Misfire Cylinder 1 & 4

[DamageINC123]

Gentlemen,

Now that I have the exact codes I need some help. I have 97 with 30,000 miles. All services including 30,00 mile tune up have been done by the dealer. The car runs like a champ!! Although I keep getting the CEL when I drive aggressive (tach around 6.5). The codes are p300, p301, p304. Pending codes 1313, 1319, 1316. All point to misfire and emmisions related to cylinders 1 & 4. I put in a new MAS but that did not correct the issue. I was thinking an air leak but I am not getting the symptons (IE wondering tach on idle). I put some techron fuel injector cleaner in last night. I am hoping that its a clog fuel injector with low miles i have. Since I am getting the same 2 cylinders every time I check the codes and reset, could it be bad coil or plug on cylinder 1 & 4? We just put new plugs in not long ago. Any suggestion would help.

[der Geist]

Check your coilpacks and especially the connections going to them. The connectors get very fragile with age and break easily. It's possible that since you just had your 30K service the connectors might have broken and are not making a good connection.

[Bladecutter]

Switch the coil packs from the right cylinders to the left cylinders, and see if the misfires follow the coil packs, or stays with the cylinders.

BC.

[DamageINC123]

Im planning on trying that tomorrow. I wil keep you guys posted.

[DamageINC123]

Ok Gentlemen,

I swapped coil 4 and 5. Test drive shows same cylinder misfire. Again, I am only getting this error when I drive aggressive and run the tach pass 6,000. Other than that the car runs like it did on day one. I have some techron fuel cleaner in it now. Someone suggested earlier a possible partial clogged fuel injector. Since the car is a 97 with only 30,000 miles its very possible from lack of driving.. I know what makes it come on and I am not experiencing any issues such as bad idle or lack of power. I guess I could just keep an eye on it to see if something develops. Let me know what you think or any suggestions to try.

[der Geist]

I would try swapping the plugs next, and if the codes still show the same swap the injectors.

[Bladecutter]

Did the misfire start after you changed the spark plugs, or was it doing that before you had the plugs changed?

In case the Techron doesn't help, here's a company I have heard good things about when it comes to fuel injector cleaning:

http://www.witchhunter.com/

I might take the extra step in swapping the injectors between cylinders to see if the high rpm misfire follows the injector, but that might be more than you want to tackle.

I can't really think of what else it can be, unless its an issue with the vario-cam system turning off at the higher rpm point, which I believe is right around that rpm point. I think you would need someone more knowledgeable about the nuances of the electronics system to chime in.

BC.

[DamageINC123]

We actually did the 30,000 mile tune up twice becasue it was only driven about 1,500 miles in the past 2 years. I believe its started after the first 30,000 mile service.