Replacing MAF sensor but not running!

[hughes2925]

I have purchased a new MAF sensor for my 99 LR Disco Series II b/c the dealer said I needed a new one and also 02 sensors. I purchased MAF part off ebay and installed it. The truck won't stay running but chokes out after 2 seconds or so. I put the old one in and it runs, but not great, kinda gets sluggish and sometimes dies at an idle start, which was the whole problem to begin with (also I have had service engine light on for probably 2+ years). I unplug the MAF and it runs exactly the same, just fine but sluggish, maybe dies in first gear from a stop. So, I though, bad part and sent it back for refund and so just installed a new MAF from a different source and same thing! Part is an exact match, trust me I triple checked on both MAFs. B/c of working late every nite I haven't replaced the 4 bad 02 sensors yet. Is this the reason the new MAF won't work? I also replaced my K+N air filter (I have had this and recharged it several times over the last few years) for a brand new NAPA gold air filter too. Do I need to do all 4 02 sensors first, then expect that the MAF will work? What can I expect if I keep running the truck with MAF unplugged? Thanks, Nate at hughes2925@hotmail.com

99 LR Disco II, custom rock sliders, WarnXD 9000 winch, OME 3" lift, Nitro shocks, wrap around brush guard winch tray, BFG AT K/O's.

 

[baddmojoii]

The fact that it runs crappy and dies at idle makes me wonder if your isn't the idle air control valve. When you replaced the MAF sensor, did you disconnect the battery to clear out the ECM? Your fueling adaptions are probably way off from the bad MAF sensor and then when you swapped to a new one the fueling could still be off until it re-adapts. Of course if you have a bad 02 sensor or two it'll run like crap too. Would need to know what codes you have after replacing the MAF and driving it for awhile to give you a better idea.

 

[LuisC]

Over the two years the service engine light has been on, how has the fuel mileage been ?
The MAF and O2 sensors usually work together to tell the computer how lean or rich to run the fuel/air mix. I would say start by replacing the O2 sensors and get the ECU cleared of the codes. If the problem still persist, then move to the injectors and last but not least, the valves. The delay in servicing of the MAF and O2 could have caused issues with them.

 

[hughes2925]

I never went below about 14 mpg for mileage. I never really had any problems until it started wanting to give out when just occassionally going from 0-5mph on a start, warm engine or not didn't matter, just intermittlently wanted to cut out on me. I will def replace the 02 sensors this weekend and then give it another go with the new MAF. I did in fact have the battery off. I dont have a computer to clear the codes, but wish I did since I have had 400 other problems with this truck over the years. I will repost after the 02 sensors go in and let y'all know what the truck runs like then. Thanks guys

 

[roverMc]

You haven't washed the engine recently have you?

 

[singingcamel]

x2 on this idle control, also i would think about crank shaft sensor , I just had one in the shop , would idle fine but when driven it would miss like hell and backfire. Read the codes.
Rather doubt it would be injectors

The fact that it runs crappy and dies at idle makes me wonder if your isn't the idle air control valve. When you replaced the MAF sensor, did you disconnect the battery to clear out the ECM? Your fueling adaptions are probably way off from the bad MAF sensor and then when you swapped to a new one the fueling could still be off until it re-adapts. Of course if you have a bad 02 sensor or two it'll run like crap too. Would need to know what codes you have after replacing the MAF and driving it for awhile to give you a better idea.

 

[FB111]

Definitely replace the front O2 sensors. I think you can hold off on the rear ones.

 

[baddmojoii]

Injectors usually aren't a problem on DII's and the valves might could cause a misfire, but wouldn't cause an intermittant stalling issue. I have seen the crankshaft sensor cause issues, but not just at idle. More than likely it's between the Idle air control motor and the 02 sensors. The passenger 02 sensor always had a tendency to get oil saturated from leaking valve cover gaskets dripping down onto it.

 

[hughes2925]

I already bought all 4 02 sensors from ebay for $80...they are used but it was a Land Rover parts guy on ebay with 100% feedback and over 500 sales. I will replace them in the morning and will repost the results. Light a candle for me! I imagine the 02 sensors are easy to remove/replace. None of the codes the truck threw were for crankshaft sensor, but one WAS for camshaft position sensor (CPS) and I will do that after I get the 02 sensors in and new MAF back into place and then see how the truck is doing. Truck only running right now with my old MAF which probably isn't even working- and it is spitting out some thick exhaust, very very rich exhaust with black droplets falling to the driveway.

After reading a good bit last nite about the CPS I have some serious fear that the LR dealer is sending me down a path where I could be throwing parts at this 11 year old truck forever! I would prefer to buy a decent 04 or something than keep this 99 going with part after part after part. I have done head gaskets twice, trans rebuild, front and rear drive shafts, all the off road mods, water pump, radiator, all the door locks and window regulators, and countless little things. I am tired of the truck draining my $$ even if I do love the rovering, ya know? It's depressing and fun, keeps me worried, but gives me offroad fun-it's love/hate. I couldn't sell it with all the dashboard lights glowing anyhow! I am about to do the ABS pump modulator too (bought for $150). Guess I can't do that one myself either b/c it needs the computer codes or something?

Thanks guys, I do feel more confident about the 02 sensors getting me fixed up and that I didn't just waste more money

 

[LuisC]

After reading a good bit last nite about the CPS I have some serious fear that the LR dealer is sending me down a path where I could be throwing parts at this 11 year old truck forever! I would prefer to buy a decent 04 or something than keep this 99 going with part after part after part.

And 4 or 5 years down the road, you will be spending money keeping the 04 going. It's a never ending battle. Just keep the one you got. With all the parts you've replaced, you almost have a new truck. LOL

 

[hughes2925]

So, I did replace all 4 02 sensors this morning, very easy to do. Then I put the new MAF in place and hooked the battery back up and the truck won't stay on. I unplug the MAF and it runs just fine. I put the old MAF back in (that LR dealer said needed replaced), plug it in and it runs just fine. I put the new MAF BACK on again and won't stay on more than 2 seconds. I unplug it and truck runs fine. Plug it back up and dead in a few seconds. What am I doing wrong? This is the second brand new MAF I have purchased! I sent the first one back b/c I thought it must be a bad part. The part numbers are exact. Why does the new MAF kill the engine? Can I just run the truck without the MAF b/c it sure seems to run fine without it?!?!

Thanks all,
Nate

 

[baddmojoii]

I wouldn't recommend driving for any extended amount of time without the MAF because it'll cause some other issues. It needs to MAF to calculate engine load properly... without it, the Trans will be an unhappy camper as well. If you knew someone with another DII, I'd say to swap it with a known good to verify that you haven't gotten two faulty new MAFs (unlikely).

By unplugging the MAF, you're causing the fuel system to go into "open loop" where fueling is controlled by a preset map. It may be that there are other issues still that are being masked by unplugging the MAF sensor.

Thinking out loud...I can't remember if the fueling adaptions are wiped out when the battery is disconnected. Did you try driving it with the new MAF in place to see if it would eventually adapt?

 

[hughes2925]

No, I couldn't drive it around with either of the new MAFs I had purchased. Both just made the truck cut off after just a few seconds, so driving was never possible. I tried to restart the truck each time about 8 times I'd say. In each case I had to put my old MAF back on and it runs ok, not great, but very rich and dark smoke and still not any better now that I have replaced all 4 O2 sensors today. I thought they would make a difference but they hadn't. Not sure what else could help. I really would like the SES light to go off too! I also show the 3 amigos as always. Dashboard is lit up like a Christmas tree

 

[JohnB]

Is the MAF a Bosch unit or eurospare? If its not Bosch you should get a Bosch. Those aftermarket MAFs are junk.

 

[mud ruts]

What codes are you getting?

 

[JohnB]

Thinking out loud...I can't remember if the fueling adaptions are wiped out when the battery is disconnected. Did you try driving it with the new MAF in place to see if it would eventually adapt?

I don't believe so but PT probably knows. I've disconnected the battery cables and held the +&- together for 20 seconds but I belive this may be an internet myth.

I'm so amazed it runs without the MAF plugged in. Mine shuts right off if you do this.

 

[FB111]

What are you worrying about if it runs fine with the old MAF. Just return the two that aren't working. The non Bosch units are junk. I have one thats brand new and it doesn't work.

 

[hughes2925]

It's the occasional power failure that I am worried about...that plus it only gets about 10mpg right now. It's like the truck is stuck in the "limp home" mode and all the heavy exhaust can't be good. I had the truck on inside my garage with the door down and now my garage door has a solid black surface in a 2 foot diameter. Anyhow, I am driving it still, so not that worried, but the SES light will never go off with the MAF throwing codes. That lite plus the 3 amigos I want to disappear if possible.

 

[WILL.TILLERY]

i have new oem ones....check your inbox.