'99 Rough idle/Misfire 2.5L - Page 2

RobMD · #16 02-02-2012, 05:05 PM

It's been a while since I've written here because I'm normally too busy. But everyday I get in my truck in the morning without warming it up, it irritates me to death when it starts shaking at idle approaching stop signs. I could also continue to complain about how it's sitting in traffic idling and people can see my truck shaking. Yeah, it's that bad.

Just as quickly as it came, it goes away as if it never happened. And that cyl. #2 misfire CEL goes out after a while of highway driving.

I swear... some electronic component is COMPENSATING for this rough idle... Identifying it is something like a nightmare. I can't believe a bad cylinder would cause this. Maybe it's a bad #2 injector. Or I could just drop in a new engine with new wiring harness. HA!

ekandresen · #17 02-03-2012, 08:03 AM

A guy on another site claims the problem is caused by recessed exhaust valve seats. He says that was caused by a lean condition from clogged injectors. Mine is not a daily driver and I'm not sure I feel like pulling the head on a hunch. I'll see how I feel in the spring. Or maybe buy a for sale sign and let it become someone else's problem.

RobMD · #18 02-04-2012, 09:28 AM

Quote:

Originally Posted by ekandresen

I'm not sure I feel like pulling the head on a hunch. I'll see how I feel in the spring. Or maybe buy a for sale sign and let it become someone else's problem.

Me either, really. Mine is a daily driver but if I let it warm up in the morning and/or just drive it in the summer, i'll never feel the misfiring or the CEL come on. I don't want to pull the head especially since I just replaced the timing belt and the water pump as preventative maintenance.

I suppose the worst thing that can happen is losing a valve when the retainers no longer hold it in due to recession in the head. Big deal, right?

ekandresen · #19 02-05-2012, 09:52 AM

Quote:

Originally Posted by RobMD

Me either, really. Mine is a daily driver but if I let it warm up in the morning and/or just drive it in the summer, i'll never feel the misfiring or the CEL come on. I don't want to pull the head especially since I just replaced the timing belt and the water pump as preventative maintenance.

I suppose the worst thing that can happen is losing a valve when the retainers no longer hold it in due to recession in the head. Big deal, right?

When my wife complains about a mystery noise in the car i tell her we will find out what it is when it finally fails. I guess we could wait till it eats a valve. Then I'll have a reason to pull the head.

DoubleOT4banger · #20 03-13-2012, 01:11 PM

I would think you should check the fuel injector. If it only messes up at idle, it sounds like the injector is trying to flood out the cylinder. Try switching two of the injectors and see if the problems moves to the new cylinder. Inexpensive diag.

B

RobMD · #21 03-15-2012, 03:32 PM

Sounds like a plan. I really hadn't thought of the fuel injector doing that - is that even possible? Does the injector screw up it's pulse width at idle? Seems to me there would be a trouble code for that... but now that I look in OBDII guides, there are no injector codes? Or am I mistaken...

DoubleOT4banger · #22 03-16-2012, 08:08 AM

If the injector is leaking, at idle it may be to rich to combust but at speed the demands of the process may be high enough and the speed of the engine enough that the excess fuel is burned without mishap. It's a shot in the dark but sounded like you had tried most everything else I could think of. The timing jumping around that you saw could have been the knock sensor doing it part to correct the problem and may have been a symptom more than a cause. I'm not sure about the injector codes, I would think you'd see a rich code if #2 was flooding but Ford's trouble codes can take a while to register so there's no telling.

juice455 · #23 04-28-2012, 01:19 AM

Just want to throw this out there 4 anyone with issues like described here. I have a 1998 ford ranger 2.5 that started doing issues identical to the ones listed here. I have been a mechanic for years and It baffled me for months. I changed plugs, wires, coils, crank sensor, cam sensor, maf sensor, main computer(ECM), injectors, iac, throttle position sensor, checked for intake leaks, you name it i did it. No matter what I changed it ran the same. The truck would miss at idle then smooth out slowly and seem fine. Rev it up a bit then let off miss would come back then go away. The higher you reved it the worse the miss was when you let off. If you let it smooth out then took off it would run without a miss until you let off to shift gears. Next gear it would miss then slowly go away under load, shift and its back. I honestly was baffled by it along with my father and all other mechanics as it ran so good until you let off the throttle to shift. It didnt seem like an internal problem in the motor but like a sensor or computer issue. Im convinced now its a valve seat thats recessed. If I rev it up to lets say 5500 then let off it will come down and die. Try restarting and it sounds like timing belt broke with no compression. As you keep trying to start it the compression will start to build you can hear it in the way the motor sounds while cranking. Then it starts and misses for a awhile then smooths out. Its once the lifters bleed down its ok. rev it they pump up and hold valve open just enough to cause problems. Im pulling the head this coming tuesday and replacing it with a 96 2.3 head. They are the same. I will repost with results but im sure this is it. If anyone wants a pic ill post a link so you can see just what a recessed valve looks like on a 2.5 ranger. People say its from an dirty injector issue causing it to run lean. Well that may be but mine I believe was caused by driving it with a broken egr tube for months. Extra air = Lean. Just saying dont bother throwing parts at you vehical like I have. I swore up and down it was like the computer was compensating to slowly. Or an injector shutting down then slowly coming back on. Its just weird the way they run fine cruising until you let off the gas. But after along barrage of parts it will be fixed right. And the only check engine light I get is for running lean. And on the upside I wont need a new sensor for awhile.

cowseatmaize · #24 04-29-2012, 07:08 AM

Weird, mines just to opposite. It runs great all winter here in NE and come the warm temps and humidity I get the shake rattle and hope I can roll. I once was in the fast lane at 75 and all I could do was hope I could maneuver to the break down lane in traffic. It had all but died and I decided to try to limp of to the next exit. Then, like it never happened, it took off again. I made it the last 25 miles without a hitch.
I'm still baffled and it's coming back but my codes have always been the upstream 02 and the small EVAP leak. Never had anything else.
I'm working on replacing the 02 now, what a pain to swing a wrench so far. I may have to buy a socket.

cowseatmaize · #25 04-29-2012, 07:57 AM

WOW, that 02 was easier than I thought. 3 minutes? I hope I was sent the right pert, I pulled the air tube and sprayed the MAF and temp sensor while I was at it. I'll see what's fixed or broken now. This truck is my first venture into OBD2.

ekandresen · #26 04-29-2012, 01:27 PM

Quote:

Originally Posted by juice455

Just want to throw this out there 4 anyone with issues like described here. I have a 1998 ford ranger 2.5 that started doing issues identical to the ones listed here. I have been a mechanic for years and It baffled me for months. I changed plugs, wires, coils, crank sensor, cam sensor, maf sensor, main computer(ECM), injectors, iac, throttle position sensor, checked for intake leaks, you name it i did it. No matter what I changed it ran the same. The truck would miss at idle then smooth out slowly and seem fine. Rev it up a bit then let off miss would come back then go away. The higher you reved it the worse the miss was when you let off. If you let it smooth out then took off it would run without a miss until you let off to shift gears. Next gear it would miss then slowly go away under load, shift and its back. I honestly was baffled by it along with my father and all other mechanics as it ran so good until you let off the throttle to shift. It didnt seem like an internal problem in the motor but like a sensor or computer issue. Im convinced now its a valve seat thats recessed. If I rev it up to lets say 5500 then let off it will come down and die. Try restarting and it sounds like timing belt broke with no compression. As you keep trying to start it the compression will start to build you can hear it in the way the motor sounds while cranking. Then it starts and misses for a awhile then smooths out. Its once the lifters bleed down its ok. rev it they pump up and hold valve open just enough to cause problems. Im pulling the head this coming tuesday and replacing it with a 96 2.3 head. They are the same. I will repost with results but im sure this is it. If anyone wants a pic ill post a link so you can see just what a recessed valve looks like on a 2.5 ranger. People say its from an dirty injector issue causing it to run lean. Well that may be but mine I believe was caused by driving it with a broken egr tube for months. Extra air = Lean. Just saying dont bother throwing parts at you vehical like I have. I swore up and down it was like the computer was compensating to slowly. Or an injector shutting down then slowly coming back on. Its just weird the way they run fine cruising until you let off the gas. But after along barrage of parts it will be fixed right. And the only check engine light I get is for running lean. And on the upside I wont need a new sensor for awhile.

Please keep us posted on your repair. Should be interesting if a new head fixes things

RobMD · #27 04-29-2012, 02:24 PM

Quote:

Just want to throw this out there 4 anyone with issues like described here. I have a 1998 ford ranger 2.5 that started doing issues identical to the ones listed here. I have been a mechanic for years and It baffled me for months. I changed plugs, wires, coils, crank sensor, cam sensor, maf sensor, main computer(ECM), injectors, iac, throttle position sensor, checked for intake leaks, you name it i did it. No matter what I changed it ran the same. The truck would miss at idle then smooth out slowly and seem fine. Rev it up a bit then let off miss would come back then go away. The higher you reved it the worse the miss was when you let off. If you let it smooth out then took off it would run without a miss until you let off to shift gears. Next gear it would miss then slowly go away under load, shift and its back. I honestly was baffled by it along with my father and all other mechanics as it ran so good until you let off the throttle to shift. It didnt seem like an internal problem in the motor but like a sensor or computer issue. Im convinced now its a valve seat thats recessed. If I rev it up to lets say 5500 then let off it will come down and die. Try restarting and it sounds like timing belt broke with no compression. As you keep trying to start it the compression will start to build you can hear it in the way the motor sounds while cranking. Then it starts and misses for a awhile then smooths out. Its once the lifters bleed down its ok. rev it they pump up and hold valve open just enough to cause problems. Im pulling the head this coming tuesday and replacing it with a 96 2.3 head. They are the same. I will repost with results but im sure this is it. If anyone wants a pic ill post a link so you can see just what a recessed valve looks like on a 2.5 ranger. People say its from an dirty injector issue causing it to run lean. Well that may be but mine I believe was caused by driving it with a broken egr tube for months. Extra air = Lean. Just saying dont bother throwing parts at you vehical like I have. I swore up and down it was like the computer was compensating to slowly. Or an injector shutting down then slowly coming back on. Its just weird the way they run fine cruising until you let off the gas. But after along barrage of parts it will be fixed right. And the only check engine light I get is for running lean. And on the upside I wont need a new sensor for awhile.

It's all so similar to mine except the fact that I've never had a lean code or ANY OTHER CODE for that matter. Just the annoying random #2 misfire. I really don't get how a mechanical issue can come and go intermittently like that. PARTICULARLY if I do excellent on the highway (no matter if pulling 2000 pounds of trailer weight) or simply when the truck gets all warmed up.

I haven't replaced many sensors. Just the throttle and I think a coolant sensor. I've checked the others with a voltmeter. I think the MAF sensor is working. I don't get it and never will get it. I'll just drive it as is, then the resulting damage will be whatever the resulting damage is!

juice455 · #28 04-30-2012, 01:05 AM

Im just throwing this out there but on the highway or cruising mine runs like nothing is wrong. When cold and oil is thick its worse then warmed up. Basically i got a theory as to why it acts up only after rev. If a valve seat is to recess badly the spring would be under very little pressure seating the valve because the spring would be compressed less at seat. On a ranger head the lifter and valve are on opposite sides of the head and the cam runs down the middle above them.(first ive seen) So with the spring having little pressure to seat the valve - the combustion force helps seat it under load. Combustion pressure pushing valve down compensating for the spring pressure lost needed to compress lifter. Then when you let out of the gas the vacuum sky rockets in the cylinder but yet oil pressure is up because of rpms. So being there is so little force on the lifter because the spring isnt pushing hard enough it pumps up and holds the valve open. Then as the motor starts going back under load, combustion starts pushing the valve shut and collapses the lifter down enough to seat the valve on the recessed seat. Thats why after shifting it misses for a bit then smooths out. Just a quick thing if I shift super fast and dont let off the gas pedal (rpms climing fast) and slip clutch and drag motor back down while still on gas so motor is under constant load it dont miss in next gear. Ill let you all know but im 99.999934% sure its this. If its not im going to hold pedal to floor and fix it right

And I replace O2 sensors also. Every sensor is replaces on it that i know exists. Timing marks dead on. Still only get lean code. But if I reset it - it takes awhile to come back. Like 3-4-5 hours of driving around. Link to pics and follow up coming soon. So maybe this will help someone else with a rediculous problem such as this if im correct which i may not be but im pretty good at coming up with theories

Usually my theories are right just not so far with this truck.

RobMD · #29 04-30-2012, 04:25 PM

Quote:

So maybe this will help someone else with a rediculous problem such as this if im correct which i may not be but im pretty good at coming up with theories Usually my theories are right just not so far with this truck.

Well, I thought I was always right with my theories and scientific analyses until I first discovered this problem with my truck 4 years ago. 4 years ago, my truck barely misfired at idle and would only do it if you raced the engine and came to a stop. Now, all I have to do is simply rev it and then let off, whoop whoop whoop whoop whoop it goes. Stupidest looking truck at any stoplight. Everyone knows I'm shaking, they can see my arm bouncing in the mirror.

Rather than pull my hair out, I decided to deal with it and if it drops a valve, well, then, I would PROBABLY ENJOY IT.

juice455 · #30 05-02-2012, 06:24 AM

Cylinder head is off. All exhaust seats recessed. Number 2 by far the worst. cylinder 2 is very noticable to bare eyes. 1,3,4 are noticable when compared to new head going on. Now its back outside to put it back together. Possitive it will run right when i get it back together. Ill let you all know but my problem is recessed seats. Also my miss started out suddal then progressivly got worse. And I also bought it this way thinking it would be an easy fix. In the end ill have myself a truck thats all new in parts. Ill post a link to pics once i find my digital camera.