93 Dodge Caravan Engine Promblems

We have a 93 Dodge Caravan, and it wasn't passing DEQ. To make a long story short what we ended up doing was changing the fuel injection on the van. Since new fuel injectors are quite expensive we bought two pairs from a junk yard, from vans that had little over 100,000 miles on them. Well when we changed the fuel injection it worked fine, and as we started off to DEQ and a mile out the van started making this really loud knocking noise. Like "ding ding ding ding ding ding". So then we some how managed to get back home because at everylight the van would stall, and then we changed the fuel injection to the second pair, but the promblem still persisted. So we finally put back the original fuel injection which the van worked fine on before other than not being able to pass DEQ. But the noise and promblem still persisted, and now we're trying to figure out what the promblem could be. Any help would be greatly appreciated. Thanks!

sounds like some dirt or small rock fell into the injector hole when you removed them. You need to pull all the spark plug wires out a see if you can borrow or rent a lighted flexible scope to look into the cylinders.
By the way. What is DEQ? Is that vehicle emissions? Also check your fuel pressure and perhaps change the fuel filters

I think its like an e-check, but a little different. they look to make sure your lights work, wipers and a few other things. this has to be done every 2 years and caust 80 bucks in MA. even on brand new cars, it has to be done. I think thats what it is. could be wrong though.

It's possible the knocking noise is a piece of carbon that fell off the combustion chamber and slapping on top the piston. Try pouring some ATF through the throttle body with the engine running and see if the noise gets quiet. Pour slowly so you dont stall the engine, there will be a bunch of smoke come out the exhaust.

It's possible the knocking noise is a piece of carbon that fell off the combustion chamber and slapping on top the piston. Try pouring some ATF through the throttle body with the engine running and see if the noise gets quiet. Pour slowly so you dont stall the engine, there will be a bunch of smoke come out the exhaust.NO!!! Don't pour atf into the throttle boby. That will coat the catylitic convertor and 02 sensors and they will not work after that. Very expensive indeed.Try the scope . He may do more damage if he continues to run the engine with whatevers in it

this has to be done every 2 years and caust 80 bucks in MA.

That's your problem.... Living in the People's Republic of Massachusettes....
;-)

I beleve it also has to be done in R.I. as well.