info
2001 town and country 3.8 HO

had issues with motor so my dad rebuilt it.

he recently put the motor back in. we went to crank it and it backfires out the intake. does not start.
i did not help him in the rebuild because we have issues so i try not to make any problems with him. he did it all by himself.
i believe it is a cam timing issue. maybe he didnt align it right. he says that it is the sensors for cam and crank. i dont believe that is true because i think (not quite sure but) the cranks and cam sensor are for fuel timing, rpm signal etc. of some sort.
any ideas? cant think of anything else besides mechanical timing.

 

excuse me its a 2000 town and country awd 3.8L

 

Backfiring out the air intake with a petrol engine says 1st. thing to check IS the cam timing which needs to be exactly right. Usually holes and pegs are to be mated according to instructions before fitting cambelt or chain. Again, usually there are both cam and crank sensors these days, and it's best to fit as a pair when replacing.
Considering the circumstances, if you can't make much headway locating the problem, could be best to get a pro/good amateur to check it over. Modern engines aren't as simple as the old ones.

Leedsman.
(n.b. on checking, this engine actually has pushrods! So it's not so modern. But it does use a camCHAIN which is better than a belt as this is an interference engine.)

Have a look at.......
http://www.allpar.com/mopar/33.html
Maybe giving your dad a printout could "work the oracle" and suggest him a solution?

 

Awesome!
And not good. I don't like the word interference. That was another thing I was worried when I heard it turnover myself. Not saying that he broke anything yet. But if an engine I'm working on is an interference motor, I'd check timing once or twice. That's just me. Haha
Another thing to clarify for my dad. What are cam and crank sensors for?? I said its for fuel injector timing and rpm signal for motor more likely but that's just off the top of my head. He said that it is for cam timing. And if it is bad it won't time itself.

 

The control micros. need to know EXACTLY where the crank is and therefore where the cam is in its rotation cycle. The cam turns at half engine revs, but it must be EXACTLY matched to the crank. Alignment holes are provided to fit the two together during reassy. As there is a chain connecting the two, the crank and cam alignment is entirely physical. One sprocket tooth out -- no good. Sensors have to be used so the micros know where the 'phase' (crank angle) is, in order that the spark timing and control may be correct. When the micro advances spark timing during acceleration, the air-fuel ratio also has to be enriched. During certain modest inlet airflow speeds the air-fuel ratio has to be about 15:1 (stoichiometric). During idle it has to be about 12:1. During full power flat out it's about 13:1. The fuel sensor is usually just an electrically hot wire in the inlet airflow -- the cold air cools the hot wire, its electrical resistance falls, and the micro adjusts the airfuel ratio according to a resident program, also along with an inlet manifold vacuum sensor. The crank sensor is small magnet that flies past a static pick-up coil, but there are other technologies to achieve the same end. The pulse-coil and magnet are the most rugged and cheapest -- old tech.
The reason I go on about this is simple. In an interference engine, if the cam timing is wrong, or a cambelt breaks (this happened to me one time) it will ruin the engine. Anything from bent valves, holes in pistons, to broken o/h camshafts (but with pushrods, yours is not OHC). When my cambelt broke, I was doing about 40mph on Leeds ring Rd. The engine just stopped as if it had been switched off. The car had to be towed in. Eventually the mechanic discovered the OHCshaft was in three pieces. The camshaft had also broken five bearings in the cyl. head, and as it was a diesel Audi 100, that broken cambelt wrote the car off as an economic write off, due to the price of a replacement diesel cyl. head. The bloke I sold it to put a petrol engine in it.
Yours has a cam chain, so if you check the alignment holes are right, or at least close, the engine should be ok. The damage happens when the pistons hit the open valves at TDC, which should be shut at that phase angle of the crank, i.e. around 0*

Leedsman.
n.b. I've known cambelts snap, but I've never heard of a chain breaking. Noises like rattles, the chain wearing its way through the ally housing due to slop, yes. But never actually breaking altogether.

 

Dizzy/Distributor fitted incorrectly. Remember way back had this fault after rebuilding one of my many engines. No battery start or bump start...Scratched my head all day until I just transferred over the HT leads. Bingo. Just wondering if this engines got a Dizzy thou...