I am changing the engine in a 2002 dodge grand caravan, 3.3 v6. The new engine is from an 2005. The timing is way off and I can't seem to be able to find out how to change it.

130

Asked by May 20, 2015 at 08:48 AM about the 2002 Dodge Caravan Sport

Question type: Maintenance & Repair

When cranking it will back fire and throw flame out of the intake. I have tested spark and
filimed the opening and closing of the intake valve along with the spark from that cylinder. the
spark come just as the intake starts to open. I have tested the TDC of the front cylinders
timed with the valves. All seem to be ok. Some years have a crankshaft sensor but I can't find
it on this one.  The flywheel from each engine were different so I used the one from the
original. I have been told some years use a torque converter sensor and I could be 180 deg
out of time. I have no idea on how to figure this one out.

28 Answers

2,375

Well you answer part of this question yourself, the spark plug should NOT be firing while the intake valve is *starting* to open, no wonder it's backfiring up through the manifold! And DO NOT continue to crank it like this, you're going to damage the fuel injectors and any sensors in the manifold that the flame licks. Distributor-less ignition? You're definitely out of time like you said.... I'm a little rusty on D.I.S. systems but look at the cam position sensor and see if it's keyed or anything, to where it could possibly be off spline....since the system is getting the 'Fire' signal at the wrong time. When the intake valve is opening, the piston should be traveling down drawing in the mixture, then the intake valve will close as the piston begins its upstroke compressing the mixture, and *this* is where it should be sparking, a little bit before the piston reaches TDC on the compression stroke. Remember of course you've got two TDC's, one on Compression stroke and one on Exhaust stroke.

2 out of 2 people think this is helpful.
130

You have this exactly right. It is firing on the intake stroke. It has a coil pack, Its only fireing the 1 time per cycle. the flywheel was different between the engines. Has the notches in a different pattern. SO I am not sure if i should be using the flywheel from the original or from the replacement. Or should I open the timing chain cover and spin the crank 360. Or change out the flywheel?

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2,375

Change out the flywheel, that's gonna be your problem. Just make sure they have the same oz imbalance (or neutral) otherwise it'll cause main bearing damage.

1 out of 1 people think this is helpful.
130

Thanks for the reply on my problem here. It seem the flywheel is pretty much married to the motor. At least that the best guess from all the local guys. Nobody around here has seen this problem and can only guess the same answer we have come to on the forum. My thoughts were that the computer and sensors would want the original parts. I even took a video to see what was happening during the motor turning over. I knew something was looking wrong and had to watch it several time to catch the spark as the intake valve opened. Knew right then the timing was wrong.

2 out of 2 people think this is helpful.
2,375

Aren't borescopes awesome? Yeah, I'm used to seeing crank sensors mounted to the front of the motor, behind the balancer and near the oil pan, but on your application, it gets its fire signal from trigger points on the flywheel instead of a ring around the crank nose. So the flywheel is going to have to be paired up with the ignition system, as opposed to the motor, buuuut like I said if the imbalance is off.....

2 out of 2 people think this is helpful.
130

I was using the flywheel that was native to the system. This afternoon I pulled the engine and installed the flywheel that came on the replacement engine. and re-installed the engine. I do not have it wired yet so do not know what is going to happen. The pattern of holes on the ring are totally different the older one having holes all the way around it and the replacement having 3 sets of 4 at approx 120 deg apart. As I now sit here thinking about it the computer is going to be looking for this pattern. I am not at all sure the timing is going to work at all. Neither wheel had any type of counter weights. I talk to the dodge parts people and the service department. They were even more confused than I am. The shade tree mechanic in me is thinking I am going to have to look outside the box to find a fix that will get this motor running.

2,375

Regardless of whether it has counter-weights, the holes in the flywheel are serving to balance it out... However if there are only holes and no weights tacked on, I would bet that it's a neutrally balanced flywheel so if the one that *belongs* with that engine is like that, it's probably going to be internally, not externally, balanced. For it to get the correct firing signal, you're going to need to use the flywheel from the old motor because it has to be a match with the ECU and ignition system. So, since you said you used the flywheel native to the system and NOT native to your replacement engine, it's time to look at a different part of the system now. Oh and by the way, I'm an idiot, you're 180 on your cam sensor. It's firing on intake, and the Otto cycle engine is of course Intake>Compression>Combustion>Exhaust...which is Down, Up, Down, Up. Since you're currently sparking on Intake, if you flip it 180 degrees, you'll be sparking before TDC on the Combustion cycle. It's been a very, VERY long week my friend.... 6 days a week, 60 hours...lol

2 out of 2 people think this is helpful.
130

WIsh I had seen this post before I pulled the engine and change the flywheel. How do I make the computer believe the cam has turned 180 deg. I am suspecting now after spending the night trying to sleep over this, I may have actually made this problem while testing the starter when the cam sensor was not yet connected. It had a minor starter problem with the old engine so I cleaned up the contacts on the starter. Another mechanic friend of mine had told me to unplug the coil and rotate the crank 360 deg with the ignition on. Am i correct in thinking either the crank sensor or the cam sensor should have been unplugged. I am still trying to get my head around the whole electronic control system. For the cam to be 180 out the crank would have to be 360 off from the cam. I some how need to add an extra cycle to the crank without changing the cam cycle. I saw some where on a paper that the dealership gave me about a "TOC learn" procedure. Maybe you have an idea about this one. Thanks for all the help you have given me.

1 out of 1 people think this is helpful.
2,375

I'm not sure whether cranking the engine over with the cam sensor disconnected would have any lasting effect. I have a hard time believing that though, I would expect it to store a memory code for No CMP Signal but then be fine after you reconnected it.... The more I try to diagnose this thing without having photographs and being able to physically manipulate it myself, the more diluted and lost this is getting in my head. Here's my problem...it's firing at the wrong Top Dead center. If it had a distributor, this would be easy...remove the distributor, rotate it 180, and drop it back in, then "rough-out" the timing by rotating it slowly from side to side until it fires and lock it when it holds a steady idle and revs cleanly, then you can go back later and fine tune the degrees. That engine is an overhead valve engine, not an overhead cam engine, correct? If that's the case, then I believe your camshaft position sensor, instead of being a static 'pickup' type of sensor like on an SOHC/DOHC motor, is going to be a gear that meshes with the camshaft in the same way a distributor would... Can you try this...with the key off and battery disconnected.... Remove the cam position sensor, taking note carefully its position...mark everything with a sharpee or some white nail polish. You aren't able to take a photo of it are you? See if the thing has any sort of keyway setup, where it can only go in one of two ways. I'm not all that well versed on DIS systems since the motors I've built have all had distributors and the DIS systems I have worked on have been plug-and-play deals, not engine swaps. All I know is that if it were a distributor, you would need to rotate the shaft itself 180 degrees and re-spline it, and then rotate the *housing* to time it..... You shouldn't be able to do anything with the timing there, but if the principle is the same, then you should be able to rotate the shaft and gear of that sensor 180 degrees and slip it back in. I really need to see what you've got there though, bud.... This is what I'm thinking your engine has: http://info.rockauto.com/getimage/getimage.php?imagekey=972522&imageurl=http%3A//info.rockauto.com/RB/689-107-007.jpg

1 out of 1 people think this is helpful.
130

Both the crank and the cam sensor are electronic pickups. http://www.oreillyauto.com/site/c/search.oap? keyword=camshaft+position+sensor&year=2002&make=Dodge&model=Grand+Caravan&vi=1440642 ... 3 wires each the pattern on the flywheel has a pattern t or 4 square cutouts at 120 deg for a total of 12 cutouts. It is an over head valve setup. I don't know if I can rotate the cam without removing the rockers to prevent a valve from getting bent on a piston. Each sensor has a single bolt holing them in place so re-positioning is not an option. I am going to try fooling the pcm tomorrow by disconnecting it and rotating the crank 360 deg. One of my dodge guys said I should try this. May have to flash the PMC if I can't get this to work. another school of thought is to disconnect one sensor rotate crank 360 then plug back in. Anything I guess to send an extra signal to the pcm and getthe spark to change order.

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130

http://www.oreillyauto.com/site/c/search.oap? keyword=camshaft+position+sensor&year=2002&make=Dodge&model=Grand+Caravan&vi=1440642

2,375

I don't know...none of that really makes sense to me, since it should be referencing the crank signal against the cam signal, so it should know where every cylinder is at all points in time, I don't see how "trying to fool it" would do anything at all. And now you're getting ignition timing mixed up with cam timing. It's not going to go piston-to-valve on you because the ignition timing isn't right....two separate things, you can turn the motor over all you want.

130

I think we are getting lost on the problem here. The firing order is 123456 on this motor. #1 is sparking at TDC on the intake stroke. At the same time #4 should fire on its compression stroke. the same goes for 2-5 and 3-6. Each cylinder is fireing 180 deg out from the cam. The crank timing looks to be perfect. The problem from what I can see is getting the cam and crank sensors to agree on the correct order. NO one who I have been able to find has the easy solution on this problem. What I would really like to find out is how the coil determines the cylinder to fire. There are only 4 wires going to the coil plug. So is 1-4 supposed to be firing at the same time? Is there a circuit in the coil that splits the spark? Its all greek to me. Guess that's the next test taking the wires from each side of the coil and seeing if they spark the same or opposite each other. Many thanks on tring to help me figure this out.

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130

More info on this fireing order problem. After getting everything back together I decided to test the fireing order of all the plug wires against the intake and exhaust stroke. I am getting different results from each wire. some are fireing only 1 time per cycle some 2 and some not at all. I have swapped out the coil with same results. A friend is bringing me a PCM to swap in and bringing his code scanner to see if we can get this figured out. Says his test pcm probably will not be right but it should tell us something.

2,375

How many coils do you have...one coil that fires all six plugwires, or two coils firing 3 and 3? As far as firing the plugs go, this is not an easy answer because some engines run a "wasted spark" system, while others run a sequential system that fires the plugs deliberately one at a time on the cylinder firing. This is in addition to the type of port injection the vehicle has...there's Sequential injection that fires one injector at a time, and then there's Batch fire systems that fire the injectors in batches of several at a time. So it sounds like you've got a wasted spark system, which means it *will* be firing some plugs at odd times other than BTDC compression stroke. But a wasted spark system should never fire during an intake down-stroke. From my understanding of the system's design, a wasted spark system will only fire twice during a full combustion cycle (4 strokes)...once at BTDC Compression and once at BTDC Exhaust. I've been a bit scatter-brained as of late so I should apologize for any potentially erroneous information I might have given you....I've been dealing with a lot of back pain from an old car accident and re-injured it at work, and the pain med I take at night makes it difficult to concentrate... So let me start over for a brief moment. Now the intake stroke is a down-stroke ...so 180-out on Top Dead Center will be at the end of the exhaust stroke and when the intake stroke is beginning. At this point in time, it's a dead cylinder, which is to say it's empty. For you to have an intake backfire, it would have to be firing while the intake valve is open, which occurs during the intake downward stroke and ends at Bottom Dead Center to prevent the intake charge being pushed back into the runner (the only exception for this is a Miller Cycle engine). So technically it would have to be firing *after* TDC Exhaust, since only the Compression and Exhaust strokes have Top Dead Centers (the Intake and Combustion cycles have Bottom Dead Centers). So given that it sounds like you have a wasted spark engine, which I didn't take into account, we might be chasing this problem in the wrong direction. Let me ask you this...have you verified your firing order and cylinder numbering? I see you've posted the firing order up there and I don't mean to second guess you, but I think this is starting to get really convoluted and I want to look at the simple things again so please keep reading and get back with me. Different engines as well as different manufacturers will number their cylinders differently, there is no standardization for this. So you need to VERIFY the engine's cylinder numbering scheme, then verify its firing order. Now if either of these don't match the old engine, you will need to swap out the engine computer for one for the vehicle in which that engine came out of. The camshaft is what determines what your firing order will be, but it's the engine computer that knows the order and it takes cues from the camshaft position sensor and the crankshaft position sensor to know WHERE the engine is rotationally to determine which cylinder to fire. You can't assume the cylinder numbering and firing order is the same going from one engine to another, even if it's only going from a V6 to a larger V6 both manufactured by Chrysler. And one more thing, the only *other* way you can get an intake backfire if the spark isn't firing on the intake downstroke, is if you have a bent intake valve that's not sealing properly. So when you say #1 is sparking TDC intake....do you mean TDC Compression, or TDC Exhaust? I'm assuming Exhaust, since Top Dead Center Exhaust is the absolute last moment before the Intake stroke begins, and any spark AFTER that point would be "classified" as a spark After Top Dead Center Intake. If it fires at 0 degrees of advance on Top Dead Center Exhaust, it's either firing 180-out or that's the second light of a Wasted Spark system and it's normal.

1 out of 1 people think this is helpful.
80

Gentlemen! The solution to this problem,replace engine and the computer as a pair. one engine, is different then the other! Same litre 3.3,but electronically controlled differently. Different sensor locations ete:.

3 out of 3 people think this is helpful.
80

if this engine was running in the other carand nothing was changed! the only reason it wouldn't run now is the computers are different! For shame! You've made your own headaches! Good Luck!

2 out of 2 people think this is helpful.
130

Should have posted earlier on this. The answer was the timing gear on the camshaft. Different years have totally different gear patterns. Looking atthe parts store who were happy to order bot years so I could look at them before taking the front of the motor apart. New set of the correct gears and a chain the motor runs great.

6 out of 6 people think this is helpful.
10

The fuel injector harnes is different between those years listed. Rewire the injector harness and it will be fine.

1 out of 1 people think this is helpful.
10

How much did your engine cost you? I may need to put one in mine.

10

How much did your engine cost you? I may need to put one in mine.

30

This will be the first and last time I post. I just wanted to say I ran into a 2005 3.3 dodge grand caravan engine for 200 buck. Bought a 2001 grand caravan for 100 and in nice shape. The 2001 engine had a spun bearing so seeing a 2005 engine for 200 I bought it of course after hearing it run. I dropped it into my van. When I tried to run it it only sparked for a sec trying to start it and after I let of the key one more time. Thats the ASD working so that turned out good. Still wondered why I had no spark. PCM controls ignition. Found out I had bad grounds. So I cleaned them. Spark problem solved. Now I had this backfire. Like it was out of time. After 2003 they changed the cam gear and flywheel and they are swappable from a vin G to a vin R. Also you have to swap the harness for the fuel rail. After all that van runs fine. Just wanted to make things clear for people looking for an answer that aren't mechanically inclined or have knowledge to look for the right answers. Well I did. Covered all my tracks so here you go and enjoy.

3 out of 3 people think this is helpful.

Tha piston #4 is now working on replacing tha full igector the same problem with hat power of the cilinder now working

Tha piston #4 is now working on replacing tha full igector the same problem with hat power of the cilinder no working with cheng crampocition sensor and camchact sensor is seme problem

i am doing this exact thing at the moment ,putting a 1999 motor in a 2004 van , it is essential that all the sensors are left with the vehicle that the motor goes in ie im useing the 2004 trans , flexplate with crank sensor cam gear, injector rail bacisly only the short block of the 1999 engine is going in the 2004 . all the electric wizardry is mated to the computer and can not be swapped over

1 out of 1 people think this is helpful.

skater0064 did you ever figure out problem. I'm doing the same thing and having same results. I kept the original flywheel from the car. My problem is I think the pick up on the cam gear is the problem. I pulled the junk motor apart. And compare it with the gear on the motor by looking through the cam sensor hole. And they definitely are different. Does anybody know is that the problem

you MUST use the cam gear and sensor that matches your computer , ie with a new motor use the gear from the old motor

130

Chevang14 You are on the right track. Everything from the original must be transferred to the new motor. Buy a new cam set for your your motor to match the original gears and chain. Get the full set so they are matching. This was done over 4 years ago and the van still runs perfect.

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