front 02 sensors the rears are deleted. Thanks for all the input so far. Do mass air flow sensors go bad? Is there a way to test them??
Well I got new 02 sensers. Took a ride with the snap on scanner. No missfires at all. MAF seems to be working fine. No other codes? What the hell is wrong with this thing???? Somebodys got to know???
Take the 2 seconds and disconnect the MAF. Those bitches get dirty and do the same thing you are describing. When mine acted up I was going nuts trying to figure it out.
Easy to check. Disconnect and go for a ride.
I had it disconected and it had a hard time idleing and finaly got to the point where it would idle and I did not even get around the block and seemed to be doing the exact same thing. Should I drive it farther with it disconected?
Car has SLP headers and y pipe, MAF, lid, and custom tune by Texas speed. Cam is 228,228 on 112LSA. Cheap Flowmaster exhaust. I aslo get codes for the front 02 sensors the rears are deleted. Thanks for all the input so far. Do mass air flow sensors go bad? Is there a way to test them??
Well I got new 02 sensers. Took a ride with the snap on scanner. No missfires at all. MAF seems to be working fine. No other codes? What the hell is wrong with this thing???? Somebodys got to know???
Take the 2 seconds and disconnect the MAF. Those bitches get dirty and do the same thing you are describing. When mine acted up I was going nuts trying to figure it out.
Easy to check. Disconnect and go for a ride.
I had it disconected and it had a hard time idleing and finaly got to the point where it would idle and I did not even get around the block and seemed to be doing the exact same thing. Should I drive it farther with it disconected?
04-23-2006 | 09:40 PM
#3
Sound mechanical to me. Did you locktite the rocker arms and torque them down to 22 Lbs-Ft?? It sounds like there could be a loosened rocker nut.
A good way to see which cylinder is your problem is to unplug each plug wire and listen for the change in engine sound, if you pull a plug wire and there is no change then that is the problem cylinder, you can do the same thing for the injectors, unplug one at a time. I still suspect mechanical problem though.
A good way to see which cylinder is your problem is to unplug each plug wire and listen for the change in engine sound, if you pull a plug wire and there is no change then that is the problem cylinder, you can do the same thing for the injectors, unplug one at a time. I still suspect mechanical problem though.