*UPDATE* My POS MPV is still hesitating at low throttle

[StageLeft]

I had this problem a while ago, low throttle only my 04 MPV with 78k hesitates and bucks a bit. It's started idling not perfectly while stopped in drive or in neutral or park (idle is perfect but every once in a while it shudders gently). I thought it might be MAF, so I cleaned that. I thought it had fixed it, but now it's more severe than before. Bad coils are common in these vans. Normally when a light fires, it's the coil. Finally last night the light did fire and cylinder 5 was misfiring. I just replaced its coil to zero effect. The OEM plugs are all quite new. What else can possibly cause a misfire beyond a fuel injector?

At mid or high throttle the thing is perfect. I have had this into Mazda twice. First time guy thought it was tranny and told me to do a fluid service as the fluid was old. I replaced all the fluid and not surprisingly no change. Second visit I don't think they even looked at it as they were replacing a leaking crankshaft seal.

I'd sell it but frankly there are no midsize minivans on the market that are at the correct price point or aren't complete sh*t. Also, this has to be a small problem, but it's driving me nuts. The van is now of no use beyond shuttling short distances because I feel it may choke.

 

[njmodi]

1. Coil
2. Plug
3. Fuel Injector

Did you swap coils between two cylinders, or did you use a new one?
Did you swap plugs between two cylinders?

Are you sure you can get away with cleaning MAF? Give you are getting a specific cyl. misfire code, I doubt it's the MAF...

 

[StageLeft]

Code is new. This problem is months old but only yesterday did I finally get a CEL. It's a brand new OEM coil. I could try swapping plugs but I could end up waiting several more months for another CEL to come. I may take out the plug, though, and see if it's still gapped properly, but I doubt the plug is a problem. It was particularly bad yesterday (it's been damp out, which in the past can exacerbate coil issues) but then after it got warmed up was better, leading me to think it was the coil. Really surprised this didn't solve it, though.

 

[njmodi]

Did you clear the code after replacing the coil? Perhaps you have a two different issues? In my experience with cars, random bucking/stallling is very much a MAF-issue - I would recommend trying to find a replacement - not sure how much they run new on your make/model.

If the misfire condition exists, the code will come back. If it points to Cyl 5 again - I don't think you can rule out the plug or the injector. You have the code now, so I'm not sure why you are worried about resetting it/and it not coming back again.

Also - you seem car-savvy - but you know that there can be more than one code stored in the ECU right? Did you get them all?

 

[StageLeft]

I did clear the code, yep. Unfortunately a new MAF is $150 for this thing and I don't know anybody else with a van to try a swap, despite it requiring only a single screw to fix.

There was just the one code. I think I may replace the plug with another OEM one. They're cheap and then I know at least that if the problem comes back it's not coil or plug.

I agree there could be two issues at work here. It may be that the coil WAS bad. I remember when my coil 3 went bad the first time it threw a code I noticed nothing. It cleared itself off and only many months later did real problems pop up.

 

[njmodi]

You can get non-OEM MAF on ebay for your car for about 50 CAD shipped... I agree on swapping the plug first - you could just swap between two cylinders too - and save a trip to the parts store.

So the code came back as Cyl 5 misfire right? Often with a bad injector, you'll get a Air/Fuel Rich or Air/Fuel Lean code too - it is detected/reported by the O2 sensors... not sure what thresholds various makers use to report these particular codes... MAF can also cause those codes.

I would focus on resolving the misfire code before buying a MAF...

 

[AMDMaddness]

Try new plug wires? I had one go bad on my Xterra not to long ago.. it ran fine in higher rpms but had a noticable miss at low RPMs.

 

[njmodi]

There are no plug wires per-se if he has a coil on each plug... it's just a harness from the ECU to each cylinder...

 

[bruceb]

Just because the plugs are new, does not mean they are not defective. If for example, the car runs fine when you go easy on the acceleraton, but misses on hard throttle, then a cracked spark plug insulator is very likely. I have had it happen on my car. Otherwise the suggestions already made should locate the problem, unless you have a valvetrain issue or heavy carbon build up in that one cylinder. Try a tank or two of
Premium Fuel and a bottle of Fuel Injector cleaner, and a new fuel filter. See what effect they have.

 

[StageLeft]

I'll give it a new plug today and another dose of Techron and see what happens

 

[brblx]

oem plugs? as in from the dealer? 'cause i would definately try a fresh set of factory plugs. and if it's a coil, you should be able to see cracks. hairline cracks typically show up well before the coil starts misfiring.

if you don't have a fuel trim code, i would highly doubt the MAF is defective.

be more specific than 'low throttle only.' is it a problem that occurs all the time with the throttle slightly open, or is it something that happens when the engine is under load at low rpm? the latter is far more likely, and more indicative of a misfire. if this is a coil on plug setup and the problem persists with a new coil and plug, i would then look at your wiring for that cylinder. made sure there's adequate pin tension at the connector and that there's not a wire that's abraded or pinched somewhere. there's really nowhere else to look for an ignition misfire.

have you ever cleaned your throttle? is the PCV system working properly? those are two places i'd look for an idle problem, but it's unlikely they would cause a miss.

 

[AMCRambler]

Hesitation/bucking could be a fuel issue like low pressure from the fuel pump. You can check that with a guage. Injector you just have to swap out to see. My money is on the injector if the plug and coil check out.

 

[StageLeft]

Injector is fairly serious labor, though, right? I'm about to swap the plug and injector cleaner now. I don't think that will fix it, but it's important to do away with inexpensive possibilities so is worth doing. As njmodi said, it's in fact possible my cylinder 5 misfire and this problem now are indeed two separate problems. I wish the CEL would fire more eagerly!

 

[brblx]

injector may or may not be hard to swap, i dunno about that engine. look for the bolts that hold the fuel rail down, all you have to do is remove those, pop the rail out (w/ injectors attached) and swap them around.

i don't see an injector causing an erratic misfire, though. if it's plugged or if the coil inside is faulty, it would probably cause an issue on that cylinder all the time.

 

[43st]

Originally posted by: AMCRambler
Hesitation/bucking could be a fuel issue like low pressure from the fuel pump. You can check that with a guage. Injector you just have to swap out to see. My money is on the injector if the plug and coil check out.

Those would both cause issues at higher RPMs though.. this seems to be a low RPM thing, which really points to the spark plugs I think.

 

[darom]

Skoorb, I know we are beating the dead horse, but are you positive that you have eliminated that PCV hose as a problem? I own a 2002 MPV which had bucking issues, besides giving me the bad coil bank, I was blessed with the dreadful P0174 code. At that point I had already replaced the coils with new ones along with new Ford plugs. I thought the issue was with the intake manifold rubber gaskets. So I got a set, pulled the intake off again (for the N-th time) to find the damn PCV hose which came loose on the PCV itself! As you probably noticed it is hard to notice the PCV hose there with the intake in the way. Once reconnected the code didn't reappear and the low RPM bucking was gone.

As far as I understand the bucking problem it may be related to the coils and vacuum leaks. Our van engines' PCM are so sensitive to such leaks... I also can't believe someone thought that changing the tranny fluid would fix the issue.

I know this is probably not related, but - there was a TSB on reflashing the tranny control module for cold engine/low RPM bucking symptoms. Mine 2002 got reflashed for free when it was under warranty.

Regards!

 

[StageLeft]

Hi darom, I have eliminated the PCV hose because I replaced it with the proper YB-ending one. The old hose wasn't perfect but had not yet ruptured. I don't know what shape the PCV valve itself is in; it looks pretty pumped up with oil, but I was unable to easily pull it for a replacement.

I put in the new plug this morning and so far so good. I've only had two drives, though. I said I'd be really surprised if that fixed it, but by the end of the weekend I'll know either way and will update this thread accordingly.

i did find a guy with an 00 MPV who had new oem plugs and a similar weird issue and when he replaced them with autolites his problem was solved. I can't believe a new OEM plug would be crappy, but possibly that is the case, or maybe a bad coil screwed it up. Who knows, but if a $3.5 part fixed it I will be pleased.

 

[Budmantom]

I have the same van and it's the same year, the first thing I thought was coils... it may be a good idea as preventative maintenance to replace them all (ebay), the MAF is tricky because it can cause so many different symptoms but I have not read about many people having issues but it may be worthwhile to find a replacement and have your van reprogrammed.


You may also check out http://forum.mpvclub.com/index.php they are a great resource.

 

[Budmantom]

Looks like you are a member Skoorbmax?

 

[njmodi]

Any updates Skoorb?

 

[Kaieye]

I had the same problem with my 2000 MPV and the ignition coil packs were all changed. The slow hesitating suddenly went away. I got over 140,000 miles on my minivan and it runs as smooth as the first day I bought it.

I was told that the ignition packs were not the most reliable thing on the MPV so I would test to see if yours might be defective.

 

[StageLeft]

I am Skoorbmax on the other forum.

Well, I put in the plug 5 and have to say the problem was 99% resolved. It was hard to detect any issues at all. The van is still much better. However, it's not as good as after I did the plug, but definitely that made a big difference. I'm then left with two options:

1) Cylinder 5 is eating through plugs
2) Other ignition coils in the four cylinders that have not had replaced coils are continuing to deteriorate.

I'm leaning toward option 2. I've now replaced all 6 plugs about 5k miles ago and coils 3,5 quite recently, plus plug 5 very recently again, so I have two cylinders with new coils and plugs and four with old coils and plugs. Unless anybody can think of a plausible reason that cylinder 5 would be eating up plugs (hence the reason for my very slow deterioration now), I'm going to swap out two more coils and plugs (the front; i Hate getting the back ones) to see how it is.

But, yes, ultimately and to my great surprise this $3.50 plug replacement absolutely made this better!

 

[StageLeft]

Wasn't sure y'all saw the update

 

[Kaieye]

Nevermind

 

[CraigRT]

Plugs can go bad even when they look good. When in doubt with weird ignition type problems rule of thumb is to always replace the easy stuff like plugs, wires, etc. (Most stuff uses coils thesedays but you know what I mean)