| Author | Message | ||
     Troy Morris (Cheapjeep2) New Member Username: Cheapjeep2 Post Number: 14 Registered: 04-2003 |
I am getting codes and the MIL light turned on frequently on my 99 D2. The codes are P0171 and P0174, which is Bank 1 and Bank 2 injectors running lean. With a description of Muliplication injector adaptive fueling lean limit exceeded. Any ideas where to look, according to the scan tool the O2 sensors are ok. I have an open element K&N on the D2 since June with no problems. Then the problems started when we (colorado) switched to the winter time oxygenated gas. I was wondering if the combination of more air from the K&N and oxygenated gas is causing a lean mixture. Thoughts? | ||
| Troy Morris (Cheapjeep2) New Member Username: Cheapjeep2 Post Number: 15 Registered: 04-2003 |
Anyone? | ||
| James Anderson (Jnjander) New Member Username: Jnjander Post Number: 25 Registered: 08-2003 |
I have a 99 Disco II and have the same codes popping up triggering the Check engine light. Cleaned the Mas Airflow Sensor, reset the codes, that lasted a few weeks, light is back on, same code P0174. I haven't noticed a decrease in gas mileage(HA) or performance or anything since the light came on, so I am not going to worry about it. That's my .02 worth. | ||
| Troy Morris (Cheapjeep2) New Member Username: Cheapjeep2 Post Number: 16 Registered: 04-2003 |
Do you run a stock air filter? It is kinda funny, even with trippin' codes, it's running better than ever. | ||
| James Anderson (Jnjander) New Member Username: Jnjander Post Number: 26 Registered: 08-2003 |
Yup, stock filter. Still averaging around 14-15 MPG, runs strong. From what I've read here on Discoweb, that mileage is about normal. Also, I am running the cheap stuff. | ||
| Douglas McMillan (Mcmillan) Member Username: Mcmillan Post Number: 65 Registered: 06-2002 |
Replace the K&N Cone filter you have with the stock air filter. Run a few tanks of Gas and reset the check engine light. All will be fine | ||
| marc olivares (Pugs) Senior Member Username: Pugs Post Number: 252 Registered: 12-2002 |
troy, these are fuel trim codes. before you buy any replacement sensors or air filters, check your fuel pressure and vacuum lines for any leaks. typically these codes are triggered by a lack of fuel in to the cylinders or to much air beyond the maf. no, this has nothing to do with the K&N or oxygenated fuel. it's not an O2 sensor problem, it is a lean fuel issue, and the o2 sensors are simply telling you that the mixture is to lean. when was last time you changed your fuel filter (that could be part of the problem). start with the fuel pressure , you'll be looking for 3.5 bar(50psi) and report back. we'll get you through it. marc oh and Douglas, please refrain from giving incorrect advice. | ||
| Troy Morris (Cheapjeep2) New Member Username: Cheapjeep2 Post Number: 17 Registered: 04-2003 |
Thanks Marc. I'll check the pressure and get back to ya! | ||
| Troy Morris (Cheapjeep2) New Member Username: Cheapjeep2 Post Number: 18 Registered: 04-2003 |
Read this... It's from a car guru buddy of mine and is very credible. He's were we all go when no know esle can figure anything out. Anyway - from the "duh!" file -- the codes are trim codes -- what's happening (as we discussed) is that the coumpter is running perfectly with all of it's sensor data -- and, for whatever reason, the computer has adjusted your mixture to as lean as it will go (which it sees as a trim figure -reducing the open-time on the injectors... a 'multiplier' as posted there) so everything is happy and your injector timing is set to minimums... ...Hmmm. On the surface - the O2 sensors are seeing rich values so the computer is trying to LEAN the injection and can't get em to go that far. I don't see this as a leak past the MAF in your intake system (that would push you lean, causing the trim to go toward rich = that's different) I don't see this as a fuel filter issue -- if the fuel filter were constricting flow, then you'd go lean (and trim would move rich = different) If part of the OEM air box had an intake air pre-heat, it could possibly be related to your MAF being a hot-wire type, and with the reduced inbound air temp it could be having difficulty fully heating the wire, leaving the computer a bit confused about the actual density of the inbound air charge (usually this causes the vehicle to lean - again the trim would go rich, but it is a Rover, so that could go the other way) I like the thought on fuel pressure (I'm not sure how that system is regulated) if you have a return loop system (like your XJ - fule is pumped to the rail and excess pressure is fed back) then a clogged return line could cause excess pressure in the rail and your injectors would pass more gas (he he) than expected, so the O2s would report rich (forcing trim lean = ? could be) -- anything that would increase the pressure in the rail would do that (bad regulator...etc) . Does your Rover have a charcoal canister? - as odd as that sounds, when the vehicle warms and fuel is circulated, the fuel expands, pressure from the fuel vapor pressurises the tank a little - that pressure is supposed to be bled-off through the vapor canister and subsequently drawn back into the intake air charge for recombustion... if the tank's vent (or the canister itself) offers too much resistance to that flow, the tank's pressure may increase the fuel-pumps pressure to the rail also reducing the ability for the rail to dump return (or in a dead-end loop like the 96+ XJs, with the regulator in the tank, just increase the pressure fed to the rail). This would be exasurbated with alcohol mixed fuels and the temperature changes we see here... I'd go with the thought on checking the rail pressure(s)- that sounds solid. How quickly does the light come back on after resetting?? Is it almost predictable?? -- thought is this - if you reset it and it's guaranteed to come on in like a day or two... Reset it, and leave the fuel-cap loose for a day or two... (you may set a Po430-series code about evaporative flow or something - you can clear that, but see if your trim code comes back as predicably... -- if it doesn't that'd indicate that your tank is presurizing excessively while driving (something that you'd NOT see on a "driveway" fuel prssure check) I seem to remember that you said that the codes seemed to set on just "normal" highway rides..? I'm assuming that you've changed spark plugs and are not running anything exotic (like a small electrode platnum or anything)? My Response: Damn, Your replys always make my head hurt.:-) There is nothing visable around the air box that would "heat" the air first. I have not changed the plugs, I do not know when or if they were changed. I'll have to consult my CD about the fuel system configuration, I'll get back to you. As far as the codes, the condition is always there, the codes are pending... Then if it reaches that condition enough times it trips the MIL light. There doesn't seem to be any coorelation driving patterns or times. It may stay off two days or 2 hours... | ||
| marc olivares (Pugs) Senior Member Username: Pugs Post Number: 259 Registered: 12-2002 |
wow troy, in the amount of time it took you to type that you could have fixed it on your own. to start with you buddy is on the right track, i'm slightly confused. actually, what he said or how you interpreted it is backwards. the PO171/PO174 codes are when the O2 sensors detect a lean run condition, PO172/PO175 are used when the O2 sensors detect a rich run condition. this is in a sense prior to any corrective action being taken by the O2 sensor. the ecu monitors the constant corrective action that the O2 sensors make and trip the code accordingly. From the OBDII power control/emissions diagnosis manual; "the monitor detecting a lean shift in fuel system operation are DTC's PO171 and PO174" .....possible causes are... FUEL SYSTEM -leaking fuel pressure regulator -low fuel pressure or running out of fuel -vapor recovery system INDUCTION SYSTEM -air leak pased the maf -vacuum leak -pvc system EGR SYSTEM -leaking gasket -stuck egr valve -leaking diaphram or evr BASE ENGINE -oil over filled -cam timing -cylinder compression -exhaust leaks before or near the HO2Ss so again I say to you, buy a cheap fuel pressure gauge from an auto parts store. connect it to your fuel rail and watch the pressure running, at idle and with the key off. the pressure should stay at or very, very near 50psi, and when off should not bleed off more that 5psi in less than one minute. this not only checks your fuel pump but your pressure regulator at the same time. i just worked on a truck last week that had the same codes (PO171/PO174), fuel filter was new and the fuel pressure was 31psi. after a new pump was installed, codes were cleared and truck was put through a complete drive cycle, everything was good. now, i'm not saying that this is your problem, but it's a good place to start. it could also be a MAFrelated problem, that just happened to throw a fuel related code first. good luck and keep us updated, marc | ||
| Troy Morris (Cheapjeep2) New Member Username: Cheapjeep2 Post Number: 19 Registered: 04-2003 |
Marc, You're awesome, thanks for the input, btw, i didn't type it, I copied from my buddies email. I borrowed a pressue gauge today just haven't had time to check it yet. I tried to find the schrader valve but must have been overlooking it. BTW, where is the fuel filter on the D2? Is it part of the pump? My Work Shop manual doesn't indicate where it is. | ||
| marc olivares (Pugs) Senior Member Username: Pugs Post Number: 260 Registered: 12-2002 |
yeah, don't look real hard for the filter on a D2, it's in the tank (they're suppose to be life time filters) i saw on your first post that it's a D2, i just spaced telling you it's in the tank. be hopeful that's not the pump. alldata pro lists this as a $378 part with 1 hour flat labor rate. could be a spendy fix. marc | ||
| Richard Garza (Rgarza) Member Username: Rgarza Post Number: 43 Registered: 05-2003 |
I had the same codes on my DII. My guess and they had to replace mine was the MAF (mass air flow sensor). This fixed the problem. Someone has a discussion on how to clean them. You might want to look for it. Richard | ||
| marc olivares (Pugs) Senior Member Username: Pugs Post Number: 267 Registered: 12-2002 |
yeah richard, this could also be a faulty MAF, but checking fuel operation is a good economical place to start. my 2001 saab also threw this code a month or so ago and the MAF was the problem. luckly, the wife insisted on the extended warranty, saab wanted $550 for an maf that i trouble shot! the crooks! hee hee hee. marc | ||
| Troy Morris (Cheapjeep2) New Member Username: Cheapjeep2 Post Number: 20 Registered: 04-2003 |
OK, Marc, checked the fuel pressure with the engine running it's 52 PSI. I am leaning on the MAF. |
