2.5 intermittent miss at idle

[Sunk]

I picked up a 2wd '99 Ranger/2.5/s spd a couple days ago. When I got it, it would stumble when the RPMs dropped to idle, and sometimes stall. I found out the bulb for the CEL was burned out, so I fixed it and pulled the codes. It had codes for Misfire on #1 and #2, and excessive EGR flow. I was able to track it down to the DFPE and IACV. I replaced those and it's much better. It doesn't throw any codes now and doesn't stumble nearly as much when dropping to idle, however it does still do it. If I stay at lower RPMs, maybe less than 2500-3k or so, it's fine when returning to idle. Also if i shut it off and restart it, it idles smooth.

I checked the PCV valve and that seems good. I couldn't find any vacuum leaks either. It seems to me that it should be throwing codes given what it's doing. It's probably something simply but I can't figure it out. Ideas?

 

[rharriman]

I am having the exact same problem! I have had it in the Ford shop twice for this issue and in comes out running better but its always rough coming from higher RPM to idle and I have a check engine light as well. I have had MAF problems in the past its just the opposite, it won't pick up RPMs and stalls. I will be very interested what you find out. I thought it was a bad wire or plugs (there are 8 BTW on this 4 cylinder engine ) They, the ford guys think its a stuck valve but a head rebuild is kinda costly for a 98 ranger....

Looking/hoping for some help here..

 

[modelageek]

a few thoughts. How are the sparkplugs? fuel filter? fuel pressure?. the ect sensor can effect the idle? did you reboot the pcm after changing parts?..........i have caught pending codes before by checking for codes when the truck is acting up but the cel is not on. I have a cheap code reader

 

[Sunk]

Yeah, rebooted the PCM after swap the parts. I ended up making a couple trips back and forth to the parts store as I was figuring things out, and kept checking codes. There were less and less codes each time.

The fuel filter is pretty new I was told. I'm not sure about the the fuel pressure; a friend who was helping me is gonna let me use his FP tester in a couple days. I haven't checked the plugs, but it was a thought. I didn't check the ECT sensor, is that easily testable, such as with a voltmeter?

 

[modelageek]

Yeah, rebooted the PCM after swap the parts. I ended up making a couple trips back and forth to the parts store as I was figuring things out, and kept checking codes. There were less and less codes each time.

The fuel filter is pretty new I was told. I'm not sure about the the fuel pressure; a friend who was helping me is gonna let me use his FP tester in a couple days. I haven't checked the plugs, but it was a thought. I didn't check the ECT sensor, is that easily testable, such as with a voltmeter?

the ect can be checked with a multimeter. I forget the resistance? a cheap codereader comes in handy! once you buy the fuel filter removal tool for $10 the filters are only $10 and imho dont get changed enough. if you change the plugs and wires only use autolite or motorcraft DP's. I used the autolite plugs and wires becasue they were a lot cheaper but still come with the hooks for the 3 tough plugs. do you have any codes now?

 

[bigjim240z]

I have the same issues, misfire on #2, and excessive EGR flow. Fixed the egr problem but still get the po302. Took it to Ford and they said it was a leaking valve on cylinder 2. They were wrong and i swapped the head for nothing because it runs exactly the same with a brand new head. Compression is within spec across all 4 cylinders. So far ive changed every sensor except the tps and oxygen sensor, ive changed the head, dfpe, egr, fuel injector, coil packs, plugs, wires, fuel filter and fuel pump. Im ready to just throw in a tps, oxygen sensor and maybe even an ecu. Ive spent way way too much money trying to fix this problem.

 

[rharriman]

a few thoughts. How are the sparkplugs? fuel filter? fuel pressure?. the ect sensor can effect the idle? did you reboot the pcm after changing parts?..........i have caught pending codes before by checking for codes when the truck is acting up but the cel is not on. I have a cheap code reader

I replaced the wires and plugs this trip still nothing, last time it was the CPU, Fuel filter I did myslef before taking it in the first time. Looking a selling a ranger now, LOL. This forum is my last effort to fix it. I am going to take the info I get here and try and figure it out....

 

[Sunk]

I checked the resistance of the ECT, and got 6.xx and that seemed to be in normal range.

http://fordfuelinjection.com/?p=28

I still don't have a CEL, but I don't know about any pending codes, I haven't scanned it. I may do the fuel filter since I already have the tool. I'm gonna go check a few plugs.

 

[Sunk]

Okay, the plugs look fine to me.

 

[Sunk]

Well the fuel pressure is just fine... I'm gonna run down to the store and check codes a little bit later to see if there's anything pending.

 

[modelageek]

Well the fuel pressure is just fine... I'm gonna run down to the store and check codes a little bit later to see if there's anything pending.

what was the koeo pressure?, koer? how many cycles did it take to get to full pressure koeo?. how much did the pressure drop in 5 minutes after you turned the truck off?

 

[modelageek]

Okay, the plugs look fine to me.

did you pull the plugs from #1 and #2 on the drivers side? Did you change the FF? Did you add some Techron to the tank?

 

[Sunk]

KOEO pressure was 65, KOER was 65, and would jump to 70 ish when you rev it. It only took a cycle or two to get to full pressure KOEO. After 5 minutes it dropped maybe 5-6 psi.

I pulled the plugs from #1 on the drivers side and #2 on the passenger side (I think, maybe the opposite). The fuel filter looks really new, I know the PO said he had it done, not totally sure when though. That's still something I'm thinking of. I haven't added any cleaner, almost did Seafoam, but decided to save the $10 for now.

 

[Sunk]

Also, I plugged in a scanner again and I have no pending codes either.

 

[Sunk]

So the CEL popped on again today while driving. I tried to borrow the scan tool from the local Kragen, but apparently they don't loan them out. The guy told me that they used to, but shops starting complaining that they were losing business so they stopped. WTF?

Can I pull codes with a test light?