Slight miss at idle...'99 Windy 3.8L

[65val]

I know there are a few (lots of) threads dealing with idle misses, and I have read most of them, but my problem seems a bit different. My miss happens just when you're coming to a stop at , say, a traffic light. Just before the stop, the engine shakes (misses), but during the stop period, the missing seems to clear up a bit. The van runs normally at all other times.This all started about a week ago when as I was starting the van cold one morning, it backfired, jamming the starter causing starter damage, requiring it to be replaced. After replacing the starter, I now have this miss at (and just above) idle.

Now for what I've done. My cheapo scan tool said the DPFE was reading a high voltage(P1401 code), so I replaced that and cleared the code. No change in miss. No other codes since. I removed the EGR valve, checked its operation, cleaned it, and reinstalled (I checked that it wasn't leaking when closed by introducing air pressure on one side, and it held seal). Again, no change in miss. I checked vacuum at the EGR hose and no vacuum found at idle (normal vacuum when revved). I've changed plugs (it needed it!) and the wires appear fine. I've cleaned the IAC, tested the TPS and still no change regarding the miss/shake. I'm going to check those small plastic bushings at the IMRC control, as was outlined in a previous thread here. The lower intake gaskets were done on the van quite a few years ago, so hoping those haven't gone out again.

I'd appreciate any further help that anyone has as I'm getting kind of frustrated with this thing. I may have to take it to the stealer (cough, cough).......

Thanks all!

[tomj76]

"it backfired, jamming the starter causing starter damage, requiring it to be replaced."

I found this:
Engine kickback or backfire. Besides generic timing problems, causes include a faulty Crankshaft Position Sensor (1996-2000 General Motors C/K, G, P, and S/T Series) and electrical system noise interference prompting the ignition module to fire the spark plugs prematurely (Hyster forklifts with 3.0L GM engine).

Could be the sensor or the wire from the sensor. 12Oz had an experience with worn wiring, I believe to the CPS.

https://www.yourmechanic.com/service...off-inspection

Have you tried switching the transmission selector to neutral as you come to a stop, to see if the engine still stalls? I wonder if carbon in the combustion chamber could be an issue.

http://forums.off-road.com/jeep-shor...dieseling.html

[65val]

Tomj76...thanks for the reply. The engine doesn't stall when coming to a stop; it just develops a slight shake/miss that seems to correct itself partially as you sit stopped at a traffic light. In all other situations, the van performs normally and has great acceleration and decent mileage. Before the backfire (which could have been caused by the overdue spark plug replacement) the van ran great and performed properly.

[tomj76]

Sorry, I'm just thinking that anything that can make it misfire could also make it stall if the condition is less severe.

How about this?
https://answers.yahoo.com/question/i...4092250AAP9pwh

https://www.yourmechanic.com/questio...is-be-by-brent

https://www.yourmechanic.com/questio...is-be-by-brent

[65val]

Thanks again Tom. I have cleaned the IAC and tested the TPS. This thing acts almost like a vacuum line is off somewhere, but I can't find any that are off (backfire could have blown one off?). All the hoses seem in good shape...soft and pliable. I checked those little plastic bushings in the IMRC control, and they're present and in good shape.

[65val]

@wiswind, @12Ounce Any ideas?

[Mustang_Driver]

the only thing that caused mine to run with a miss was a bad coil pack as it is in an awkward place under the windshield wipers near the fire wall bad placement by ford but it seems the epoxy under neath it cracks and sorts out causing a miss ... just what happened to me but worth a look

[12Ounce]

I'm inclined to suggest a upper intake manifold removal, inspection, cleaning with replacement of all gaskets and seals involved. Work from the top. Remove the wipers and all the cowling. The idea is to do an inspection of as much of the engine's "top" and engine box as possible ... all without really doing a lot of invasive, scary engine mechanical work. The problem may be almost anything ... but you are very apt to find whatever it is with a bit of looking. It will give you a good opportunity to inspect, clean and lubricate a number of details .. such as the EGR injectors, the IAC valve, the synchronizer, the ... etc, etc. And Yes, inspect all the electrical harness you can get your hands on while in there.

I've just changed my engine oil at 471,000 miles ... and I'm about to do exactly what I've suggested above to my ole Winny. It won't be the first time for me, so I have a secure comfort level, but I've picked up the leak codes recently and I also have a bit of power loss and poor idling. Just received my gaskets from Rock Auto ... so its time for this old bird to get busy!

... jump in and good luck!

[Mustang_Driver]

yeah i had the lean codes for the isolator bolts so i went ahead and changed the spark plugs, wires,coil pack, along with all the upper intake gaskets throttle body gaskets, IAC, AIR CLEANER i figure if i am that far in i might as well change it all... still only average 13 mpg approx 437km or 272 miles to a tank of fuel 98 liters so it's not the most fuel efficient vehicle but i haven't seen a CEL TO SAY ANYTHING IS WRONG.....


after all this i need to change the plugs on my 08 escape and that requires the upper intake to come off as well.. poor design by ford but i guess they do charge by the book so the longer it takes the more money they make.....

i hear they are getting rid of all the car lines by 2020 and focusing just on cuv's,suv's and truck line so i guess the car market is slowly dwindling down

[tomj76]

@Mustang_Driver

For what it's worth, I get about 20 mpg for highway driving @ ~65-70 mph from my '96 3.8L. That works out to about 400 miles per tank. Of course fuel economy varies with driving habits, so your mileage may vary.

I keep a record of fuel purchases and enter them into a spreadsheet for mpg calculation. I noticed that before my transmission failed the mpg's were steadily falling (to about 14 mpg) and then recovered when it was rebuilt.

[Mustang_Driver]

yeah ford's fuel economy isn't a strong suit of theirs i had a Plymouth voyager mini-van that i traveled on the hwy approx 180 miles and only used about 20 dollars of fuel or 16 liters of fuel... now this is a 3.0l Mitsubishi motor versus the 3.8l ford but i figured the mileage should be similar but i guess that i do have the se sport with front/rear heat/ac and what other options it came with so it might be a heavier van but the best i can pull out of it is 15 MPG city

[tomj76]

Based on your numbers, you're saying that the Plymouth gave you 42 MPG! The spec on a 2000 Voyager with 3.0L engine is 18 city / 25 highway, so you must have been doing something to achieve those results!

My fuel economy results are for typical interstate highway driving at a consistent speed. I'll double check the numbers to make sure. The reason I mentioned my results is that if fuel economy is low, then there may be a connection to your issue.

[Mustang_Driver]

I assure you i did nothing except an oil change before we went on the trip.... that van i didn't want to give up as it was actually a nice van up to the point where the water pipe sprung a leak which meant i had to take the whole top end of the motor apart to get at it. but now that i know how to repair i kick myself everytime i see one of the older chrysler vans... i keep saying i miss my old van and i always seemed to have money in my pocket and i drove it everywhere.. this ford is bleeding me dry as i could be driving a 5.0L mustang and getting better mileage i know as i had a 98 with the 4.6 and i was getting 17M.P.G in the city and that was driving it hard..maybe it's something mechanical or computer related to the ford van but i am not paying 170 per hour labor at the dealer here in BC ,Canada to find out

[12Ounce]

MD, one system that can drive you crazy without giving any fault codes is the fuel supply system. If you don't have the proper pressure for correct fuel injection ... you will have substandard performance and economy without much chance of the OBDII ever complaining.

I've only changed out the fuel filter perhaps three times, but I'm on my fourth or fifth fuel pump. (I've lost count!) I've learned to "sense" when the engine is bogging down because of lack of fuel pressure. I change the pump and all is well again. ...that's been my experience thus far. I hope I never drop that tank for no reason!

[Ed_Strong]

Originally Posted by 12Ounce

MD, one system that can drive you crazy without giving any fault codes is the fuel supply system. If you don't have the proper pressure for correct fuel injection ... you will have substandard performance and economy without much chance of the OBDII ever complaining.

I've only changed out the fuel filter perhaps three times, but I'm on my fourth or fifth fuel pump. (I've lost count!) I've learned to "sense" when the engine is bogging down because of lack of fuel pressure. I change the pump and all is well again. ...that's been my experience thus far. I hope I never drop that tank for no reason!

This makes me very nervous... mine has been acting up recently to the point it's almost undriveable. it feels like its missing (coil) or like trying to drive in two gears at the same time (tranny) but it cannot decide which gear to stay on. It also feels under powered and slow, bogging down as I depress the gas pdal (plugged cats). It drives like that for a few days... then all of the sudden next day it cranks and drives like a champ...nothing wrong with the darn thing!!! Mayor problem is there are never any DTC codes stored in the computer. Im afraid it may be the Fuel pump going out! Just hit 150K miles. Do you have a tutorial or video or step by step process. I still need to diagnose it first to make sure, but would like to know ahead of time if possible what im getting to doing that repair