QuestionI have a 1996 Ply Gr. Voyager with the 3.3 engine.A few days ago my engine started to run a little rough, not really bad but just enough to notice it. After about 5 minutes of driving it set off check engine light. I was able to have someone hook up a scan tool. It read misfire on # 5 cyl. He cleared the code but it came back a while later. Thinking I might have gotten bad gas, I filled up the tank and added dry gas. Two days passed and no improvement. I decided to try something else. Since I installed new plugs about 18 months ago, I figure they are OK. Yesterday I decided to replace the wires since the van has 106K and the wires looked to be original. That also did not work. Any Ideas on my next step. I'm thinking of replacing the ignition coil or fuel injector? Any suggestions will be appreciated.
AnswerHi Jerry,
A '98 troubleshooting manual suggests the following items:look at the high voltage trace with an engine analyzer with scope (this sounds like a shop job)
look at the scope while disconnecting one spark at a time to see if when disconnected is 25 kv or more, if not replace ignition coil, check ignition cables (you replaced those),
see if all cylinders have a compression of at least 100 psi and are +/- 25% of eachother (see if #5 is low), if not then find out why that cylinder is low;
using a diagnostic box, kill the injectors one at a time. if killing #5 dosen't change scope pattern or rough idle then change #5 injector. Using a timing light make sure spark is advancing at 2000 rpm compared to idle rpm. Attach vacuum gauge to manifold, verify vacuum is at least 13 psi at idle. Inspect valve train and timing of valves of #5 cylinder.
Because the #4 and #5 plugs fire simultaneously, it would seem that both should misfire if it was the spark coil that was the problem. I'd check the compression on #5 and if that seems to be in spec, then consider cleaning or replacing its injector.
Roland
