I had this happen to me once before, and today it happened again, on the same strech of highway, no less which is kinda creepy. Anyway. The engine will misfire at all speeds and the tach will fluctuate rapidly with the misfire. As before, the problem cleared itself up on its own and the tach read normally as it did before. This isnt the only problem ive had ignition wise. It also will ocasionally cut out at idle. I pretty much take this as a hint to replace the ign. module before it leaves me stranded but are there any other components, such as the ignition coil or the pickup, that can cause similar symptoms? Since the signal on the tach also corresponds to the missing it would seem that the module would be the most likely suspect but I want to make sure there isnt anything else i may overlook.

 

Run a ground wire from the firewall to the engine block.

Worked for me....

 

the ecm already has didicated grounds as well as a copper braded wire running between the pass side head and the firewall but checking the grounds in addition to possibly a new module is definatly a good idea now that you mention it.

 

think i fixed it... I noticed alot of static in syncrony with the engine in the radio on teh way home. One of the terminals in the spark plug boots wasnt clipped onto the spark plug. Dont know how long its been like that but it was just sitting on the end of the contact. The silicone didnt look carbon tracked, just the terminal itself apeared to have been arcing so i jsut cleaned it up and made sure it fully clipped onto the plug and the static went away. Hopefully that solved it.

 

guess they where unrelated. Still having the same problem. Could a faulty coil thats arcing internally also cause this? The problem dissapears as suddenly as it occures.

 

Check all the wires going to the coil and the ignition module. I had a similar problem with my old formy. It started acting up, so bad, until I finally had to pull over. After some investigation, I found that the primary wires to the ignition coil were loose. I pushed them back down, and voila, problem solved.

 

I did check over the wiring and all of it apears to be sound. To be more precise, when the problem occures, the engine will misfire and with each misfire, the tach will rapidly jump 300-400 rpm and then return to normal. I noticed that the problem only seems to occureafter the engine has been put under load at some point. Dont know if its related or just a coincedence. I guess ill just do the exaustive approach and replace the coil and module along with a new cap and rotor. What bugs me is that it only occures occasionally so I wont know if ive ever fixed it or not.