Rough Idle and Poor Gas Mileage 2.3L

[Fitzy]

I have a 1994 X-cab 2.3L that has turned into a giant headache. It started with an oil change at Walmart and they upsold me to a fuel injection cleaning (bad idea). They dumped some in the tank and connected a line to the fuel rail. I had less than 1/4 tank and they told me afterwards to fill it up as it was shaking bad when I picked it up (was fine before). Since then it shakes bad at idle (starts ok). Thought it was down a cylinder. Have taken it to two different mechanics and they don't know what it is. So far have new plugs (all 8), new plug wires, new exhaust, new cat, new battery, had the fuel injectors cleaned (professionally) and flow tested (good), cleaned the MAF sensor (girlfriend's brother did this, ex ford service manager), compression is good on all cylinders (tested), checked for vacuum leaks (couldn't find any), and there are no codes (took to autozone plugged OBD1 reader in) and the CEL has never come on. Sorry for the long post but I don't know what else to do, this thing is driving me crazy. Oh, and my fuel mileage is way down and there is a loss of power. Thank you in advance for any help.

 

[RobbieD]

Not a long post, and welcome. In all that's listed, you didn't mention the Idle Air Control (IAC) valve; was this cleaned or replaced?

 

[Dave R]

Did either of the mechanics do any form of cylinder balance test to try to figure out if it's limited to one cylinder or something that is randomly effecting all of the cylinders?

 

[DCarey515]

Could the fuel injection cleaning have killed the cat?

 

[Fitzy]

Thanks for the replies. What is the best way to clean the IAC valve? How is a cylinder balance test done and what does it show? The engine will shake pretty rough at idle so that's why we originally thought it was down a cylinder causing the imbalance but we pulled the plug wires trying to isolate a down cylinder but they all "seemed" to be firing, but I'm probably wrong. The cat was replaced after the injection cleaning. I think that it might be starting to use oil now. I went to the local Ford dealership and they said that they charge $94 for a diagnosis, I'm tempted to do this as I want to figure out what's wrong but I hate to keep pumping money into this thing with no results...argh!!!

 

[97ranger xlt]

did anyone reset the computer? if not disconnect the battery for 10 mins...

and clean the IAC and check TPS.

 

[Throwbot]

Still, power loss, bad mileage, rough idle

Fitzy,
I've read thru this thread, and still have yet to see a coherent answer. Sadly, I can't provide one either, worse yet, I intend to add to the question.

Status:
I have a 97 ranger extra cab, 2.3L Manual trans 245,000 miles.
I bought the truck with most of the problems I am about to list, EXCEPT the poor mileage. The idle used to porpoise and then die occasionally when at a stop. It would also idle very rough, and was basically gutless(typical I hear). I started with heavy diagnosis, which resulted in, on one test drive, forgetting to plug back in the TPS. From that drive forward, my mileage has never been the same. ECM-reset. TPS replaced. ECM-reset. IAC replaced and MAF cleaned. During my check of the MAF, the engine sputtered, revved, and almost died. So, I replaced the PIG-tail to the MAF with a junk yard part. [yes I tested resistance across all lines (for both) and found no conductivity issues] ECM-reset. The Engine still idles rough, almost dieing but now, no fluctuation. I turned the idle up slightly with the manual screw on the throttle body. The ECM seems to be compensating for this and dropping the RPM's at idle to the very rough, engine shaking low speeds. During the following two weeks, and two tanks of gas, I verified the mileage went from 22+mpg to about 16mpg. And a new problem has surfaced; the motor now stays at high RPM when when decelerating. If I drop out of 4th into neutral to stop (or other) the engine stays around 2000 rpm until the truck has come to a stop. (I will turn the manual idle screw down on the throttle body immediately after placing this post.) The next service performed; I removed the throttle body, the EGR-valve and the top half of the intake manifold. I cleaned them all, removing a significant amount of tar-like buildup from the manifold. The EGR moved freely and easily. Care was taken to make sure the vacuum lines were correct. I did a smoke test to make sure no leaks were present. The fuel Pressure Regulator on the injection Tree was tested manually, and it moved as expected. I then re-assembled, ECM-reset and placed a fuel Press-testr on the tree and went for a drive. It delivered a steady 40 psi at speed and dropped to 33-36 psi at idle. I unplugged the vacuum assist back into the F-P-Regulator, and drove again. During the drive and idle, the Pressure did not once move from 40 psi. Vacuum line re-attached. ECM-Reset. 2 more tanks of fuel used, and still getting 16-17 mpg with intermittant periods of No power and absolutely no F-ing power. I pulled off 1 spark plug wire at a time, replaced it, then went to the next and observed no change in idle. This is an 8 plug system, so that was expected. I have 8 new plugs to install, but of the 4 I have pulled and checked, all are at the right gap, and with a clean brown color, and white insulator.

Can anyone give me some new idea what I can do?

I HAVE:
checked the brakes, and none are dragging.
maintained the proper tire pressure.
Checked the u-joints, and rear axle grease level.

Yes, I will check the compression.
Yes, I will check the speed sensor(after turning down the idle screw).
Yes, I will put in the 8 new plugs.

 

[Mazda]

Okay 2.3L has a POWER STERING PUMP SENSOR switch. What this does is control the idle when you first start the truck and your one of those start and hall ass down the road drivers. It is supposed to keep the idle high when you move the steering wheel to drive. But this sensor does not always send the right signal to the computer telling it we are good now and turn off or turn on. So what you may be experiencing is the switch not turning on and the computer gets the wrong info and you have a "BAD IDLE" the whole time. Also this sensor is very susceptible to oil/grease/fluid especially if you have a leaking PS cap or hose. The wires can become worn and rusted. Also in my experience with this switch it will not always throw a code to the computer when its malfunctioning.

I know you guys don't want to throw money at parts but a new one is about $25.00 at the parts store and it will most likely be your problem.

Also bad gas millage at your trucks mileage is 100% the O2 sensor. Replace it and watch how you pass by the gas station more often.

Bryan

 

[tomw]

I will make a SWAG. They cooked your fuel pressure regulator with their injection machine. That would explain the poor idle - pressure higher than normal, and bad fuel mileage for the same reason.
THIMK. {old IBM signe mocked by Mad Magazine..} This all started when the 'mechanics' at Wally sold you a 'injector cleaning'.... Nothing else changed. Drove in smooth, and drove out broke.
They broke it. Their machine either ate or jammed the regulator. Maybe the tech did not adjust the pressure properly, and popped the diaphragm or jammed the thing/bent/distorted. I dunno.
I would either boneyard another regulator or purchase new. OTOH, a cooked O2 will report 'lean' and the computer will try to compensate, but that should not frack the idle, and the mileage would not drop THAT far. A bad regulator can goof the idle and kill mpg. I fixed a 4.0 with a bad regulator. Must have gold plated gizzards as it cost an arm, leg and 1st born... for a regulator??? But the mpg doubled and the idle went back to smooth.
tom

 

[Throwbot]

continuing Ranger Headaches

to Mazda,
Thank you for your reply. I will certainly check/clean/test the PSPS-switch. I would hope that you would gather from the depth and clarity of my post that I am not "one of those start and hall ass down the road drivers." I do infact, give it about 2 minutes minimum of warmup before pulling out of the driveway. And often much more. usually waiting on the lady.... And since this truck Barely reaches 60mph, down a hill, with a tail wind, yeah.... not so much.
1. I turned down the mechanical Idle screw on the throttle body with no change in results.
2. I installed a new upstream O2 sensor, which I forgot to mention in my first post. I am told that the DownStream o2 sensor doesn't do much. At 18$ for a new DS-o2 sensor, I am willing to try it.
--Also, I am very willing to throw parts at it, as can be implied from my first post. I believe to date I've spent about 165$ over a 3 month period, and thats acceptable.

To tomw,
When you say you "will make a SWAG", does that mean "Secretly We Are Gay"? You are replying to a user who posted in September of 2007, i doubt he will reply. I invite you consider the currently proposed problem, Not the old Wal-Mart one, and apply your knowledge about the 2.3L Ranger motor. Here is some more information for you;
I am getting codes, and they include cylinder 2 mis-fire and something to the effect (I can't recall perfectly) that the o2 reading is resulting in the system pushing the mixture to Lean as far as it can [still rich at the sensor]. It is the same code with the old o2 as with the new o2 sensor. I remind you, the pressure at the injector tree is a steady 40 p.s.i. This concerns me because I have seen several posts saying this should be 70 p.s.i.

Perhaps my injectors are clogged, damaged. They are next on the "throw parts at it" list.

 

[Mazda]

to Mazda,
Thank you for your reply. I will certainly check/clean/test the PSPS-switch. I would hope that you would gather from the depth and clarity of my post that I am not "one of those start and hall ass down the road drivers." I do infact, give it about 2 minutes minimum of warmup before pulling out of the driveway. And often much more. usually waiting on the lady.... And since this truck Barely reaches 60mph, down a hill, with a tail wind, yeah.... not so much.
1. I turned down the mechanical Idle screw on the throttle body with no change in results.
2. I installed a new upstream O2 sensor, which I forgot to mention in my first post. I am told that the DownStream o2 sensor doesn't do much. At 18$ for a new DS-o2 sensor, I am willing to try it.
--Also, I am very willing to throw parts at it, as can be implied from my first post. I believe to date I've spent about 165$ over a 3 month period, and thats acceptable.

The way I found out about the sensor is I to start the truck and let it sit for a few minutes before I take of. You know usually putting on my sun glasses, getting situated, listen to the radio a bit. Stuff like that. The thing is that if you move the wheel even 1 degree when starting or sitting there it will throw off the computer if the sensor is malfunctioning. I only have one O2 sensor on mine. I think they put 2 after that.

Hope you find the fix soon. I know things like this drive me crazy.

Bryan

 

[tomw]

SWAG== Scientific Wild A*s Guess.

I think the pressure should bump above 40 when you remove the vacuum line. Manifold vacuum is higher under light load. The increased vacuum is proportional to fuel needed, so the regulator drops pressure with light load, and increases pressure with higher load(low vacuum - WOT or accel) only to drop it back at cruise.
The store cooked something and you are shot gunning all kinds of stuff(cannot remember and too lazy to go back and re-read). Get back to what they futzed with.
I suggest a FPR. It could have gotten hit with high pressure if 'Bob the Mechanic'(says so on his uniform shirt) attached the 'douche' machine and did not adjust pressure before powering up. [just a SWAG, but what else could be affected?]
tom

 

[Throwbot]

To all,
An update: I did a compression check;
1: 20
2: 170
3: 135
4: 11
I tested and retested, I tested from both sides on the 1st and 4th cylinders. I used a press-rubber nozzle, and then a screw in sealed type for cylinder 1 and 4. So, all these other tertiary failures (o2 sensor, steering position... ,TPS, IAC, etc.) are really not important until I put new heads on it.

I Don't think it is the Cylinders Piston rings for the following reasons; I have had o-ring failure before and it resulted in a 50-70% decrease in pressure, I have experienced a failed valve, and that resulted (like now) in a 95% pressure failure. Time to cut and paste...

 

[tomw]

Were it mine, I would be removing the cam/rocker cover and checking the followers and adjusters - 'lifters'. Being the two cylinders are at opposite ends, theres zero likelihood it is a head gasket, so it must be valves.
If it came out of nowhere, it is 'possible' the Wally goons took it out and revved it w/o having oil pressure, and jammed the adjusters. Possible. And a lot cheaper to fix than a head. The adjusters hold one end of the followers, and could be keeping the valves off-seat if they jammed. I'd take a look at the two cylinders, and try a manual bleed-down of the 4 lifter/adjusters. You should be able to apply pressure on the end of the follower and collapse the adjusters. They should re-fill with oil and take up the slack within a minute of engine startup.
NOTE: You can run the engine with the cover off *IF* you want to rustproof the engine bay with oil.
It couldn't hurt to see what's going on before doing more work, and you have to take the cover off anyway.
tom

All the above applies only if the misfire began after the 'work' was done.

 

[Throwbot]

Seriously Tomw It's 8 years old..

tomw,
You gotta know, this thread has morphed into something completely separate from the dude 8 years ago, who took his vehicle to Wal-Mart for repairs.

I am working here because the list of failures my vehicle has experienced is so similar to his. But, they are different, and there are more.

Last night I dove into the timing belt, and discovered that it may look wrong at first, but keep rotating, and it will eventually line up. I thought the alignment marks were all correct, but then I would rotate it and one of them would look 1 tooth off. Two more complete rotations of the crank, and they were in alignment again. Very frustrating.

tomw I do think you have a really good idea. I was planning to remove the head, and replace it. I removed Exhaust and Intake last night. Before popping the Valve/Cam cover I read your reply. I will attack the Lifter tonight. Thank you.