99 ranger 3.0 flex fuel - rough idle and stalling

[jlisk]

Hello everyone,

After searching for a while I've been unable to find a solution to my problem, so I hope you all don't mind helping me. I have a 99 ford ranger, with the 3.0L flex fuel engine. Recently I've run into the issue of the engine idling very rough at startup, and even dying once or twice before it eventually runs normally. It seems like the engine runs really rough at startup if I don't drive it for a couple of days, and takes about 45 seconds or rough running and dying a couple of times before running normal. If I just go to the store and start the truck after having only been shutoff for 20min or so then I may notice the rough idle for 10sec or so and it may die once or not at all. I have replaced the spark plugs, battery, and spark plug wires within the last 6 months. The engine seems to run just fine after it gets past the stuttering and dying, making me think the fuel pump is fine.

Anyone have any ideas? I am thinking it may be a fuel pressure regulator going bad? Last fall I tried to get a reading of fuel pressure but the auto parts store didn't have a tool that would work, so I haven't been able to confirm fuel pressure. Looking forward to your help, thank you in advance!

 

[McCormack]

Things to check = Idle Air Control circuit; Emissions sensors (MAF valve, etc.); EGR circuit, including DPFE sensor; PVC valve

 

[jlisk]

Update: I haven't had a chance to check the PVC valve yet, but today I tried priming the fuel system by turning the key to "on", letting the fuel pump run for a second or two until it turned off automatically, then turning the key back to off, and repeating this procedure 3/4 times. I tried this procedure this morning, and after work, and neither time did the engine have the stuttering/dying problem.

Does this help narrow down the possible causes? I forgot to mention the truck has ~100k miles, and about 5 months ago I cleaned the MAF and checked resistance for the MAF, DPFE, and TPS and they all fell within specs.

 

[stmitch]

Are there any codes?

 

[jlisk]

I've gotten the Bank 1 and 2 lean p0171 p0174 codes and reset them. Also, I replaced the fuel filter and this didn't change the issue.

 

[jlisk]

Hey guys, I'm still having this issue. Just cleaned the MAF sensor, and replaced the fuel pressure relay, and fuel pump. Have cleaned the EGR valve, replaced the idle air control valve, checked all the vacuum lines.

Any other thoughts on things to check?

 

[Rearanger]

Same codes?

I think you are going to have to find a way to hook up a fuel pressure gauge to see what it does on cold/hot start-up. Right now your just guessing with no info.

 

[txgocartB3000]

Are you able to repeat the on/off method you did on post #3 and get good results again?

Ray

 

[Pacman88]

Have you checked your fuel injectors? Meaning, 1 being stuck partially open allowing that one or more cylinders to flood and causing the others to lean out. The one (or multiples) that are flooding will cause a momentary rough start up until it clears. I assume you're not using coolant? A coolant leak would cause the misfire at start up since the plugs are trying to burn the coolant (which doesn't burn well). What you're describing leads me to those two options.

(Joined Nov. 2011 and THIS is my first post. I'm still looking for an affordable Ranger...)

 

[jlisk]

Hey guys, thanks for the responses.

Turning the key on/off to "pressurize the fuel system" doesn't have an impact any more. I have checked the fuel pressure and it is good prior to and during startup. I have run injector cleaner through my ranger every few tanks for some time.

Also, I notice that when I start the vehicle, as it gets down to a low idle prior to dying, if I give it some throttle this seems to make it want to die more (lean), and when I let off the throttle it blips the rpm a little higher before bogging back down and dying or nearly dying. Can also hear pinging when the engine gets to a really low rpm (preignition) prior to stalling. The engine runs just fine after it gets warmed up, seems to have its rated horsepower.

Just to compile a list, here are things that are new:
1. Fuel Pump
2. Fuel Filter
3. Fuel pump relay
4. Intake Manifold Gaskets
5. IAC Valve (cleaned the OEM, then replaced it completely, no change from either)
6. Engine Temperature Sensor
7. Spark plugs and wires

- I have checked all the vacuum lines and not been able to find a leak.
- Cleaned the MAF sensor, and air intake sensor, confirmed air inlet flow is not obstructed. Has anyone had a MAF sensor go bad?
- Battery and alternator are just fine
- Cleaned the EGR - EGR makes the engine more rich, not lean, so my "throttle test" above makes me think this is not the issue
- I use injector cleaning pretty regularly. Am going to run a tank of E85 through to do a little more cleaning as well. I normally run 87 octane, non-ethanol 100% gasoline.
- I have coolant/anti-freeze in my truck (live in Iowa), I have smelled the exhaust at start-up and don't get any indications of burning a significant level of coolant

________________________________________________________________________
1999 Ranger, 3.0L Flex Fuel, Automatic Transmission, 4x4, Extended cab step side

 

[Rearanger]

Same codes as before?

 

[jlisk]

I cleared all the engine codes this morning, then used the truck today and checked the codes this evening. Turns out I have even more codes now than before. Here are all the codes I got just today:

P1000 - Onboard diagnostic not complete
P0401 - Insufficient EGR Flow
P1131 - Bank 1 sensor 1 - Lack of O2 sensor heat (aka: lean)
P0171 - Bank 1 lean
P0174 - Bank 2 lean


It is sounding to me like I might still have a vacuum leak somewhere, does this sound right? Any areas that are more suspect to leaks than others? I have spent our looking for vacuum leaks, they are quite challenging to find!

 

[Rearanger]

P1000 - Onboard diagnostic not complete
P0401 - Insufficient EGR Flow
P1131 - Bank 1 sensor 1 - Lack of O2 sensor heat (aka: lean)
P0171 - Bank 1 lean
P0174 - Bank 2 lean

It is sounding to me like I might still have a vacuum leak somewhere, does this sound right? Any areas that are more suspect to leaks than others? I have spent our looking for vacuum leaks, they are quite challenging to find!

The P1000 is because you just cleared the codes.
P0401 may be just a blocked tube. EGR systems are prone to blockage.
P1131 looks like the O2 heater is not working. Maybe a wire connection.

The two lean codes are best diagnosed with a scanner. Maybe try propane to find leaks but smoke test is best and fastest.

I'd fix/clean the EGR first. They can also be a vacuum leak source.

 

[enjr44]

Update: I haven't had a chance to check the PVC valve yet, but today I tried priming the fuel system by turning the key to "on", letting the fuel pump run for a second or two until it turned off automatically, then turning the key back to off, and repeating this procedure 3/4 times. I tried this procedure this morning, and after work, and neither time did the engine have the stuttering/dying problem.

Does this help narrow down the possible causes? I forgot to mention the truck has ~100k miles, and about 5 months ago I cleaned the MAF and checked resistance for the MAF, DPFE, and TPS and they all fell within specs.

I am not sure about the rest of it (the codes); but, on my 02 it started great when I cycled the key and not so great if it sat for longer that 4 hours without cycling the key. It was the fuel pump losing pressure and one day it just completely quit.