Engine hesitates and then pops when accelerating
Engine hesitates and then pops when accelerating
Hey everyone! I recently purchased a 1996 XLT Ranger with the 2.3l and 5sp manual tranny. It has 152K miles on the odometer now, and coming home today I noticed a problem. I don't have a tach so idk what the RPMs were but I will give as much info as I can. I think this is an engine issue but I could be wrong. Let me explain...
It runs great and has no issues before I get on the freeway and while I am on the freeway, but immediately after I got off the freeway (after about 15 miles) I come to a traffic light and stop. Everything seems fine. When the light turns green I put it in first and start to accelerate. It goes forward but acts like it is working hard and then hesitates at about 5-8mph, then I hear a single pop of some sort coming from somewhere in front of the firewall but I couldn't figure out where. After it popped it immediately regained power and accelerated just fine. At the next light it does the same thing in first, then repeats the process when accelerating in 2nd, and also again in 3rd. It didn't do it in 4th, but it did not want to be in 4th going 35mph (It usually does just fine at 30 or more in 4th) and I had to shift down to 3rd to maintain my speed going down the road. I have no idea where the popping is coming from, it doesn't seem to be the tranny but I could be wrong. It seems like something I need to fix soon, as it is my daily. (Put about 800 miles on it in the last 2 weeks) Does anyone have any ideas as to where the popping is coming from and how I can fix it?
The only other problems related to this that I have noticed is after getting off the freeway in the past (only after being up to speed for 15 minutes or more) it would not really want to accelerate, and then have a sudden burst of power in the same situation. It seems to be worse the longer I am at speed. For the first week or so I assumed that I just still needed to get used to the transmission, as it shifts a lot different than any manual I have driven. But I don't think this is the case at this point. Any help would be appreciated.
It runs great and has no issues before I get on the freeway and while I am on the freeway, but immediately after I got off the freeway (after about 15 miles) I come to a traffic light and stop. Everything seems fine. When the light turns green I put it in first and start to accelerate. It goes forward but acts like it is working hard and then hesitates at about 5-8mph, then I hear a single pop of some sort coming from somewhere in front of the firewall but I couldn't figure out where. After it popped it immediately regained power and accelerated just fine. At the next light it does the same thing in first, then repeats the process when accelerating in 2nd, and also again in 3rd. It didn't do it in 4th, but it did not want to be in 4th going 35mph (It usually does just fine at 30 or more in 4th) and I had to shift down to 3rd to maintain my speed going down the road. I have no idea where the popping is coming from, it doesn't seem to be the tranny but I could be wrong. It seems like something I need to fix soon, as it is my daily. (Put about 800 miles on it in the last 2 weeks) Does anyone have any ideas as to where the popping is coming from and how I can fix it?
The only other problems related to this that I have noticed is after getting off the freeway in the past (only after being up to speed for 15 minutes or more) it would not really want to accelerate, and then have a sudden burst of power in the same situation. It seems to be worse the longer I am at speed. For the first week or so I assumed that I just still needed to get used to the transmission, as it shifts a lot different than any manual I have driven. But I don't think this is the case at this point. Any help would be appreciated.
It just happened today again, but this time it was only when I started going up a hill. It sounded and felt kind of like when you shift gears wrong on a bicycle. The only difference is that this is not a bicycle and should not be making that sound.
As far as I know it is 100% stock, although I was beginning to suspect the fuel filter. When I changed the oil a couple of weeks ago I noticed that the fuel filter looks like it hasn't been changed in a long time, so I will be changing that in a few days. After that I will see if it solves the problem, but it might be a few weeks before I drive it enough to know for sure with this quarantine stuff happening.
So after changing the fuel pump, it did not seem to solve the problem. It actually got to the point where it wouldn't accelerate at all on Thursday, and I had to put the clutch in and rev it up to about 4k rpms before letting the clutch back out slowly. Thankfully that worked. It seems that I might have to live with this, and just rev the engine a little higher when starting from stopped after getting off the freeway, but I hope that is not the case.
I have experienced this exact issue. Although not as severe as you are experiencing this..I usually get the popping after coming off the freeway sometimes midway in 1st or after shifting into 2nd. All while accelerating popping sounds middle firewall area. No check engine light etc. I have a 1998 2.5l 5spd with 198k and climbing.. truck runs decent (picked it up with a blown head gasket found out cylinder 1 had a decent crack replaced the gasket and put some liquid headgasket after...that was 2 years ago.) I have not had the issue in a few months. It kinda of just went away..the only thing I think I have changed is the battery clamps my positive clamp was extremely corroded. I am actually looking for a new motor now. But I am curious if we can find something that is similar between our trucks to hunt this issue down! It's a horrible feeling especially when everyone is in a rush and on your A$$ leaving the light
It reads like there is a misfire, which dumps unburned gasoline into the exhaust manifold, then next cylinder, that fires, cause the unburned gasoline to ignite in the exhaust manifold, the "POP" noises
With 1995 to 2001 2.3l and 2.5l you have dual spark plugs and dual coil packs
This means you can check if all spark plugs are working
After engine is warmed up shut it off
Unplug either coil packs 3 wire connector
Start engine
Should idle smoothly, REV it a few times
If its missing then a spark plug is bad on that side
Repeat but unplug the other coil pack to see if all spark plugs are working on that side
With 1995 to 2001 2.3l and 2.5l you have dual spark plugs and dual coil packs
This means you can check if all spark plugs are working
After engine is warmed up shut it off
Unplug either coil packs 3 wire connector
Start engine
Should idle smoothly, REV it a few times
If its missing then a spark plug is bad on that side
Repeat but unplug the other coil pack to see if all spark plugs are working on that side
I have experienced this exact issue. Although not as severe as you are experiencing this..I usually get the popping after coming off the freeway sometimes midway in 1st or after shifting into 2nd. All while accelerating popping sounds middle firewall area. No check engine light etc. I have a 1998 2.5l 5spd with 198k and climbing.. truck runs decent (picked it up with a blown head gasket found out cylinder 1 had a decent crack replaced the gasket and put some liquid headgasket after...that was 2 years ago.) I have not had the issue in a few months. It kinda of just went away..the only thing I think I have changed is the battery clamps my positive clamp was extremely corroded. I am actually looking for a new motor now. But I am curious if we can find something that is similar between our trucks to hunt this issue down! It's a horrible feeling especially when everyone is in a rush and on your A$$ leaving the light
Okay so update on my 98. I have checked the plugs as previously suggested via unplugging coil packs. Drivers side set of plugs idle is smoothish definitely not perfect. Now when I unplug the passenger side coil pack definitely a rougher idle stumbles here and there. One thing I did notice is that passenger side coil pack is broken right where the 3 wire connector plugs into it. It has some flex up and down could probably break the connector port right off if I wasn't careful. So I will be replacing that today see what happens after that! Plugs will be next just curious how different it runs with a 100% coil pack
The dual spark plugs were added for better performance, the 2.3l(2.5l) Lima engine ran just 4 spark plugs and distributor from 1974 to 1988, in several Ford vehicles
When they went distributorless in 1989 the heads were redesigned for 2 spark plugs
Dodge Hemi used dual plugs for same reason, performance
So your 2.5l should idle smooth and run/drive OK with just 4 spark plugs working, not quite as "peppy" but should run OK
When they went distributorless in 1989 the heads were redesigned for 2 spark plugs
Dodge Hemi used dual plugs for same reason, performance
So your 2.5l should idle smooth and run/drive OK with just 4 spark plugs working, not quite as "peppy" but should run OK
So I did that test today, and it turned out exactly as you said it would. I dare say it even ran a little smoother with only the right side plugs, but I plugged everything back in when I was done anyway. I took a video of them all to compare them and I am pretty sure one of the left side plugs is out.
All spark plugs, "normal" operation:
Left plugs only, missing and stumbling a bit
Right plugs only, seems to be a lot smoother:
So now, I suppose the next thing to do is to change the spark plugs. I am pretty busy for the next few weeks but it can wait a month or so. My question as far as that goes is exactly what all I really need to replace when I change the plugs. Obviously, getting new spark plugs is a start, but I have heard that on an older vehicle such as this you should always change your spark plug wires when you change the plugs, is this true? I can get a set of plugs for $40, and then the wires are another $40, so I don't necessarily want to spend the extra money if I don't have to, especially considering the current state of the economy. Also, is there a way to test the left side distributor to make sure that that is not the problem, or would I only know if changing the plugs and wires doesn't solve the problem?
All spark plugs, "normal" operation:
Left plugs only, missing and stumbling a bit
Right plugs only, seems to be a lot smoother:
So now, I suppose the next thing to do is to change the spark plugs. I am pretty busy for the next few weeks but it can wait a month or so. My question as far as that goes is exactly what all I really need to replace when I change the plugs. Obviously, getting new spark plugs is a start, but I have heard that on an older vehicle such as this you should always change your spark plug wires when you change the plugs, is this true? I can get a set of plugs for $40, and then the wires are another $40, so I don't necessarily want to spend the extra money if I don't have to, especially considering the current state of the economy. Also, is there a way to test the left side distributor to make sure that that is not the problem, or would I only know if changing the plugs and wires doesn't solve the problem?
I would definitely change both plugs and wires. It is a bit more expensive but worth it. You can Ohm out each wire to see if you have a bad one but then again it's easier to just put all new ones and be done.
Finally got around to changing the plugs and wires today (along with the timing belt, water pump, and thermostat), and I daresay that #4 driver's side spark plug wire is quite the bear to access. The old plugs I pulled out were all out of whack, none of them were anywhere close to the spec gap of .044, and they were anywhere from .02 to .09, the one out of the passenger side of cylinder 3 was also fowled pretty bad. (This was the plug with a gap of 0.02) I drove it around in town and a bit on the highway afterward and the problem is still there. After getting off the freeway I have significantly less power, and if I push the gas pedal far enough while it is refusing to accelerate (at least in a timely manner) it still pops, which I am pretty sure is a backfire as the sound is coming from where the exhaust manifold is, sometimes a little farther down the exhaust pipe.
This was somewhat discouraging, as I was hoping that after spending two days (I'm not an experienced mechanic, but I am reasonable mechanically inclined) tearing the engine apart and putting it back together again to do all that work, there doesn't seem to be any improvement. I will try redoing the test where I disconnect each coil pack separately and see how it runs if not tomorrow hopefully sometime soon. If the results are the same would the next thing to check/replace be the coil pack itself? I don't want to just go replacing parts *****-nilly because that adds up fast, but I suppose that is the next thing to try. Is there is good way to test the coil pack before I go out and spend the money on a new one?
This was somewhat discouraging, as I was hoping that after spending two days (I'm not an experienced mechanic, but I am reasonable mechanically inclined) tearing the engine apart and putting it back together again to do all that work, there doesn't seem to be any improvement. I will try redoing the test where I disconnect each coil pack separately and see how it runs if not tomorrow hopefully sometime soon. If the results are the same would the next thing to check/replace be the coil pack itself? I don't want to just go replacing parts *****-nilly because that adds up fast, but I suppose that is the next thing to try. Is there is good way to test the coil pack before I go out and spend the money on a new one?
Last edited by saulcuddy; Jul 8, 2020 at 12:39 AM.
Just running the engine on one coil pack is good enough to test that coil pack, engine needs to be warmed up first for best testing, coils run hot and can test "OK" cold but start to misfire when hot
If you get misfires on one coil pack then swap spark plug wires around(from other coil pack) to take new spark plug and wires off the table, if that coil pack still misfires then test other coil pack first, if its OK swap them around and see if misfires stays with coil pack or the WIRES from computer
The computer can get bad transistor used to "fire" a coil in the pack, so coil pack is OK the misfire comes from computer
You can use an ohm meter to test an ignition coil but there is a problem with that, test can tell you if a coil is bad, but can NOT tell you if coil is good, because of the temp issue
If you get misfires on one coil pack then swap spark plug wires around(from other coil pack) to take new spark plug and wires off the table, if that coil pack still misfires then test other coil pack first, if its OK swap them around and see if misfires stays with coil pack or the WIRES from computer
The computer can get bad transistor used to "fire" a coil in the pack, so coil pack is OK the misfire comes from computer
You can use an ohm meter to test an ignition coil but there is a problem with that, test can tell you if a coil is bad, but can NOT tell you if coil is good, because of the temp issue
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fordstranger
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Jul 28, 2009 07:58 PM



