2.3L ('83-'97) Extremely rough idle at low rpm.

[lilblueskeeter]

I'm working on a 96 2.3l manual trans 2wd. It started a few days before Christmas. Went to start it and it just cranked and wouldn't fire up. It was driven a few days before and ran and drove fine. After messing around trying to get it started I put it in clear flood mode and it started and died. It would only stay running if you gave it quite a bit of throttle and it smelled rich. So I pulled the plugs and decided real quick to replace them. They were shot. Some were worn down so bad the gap was at .080. After replacing the plugs and wires it would start without putting it in clear flood mode, but still ran horrible and still had to feather the throttle to keep it running. I put a code reader to it and it showed the coolant temp sensor reading -45 degrees so I replaced it and now seems to be reading correctly. I really was hoping that was it but it didn't change anything that I could tell. It still smelled like it was running rich. I was able to take it out for a drive although quite difficult was able to drive it about a mile before I decided to come back before I got stranded. It didn't want to run at low rpm, ran really rough but ran great at high rpm. I've pulled the plugs a few different time through this ordeal and none of the plugs were wet or smelled of raw fuel. I checked the FPR for fuel in the vacuum line and it was dry. I've cleaned the MAF sensor. I've done a few other tests but can't recall everything at the moment. I'll update as I remember them. I appreciate any help I can get. Thanks in advance.

 

[Ghost of Progress]

I'm working on a 96 2.3l manual trans 2wd. It started a few days before Christmas. Went to start it and it just cranked and wouldn't fire up. It was driven a few days before and ran and drove fine. After messing around trying to get it started I put it in clear flood mode and it started and died. It would only stay running if you gave it quite a bit of throttle and it smelled rich. So I pulled the plugs and decided real quick to replace them. They were shot. Some were worn down so bad the gap was at .080. After replacing the plugs and wires it would start without putting it in clear flood mode, but still ran horrible and still had to feather the throttle to keep it running. I put a code reader to it and it showed the coolant temp sensor reading -45 degrees so I replaced it and now seems to be reading correctly. I really was hoping that was it but it didn't change anything that I could tell. It still smelled like it was running rich. I was able to take it out for a drive although quite difficult was able to drive it about a mile before I decided to come back before I got stranded. It didn't want to run at low rpm, ran really rough but ran great at high rpm. I've pulled the plugs a few different time through this ordeal and none of the plugs were wet or smelled of raw fuel. I checked the FPR for fuel in the vacuum line and it was dry. I've cleaned the MAF sensor. I've done a few other tests but can't recall everything at the moment. I'll update as I remember them. I appreciate any help I can get. Thanks in advance.

I had a similar issue last month, at least it started out with the same symptoms before it decided to change on me... anyway

I would check your Idle air control valve to make sure that it is actually actuating, and probably clean it while you are at it. Then test the injectors to make sure that they are not leaking by putting the petal to the floor and trying to start it, it should not start at all, if it does start check your gas pedal to make sure that there is no slack in the cable, if there is you can get rid of the slack with zip ties, there are write ups on how to do that.

It would also be worth checking for any vacuum leaks and testing idle fuel pressure. It is possible that your fuel filter or fuel relay is going bad, so if you have poor pressure you may need to test the fuel pump to verify it is getting the correct voltage.

If everything else tests good it could be worth looking into the icm, those do go out every so often and the symptoms of a bad can line up exactly with what you have going on.

Here are some links I found helpful while working through it:
https://easyautodiagnostics.com/ford/2300/icm-and-crank-sensor-tests

Repair and Diagnosis — 1996 Ford Ranger 2WD L4-140 2.3L SOHC Service Manual | Operation CHARM

Detailed repair manual for the 1996 Ford Ranger 2WD L4-140 2.3L SOHC.

charm.li

 

[lilblueskeeter]

Thanks for the reply. I replaced the fuel filter after you mentioned it. I put it in clear flood mode, it does start. I did the zip ties to the cable years ago, but just to be sure that it was reaching wide open throttle I had somebody else outside the truck opening the throttle by hand via the linkage. I also read on this forum about disconnecting the coils and then turn it over in clear flood mode or something like that, I believe it was to also determine if the injectors were leaking. I tried that as well and so far I haven't found any sign of fuel in the cylinder or at any other time through this entire thing. like the injectors are leaking. What determines that it's at wide open throttle for it to go into clear flood mode? TPS? So far the only thing I've found for sure was the hose coming off the bottom of the throttle body and eventually goes to the thermistor and evap purge valve was split and cracked so I'm sure there was a vacuum leak there. The owner of the truck wanted me to pull the injectors and see how they bench tested. So I'm currently in the process of that and sealing up a few long overdue oil leaks. Will update as soon as I get it put back together. Oh and one other question, the tip of the injector that goes into the intake has a small Crack in it, on like 3 of the injectors. Will that cause an issue? Oh and does this truck have an ICM? I thought they stopped using them in like 94 or something. Thanks in advance.

 

[scotts90ranger]

For what it's worth going to wide open doesn't stop my '97 from starting either and it runs like a top and gets 23ish mpg, does have a slightly uneven idle but it has 225k miles so I'll allow it... I changed injectors chasing some things but it didn't change anything so they're likely fine...

The WOT condition is measured from the TPS, my '97 shows 96% throttle at WOT, I've added zip ties and it didn't change anything, I think it should be enough to be considered WOT but not sure... I haven't dwelled on it

The plastic part that keeps the O ring on the bottom is fine to be cracked, not ideal but won't cause a problem, if the tip was missing that would be more of a concern

No ICM starting in '95, it's done in the computer.

 

[lilblueskeeter]

Ok. I was close on the icm. Lol. So starting at wot, what does that mean, that the computer isn't going into clear flood mode? Or that its still firing injectors when it does? Just curious in case I need use of that mode in the future. Thanks for the info.

 

[scotts90ranger]

Honestly I'm not sure, I've tried using clear flood mode and that's the only reason I added zip ties to the throttle cable so I've given up on it... I've wanted to use it to prime the oil pump but nada... from everything I'd read when I was looking into it my throttle voltage and percent was well within the range that should work, I'm pretty sure they didn't put it in the engine calibration...

 

[lilblueskeeter]

I've done some more testing. Fuel pressure at idle is 38- 39psi. While idling I unhooked the vacuum on for. And the pressure dropped a little. I also unplugged the iac while idling and it killed the truck. To be fair it was barely running as it was. I also unhooked the coils and put a screwdriver up to the injectors while I opened the throttle up to wot. And the injectors were not firing. I could back of the throttle a little and they would start clicking. So that tells me that it is going into clear flood mode. And it does start at wot everytime I try it. So I assume I need new injectors. Last Night I left the pressure gauge hooked up to the rail at 39 psi. It was at 20 psi when I checked it today. Is there anything else it could be besides injectors? I'm not really wanting to drop that kind of cash on parts if I'm not sure they will at least improve my situation. Thanks in advance.

 

[lilblueskeeter]

Finally got this problem fixed. Turned out to be the MAF sensor. But I'm still having an issue with it not holding fuel pressure. Also I was informed that it's hard to start after being parked on an incline. Not sure if these 2 problems could be related or not. It seems to only occur on an incline. Otherwise even with the pressure bleed it's pretty easy to start. It now has new injectors and therefore new o rings. FPR isn't leaking. Well put it this way no fuel is leaking on the outside of the system. It doesnt effect the running of the motor. It runs great now. But not sure if it will cause any future problems. Any help will be appreciated.

 

[perpetualslack]

Finally got this problem fixed. Turned out to be the MAF sensor. But I'm still having an issue with it not holding fuel pressure. Also I was informed that it's hard to start after being parked on an incline. Not sure if these 2 problems could be related or not. It seems to only occur on an incline. Otherwise even with the pressure bleed it's pretty easy to start. It now has new injectors and therefore new o rings. FPR isn't leaking. Well put it this way no fuel is leaking on the outside of the system. It doesnt effect the running of the motor. It runs great now. But not sure if it will cause any future problems. Any help will be appreciated.

Hi,
Other issue may be fuel pump. The check valve (inside the fuel pump/tank) is known to go bad I think.

Fuel Pressure Drop

Okay I have a 2003 Ranger EDGE 3.0 with a hard start and codes popping up for multiple cylinder misfires and #2 misfire. Truck still runs but seems to have a little stumble, mostly at idle, and a little at acceleration. Other than that is seems to run fine. I first checked the fuel pressure...

www.therangerstation.com

I have similar issues to you on my 4.0. One thing that I I haven't seen mentioned on this forum, it is possible for the the fuel pump relay had a bad connection to the pump at the fuse box wire connections, not just the relay connection). My truck would die after large bumps at times when I shut it off, and I would have to go into the relay box and smack it and the engine would start again before.