Intermittent misfire

[windimpala]

Originally Posted by 12Ounce

tomj76'

Windimpala,
Is there a chance someone has adjusted the throttle stop screw ... leaving the plate "too open" when the plate should be closed?

I can't see the stop screw being moved. It looks like a set screw with out a hex for an allen key! But it would be possible to do this with a couple of nuts jammed up together. Any ways to answer your question NO it has not be tampered with. Good thought. Still waiting for warm spell here or Santa to bring me a heater for my garage.!! The van is running well when it not missing. 256K and counting.

[tomj76]

[quote=12Ounce]tomj76'
Did you get your problem resolved? By the way, the firing order on all Windstars (I believe) is 1-4-2-5-3-6. Therefore, the "pairs" are 1&5, 2&6, 3&4.

Well, as the problem is intermittent, it's been gone for a while now. The MIL came on one day last week when my wife was driving it, presumable for the same symptom, then went off the next day. In short, I haven't tried any fixes yet.

[Seeler]

You may want to purchase new fuel injector end caps (also called "pintle" caps) before you clean the injectors. One of my end caps had become brittle. Auto parts stores carry the o-rings but not the end caps. You can find pintle caps on e-bay.

[s1120]

Originally Posted by Seeler

You may want to purchase new fuel injector end caps (also called "pintle" caps) before you clean the injectors. One of my end caps had become brittle. Auto parts stores carry the o-rings but not the end caps. You can find pintle caps on e-bay.

I got oring/cap kits for my inj's from a guy called Mr Injector on ebay. GREAT service!!!! I have rebuilt the ones on my Windstar, and my Bronco

[tomj76]

Still have not yet found the cause of this, however I noticed while driving on Monday that it now makes a gurgling sound in the back (gas tank?) when you first turn the key on after it has sat for 15-20 minutes, after being driven. If you start it right away, it misfires. If you don't but turn the key on/off several times until the gurgling stops, then it runs OK. I'm guessing that turning the key several times is needed since the pump only runs for one or two seconds when you turn the key on.

I need to check for a possible leak in the fuel line (air getting into the fuel line, apparently on the supply side, if misfire is due to air in the fuel line).

It's interesting that you don't notice this when the vehicle has sat for long periods of time.

[12Ounce]

Aha! New clues! It's possible that the gurgling you are hearing is caused by the fuel pressure regulator (located on fuel rail) is not re-closing properly. I would replace the regulator ... not that expensive.

... you could first test the gasoline pressure if you have access to a test gauge.

[tomj76]

I have a fuel pressure gauge and I was planning to check fuel rail pressure at the fitting as well. I'm not sure how even an open regulator would cause this, but I'm open to anything on the path to uncovering the real cause. I want to fix the real problem. Right now I'd expect that the gauge will read low before turning on the key. I think the fitting is behind the regulator, on the fuel rail, so I won't see the pump output pressure directly.

My idea of this problem is that once the gurggling sound stops any bubbles (air or gas vapor) have been pumped through the fuel circulation lines and back to the tank.

[tomj76]

I downloaded the troubleshooting chart from Autozone website, and I checked the fuel pressure as described. It's 38 psi without the engine running, with the pump running. It drops to 30 psi when the engine is running. It goes up to 40 when the engine is running and the vacuum is disconnect from the regulator. It holds pressure when the engine is turned off. It follows (albeit very slowly) variations in the vacuum level.

However, things were "working right" (i.e. no symptoms) when these tests were performed. In addition, I tried to get it to "make bubbles" as mentioned in my previous post, but I couldn't get that to happen. It still happens, but only under the right conditions (including away from my garage!). Fortunately, the vehicle works and passes emissions, so I'll continue to keep and eye open until I can get to the cause of all this.

[MARZBX157]

I would replace the coil pack as suggested by 12Ounce as this could be the cause of the problem. Another member who has been posting for a while now, has just figured out that the issue with his van was the coil.

http://www.automotiveforums.com/vbul...=756904&page=3

[tomj76]

Thanks for your suggestion Marz. I saw that thread and for a lot of misfires that might be the cause. I'm not so sure in this case, because of the whole gurggling symptom. I've started the car, noticed it misfiring and then turned it back off. Then upon turning the key to run without starting the engine, the gurggling can be heard. Once you cycle the key enough to get it to stop making that sound, it starts and runs fine.In addition, I've heard the car gurggling before starting it, and if I did start it then it would misfire. On the other hand, if I cycled it until the gurggling stoped (without ever starting it), then it would start and run fine.I firmly believe (right now) that the misfire is fuel related, not spark, but as always it's best to keep an open mind. I'll just have to wait for more evidence before running out to buy parts.

[tripletdaddy]

It seems you have clearly described a situation where air or maybe a vapor/vacuum is being created in your fuel lines, likely due to the draining or loss of fuel, after you shutoff and before you start your van. So the million dollar question is where it's coming from or what is creating it, ie. what is allowing the movement of fuel? 12ounce suggested the fuel pressure regulator could be faulty. It could be allowing drainback if not closing fully, causing a gap in the fuel. It also could have a diaphram leak into the vac connection. Pull the vac line to the fpr to see if it is leaking fuel there. What sort of fuel pressure do you have after letting it sit for awhile? Is there a strong odor of gas at the engine? For some reason I think there is also a check valve in the fuel system, but I would need someone else to confirm that and its name. Could this also be related to the evaporative emissions control system, EVAP ? It's been know to cause poor idling, stalling, and poor driveability. I know there is a vapor management valve on the top the tank that's part of the evap. If not closing properly, it could allow air to leave the tank via the evap line and allow fuel drainback. Any supporters?

[tomj76]

tripplet:

Thanks for the suggestions.

I detected no gasoline odors either in the engine compartment in general, or at the regulator vacuum port.

It repeated the behavoir last night after I drove it 15 miles and let it sit for ~30 minutes. Upon turning the key to "ON" I could hear the gurggling sounds. Later I tried to repeat the event, so I ran it at idle while parked until the fans came on. Then I turned it off and let it sit for 30 minutes. It did not gurggle again when I turned the key to "ON". I don't know if taking it for a drive would cause it or not.

Those are good places to look. So far, I've eliminated the fuel filter as there is good pressure both prior to startup (no flow) and while running without the vacuum connection to the regulator (heavy flow). The pressure with the vacuum connected is low (30 psi compared to spec of 35 to 45 psi), so the regulator is still suspect in my opinion. The pressure responds as expected to low vacuum.

The pressure is well maintained with the engine off, with no noticeable drop after five minutes. I does drop to ~20 psi after 30-60 minutes.

I didn't notice a check valve described in the manual, but I'll check for that again. I'll also check for any potential connection to any EVP issues. I don't recall how the EVP is connected to the fuel injector delivery loop, if at all.

[tomj76]

Well, I replaced the pressure regulator ~4 weeks ago, and since then I've not heard the gurggling noise. There were a few times when I thought it might have been running rough at startup, but the CEL never indicated that there was a significant misfire.

It looks like the regulator was somehow the culprit, although there was no reason to suspect it. I ran the troubleshooting proceedure outlined in the manual, but did not find any fault. The only reason I changed it was due to a confusion in the service manual about the spec for the regulated fuel pressure (two different values/ranges quoted in different parts of the manual). I didn't notice my mistake until after the regualtor was changed.

Thanks for the help.

[tomj76]

I guess I spoke too soon. My wife reported that the gurggling was heard again resulting in the CEL turning on when she drive it on Thursday. The search continues.

[tomj76]

I think/hope this was resolved recently as it has not occured for about two months. It stopped after the transmission was removed (via subframe removal), torque converter replaced, and reinstalled.

I'm guessing that the routing or connection of some fuel line was not done properly the first time the transmission was serviced, which introduced the problem. The redo must have "got it right".