Rough Idle when warm

[RustySJohnson]

I'm 3 for 3, E-v-e-r-y. S-i-n-g-l-e. o-n-e has had this same problem. I drive around a while, turn it off - grab a couple things at the Quick Stop, and BAM - it runs like $h!t and pull out of my parking space holding my head in shame as if I'm another schmuck who doesn't maintain my ride. Sure, I could rev it a couple times and it goes away, while strangers stare in disgust and shake their heads and glare. I shrug my shoulders from humiliation, tuck my tail and wave my hand in a motion that says "I wont rob or kill you".

Well, I've solved this problem - several times. Not only for myself, but other's on this forum as well. For free I might add, no payment required, it's for my pride.

'Bout time I write this up and spare every Explorer Forum's readers pride.

 

[dking]

My 92 is doing the same thing. How did you fix it?

 

[Shroudedinlies]

I have a "rough start" when warm, but after a quick few revs or 10 seconds of waiting it is back to normal. Seems like a flooding cylinder, hopefully due to a sensor? Interested to hear more

 

[RustySJohnson]

The short answer

Dirty fuel injectors.

There are a couple more things to check, but you'll address it when you remove the injectors for service.

 

[Shroudedinlies]

Just picked up one of those sensors, and I will check out the fuel injectors. For $23 I figured the sensor was definitely worth a shot.

Seems like I need to take off the stock intake tube and maybe some other stuff to get to it? Haven't looked at it in the daylight.

 

[RustySJohnson]

Just picked up one of those sensors, and I will check out the fuel injectors. For $23 I figured the sensor was definitely worth a shot.

Be sure and give us some feedback if this works. This could be a First step in a troubleshooting guide, cleaning\rebuilding the injector's are much more involved.

 

[Shroudedinlies]

Yep I will let you know, should be putting it in this week/weekend.

 

[RustySJohnson]

Carb Cleaner

I'll soak the injectors in carb cleaner for a couple days. Now, I'm not exactly sure how long you should do this for..... I've forgot about them before and left them in this solution for a couple months - and I'm not kidding, yes they still worked fine.

After this, ultrasonic bath. I got a new one for X-mas. I'm about to find out if it's better than the Harbor Freight one's I keep burning up (by my own fault). I've done some modifications to them you're not supposed to do.

 

[arco777]

I'll soak the injectors in carb cleaner for a couple days.

Berryman's Chem-Dip like you showed is not supposed to be used on plastic parts; I worry it might make the plastic brittle or break down.

When I soaked my injectors, I used a tupperware container (sorry wife) and a can of Berryman's (same brand) fuel injector cleaner. Worked well.

 

[RustySJohnson]

B12 Chemtool like you showed is not supposed to be used on plastic parts; I worry it might make the plastic brittle or break down.

When I soaked my injectors, I used a tupperware container (sorry wife) and a can of Berryman's (same brand) fuel injector cleaner. Worked well.

http://www.berrymanproducts.com/products/gasoline/b-12-chemtool-carburetor-fuel-system-and-injector-cleaner/


I like it. It probably is better. I have multiple sets of injectors I haven't serviced yet, I think I'll pick some up and give it a try.

I haven't noticed any brittleness or breakdown of the plastic from the Carb cleaner, other than the almost 20 years of age have done.

 

[arco777]

I made a test harness from gator clips, a momentary pushbutton switch and an injector connector. Lets you pulse power momentary to the injector to open it so you can blow through it. Really easy to do and handy for testing injectors on the vehicle (just don't flood a cylinder).

 

[RustySJohnson]

Pulse Tester

I made a test harness from gator clips, a momentary pushbutton switch and an injector connector. Lets you pulse power momentary to the injector to open it so you can blow through it. Really easy to do and handy for testing injectors on the vehicle (just don't flood a cylinder).

I built one of those as well, It's shoved way to the back of my toolbox now. Be careful with the alligator clips, injectors, and sparks. I started a fire not paying attention.

For pulsing the Injectors, I'd suggest building this:
http://www.youtube.com/watch?v=kuezC1AX9yQ



If you like to solder - It's cheap and easy. Build a harness to plug in a factory connector to the injector. Cut one off a compatible vehicle at the bone yard.

 

[natenkiki2004]

Randy, I've come across a few of your posts praising fuel injector cleaning and I have a few questions for you. First a little bit of background on my rig;


It's got 225K miles. I know the injectors have been removed but I don't know if they've been cleaned and if so, how well or how long ago. I used to have a constant cold startup issue where it would never start the first time you crank it, it had to be cranked twice. It was like only a 1-3 cylinders were firing and if you cranked long enough, it would slowly turn into a low idle. I diagnosed a faulty IAT sensor and that problem immediately went away.

However, since then, 2 new issues have slowly popped up. The first is what you've talked about, warm engine starts and idling issues. The other issues is a reincarnation of the IAT sensor where cold starts will either die or slowly idle to life. Neither of these issues happen on every start, but intermittently, perhaps 1/3 or 1/4 starts.


I've solved a couple of vacuum leaks but there might be others as I haven't put a gauge on it yet. But, I've replaced the IAT sensor, the ECT sensor tests good, the MAF sensor is cleaned, the TPS tests good, spark plugs were replaced with Autolite 765, new air filter and the computer has been reset several times and throws no codes.

With all of that said, does it sound like injectors need cleaning? Being an intermittent issue, my thinking (and I'm not a seasoned mechanic) is that they're dirty and not letting fuel through or draining the fuel out or something like that. I've never cleaned injectors, let alone rebuilt them. I am competent in soldering but I'd rather not source the parts for that diagram (which I don't fully understand either). Can I get away with running 12v to them with a momentary switch and squirting carb cleaner in there? Is there a guide on rebuilding them?


(Sorry for the story and questions, I'm not really knowledgeable in this area but I am curious. Thank you if you read it all )

 

[arco777]

Can I get away with running 12v to them with a momentary switch and squirting carb cleaner in there? Is there a guide on rebuilding them?

It worked for me. I used a momentary switch and gator clips to the battery. Just make sure it's actually just momentary, if you hold the injector open you can burn it out.

Carb cleaner may help but for best results, soak them in fuel injector cleaner for at least a day. Remove the filters and replace them; removal is easy if you put a screw in a vice grips, screw it into the brass ring of the filter, and pull hard. The new filters just press in.

When I rebuilt my injectors the best deal I found on a real rebuild kit (with filters) was from RJM Injection Tech. Cost me $32 shipped for 8 sets of new O-rings with new filters and pintle caps.

 

[natenkiki2004]

Arco, that was actually the question I was trying to ask, whether or not it will hurt them pulsing them too much.

I already bought o-rings, some silicone ones as I knew I needed them when taking them out. Is there any way to get just the filters and pintle caps? Where do I get that much fuel injector cleaner? Would kerosene work?

Thanks.

 

[arco777]

The orings are sold commonly, the pintle caps are available, but the filters alone are hard to find. That's why I bought the RJM kit. It's hard to get the filters out without damaging them. The plastic in the filters and caps is weak too after 20 years soaked in gas, so they like to break.

I used a single can of Berryman's fuel injector cleaner. It's the stuff you put in your tank. Look for a blue/red/yellow/white can the size of a sea foam can. I dumped it into a Tupperware container with the injectors and agitated it periodically. When the fluid got dirty I strained it through a Scott Pro Shop Towel (blue paper towels) and re-used it on the injectors again. This was after removing the filters of course. Soaked for three days total though one day would probably have been fine. Hooked up the momentary switch rig (injector connector clipped from junkyard truck) and pulsed 12v while blowing through the injector. Cleaned them out nicely.

 

[natenkiki2004]

Did you have the warm start issue and did your method of cleaning solve it?

I wonder, would it be a horrible idea to use a can of Seafoam and then when done, filter the Seafoam through, say, a coffee filter a couple of times and then put it in the gas tank?

 

[arco777]

Did you have the warm start issue and did your method of cleaning solve it?

I wonder, would it be a horrible idea to use a can of Seafoam and then when done, filter the Seafoam through, say, a coffee filter a couple of times and then put it in the gas tank?

I was chasing down other issues at the time, did not have a warm start issue, so can't say it cured anything. But, it did make my engine run a bit smoother.

As for your second question, I don't know if Seafoam would work as well. Someone else may have an answer on that.

 

[RustySJohnson]

2 new issues have slowly popped up. The first is what you've talked about, warm engine starts and idling issues. The other issues is a reincarnation of the IAT sensor where cold starts will either die or slowly idle to life. Neither of these issues happen on every start, but intermittently, perhaps 1/3 or 1/4 starts.

I think you have two issues; vacuum leaks and dirty injectors. Erratic rough idle is probably a vacuum leak, the little rubber boots connecting all the lines are probably dry rotted, cracked, and leaky, expanded, and are causing fuel pressure irregularities. When the rubber boots expand and contract with changing temperature is probably why it's not consistent. If you go in the "help" section of any auto store, you'll need two sets of the elbows and straight connectors for the vacuum lines. replace ALL of them, especially the one on the fuel pressure regulator and on the vacuum tree. Money well spent.

I wonder, would it be a horrible idea to use a can of Seafoam and then when done, filter the Seafoam through, say, a coffee filter a couple of times and then put it in the gas tank?

Seafoam, I love Seafoam. It's amazing stuff. It makes my Explorer run amazing. Follow the instructions on the can. But it doesn't solve the rough idle when warm, or cold.

Arco, that was actually the question I was trying to ask, whether or not it will hurt them pulsing them too much.

I already bought o-rings, some silicone ones as I knew I needed them when taking them out. Is there any way to get just the filters and pintle caps? Where do I get that much fuel injector cleaner? Would kerosene work?

Yes, you can hurt them by pulsing them too much. It would have to be almost intentional to destroy them this way. I mean apply 12v until they burned up.


Kerosene..... I don't know. I think arco777 has the right idea for a solvent. The trick to cleaning the injectors is not what you soak them in alone, but reverse flowing them, which means you need to pulse to open them and to force tiny particles out back the way the came. To do this, the tiny filter screens have to be removed, otherwise it'll just go right back in. The tiny screens, most of the time I've removed them, they're damaged; either by age or by removing them. Most I remove are damaged by age, the screens have holes letting contaminants into the injector nozzle. Only way to free it is to reverse flow them. The ultrasonic bath frees the tiny particles. They come out super clean.

Here's where I get the "rebuild" kits.

http://www.bonanza.com/listings/Fuel-Injector-Service-Rebuild-kit-6-Cylinder-Engine-Bosch/52065711

Rusty

 

[RustySJohnson]

Soaked for an entire month

They've been soaking a while, I don't think it's necessary to do it this long but I've been under an overwhelming workload here lately and haven't had time to tackle this. I finally got a chance to use my Xmas gift ultrasonic cleaner. It's much stronger than the one's I purchased and modified from Harbor Freight. The Harbor freight one's are great for the money though, not dogging them.

The set I'm installing were pulled from a salvage yard, reconditioned as described above. Other than being a high mileage first Gen, I have no background on the donor injectors or vehicle(s). There's also no telling if the 6 I'm working with even came out of the same vehicle. I hoard these as well as other expensive electronic parts for the Gen's, maybe even soon to be unavailable as the vehicle ages.

The one's I reconditioned were some of the worse I've seen as far as filter screens are concerned. All but 1 were deteriorated to the point the filters had decentigrated. I'm sure some of the contaminates outside the usual crap that makes it past the filter include tiny pieces of the screen. In case you're wandering, I remove the screens prior to soaking or cleaning them, so the carb cleaner is not the cause. 1 injector was purchased rebuilt at some point in time as you can see the filter is in good condition and it's like the one's I buy.

Now, I have a question...... I think it's relevant to this thread. It's about using talcom or baby powder to treat the intake manifold gaskets prior to reassembly in order to keep them from sticking so you may reuse them if so desired. I've heard of it, haven't researched it much, but was curious if there are any qualified mechanics that can chime in on this? Just FYI, I am not a mechanic, only a tinkerer. I have never been employed as a mechanic, I'm "Internet Qualified" and built my own setup for Inejctors, so take my advice with this in mind. I am a Business Software Developer by trade, and an Automation Engineer, not any type of certified mechanic. I just enjoy picking up a wrench on the weekends, it's therapeutic in an odd way. I know the first Gen up and down, so I stick to what I know and make sure it's well maintained.

Her's some photos, aren't they beautiful?