Mechanics

MISSFIRE #2

1998 Ford Ranger

I have 98 ford ranger 2.5L 4 banger manual 5 speed. This problem has been an ongoing issue for a while now. It started out as a rough idle after acceleration or after revving the engine (anything above about 1800 RPM’s). It has been progressively getting worse as time goes on. It’s to the point now that until it’s completely warmed up it will stall and hesitate on acceleration. I CAN how ever keep it running if I give it enough gas to keep it some where around idle. I didn’t get anything for about 2-3 months, and then I got the check engine light. I pulled the codes and it came back P0302 (cylinder 2 misfire). I changed ALL spark plugs wires and injectors. Still runs bad but the check engine light has not come back on, symptoms still identical though. I did happen to get a P0301 code one time in the process of deleting the codes and trouble shooting before I replaced everything. In the mean time I’ve replaced the EGR position sensor and the EVR valve and tested the EGR valve, and all the intake manifold gaskets. (Just for the heck of it after hearing the tapping). I’ve noticed too that if I accelerate through the roughness (like getting on the freeway) I have a slight taping sound from the under the hood. (Tapping sound is louder when the engine is cold, as the engine heats up it get less noticeable, and pretty much gone after about 30 minutes of driving, still runs rough but for a less amount of time at idle.) I was thinking maybe exhaust manifold gaskets but at this point I’m just trying to trouble shoot rather than replace my entire truck.

Extra info……. Today I killed my batter ( left lights on, I know, moron) I replaced it, and the truck idles a lot better, could this be because something hasn’t completed it’s diagnostics and the computer is leaving that out for now and it’ now running better with out that info?

Thanks again, sorry for the novel, just trying to be as detailed as possible.
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Flydork20
May 9, 2006.




I love novels especially " Who dunnits" or in this case what's causing it. : D

A lot of newer vehicles run mainly off the battery with the alternator just there for charging purposes. A weak battery can cause running dificulties all by itself.

Did you clean the EGR valve and port?
Check for any other vacuum leaks along the hoses and throttle body.
Clean the throttle body and IAC valve and port.
Check the IAC valve. It controls the idle.
Try tapping the throttle position sensor with the handle of a screwdriver wiht the engine at idle. Sometimes if they are going bad tapping on them will show up as asurge or stumble in the idle.
Try swapping plug wires and or coils and see of the miss moves also.
Check the fuel pressure at the rail.
Do a compression test to check for mechanical faults such as a broken valve spring.

Good hunting and let us know. : )

Tiny
Peppermrj
May 9, 2006.
I should have mentioned in my book that I wrote, that I did all that except tap the TPS, compression check, fuel pressure check. I'm going to get this spark tester to check the plugs. I have to go buy those tools so I'll get back to you and let you know. Thanks again

Oh the code has been gone since I cleaned and changed all the plugs, wires ect. It just continues to run bad.

Tiny
Flydork20
May 10, 2006.
K I've only checked the fuel pressure because I started with that and when I did it seems high. I get 59-60 key on. When it's at ilde I get 68-70 supposed to be 35-45 right? Also when I disconnect the vacum line to the regulator theres no change.(I don't know if thats a problem though) Is that my problem you think? Or is it one of many? I haven't done anythiing else cause I figure I'll just fix stuff as I go that isn't correct. Thanks!

Tiny
Flydork20
May 10, 2006.
Have you done a vacuum test? Plugged Cat?

Tiny
Peppermrj
May 10, 2006.
Vacuum check is good, and I just bought a brand new cat with an exhaust. I did that about 2 months ago hoping that would fix the problem. I've got that portion covered. What do think about the Hi fuel pressure?
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Tiny
Flydork20
May 11, 2006.

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