QuestionQUESTION: Hi,Roland I need a bit if info.on a 2.7 Intrepid.
The story started when a customer towed his car to the shop,said it wouldn't start,had it boosted by a garage drove it to their shop and it hasn't started since.They said the motor was no good.He towed it to a Dodge dealer they informed him it was firing on 3 cylinders and possibly the computer was faulty.The car was to old to spend a lot of money he didn't have.He wanted us to try and find a solution.I checked the spark and only 2 plugs fired the second one on left facing the front and 1st on the right.We found a computer at a recycle dealer and we have spark on all plugs the only thing is it seems intermittent.The previous shop said the motor was no good because they took a compression test.When we did the same test, compression was 180-165 lbs on all cylinders which seems good.I wonder could you tell me the plug firing sequence and describe the ignition operation.I know there is an ASD relay but can't remember if this could stop the fire.We are thinking of changing the crank sensor and cam sensor but would like to have advice before doing so.
Thanks,
Wayne
ANSWER: Hi Wayne,
The firing order is 1-2-3-4-5-6. The firing is timed and ordered by the cam and crank sensors which you could test statically by checking that they pulse between 5V and 0.3V numerous times per revolution when you turn it over by hand via the crank pulley bolt with the ignition key in the run position. You would measure the voltage between the black/light blue common ground wire and the tan/yellow and the gray/black wires, respectively for the two sensors. The orange wire should have 8V on it. Also if you had an OBD-II reader the codes for a bad sensor are 0340 and 0320, respectively. Each plug has its own coil so you could check that out by switching then around and observing whether the problem follow the coil or not. There also is a capacitor on each bank that stores energy for the primary side so those might be an issue, located about the middle of each bank with the same dark green, common 12V supply wire that goes to each coil. Each coil of course has its own driver wire from the computer. The ASD provides the 12V to that wire and to the same wire for the injectors. The ASD will remain closed so long as the computer is getting pulses from the cam and crank sensors.
So those are the basics.
Roland
PS Use the 'thank/rate' tab below to get back to me with further questions, to which I will respond. While you are there if you will note in the evaluation area an item called "nomination?", and if you would change the 'no' to a 'yes' that would give me a vote for November's 'expert of the month' award. Thanks
---------- FOLLOW-UP ----------
QUESTION: Thanks for the quick response, Roland.We had switched two coils the first and second on the right facing the motor and the trouble stayed the same.I am not sure if the cylinder count is 123 on the left and 456 on the right could you clarify this for me.I should mention there was plenty of gas on the plugs and we left them out for awhile to dry the gas up thinking the engine was flooded.I will be away a couple of days next week and when I get back I will check the voltages.I think the owner is going to try and hire a mechanic friend to bring his portable Genisys tester to check for codes.We used one but it only checked for emission codes and there were none.
Thanks again,
Wayne
AnswerHi Wayne,
The numbers are 135 on the right bank and 246 on the left, where left is the driver's side. Best of luck, and let me know if you get any relevnt codes that I can give you some advice about.
Roland
PS Thanks much for the vote. If you fell so-moved do it again! (I have requested that the management limit it to one vote/questioner, but they haven't done it yet, and the fellow I'm neck and neck with has all sorts of multiple votes from questioners).
