Gentlemen:

New Ranger convert, former unhappy S10 ZR2 owner, would appreciate any and all help. Just bought a 98' 3L 4WD w/5spd stk and converted it to flex fuel with a $425 kit from DriveFLexFuelUSA. Before I installed the conversion kit I replaced the downstream O2 sensor, the engine idle always seems to be a little high 1000-1100 rpm, also seems to delay in dropping down. I have been runnig e-85 / $2.70 per gallon, here in Wisconsin, for the past 1500 to 2000 mi. getting about 15% less milage (17 flex, 20 regular gas)but the engine is running fine, except now I'm getting unclearable codes 0401, 0171 and 0174. I don't want to replace the DPFE sensor unless I know that it's failed. What's the output from this sensor supposed to look like to the computer?? I'm thinking that it's a PWM signal that I could look @ with an O'scope? The electronics for the flex fuel conversion are supposed to be adaptive, but I might of had the problem before converting to flex. Help!!!!

 

I just used my Scanner and looked up the code which defines what it is:

EGR FLOW INSUFFICIENT. check your EGR Valve and exhaust manifold very closely. You might need both of them replaced. P0171 : system too lean bank #1, P0174 System too lean bank number 2. Did you change the injectors or are you still using the stock ones? You might need upgrade the injectors cause it's not getting the fuel it needs to function properly. I'd also check on your fuel pump, the ignition timing and ECU programming because it may have the wrong program that you actually need to run E85.

 

DPFE Troubleshooting

 

that should help him out. That's also why I ruled out Flex Fuel. Too many mods to do to run it. If I wanted to convert it I'd take it to a Ford dealer first and ask alot of questions.

 

thanx to all, good info, especially the techtips. my truck is'nt running any differently on the flex-fuel than it ran on straight gas, just getting the expected 15% less milage. the injectors are standard, fuel pump also standard. the conversion kit is just an inline splice to each injector solenoid from the controller box (inside are 2 PIC microcontrollers, one for each head ??) Again, the manufacturer claims that the rangers computer learns to adapt to the retrofit. I made the mistake of installing the kit before I had cleared the engine codes. that could be a problem.

 

Yes it could but I think you just got part of the package needed to run flex fuel. They ripped you off a little bit. Go to your nearest ford dealer and get the Injectors and fuel pump needed and changer your EGR valve. Those guys just sell part of what's needed. You're welcome dude. I'm glad that we can help you on this because wether we like it or not Ethanol is the future. In fact if you look closely at your local gas pump you might se a sign that says contains 10% ethanol. It's not on all pumps but most.

 

The 3.0 flex fuel injectors are actually just 4.0 injectors along with the modified computer settings to run E85. You have to have the kit to modify injector hold open length to get more fuel, now you need the hardware to get the necessary fuel flow required. Especially the injectors.

 

Yep. That is true. A local service writer at a dealer showed me the injectors and said basicly what you said. She has been a friend and in business with ford for at least 15 years.

 

Suggest you replace the DPFE, THEN clear the computer. My typical DPFE failure is noticeable long before it lights the CEL. My truck is also a stick. I drive 2 miles @ 30 mph 4x a day (4th gear, barely touching the gas). When the DPFE is "going bad", I feel a surging. Feels as though I'm towing a trailer and the driveline is constantly taking up and releasing its slop, but at a faster rate than you can duplicate with the gas pedal. Hard to feel with an automatic, I would imagine. It gets so annoying that I force the CEL to come on so it will shut off EGR and run 1/2 decent until I get around to replacing it.

If you want to feel the difference, simply pull the vaccum line off the EGR valve, plug it and drive.

I'd clear up that issue before I got too worried about the lean codes. IIRC, the Flex injectors are 25.3. I'm assuming your kit simply lengthens the pulse duration, so it may work just fine on the original injectors. Plastic DPFE's run ~$54. I'd also look for a vaccum leak. Unmetered air will make it lean.

The idle is a little high, you may have a problem. As far as idle dropping, it won't drop to normal 800 until almost stopped. Mine hangs @ ~ 1000 then drops to 800 (but the Scanguage shows it @ 736-780's). If you don't like that, the only cure is to interrupt the VSS signal. That'll kill ABS and speedo/odo though. I get the impression you are after good fuel economy. I don't know if getting the idle to drop sooner would help much or not. I'd suggest cleaning the IAC and its ports, see if that helps.

I can tell you this much, with the Cruise off, ANY deceleration still supplies fuel through the injectors. With Cruise on, a downhill speed increase over the set speed WILL shut off fuel to the injectors in an attempt to maintain the lower set speed. Letting your foot off the gas never yields that result. I use that to my advantage, set it @ 30 or so, then drive the gas pedal as normal. Then when you DO decelerate, it kills fuel flow until the set point (which can surprise you if you forget). That tactic will help fuel mileage.

Welcome to R-F.

 

You have a good point except according to my friend who's been a service writer for 15 years the injectors are where most flex fuel conversion kits cause problems. The injectors that are flex fuel capable flow much higher. he's better off without E85. The ultimate fuel saver is weight reduction. The less weight that engine carries the better. Although E85 could be the future. I've got mixed opinions about flex fuel.

 

Approaching dementia Earl:

Thanx, xcellent info, i think my main problem is in the EGR system, will check for leaks before replacing the DPFE sensor. Just cleared the codes and refilled the tank with straight gas, the 401 fault came back but the lean codes 171 & 174 did not. I'm guessing all 3 codes will come back when I refuel with E85. Your lower setpoint cruise technique sounds workable, does the 'coast' overide work the same way?? by killing the fuel flow???