What happened to this car?

Rochev

Rochev

Joined
Dec 3, 2016
Messages
240
Location
Maine
Kinda long but its descriptive. I picked up a V6 Mazda MPV that sat for 3 years. It ran and drove great, when I got it the CEL was on for post-cat o2. (Heater circuit not responsive) but after about 20 miles since it sat it started misfiring badly on cyl-1.

It had 1/4 tank of old gas. I filled it with 93, put in octane booster, seafoam, some mystery oil, drove 1 mile back home and it sat overnight.
Next day I took the manifold off to see the plugs, (also egr, intake, battery, myriad of vacuum lines etc). I checked cyl 1+2. Both looked good. I swapped the plugs to see if it'd misfire on cyl-2.
The valve ports and manifold were caked with gunk and carbon. I cleaned it using carb cleaner and a rag. Nothing fell into the valves.

When I tried starting it I knew it would stall a couple times. However it wouldn't run for 15 minutes. Then it would only run if I feathered the gas but rev to 3-4k and stall out.
Theres a delay with the throttle and response, it shakes and misfires and seems like its not getting fuel or air. Now it'll start and rev to 3500 rpm and idle around 200. Smells horrible, like carbon and bad gas.
When driving and slowing down it dies to 150rpm, shakes and warning lights come on because its basically off.

I adjusted the idle screw to keep the idle on 2k. Itll randomly rev high. Again, smells HORRID. I used Forscan and my scanner and nothing is coming up. I checked coutless times that everything is put back.
Could it be clogged injectors, fuel pump, fuel filter, vacuum leak? I cant figure it out!
 
Check the throttle body and IAC valve, you might've disturbed something or knocked a chunk of carbon into something

This is a 3.0 Duratec 30 V6, same as a Taurus twin, Escape siblings, or later 500/Montego/Freestyle

So same issues with coil pack failure and sensitivity to vacuum leaks on the upper plenum or PCV apply

What fuel trims is FORScan showing you?
 
Thanks for the reply. It does seem like a massive vacuum leak. This is the older 2.5 but pretty much the same as the 3.0 with the setup. I'm heading outside soon to run Forscan again and will post what it says.
I should mention that it does drive ok and doesnt misfire on acceleration. Its starting, idling and slowing down thats having issues. There is a lack of power though, but not much.
 
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Yes it had just under a quarter in it. Thats what I'm wondering, if it was a coincidence that it acted up after i pulled the plugs because the old gas just screwed it up at the same time.

I took everything apart again and put it all back to make 100% sure. It started after the second try without me balancing the rpms. It ran ok but was stumbling still.
I bought two sets of different plugs and neither of them will start to thread in. I'm thinking a full tune up might fix it but as a yard vehicle im not sure i want to waste time throwing parts at it.
As for forscan, its currently not reading long term fuel trims, and short terms are all 0%. Not sure if its not reading things correctly or what.
 
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How's the flow out the exhaust?

My brother bought a truck that sat for some time, once it was running it would barely run and had no power, didn't want to rev very high. Turns out the catalytic converters was broken inside. Once that was fixed it turns out the muffler was plugged up from something living in it.
 
I dumped about 14 gallons of old gas in my Yukon once. It turned out to be older than I was told. Smelled like turpentine. Mixed in with 20+ gallons of fresh I kind of wonder how well old gas mixes with fresh because it ran fine that day (40 miles). But man, the following day when I started it up, it fired up fine and then not long after it started struggling. spark knock if you gave it too quick of a throttle input, low power, low idle etc. I tried topping off with 93 that day but it didn't balance out until I ran that tank most of the way out and refilled.
 
If it's the same as the Escape 3.0 and a vacuum leak look at the back of the intake. There's a fairly good size elbow that you won't be able to tell it's bad till you pull it off, I want to say it's for the PCV but I could be wrong.
 
Blocked/broken up cat convertors caused my EGR valve to keep blowing out on my Duratec. Did similar things yours is doing.
 
This is a 2000 with the 2.5. I inspected the pcv elbow, had it leak on an old Taurus I had. Unfortunately the car sunk up to the rocker panels in mud, so i cant see if the cat converter is rattling. Its not throwing any new codes still.
 
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Im thinking it must be bad gas. Im hoping it'll run its course and smooth back out. I pulled it out of the mud and banged on the exhaust but didnt hesr any rattling.
Thanks everyone for chiming in!
 
I had a ruptured fuel pressure regulator on a ford/mazda product. It was sucking tons of gas in the intake, and ran worse at idle b/c the ratio was waaaaay off then. You can check yours by just seeing if the hose is full of gas.

With the car having been parked then disturbed, you could have ruptured the diaphragm.

You should also check to see if the PRNDL switch is communicating properly-- it might not "know" it has to idle if it thinks its in the wrong gear.
 
I'll check the fuel regulator. When I had the plenum off I noticed the intake was split up to 12 holes instead of just 6 open ports for the 3.0 I'm used to. Excuse my lack of knowledge, but theres valves that are connected and one next to every intake port. These valves wouldn't open by hand and I'm unsure if they're supposed to or not. Heres a pic of the same motor for reference. Mine were caked in crusty gunk.
[Linked Image]


Also the car is starting ok now but is skipping going uphill only above 40mph, and stalling out (idle around 100rpm) slowing down 30-0 until I hit the gas again. Still, no engine code other than rear o2. It stalls in neutral too. I cleaned the egr, tb, iac and maf as well.
 
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It was parked to be donated at a family church, but they moved back to their country and didnt leave a title. It ran great at first. Hoping its just junk gas. Its a backup car so I'm not too concerned with it, even though I'm under the hood every day.
 
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Might be multiple issues. You need to start ruling them out. The additives you added are all not very effective against water in gasoline, which there surely is a lot after 3 years of sitting. Dump it all, and add in several bottles of good old methanol based dry gas like heet. No, ethanol in the E10 will not negate the need for Methanol.

I would pull and test every fuel injector. It's already been mentioned, but clogged cat and vacuum leaks need to be ruled out. Try the carb cleaner spray trick around the engine and see if idle changes. I don't know how hard it is on this car, but sometimes you can pull an O2 sensor and use a cheap ebay borescope to see the cat condition.
 
Originally Posted by clinebarger
Bad-Rotten-Varnished gasoline can cause sticky valves......Run a compression test on all 6 cylinders.


+1
Bad/old/varnished gas can also cause sticking and/or clogged injectors. The foul smell you are getting when it is running is from that old gas burning. You should have drained that old gas and replaced it with fresh gas before you tried to start it. You can't dump any additive in it to make it better.
The Mazda 2.5L V6 used in early model MPVs is an entirely different engine than the Ford Duratec 3.0L V6 used in later model MPVs.
 
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