fuel injectors

[Lupin398]

Hey guys, I've heard about fuel injectors wearing out slowly over time. My truck has 197,700 miles and I'm fairly sure they're the originals, I'm occasionally getting rough running like a cylinder just gets skipped completely, no detonation or preignition and get a much rougher running while doing 30MPH while maintaining speed but not faster or slower.

Could this be the injectors going out? And if so, new injectors shouldn't hurt fuel efficiency, correct?

[bubba22349]

They will get deposits in them that effect the spray pattern. Only way to know if used injectors are still working right is to have them flow tested on a bench. Some racers looking for a bit more power used to go through a number of injectors just to find a matched set that all flow the same.

[Lupin398]

Hm. I was just wondering if it was worth it to pony up $100 or so and get a set of flow-matched refurbished injectors, these have 200,000 on them and I'm mostly looking for trouble before it finds me one day on the side of the road

[StrangeRanger]

Feed it a couple of bottles of injector cleaner and see what happens.

[Emerald 74 4X4]

I would be more inclined to say your problem is ignition related at a certain load. Very well could be injector, but injector symptoms usually occur at cold startup and warmup periods, not hot at specific loads.

A new set of injectors can sometimes surprising wake up an engine that you never knew had it in it. Testing or replacing is the only real way to know for sure though.

[Lupin398]

I see. For the $90 some it is for a set of 6 that are matched on eBay I think I might give it a shot. The EFI trucks are suppose-to go rich-lean-rich-lean back and forth fairly quickly, right?

[Emerald 74 4X4]

Yes, rich and lean fluctuation is normal. It is the o2 sensor sending a voltage to the ECM telling it to enrich or enlean the engine, but only under idle and cruise driving. It will go rich under accel (0.5 to 0.9 volts) and lean under decel (0.5 to 0 volts). If it is slow, then maybe an o2 sensor is in need of replacement. If it stays rich or lean, then you probably have an issue other than an o2 sensor.

Be careful of cheap injectors on ebay. Sometimes you get what you pay for, and could get improperly flow tested injectors, or poorly rebuilt ones. (aka krylon rebuild). The I6 also uses smaller injectors and higher fuel pressure than what normal flow testing is performed under (testing is usually done at 43.5 psi, the I6 runs about 58 psi) Do your homework and make usre you get the right sized ones.

[Lupin398]

Yeah, I'm looking at remanned ones, they specify I6 so I would assume they're probably junkyard pulls that got remanned.

http://cgi.ebay.com/ebaymotors/Set-6-19 ... ccessories

[Luckyman]

Feed it a couple of bottles of injector cleaner and see what happens.

What SR said.

Chevron's brand has worked as advertised for me in 3.1 and 3.8 brand "B" V6's for a number of years now. $5.00-7.00 per bottle in discount and auto parts stores. $2.66 per if you dont mind getting 6 at a time at Costco (if available in your area).

[Lupin398]

hrm, while cruising my O2 sensor will occasionally report very lean and very rich and stay there, yet other times fluctuate. Also at 30mph it stutters like it wants to shift and while doing so the O2 sensor is reporting very rich.

I was going to get my ignition control module that's mounted on my driver side fender checked but I don't know if it will only detect completely dead modules or ones that are on their way out.

[StrangeRanger]

The function of the ICM has nothing whatsoever to do with the control of the fuel metering system and whether it is running lean or rich.

If you are still running the stock narrow band HEGO sensor, you are expecting way too much response out of it. Narrow band sensors are constantly switching and constantly causing the system to alternately run either rich or lean at warm cruise but they are supposed to keep the A/F ratio oscillating back and forth through a fairly narrow deadband around 14.7

[Lupin398]

Hm...I didn't even think of the fact that it may be switching so quickly that the gauge I got just stays at lean or rich and that when it switches more slowly that it shows it.

[Harte3]

A narrow band AFR gauge in a carbed application really puts on a light display with all the switching...takes a while to read it and using a vacuum gauge in conjunction with the AFR gauge helps translate what its saying.

[Lupin398]

Mine's a '94 EFI though, it just kind of makes me nervous when it does the digital equivalence of pegging lean and staying there or pegging rich and staying there. Pistons and cat. converters aren't cheap

[rikard]

I use Berrymans B12 in all my vehicles twice a year.
regards
rikard

[StrangeRanger]

The HEGO sensors are only good for 60-80K miles. When they deteriorate, they do not set a code, they merely slow down how quickly they switch. If yours is older than that perhaps it's time to replace.

[Lupin398]

Mine's brand new, less than 1,000 miles on it. Computer was throwing the same rich code before that so I figured it could be going bad and it's not that expensive so I replaced. The code is still there, as well.

[StrangeRanger]

This is the first mention of codes.
Exactly what codes are you seeing?

[Lupin398]

173 C HEGO sensor circuit indicates system rich (right side)

179 C Right side still rich, at leanest adaptive limit, during part throttle.

634 C Transmission Manual Lever Position Sensor circuit out of self test.

Code definitions taken from Fordfuelinjection.com

I have witnessed it sit at lean the other day while cruising down the road(55-60MPH) and sometimes it went beyond the gauge's capability of reading lean.
I have also witnessed it sit on almost the gauge's most capability of reading Rich while cruising, neither times would it sweep or move really, it just sat in said positions until the throttle changed.

Codes taken with an Equus 3145 code scanner.