2005 Grand Caravan SXT 3.8L, 150K miles.
Recently had oil changed (about 1K past due). After that, the van started running rough. it has progressively gotten worse (over about two weeks) to the point I don't feel it's safe to drive.
No fault codes. Visually inspected vacuum hoses--don't see any breaks or cracks. Oil level seems correct. New filter is indeed on the van, and I don't see any dripping from anywhere.
Changed the air filter, again, because it acts like it's not getting enough air.
So far, I've:
Cleaned the throttle body
Replaced the intake air control valve
Replaced the Intake Charge Temperature sensor
Replaced the MAP Sensor
Replaced Coil pack, wires and plugs
Still runs VERY rough (rough idle, sputtering, loss of power when try to drive)
Any ideas on what to change or check next? I've run this on two different OBDII readers, no fault codes, no engine check light. Alternator outputting correctly. Vacuume reads anywher from -16 to -20. Idling around 750rpm.
Any sugggestion welcomed--I'm out of my league here and about to throw in the towel--I'm more a brakes and tune up guy. Not even a shade tree mechanic.
Planning on tryign the EGR valve next, then I guess the PCV and O2 sensor.
Don't listen to anyone who suggest replacement over diagnosis, period. That's the worst type of advice you can get.Other forums gave me suggestions on things to replace.
@hixster Update: finally fixed
EDIT: It's fixed. Didnt have new PVC Valve seated correctly. Changed plugs and wires--frobt bank plugs looked okay, so I figured back were too. Nope. Pray-begged a lot. Seems like prayer +plugs &wires did it. Note: rear plugs were stuck until I prayed the tap-the-socket trick would work. It did.
Thanks for all the tips and suggestions--learned a lot about fuel injection on this one
@chucktobias @imperator @troglodad thank you for updating us. We do appreciate the positive feedback!
I agree diagnostics are the best. Unfortunately, my only means of diagnosis is observing the vehicle and its pieces and parts and my OBD2 scanners, which offer more abilities than I know how to use.
There are plenty of youtube videos on how to analyze live data. Even just looking at fuel trims and sensor outputs can often help solve a problem.
In the past, any proiblem I've had has produced a fault code. I've looked it up, then replaced a part and problem was solved.
You were lucky if that worked. Fault codes don't tell you what parts to replace, they tell you a condition exists that can have multiple possible causes. Looking at codes is just the bare beginning of the diagnostic process.
I'm doing the part-by-part replacement as I have no other alternative other than an expensive trip to a shop
The parts cannon approach rarely produces a good result. If it does finally solve a problem it is usually at the tail end of spending lots of time and money replacing parts that didn't need to be replaced.
To check fuel pressure you can probably borrow a fuel pressure gauge from a parts store. (Many will loan out tools.) Unless your scan tool is extremely basic it has the ability to display live data. If it doesn't you should buy one that does. (Even most of the cheapies can do it these days.) There are options, you just need to take advantage of them. These days you have the advantage that there is a wealth of information available in seconds via your favorite internet search engine.
@chucktobias Thanks! I keep forgetting about the rental/loaner tools. My philopsphy on tools has always been if I don't have it, but need it, go buy it... but some of these car tools are a little pricey for that.
It's unlikely the engine has a lack of air, so the other ingredient it needs is fuel. The first thing I would do is check fuel pressure and fuel trims, and also misfire count if your diagnostic tool has that.
Visually inspected vacuum hoses--don't see any breaks or cracks
this isn't good enough. leaks can be anywhere including the intake parts, and often they're invisible. Do it once , do it right, use a smoke machine. Scotty has videos about it.
@imperator I like his cigar makeshift smoke machine video the best. I'll give that one a try once I get the last of the parts I already ordered on, then it's probably time to take it to the shop.
more abilities than I know how to use... I'm doing the part-by-part replacement as I have no other alternative other than an expensive trip to a shop
You either need to learn to use the abilities, or find a reliable diagnostic shop. I guarantee the parts cannon is the most frustrating, time and money wasting approach. You might have gotten lucky in the past.
That's quite the parts cannon. Did troubleshooting or testing show that those parts were actually bad? Were the replacement sensors and AIC valve OEM?
How old are your filters? Did you test fuel pressure? It might help if you took a look at live data to see what's going on. Given the age and mileage a compression test would not be a bad idea.
@chucktobias
Other forums gave me suggestions on things to replace. I'm slowly going through all of the list.
None of the parts are OEM
EngineAir filter is brand new, off the local AutoZone shelf this month. I assume the oil filter is fairly new--Valvoline Instant Oil change put it on beginning of this month (back problems make it difficulty for me to get on ground, so I just pay for oil changes)
Don't have the gear to change the fuel pressure. Years ago, fuel issues triggered fault codes and I changed the injectors. No fault codes this time has me hesitant to go to a garage or get the stuff to chck fuel pressure until I can do all that I can do on my own.
What live data do I need to look at on my OBD2 readers (one is a Harborfreight plug in, one is a bluetooth-to-phone module)
It is much better to replace parts indicated as needed by diagnostics rather than guessing. Also, aftermarket parts frequently do not work properly, especially sensors. Amazon and eBay are particularly known for poor-quality knockoff and counterfeit parts.
In live data I would start with basics like fuel trims and upstream O2 sensor output. There are plenty of videos on youtube showing how to do that.
@chucktobias I agree diagnostics are the best. Unfortunately, my only means of diagnosis is observing the vehicle and its pieces and parts and my OBD2 scanners, which offer more abilities than I know how to use. In the past, any proiblem I've had has produced a fault code. I've looked it up, then replaced a part and problem was solved. This rough running without a fault code is maddening. I'm doing the part-by-part replacement as I have no other alternative other than an expensive trip to a shop where I'm sure they'll just start replacing parts themselves.
I would test the coils one at a time just to make sure its not one of them...But if it is I would think you would have an check engine light for misfires.
@thdesha On the Dodge Grand Caravan it's one single coil with six plug connectors. I've replaced it, didn't make a difference. I had previously replaced it in the past... pretty sure it did a code back then.
UPDATE: In course of changing PCV valve, found that those tube/hose from the PCV valve housing was super cracked right at the valve cover (didn't see it before). Put on a new hose and voila! Engine idles way better. Almost as goid as a few years ago.
Still runs poorly in gear, even with new PCV valve.
Next up, changing the EGR valve. (last one was 2019).
I did have a steady oil leak several years ago, from front valve cover gasket. Oil leaked down everywhere. Wondering if some oil-stem got sucked into the EGR valve an gummed it up (it's on front, right next to oil dipstick tube)
Also... anyone know where I can get a new airbox-to-front valve cover crankcasevent tube? It's also crack at the valve cove, but just barely--stuck a hoseclamp on it for now to tighten up the cracks. Amazon nor Autozone have one in their system