Off idle hesitation, cant seem to figure it out

[pureroundcircle]

Yeah i'd looked up a picture of it as well but thought maybe it looked a little different for later years, I just don't have that anywhere under my hood. I've looked all over it just isn't there, unless its hidden under the fender well or tucked deep under the headlight area or something.

I have a single wire to ground connector that I figured out must have something to do with abs, as when I unplugged it the ABS light came on, oops. I also have a 2 pin connector that hangs from the brake proportioner wiring, it is not the same as that one pictured but seems similar given that it is 2 wires with a plug on the end. The plug doesn't bridge the pins, its just a cover. I tried bridging the pins and didn't seem to run any different. I had a timing light on it and when I first started the engine it was around 10*btdc, but after warming up it appeared to adjust itself in such a way that I could no longer see the mark with my timing light. Bridging the pins had no effect.

I drove it with a loose gas cap today and it ran like a champ. I guess this weekend I'll have to see If i can figure out some way to test the gas cap, and charcoal canister valves.

I have a membership to alldatapro and their test procedure was pretty useless, generally alldata is aimed at independent shops so their tests don't require dealer only tools. But their test procedure for the evap system involves the Ford NGS tester, and a pressurized smoke machine... UGH

Paul

 

[greasemonkey6886]

I have a 92 with the same problem. After reading this last night I decided to drive to work this morning with the gas cap off. Wouldn't you know, it ran a ton better. It had a couple little hickups but I figured that the computer was just trying to relearn the system. I looked at my evap system this evening and found that mine only has two hoses from the canister, one from the tank and the other going to the intake. The way I figure is that the cap vent is plugged up and therefore creating pressure in the tank to build up. When this happens it just sends it up to the canister and on into the intake creating a rich mixture on idle and part throttle. The mixture would be near correct for the higher rpm range and thats why it runs good after the rpm catches up. Also found the spout connector, well actually foun two for some reason on mine. The first one is on the passenger fender well in a harness that also has the diagnostic plug. It will be between the power dist. box and the heater blower motor. Your 98 probably wont have this one due to the OBDII system on it. Your diagnostic port is off course under your dash. The other one I found was on the drivers side of the engine in a harness next to the DIS box witch is mounted on the lower front side of the intake manifold. I bought a new gas cap and a can of MAF cleaner on the way home. Will try both and let everyone know what happens. I think together we will geet this figured out. Wonder how many more trucks are running around like this and the owner is just thinking it because it's a 4cyl?

 

[greasemonkey6886]

Well just got done replacing the gas cap and cleaning the MAF. The MAF looked clean and new but I cleaned it anyhow. Also took the top off the air filter box and used the MAF cleaner to clean the temp sensor that sticks in through the top of the box. After all was completely dry and re-installed I drove it and was pleasantly surprised. Truck ran great and had a lot of low end power where it had absolutely none before. That was with the a/c going too! Hope this helps!!

 

[pureroundcircle]

Well I'm still not satisfied, I had sort of thought the gas cap thing might have been the issue, but I feel it is probably not completely at fault. I had also put in some techron fuel injector cleaner at roughly the same time as the gas cap being left off. For that 1/2 tank of gas that was in there with the injector cleaner it ran perfectly, both with and without gas cap. I tested for about 10 miles of each on the same day. For the next fill-up it was back to hesitating, though not quite as bad, again with or without gas cap. So i'm leaning toward dirty injectors, or one or more injector may be getting weak. I still haven't checked resistance on the coils o the injectors. I can't imagine 20oz of fuel system cleaner to 7-8 gallons of gas can make THAT much of a difference but it did, at least temporarily. I guess now I'm debating what more invasive method to try and clean my injectors I might try. I know there are some pour in the tank solutions and some more pro ($$) systems that run directly into the fuel rail. Any experience with injector cleanings? I haven't even checked yet but 7-8 years ago I could have got a whole set of injectors from "5-0 motorsports" for less than $100, would be cool if that is still the case.

 

[modelageek]

change your fuel filter. Here is a link showing how to do it go to post #15

http://www.explorerforum.com/forums/showthread.php?t=102197

You can get the tool for less than $10 I have a little different style than is in the thread. Walmart sells the filter for about $8

 

[pureroundcircle]

Figured it out finally... (i hope)

Ended up being an intermittently bad ignition coil. It would stop firing one plug on the #1 cylinder when one of the coils got hot. The engine runs pretty well without that second set of plugs until the engine get under a pretty good load then it runs like crap. Which explains the good idle and descent higher rpm running.


Anyhow, I had already checked the coils when the engine was cold and both worked, but after dealing with this for weeks and it only getting worse i decided to start diagnosing it hot since it was worst when it was hot and managed to find it not firing.

I would have thought this was something that would set a CE light or code, but apparently not.

As for the Gas cap and Fuel cleaner making it work great for a couple days, well i dunno, i guess since the problem was only intermittent and worse when it was hot I guess it just happened to work well those days, or maybe the cleaner burns a little different and it just ran a little better? Anyhow intermittent problems suck.

Thanks for all your help.

Paul

 

[greasemonkey6886]

Good to hear it's running better. Now I need to check mine. Since my last post I noticed that while it does still run better than it did the problem isn't completely fixed. As with yours it seems to be worse when it's hot. I looked in the tech library for an explanation on how to test the coils and didn't notice one. If anyone could help here please do so as it sounds as though this is my next step. Thanks

 

[pureroundcircle]

There are a few pretty easy ways to test your coil pack. But unfortunately if it is intermittently bad that's where testing gets a little harder. I'm sure there is a computer testing method, but we'll skip that.

You can unplug 1 coil pack and run the engine, it should run smooth at idle with either pack running. If you notice poor running at idle with either pack unplugged than you should look for your problems there. You can loosen the wires from the coil pack to test spark at each post also. The with it running just lift the wire off the post, and prepared to get shocked a few times. If you don't like that method you can hook up a timing light to every wire and just see if it blinks or not, if it doesn't then that plug isn't firing. One good thing about the timing light is that you can tell if a coil is firing to any cylinder and you can rev it up a little and still be able to check it. My timing light is kinda cheap so after about 2000 rpm my timing light can no longer see a spark and make the light blink.

you can also check coil resistance, I'm sure there is a value (ohms) floating around somewhere for testing these coils, i don't know that value off the top of my head.

Just a few things to get you started if you think that's where your problem is.

edit: i as assuming you had the dual plug setup with distributorless coil packs. if you don't you can still use the same method for the most part, you just might not have that same type of dual coil pack.

Paul

 

[greasemonkey6886]

Ok thanks. I will do that today. And yes I have the dual packs and 8 plugs. I am thinking that I may have one bad too as our problems seem to be identical. I know these little engines only produce 100hp but it should have more bottom end than it does. It literally feels like I am dragging an ancor on take-off sometimes and others it does fine.

 

[Duane867]

Not that any advice or ideas already given are not up to snuff ....
But a MUCH safer way to check for spark would be an in line spark tester.
You can get one from Harbor Freight for around $5.00. You hook one end up to the coil pack terminal and the other to a plug wire. Have an assistant turn the engine over and if there is spark you will see it in the clear tube between the test wires. No risk of shock from pulling off plug wires while the truck is running that way.

Hesitation / rough idle "could" also come from a worn or stretched timing belt. As well, have any of you with the same problem noticed a faint rattle under the hood near the timing cover ?
When the belts stretch they will lightly hit the belt cover and make that noise. They don't always do this but its a tel tail sign.
Either way if they are stretched enough or the tensioner pulley has lost position a little causing slop, it could cause this at low rpm. It only takes a degree or two in either direction to give a rough idle or a misfire and low power at low rpm until the computer overides it at higher rpm.
I have not personally changed mine or any one elses yet. I need to change mine soon though. I have seen this diagnosed at my friends shop on a regular basis though.

Not saying its what you all are experiencing but it may well be the problem ?
Just thought I would throw that out there...

 

[greasemonkey6886]

Thanks for the advice! I actually have that spark tester you described. I have been too lazy to test mine yet plus it's been hotter than heck here lately. As far as the timing belt I need to replace mine anyhow due to the fact it's got around 80000 miles on it. I have the new belt just haven't done it yet. I know, I know... get it done soon. Has anyone had experience with a 92ish 2.3 timing belt? I know the older ones without EDIS are simple. I was wondering about the crank sensor on mine. The B.S. book I have on it says there is a special tool needed to readjust the gap after replacing the belt. I have to wonder if I even need to remove it to replace the belt. Any help would be awsome!! Thanks guys.

 

[Duane867]

Nope,
This is what you will need to do though......

Bring the #1 cylinder up to TDC on the compression stroke.
The easiest way to do this is to use a compression gauge. Remove the plug from the #1 cylinder ( unplug both coil pack harnesses before going further ! ) Have an assistant bump the engine over at the key until the gauge just starts to read compression then stop bumping the ignition immediately. This should get you with in 10 -15 degrees of TDC on the compression stroke. Look down at the crank and the timing mark on the crank should just start to register on the timing guide hashes. Turn it over by hand ( socket on crank bolt ) until the mark lines up on the crank at "0" TDC. You are now at TDC on the compression stroke.
Not every one has a compression gauge handy though so here is the old fashioned way to do it.... Stick the cut off end of an old plug wire into the #1 cylinder. Rotate the crank by hand then measure ( mark it with a marker on the wire ) each strokes high point. The higher point is the compression stroke. This way should bring you to 10 - 15 degrees out and just registering on the hash scale as well but its a little trickier.
DO NOT ROTATE CAM DURING REMOVAL OR INSTALLATION. Its ok to line up the indicator because you will only be a degree or two off at best on the cam when lined up on the crank pulley. Do not make revolutions on the cam with the belt off though or you will blow all the work you did getting every thing to TDC on the compression stroke before hand if you do.

BELT REMOVAL:
1: Loosen and remove alternator bolts
2: Drain coolant
3: Disconnect upper radiator hose
4: Remove water pump pulley
5: Remove crank pulley
6: Remove timing belt outer cover and bolt
7: Loosen belt tensioner pulley assembly
8: Remove belt.

BELT INSTALLATION
1: Install new belt
2: Release timing belt tensioner pulley
3: Set cam shaft timing
4: replace timing cover and bolt
5: Replace alternator and bolts
6: Replace water pump pulley
7: Replace crank pulley
8: Replace upper radiator hose
9: Fill with coolant and check for leaks
Check ignition timing and adjust ass needed.

Hope this helps.

Be doing mine this weekend.