QuestionMy Caravan (3.3 6 cyl) is running on 4 cylinders. The controller has been changed four times to no avail. All injectors replaced. Wiring appears fine. All plugs and plug wires replaced. 2 local mechanics and a Chrysler technician are baffled and have given up. Have spent four hundred dollars and missed a weeks worth of work. I'm getting desperate here.
One mechanic mentioned "reed switches on flywheel" but it wasn't explored further.
Please help...
Thanks Tom
AnswerHi Tom,
Let's try and sort this one out. First, have you tried to get the fault code readout from the engine controller? The most useful thing to do would be to try to get the fault codes that may stored in the engine controller memory to readout. Try using the ignition key: turn it "on-off-on-off-on" and leave it "on" (doing this quickly, no longer than 5 seconds). By "on" I mean just the normal position when the engine is running, not the cranking position. The 'check engine'light will remain on when you leave the key in the "on" position with the engine still not running. But then watch the 'check engine' light to begin flashing, then pause, flashing, pause, etc. Count the number of flashes before each pause and keep track of the numbers. Repeat the readout and verify the counts are correct. Then group them in pairs in the order that they came out, thus forming two digit numbers. You may notice that the pause is shorter between the digits of a given number, and longer between the numbers themselves. Then send me a 'follow-up' question telling me the results of your readout. By the way, 55 will be the last number (two groups of 5 flashes each) and that is the code for "end of readout".
About the history: Do you know which 2 cylinders are missing? Or is the "running on 4 cylinders" a figure of speech or perhaps the missing is random? Try pulling the spark plug wires one at a time while idling and notice which 2 don't make the missing worse. Those are the ones that are failing to fire.
Have you done a compression test on those cylinders? Have you tested those two for spark? Have you looked at the plugs for those cylinders after letting the engine sit for 5 minutes following running it warmed up, to see if they look wet? When did the problem start, and was it gradual or abrupt? Anything concurrent happen at the time you noticed it? Was wiring to the injectors actually verified or just based on external appearances?
It would help if we knew whether the issue is fuel or spark or compression related.
Does it miss at all rpm's and load conditions?
Fuel filter been changed lately?
EGR valve observed for normal movement of the valve stem?
Vacuum lines traced for leaks, using underhood sticker as road map?
Those are alot of questions, I know, but there are a lot of possibilities. Most of them don't require expensive testing or expensive part replacements. I have the '93 van shop manual that covers the 3.3L engine.
Roland
