Off idle hesitation, cant seem to figure it out

[pureroundcircle]

I posted this in one other location (another site) but am having quite a bit of trouble figuring it out. I have lurked on this site and managed to find some good info in the past so it seemed like a good time to pose a question.

Well as the title says I'm having some poor running conditions. My truck is a 98 2.5. About 2 months ago I started getting an occasional hesitation off idle, but only very slight and only once in a while. It has now progressed to almost stalling, and having a hesitation in any gear when under acceleration from idle to about 2500rpm. It doesnt do it all the time, but it does it more than not.

I get no CE, and no codes, I tried using my OBD reader even without the CE light being on just to check, but nothing stored.

In the past year i've replaced the plugs and wires.

For this problem I started off by cleaning the MAF, the problem went away for maybe 1 day, or so I thought. I bought a new MAF thinking that was it for sure since the problem seemed to have gone away after i cleaned it for a while, but no that wasnt the issue.

I then checked all over for vacuum leaks, no hissing, no loose lines, the pcv looked ok, i cleaned it out with some carb cleaner, I did replace one section of hose that was rotten, but it wasnt leaking. I ran the engine and sprayed around all the hoses and vacuum lines checking for idle changes; none found.

I checked the TPS, it seemed ok, like the readings were linear but the lower reading was a bit high and the WOT was a bit low, and since a TPS is only $20, I went ahead and replaced it, again not the problem.

I rented a fuel pressure tester from autozone, I read about 65psi in all situations; idle, near WOT, and under load all read 65psi. So i'm thinking fuel pump and filter are A-ok.

I unplugged wires from the spark units with it running just to make sure both units were sparking, they are.

At this point i'm stumped. I'd think id get an O2 code for an oxygen sensor and unless this truck is unusual they usually don't cause this much trouble when they are bad anyway. I do have an O2 meter gauge I had for a car a long time ago I could probably splice in to check the O2 signal when it wants to stall?

Other than that I just dont know what to do, are there any other common 2.5 problems maybe i'm overlooking?

Thanks,
Paul

 

[BRUTUS_T_HOG]

the cam or crank sensor signal could be weak, i think ford did away with the "dummy shaft" cam sensor and just mounted it into the side of the block. you should see it under the intake manifold area next to the timing cover.

you could also try to unplug the SPOUT connector to see if it changes the symptoms

 

[pureroundcircle]

Hmm, read up a bit on the spout connector and am remembering messing with this on another Rager I worked on 5-6 years ago. Does a 98 even have this connector. Where is it? I didn't see it when i was rooting around in there.

 

[modelageek]

you could also try to unplug the SPOUT connector to see if it changes the symptoms

Whats a spout connector?

 

[modelageek]

I posted this in one other location (another site) but am having quite a bit of trouble figuring it out. I have lurked on this site and managed to find some good info in the past so it seemed like a good time to pose a question.

Well as the title says I'm having some poor running conditions. My truck is a 98 2.5. About 2 months ago I started getting an occasional hesitation off idle, but only very slight and only once in a while. It has now progressed to almost stalling, and having a hesitation in any gear when under acceleration from idle to about 2500rpm. It doesnt do it all the time, but it does it more than not.

I get no CE, and no codes, I tried using my OBD reader even without the CE light being on just to check, but nothing stored.

In the past year i've replaced the plugs and wires.

For this problem I started off by cleaning the MAF, the problem went away for maybe 1 day, or so I thought. I bought a new MAF thinking that was it for sure since the problem seemed to have gone away after i cleaned it for a while, but no that wasnt the issue.

I then checked all over for vacuum leaks, no hissing, no loose lines, the pcv looked ok, i cleaned it out with some carb cleaner, I did replace one section of hose that was rotten, but it wasnt leaking. I ran the engine and sprayed around all the hoses and vacuum lines checking for idle changes; none found.

I checked the TPS, it seemed ok, like the readings were linear but the lower reading was a bit high and the WOT was a bit low, and since a TPS is only $20, I went ahead and replaced it, again not the problem.

I rented a fuel pressure tester from autozone, I read about 65psi in all situations; idle, near WOT, and under load all read 65psi. So i'm thinking fuel pump and filter are A-ok.

I unplugged wires from the spark units with it running just to make sure both units were sparking, they are.

At this point i'm stumped. I'd think id get an O2 code for an oxygen sensor and unless this truck is unusual they usually don't cause this much trouble when they are bad anyway. I do have an O2 meter gauge I had for a car a long time ago I could probably splice in to check the O2 signal when it wants to stall?

Other than that I just dont know what to do, are there any other common 2.5 problems maybe i'm overlooking?

Thanks,
Paul

a few thoughts. Have you cleaned the idle air control valve? when you did the fuel pressure test did you check to see that after you turned the truck off that the fuel pressure did not drop more the about 8 psi in 5 minutes? WHAT PLUGS AND WIRES DID YOU USE? Have you added any fuel injector cleaner and if so did you notice any difference?

 

[BRUTUS_T_HOG]

Hmm, read up a bit on the spout connector and am remembering messing with this on another Rager I worked on 5-6 years ago. Does a 98 even have this connector. Where is it? I didn't see it when i was rooting around in there.

on this year it should be on the passenger side of the truck in the front grill area, they all have them as a way for a tech to check "computed timing"

Whats a spout connector?

Spark-Output- Ford. GM calls it EST, Electronic Spark Timing. just a name for the same thing

 

[modelageek]

on this year it should be on the passenger side of the truck in the front grill area, they all have them as a way for a tech to check "computed timing"



Spark-Output- Ford. GM calls it EST, Electronic Spark Timing. just a name for the same thing

so on my 99 is it in the same spot passenger side grill area. besides checking the timing does it do anything else can it cause a problem with the engine management of the truck? or is just a data port type of thing

 

[BRUTUS_T_HOG]

so on my 99 is it in the same spot passenger side grill area. besides checking the timing does it do anything else can it cause a problem with the engine management of the truck? or is just a data port type of thing

it should be located there, if its not there then it will be on the firewall

on this year the PCM directly controls ignition timing. unplugging the SPOUT put it into base timing mode and does not allow it to advance timing.

on older systems with a separate ignition module the computer sent a signal from the SPOUT to the ignition module to do the same thing.

i had a bad ignition module that wouldn't allow me to even drive the truck or keep it running... unplugged the SPOUT and it would run great i ended up driving it for over a year on base timing until i could replace the ignition module

 

[pureroundcircle]

a few thoughts. Have you cleaned the idle air control valve? when you did the fuel pressure test did you check to see that after you turned the truck off that the fuel pressure did not drop more the about 8 psi in 5 minutes? WHAT PLUGS AND WIRES DID YOU USE? Have you added any fuel injector cleaner and if so did you notice any difference?

I have not cleaned the IAC. I did unplug it, and the idle drops significantly 2-300rpm. So I figured it was working, though I suppose it could be leaking air by or something so probably worth a look. I have not added fuel injector cleaner, for the fuel pressure test I just connected a gauge to the valve on the fuel rail. I didn't actually time the fuel pressure drop after shutdown. I still have the tester so I can re-do it tomorrow. I know it didn't drop below 45-50psi after about 20 min because that was looked at but I wasn't aware 8psi drop in 5 min was the spec. As for plugs and wires, autolite platinums, and autolite wires I believe. Ever since I had an explorer and put bosch platinums in it and it ate the tips, i don't go that route! (which is what I assume you were getting at).

I'll drive the Audi to work today, maybe i'll get a chance to look this stuff over tonight ( if the wife doesn't have other plans...)

 

[modelageek]

Coilpacks? You can check resistance and or swap them if the problem changes at all then you knowit isa coilpack

 

[modelageek]

I still can't find my spout connector. I have search the engine bay over the years the only connector. I ever saw is one off the rabs"pump" I assumed it was to check the rabs

 

[pureroundcircle]

May have figured something out. I got gas today and forgot to put the gas cap back on. It ran great all the way home. Well it was also cool and raining, so i'm not sure if this as just a fluke event or is really related to the problem. I put some fuel system cleaner in today, and also re-did the fuel pressure test. In 5 min fuel pressure dropped about 3psi. I also tested fuel pressure with and without gas cap, both under load and not, no difference, 65psi all the time.

Does anyone know what might be wrong if the truck is running good without the gas cap. I guess some sort of check valve or charcoal canister type issue. I'm not sure how this setup works, any ideas what to look at?

I cant seem to find the SPOUT connector either. There is a single wire coming out of the harness near the coil packs and connecting to a resistor to ground with a little grey connector, and also another 2 wire plug on the same line as the brake proportioner, but the end connector is round and is just a cap and doesn't actually join the pins with the cap on.

Paul

 

[modelageek]

I think it is possible the gas cap is the issue, however, I would have thought it would throw a code. Go buy a new gas cap

I also have a single wire near the coil pack with what looks like a fuse holder on the wire. I assumed it was a fuse, could that be my sprout connector

 

[alwaysFlOoReD]

I don't have a lot of knowledge about where the spout connector resides for different years but it does look like an inline fuse holder. Pull the 'fuse' to do your base timing.
Richard

 

[BRUTUS_T_HOG]

May have figured something out. I got gas today and forgot to put the gas cap back on. It ran great all the way home. Well it was also cool and raining, so i'm not sure if this as just a fluke event or is really related to the problem. I put some fuel system cleaner in today, and also re-did the fuel pressure test. In 5 min fuel pressure dropped about 3psi. I also tested fuel pressure with and without gas cap, both under load and not, no difference, 65psi all the time.

Does anyone know what might be wrong if the truck is running good without the gas cap. I guess some sort of check valve or charcoal canister type issue. I'm not sure how this setup works, any ideas what to look at?

I cant seem to find the SPOUT connector either. There is a single wire coming out of the harness near the coil packs and connecting to a resistor to ground with a little grey connector, and also another 2 wire plug on the same line as the brake proportioner, but the end connector is round and is just a cap and doesn't actually join the pins with the cap on.

Paul

this is what it looks like on ford, courtesy of google: