| Author |
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Matt Rigby (Mrigby)
| | Posted on Monday, September 23, 2002 - 02:01 am: | 
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OK, previously I posted a question about some OBD-II codes and got no response. I now have more info to give so hopefully someone can help me out.
96 disco with symptom of cutting out under acceleration, like it is governed or something. It is intermittent. Recent code is P1171:"O2 sensor system too lean bank A & B". It takes approx 150 miles to throw code each time I clear it. Freeze frame data shows code thrown at 65mph with Air Flow= 0.00 lb/mi ? This doesn't seem right, but I don't know what it means. Also shows Long term fuel trim in B1 and B2 at -25%. I don't know what this means either, but hopefully someone out there does.
New plugs and wires and fuel filter within a month, fuel pump ok with dead head test of 72psi, alternator checked out ok, this week replaced fuel pressure regulator, VSS, and battery.
I'm thinking it could be mass air flow sensor or throttle position sensor, but I don't know enough to decide which one. I also wonder about fuel injectors, but don't know how to test those to decide. Any help is greatly appreciated.
Matt Rigby |
Matt Rigby (Mrigby)
| | Posted on Monday, September 23, 2002 - 10:42 am: |
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Nobody wants to tackle this one huh. Well, here's a little more info just in case it starts looking like an obvious problem to someone. While on my way to work I monitored the dynamic data and I observed the following:
Air Flow= always between 0.00 lb/min and 0.06 lb/min. (this seems very low to me, but I could be wrong)
Gas milage MPG: very weird reading ranging from about 1100 MPG to 5500 MPG. I don't know about everyone elses trucks, but I know I'm not getting gas milage anywhere near these values. My question is, what sensors on the truck are used to figure out MPG in the ECU. This might be the clue I need to solve this problem? Thanks for any help.
Matt Rigby |
bryan
| | Posted on Monday, September 23, 2002 - 10:45 am: |
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Not much help, but TPS is the cheaper of the two to try for starters. I had MAF problems recently but on a 95. If you need a new MAF contact [email protected], hundreds cheaper than the dealer, TPS is much cheaper as well. |
muskyman
| | Posted on Monday, September 23, 2002 - 01:03 pm: |
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i would say it sounds like you have 2 injectors that are going bad.
injectors on some vehicles fail as a too rich at low speed high torque load and to0 lean at highway cruise.
that is what my GUESS would be from the limited info I have here |
Matt Rigby (Mrigby)
| | Posted on Monday, September 23, 2002 - 01:18 pm: |
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Thanks for the help. How do I test the injectors to determine which ones are bad or is it more of a trial and error thing?
Matt Rigby |
muskyman
| | Posted on Monday, September 23, 2002 - 02:25 pm: |
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you need to pull them out and put them on an injector flow bench...it is a devise that pumps fluid through the injectors and you can view the patern they are spraying as well as measure there volume output.
some good euro car repair places will do them for you for about $10 a piece....only replace the bad ones dont fall for the "cleaning" routine, in my expierience allthough you may see bettert performance after the solvent has been pumped through them the improvements are often very short lived ...even as much as causing a complete failure of the injector after "cleaning". turns out the very strong solvent sometimes just softens the caked on varnish causing it to stick the flow disc closed soon after cleaning.
if a number of the units come back at less then stock I would also look into a matched set of injectors. a matched set will outperform luck of the draw every time |
Matt Rigby (Mrigby)
| | Posted on Monday, September 23, 2002 - 02:43 pm: |
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Thanks for the help. I've lined up a shop to help me out with it this afternoon.
Matt Rigby |
JB
| | Posted on Monday, September 23, 2002 - 04:21 pm: |
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TPS - check with voltmeter just to be sure. Manual should have test specs. bad tps causes dead spots around 65mph when you give it gas. |
Dee Cantrell (Discodad)
| | Posted on Monday, September 23, 2002 - 06:02 pm: |
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MM,
I have to aggree it sounds like craped Injectors
I just had a shop run my injectors through the machine last week, The flow before cleaning was really weak intermit spray pattern. Then after the process all 8 had a nice even pattern good flow just like new. This is not the same lame Quickie lube injector cleanings don't go that route its a waste of money and can possible do harm to your O2 and Cats the only way to really clean them is remove them and have them bench cleaned... mine were 5.00 each
Make sure you put new o-rings on them.. |
pk
| | Posted on Monday, September 23, 2002 - 06:23 pm: |
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Hmmmm,
No. It is the Vehicle Speed Sensor. It is screwed into the rear side of the transfere case. It is a pain in the ass to get it out but it is pretty cheap, like about $70.
pk |
Dee Cantrell (Discodad)
| | Posted on Monday, September 23, 2002 - 06:29 pm: |
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Yep could be that also mine was rusted and had a crack in it. But those lean codes tell me not enough GOGO Juice
But even if the injectors are not completely at fault a good cleaning will help the performance... I also pulled the Stepper motor it was full of grime? Fix one fault it will peal away another welcome to the wonderfull world of Land Rovers |
Matt Rigby (Mrigby)
| | Posted on Tuesday, September 24, 2002 - 03:15 pm: |
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Thanks for all the feedback. I was thinking VSS and replaced it. Didn't really notice a difference so I guess I now have an extra one for when the new one breaks. After some additional testing we are pretty sure it is either an injector or coil pack which I have to wait until Wednesday to test. I will also check the TPS per advice. Thanks and I'll let everyone know what I find out.
Matt Rigby |
Matt Rigby (Mrigby)
| | Posted on Tuesday, September 24, 2002 - 03:31 pm: |
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Thanks for all the feedback. I was thinking VSS and replaced it. Didn't really notice a difference so I guess I now have an extra one for when the new one breaks. After some additional testing we are pretty sure it is either an injector or coil pack which I have to wait until Wednesday to test. I will also check the TPS per advice. Thanks and I'll let everyone know what I find out.
Matt Rigby |
Dee Cantrell (Discodad)
| | Posted on Tuesday, September 24, 2002 - 05:32 pm: |
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Matt,
Good luck, like It always happens when you fix one problem it will peal away five more... My money is on the injectors |
Matt Rigby (Mrigby)
| | Posted on Thursday, September 26, 2002 - 10:21 pm: |
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OK, here's the update. I'm still praying someone is going to figure this one out. All injectors are good per tests. Replaced TPS and fuel pump today and no change. I have now replaced the TPS, VSS, Fuel pressure regulator, and the fuel pump. I've checked the coils and all 4 check out ok. I have also checked for intake side airleaks from the MAF sensor back to the plenum and around injectors by spraying brake fluid around those areas and observing for increase in RPM and there is no sign of air leaks. Still throwing lean and multiple misfire OBD-II codes and all spark plugs are white as a ghost. Also have Long Term Fuel correction Bank A and Bank B at -25% (maxed out).
I'm beginning to lose both my sanity and my sense of humor so I helplessly await your opinions.
Matt Rigby
96 D1 |
Dee Cantrell (Discodad)
| | Posted on Friday, September 27, 2002 - 01:35 am: |
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like it is governed or something. It is intermittent. Man this is a tough one. I had similar with my 88 RRC it had a 3.5 and the final fault was the timming chain... Long shot the cats could be restricting the exhaust? |
muskyman
| | Posted on Friday, September 27, 2002 - 01:43 am: |
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restricted exhaust would be rich not lean I'd guess
plugged or restricted fuel line/rail? |
Mark Smith (Msmith)
| | Posted on Friday, September 27, 2002 - 10:05 am: |
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Better have your ECU checked out. To make sure it's dealing with input data and outputting correctly. Sounds like you've checked most of the hardware involved. Also, you haven't mentioned replacing the pre-cat O2 sensors. They could be at fault. Especially if it only does this once the truck is running closed loop (warmed up). Also, have you traced the fuel lines back to the tank, making sure there's no kink? |
Mark Smith (Msmith)
| | Posted on Friday, September 27, 2002 - 10:10 am: |
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Check the timing to make sure it's advancing. And what kind of gas are you using? Make sure its premium and that it is ethanol free. Can you hear the misfire? |
muskyman
| | Posted on Friday, September 27, 2002 - 10:38 am: |
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believe he has coil pacs no Dizzy to time |
Andy Nix (Andy)
| | Posted on Friday, September 27, 2002 - 01:45 pm: |
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Matt, where are you located? |
Dee Cantrell (Discodad)
| | Posted on Friday, September 27, 2002 - 01:58 pm: |
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MM it could be running lean now but who knows the prior condition? What type of 02 sensors? factory or cut and splice cheepies? if spliced incorrectly it could have dammaged the ECU or its sending false siginals to the ECU |
muskyman
| | Posted on Friday, September 27, 2002 - 03:08 pm: |
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yea no doubt Dee...cut and splice can be bad just from the resistance of a crappy splice. but I'm starting to think this is ECU or a plugged fuel line or something.
for god sake he's replaced everything else??... |
Matt Rigby (Mrigby)
| | Posted on Friday, September 27, 2002 - 03:28 pm: |
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Again I must thank all of you for taking the time to think about this problem with me. You've brought up stuff I never thought about. To answer some questions:
- yes, I can hear the misfires when they occur on the freeway.
- no, it does not have to be warmed up. It happens when warm or cold.
- I am located in Salt Lake City Utah
- I will check the fuel lines tonight, although I assume they are alright because I am getting the correct pressure at the fuel rail.
- Yes, the timing is advancing. It starts out at 15 degrees at idle and has gone as high as 45 degrees under load on the freeway.
- I have always put 91 Octane in it from reputable gas stations since I got it with 38,000 miles. Now has 98,000 miles. My wife thinks I'm nuts, but I have always insisted on the top gas.
- I have only replaced the passenger side pre-cat O2 sensor when the computer indicated it needed to be changed. I replaced with a genuine from Nathan at Discount Rovers. The other sensors appear to be working great per static OBD-II data.
I think you're right that it may be ECU or something just random and strange. I have this weekend to figure it out and then I have to admit that I'm giving up and taking it to Land Rover Centerville (dealer) because I'm not comfortable with continuing to drive it when it is running so lean.
Matt Rigby |
Dee Cantrell (Discodad)
| | Posted on Friday, September 27, 2002 - 04:39 pm: |
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Man thats a tough one hopefully it will be a faulty wire conection. Good Luck |
charles pastrano (Charles)
| | Posted on Saturday, September 28, 2002 - 09:18 pm: |
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With all your replacements you've got a new truck. Good Luck |
Mark Smith (Msmith)
| | Posted on Monday, September 30, 2002 - 12:21 am: |
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Matt,
No I wouldn't run the truck much at all if its misfiring...it needs to be repaired asap. It's been said that for every mile you drive with the engine misfiring (detonating), you add @ 10,000 miles of wear to the engine. It's really tough on the motor. Besides, Rovers are supposed to run rich. I think I'd let the dealer look at the ECU. At this point, I'd say it is most likey the culprit. Sounds like the injectors are just not getting the pulse time needed for proper mixture.
Mark |
trevorgriffiths
| | Posted on Monday, September 30, 2002 - 12:28 pm: |
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I haven't seen anybody suggest checking the ground connections for the engine harness. It is not uncommon for strange things to come and go with temperature related expansion and contraction at ground points, or even from oil/coolant saturation and contamination. |
Paul T. Schram (Paulschram)
| | Posted on Monday, September 30, 2002 - 12:37 pm: |
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What about checking the compression? Sounds like that is a crucial piece of diagnotsic information we don't have-unless I missed it the first time around. |
Matt Rigby (Mrigby)
| | Posted on Monday, September 30, 2002 - 01:45 pm: |
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The answer finally! Bryan, you were right. It was the MAF sensor. It was hard to find because it was failing intermittently and masking the problem. It made me feel better that it took the dealer awhile to determine the problem too. They swapped out a new one and it solved all the problems. I don't know how I would have diagnosed this or tested it on my own, because the data from the MAF sensor on my generic OBD-II looked right per multiple conversations with people who use them for a living.
I did check all grounds and compression as suggested and yes I now have an almost completely overhauled truck not to mention how much I learned about my truck. Again, thanks to everyone who helped me out with this and I hope someone else can gain from this later.
Thanks.
Matt Rigby |
bryan
| | Posted on Monday, September 30, 2002 - 06:10 pm: |
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Matt,
Holly $hit....I've learned enough to help someone else out, that's real scary but I'm glad you were able to get your rig fixed. I hope the dealer gave you the courtesy of "a reach around" and some complimentary KY while they were bending you over with their $800-$1000 price on a MAF sensor. I just love dealer service, they have "expert techs" and high dollar computer systems to help do their job, but how do they fix most problems........by throwing overpriced parts at your rig until something works. I wish somebody would pay me $80-$100 an hour to play guessing games. |
Matt Rigby (Mrigby)
| | Posted on Tuesday, October 01, 2002 - 09:34 am: |
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Actually Bryan, I was only into the dealer for $178.00 for diagnostic fee. I then asked them to put my truck back together and I brought it home and promptly called Nathan. He hooked me up with a much cheaper remanufactured MAF. The dealer price would have been about $850.00 and the funniest part is they quoted me a $50.00 fee to install the damn thing. All it takes is unclipping the section of air intake with the MAF on it. It takes more time and energy to swap out the air filter.
Matt |
jim
| | Posted on Thursday, October 03, 2002 - 02:23 am: |
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Matt,
FYI Clarke at Regent street service on main and 1300s instead of dealer. At least he does all my work. Usually things Centerville can't figure out they take to him.
jim
97 disco |
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