Fuel additives???

Has anyone used any fuel injector cleaner / additives with any success? I have a 93 with 140k that idles real rough once its warmed up. It never dies or gives any codes, but something isn't right. I'm thinking maybe a bad or dirty injector? I can hear it missing in the exhaust too. It runs great on the road, good power, no misses, just at an idle...any other ideas?

I have a 92 that does the same exact thing. I am starting to wonder if it could be the injecters. I have used fuel injecter cleaner in my old 3.0 and didn't notice any difference. If you happen to figure out your problem let me know what it is, I have tried everything but cleaning the injecters.

86ltrain, thats the very same thing that mine does. Mine is a '96 with 204.3K miles on it.

I've used fuel injector cleaner and Octane Boost but neither had any effect on it.

The cause on mine is a vaccum leak in the fuel and emissions control system. Have you actually tried pulling codes? Or did you assume there no codes because the Check Engine light isn't on? my CEL wasn't on but I still managed to pull the P1443 code off of mine, which is Auxilliary Emissions Control. Don't think the '93 is OBDII though, so your codes are different I think.

The likely causes on mine, and possibly yours too, are: Bad Gas Cap (yes.. the gas cap...), Bad Purge Flow Valve, Bad Vapor Canister, bad EECS Valve.

For the gas cap, the cap might not be sealing properly and its letting pressure out through the seals. Tighten your gas cap and see if the problem improves any, or jsut replace it. If pressure escapes through the gas cap, the computer will notice and trigger the P1443 code, but it will not trigger the CEL. The computer isn't smart enough to tell you that pressure is leaking through the cap, it'll think that theres a problem with the emissions system.

The Vapor canister, if its cracked or not functioning properly, can cause your problem also. I *believe* the canister is located close to the gas tank. I haven't taken the time to try and find it yet, so it might be somewhere else entirely.

The Purge Flow Valve could be bad, its part of the emissions control system. I've heard from several people that this is *usually* the most common one. I read somewhere on the forums here that a simple cleaning doesn't seem to fix the problem so replacing the part seems to be nessecary.

I personally don't know a dang thing about the EECS valve, though I've seen it listed as a problematic candidate as well.

If you don't want to take the time to check them all out and possibly go replacing unnessecary parts, a Ford dealer *should* be able to perform the "Nitrogen Pressure Test". I just heard about it recently, but apparently they pressurize your fuel/emission control systems with nitrogen and check for leaks, etc. If theres a leak somewhere, the test will show it, and that also means that your problem is a vaccum leak located wherever the nitrogen is leaking from.

I have a 92 that does the same thing and I know that the Purge Solenoid leaks but I have unkooded it and plugged the line and nothing changed, so wouldn't that rule out the emissions control system.

During my initial inspection of the truck (just bought it) I had the negative cable off due to a bad clamp. So in doing that I lost anything that was stored. I should still check the codes though as it may have triggered something since last week. I have not seen a check engine light however. I've checked every visible vacuum line and all seems to be good, I did a fuel pressure check out of curiosity and although it was on the low side, everything checked out ok. I'll maybe replace the gas cap and when I can get my hands on a code reader, give it a look. What generic code reader do I need to check my 93? Thanks for the feedback...

Automan, the purge solenoid might still be good, but remember theres still alot of parts left over to check. As I said, the cause of my issue, which is very similar to 86ltrain's is 99% likely to be one of the reasons I listed...theres likely even something I missed.

86ltrain, I didn't get a Check Engine Light when I pulled the code from my '96.... assuming the cause of your plight is one of the reasons I listed previously you may not get a CEL either. A visual inspection of the vaccum lines would only reveal visible cracks, not hairline fractures that are common amongst the rubbery vaccum lines. When you did the pressure test, did you listen to different areas of the truck to try and hear anything leaking? Even low but acceptable pressure suggests to me that something is amiss. If not I'd suggest it, and if possible I suggest you should still take it to the Ford Dealer for the nitrogen test.... I know I'm going to take mine to the dealership for the testing.. just to get a second opinion on my diagnosis.

I rather think the gas cap would be a very cheap and easy fix... I'm going to replace mine just for shits n giggles. Just to see if it makes a difference. Even if it doesn't work, hey its one less part I gotta replace later on right?

As for the code reader, google is your best friend. I don't know a dang thing about pre-OBDII systems.

What is an EECS valve? Where is it? I can't seem to find any info on it...I'm full of questions here, what do you mean by listening for noises while testing fuel pressure? Would a manifold vacuum test tell me anything?

I haven't quite figured out the EECS valve one either. It was mentioned a couple of times through conversation with a mechanic at the Ford Dealer but he never did explain wtf the thing is.

What I mean by listening for noises is exactly that. Pressurize the fuel system and get underneath the truck and stick your ear along the entire fuel line and emissions system... see if you hear any whistling noises. *If* you hear any whistling while you've got your ear down there, you've found a problem area.

A Manifold test couldn't hurt. It'll at least tell you wether or not the manifold is in good shape.

I tested my fuel pressure again, shouldn't it build pressure than hold it once the key is turned on? Mine doesn't always hold pressure, once it starts it stays right at 30, but if I turn the key on/off, on/off it builds then drops right away again until i start it. It does seem to crank too much before it starts, i usually cycle the key a couple times. I don't think this is causing my idle problem however...