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Just wanted to toss things around everyone just because I was bored today. And yes, I've read every single thread with MAF in the name, and have a complete list of all the suggested culprits of codes thrown in the name of the MAF and intake temp sensor. All that said:
In my 03 XJR, the last two years I've run a Mina intake tube to a K&N cone filter in a homemade heat shield that sealed against the hood when shut with rubber gasket material to minimize heat. Last summer, I started getting some Failsafe kicks, sometimes a lot, sometimes I could go for days without. I forget what the code was, but pretty sure it was the TPS sensor code, or whatever, but basically pointing to the throttle body. Strangely, that issue stopped once the cooler weather hit last year. Perhaps the first year was fine but then things stopped adjusting correctly to increased heat with the filter? I didn't check real-time numbers at the time, so who knows.
Fast forward to a few weeks ago. Started getting 0171 and 0174 Lean condition codes. Pretty much every other day. Car ran fine no noticeable stuttering, but obviously a concern. I had had a minor off-road incident, that I thought perhaps had knocked something on the intake out of whack. First glance, everything looked fine, nothing looked loose or ajar. First thing I did, was to replace the cone with the factory airbox again after cleaning the heck outta the MAF assembly. This was the thinking that perhaps over time, the MAF had just finally had enough of the aftermarket, and maybe it would help. Afterwards, the codes dropped from actual fault codes to the Intake Temp Sensor (forget what that code # was). Ok, strange. Pulled the connector off, and thought hmm, it seems like it wasn't fully seated, maybe that was the issue (the clip is broken so perhaps it vibrated loose). Unplugged it, connectors are all nice and shiny still, plugged it back in and made sure it was fully tight in place. And then the codes switch back to the 0171/0174 lean codes, and the Intake Temp Sensor code disappeared.
No obvious shorts in the wiring that I can see, connector looks to be in great condition as far as the contacts are concerned. I just replaced the MAF unit with a used one from ebay, no easy feat on the SC cars to find 2nd hand), and disassembled the complete tube assembly from TB to filter housing, and reassembled, tightening everything up.
My question after all that ramble, is would there be any particular reason there should be a change in codes? The plug itself could've been a coincidence, who knows. I've been cleaning the sensor every time I've pulled it apart, figuring it can't hurt my chances. But it just seemed strange that it was one set of codes, or the other. Anything make sense to anyone? I was going to put the factory air tube back on if I have to, just to try to narrow things down even further.
Or, could this possibly still be TB related somehow? After last year, I really do need to get it rebuilt before hot weather gets here. These codes just throw restricted right now, and annoying as they are to clear, at least I'm still driving. But nothing frustrating like having the whole car shut down in traffic at random while I panic and fumble through to get Torque on screen again to clear and get moving again.
Anyway, just rambling, and looking for thoughts of others. Cheers!
As for the TB issue - did you change the pins out with the gold plated pins, there was a tech bulletin for this?
As for you P0171/P0174 - This could be numerous things causing these codes, specially since you have the supercharged 4.0L.
I've had many MAF sensors fail on the early V8's, most of the ones I had never logged any DTC's. I had one simulate a slipping transmission. Others the vehicle was in park, and when revving manually at throttle body or using pedal, the engine would struggle to rev up to 2-3k RPM. The few I've had actually log codes, I was monitoring fuel trims at idle with engine at operating temp, and would spray down intake area and vacuum pipes looking for any change, when I didn't find any change, I would suspect the MAF. Sometimes I was able to get away with cleaning, others weren't so fortunate, and had to be replaced.
In regards to your restricted performance, I would start from square one. Check the codes, write them down, and let us know which codes you are getting. In the mean time, if you need to clear them, keep writing them down as there may be some common ones returning and you can focus on these ones.
When you say it shuts off in traffic, is this when its still cold or after driving a bit? When this happens, do you get the restricted performance or no?
The traffic one - and again, I can't for the life of me remember off-hand what it was. I'll have to search back and see if I screenshotted the app at the time - but I could be driving along, and the most common instance was letting off the throttle to come into towns and the like. The car would kick straight to failsafe, and drop to idle with no 'go' until I would clear the codes from my phone. At that point, it'd kick right back up and go on until it happened again. Sometimes it would happen multiple times in a trip, and then other times I could go all day, or even days without it. I took a few hundred mile trip, a car cruise with lots of stop and go, on a 90+ degree day, and never had it happen that day. The next day driving to work, three times. It never seemed to have a rhyme or reason to when it would do it, or conditions in which it would do it in, other than the most common time would be slowing off the throttle. But like I said, that issue has since gone away so far for winter time, so it makes me think something with the warmer temperatures, warmer air, etc. Whether or not switching back to the factory airbox instead of my cone filter has an effect will remain to be seen. I did replace the sensor on the side of the TB though, forgot to mention that.
As for the gold pin upgrade, I have not done that. Mainly because it's my daily driver, and the last couple years, my hours have been sporadic and leaving very little daylight to work on it. They had no signs of corrosion, but I did spray them thoroughly with contact cleaner.
The car is at 195k miles, so it's definitely time to go through all the systems and start catching back up. It just surprised me to have the codes changing back and forth the way they've been. I will also admit that I haven't researched the full workings of reading and understanding the real-time trim levels and what should be ideal under which conditions, and that once I figure that out, it might point more directions my way.
May want to check your battery as well just for fun....... batteries beginning to fail can cause lots of issues.
As for fuel trims - there are a few ways to check. I've usually done it at idle with engine hot and have been able to source the issue, which the short term fuel trim or STFT should be below 5%, and it will fluctuate above and below 0% a little bit. Anything over 5% positive or negative will indicate there is an issue.
Start with battery, check it to make sure its ok. You may need to take it somewhere to have it load tested if you don't have a tester at home. Definitely try a hard reset as Sean stated and see what codes come back, if any.
so having Short Terms that are showing at 25% might indicate something amiss.. If Torque is to be believed, the short term readings were showing 25% at idle, with the car warm, dipping down to about 15% underway, and then back again releasing the pedal.
I'll have the battery tested again. Something definitely out of whack somewhere though. And, as you can tell, the replacement MAF had no effect, other than to lighten my wallet.
Sorry to just get back. Trunk is still full of all my gear so I haven't been able to get through anything battery-related yet.
P0121 is the code that I have screened that was tripping my failsafe this summer. Reading down the 171/174 culprits is disheartening only being as so many little things or big things it could potentially be, but I do need to start whittling out ideas.
One question though - given my P0121, and the likelihood that a rebuild or replacement TB is in order, are there any chances that the 0171/0174 could be related, and/or potentially solved when I go that route? My guess is probably not, but there IS the last line in the 174 codes that it could be related to ECTS/MAFS/IATS/TPS so maybe?
Not trying to just blindly through things around, obviously, just spitballing while forming a plan of attack.
One question though - given my P0121, and the likelihood that a rebuild or replacement TB is in order, are there any chances that the 0171/0174 could be related, and/or potentially solved when I go that route? My guess is probably not, but there IS the last line in the 174 codes that it could be related to ECTS/MAFS/IATS/TPS so maybe?
According to the DTC Summaries, the common possible causes between P0121 and P0171/P0174 are a problem with the TPS or the TPS-to-ECM wiring. So it would be worth testing the TPS, cleaning its connector, and checking the state of its wires that connect to the ECM.
I know they looked good last time, but that was last year and 30k miles ago, and with the addition of the new stuff rearing it's head, I'll definitely go back through them again and look close again, and see what I can find out. Thanks again for the pointers, hopefully I can sort this stuff sooner than later!
Wish I had an update on this, but hopefully might have more after this weekend. Got tripped failsafe three times on the way home last night, it was the P1121 code that was doing it which I do remember from last year - recognized it instantly. But this weekend I'll be using a DIY smoke machine to check for more leaks, in addition to swapping the intercooler pump, brake booster, and lines. Bunch of things all at once, I guess.
I did notice a gob of stuff around the brake hose into the throttle body that I somehow didn't see before, so that adds more suspect into my life. I'm thinking a rebuilt TB is in the works for the spare check I have coming in June, but I have to pass inspection before I can think that far ahead.
I also topped the trans fluid up which solved one issue, but I do notice it seems a little flatter in the upper RPM range. Not sure if the 0171/0174 would be the cause of that, or if I'm seeing fuel pump fluctuations. With my trans liking to pop out of gear lately, I haven't been pushing the car hard enough to notice that, so I don't even know when it started. Otherwise everything runs fine, but I'll have to test pressure sometime I guess, if whatever this other issue doesn't solve it. They probably need to be replaced anyway but I'd rather do that on my own time, than throw money at them if they aren't the main cause right now.
Frustrating, but that also comes from having a mud driveway, no shelter, no garage tools, and no indy that I trust near me.
You confused me there for a minute jumping from P1121 to testing for leaks, but I think I follow - you must still be suffering the P0171/P0174 lean codes you reported earlier. We'll be interested in the results of your smoke tests.
You probably already know, but for the benefit of others, P1121 indicates a problem with the pedal position sensor, its cable or its circuit:
Sorry about that. But yes, still have the 171/174s, but the 1121 was a problem last year that had gone away during winter, strangely. Now that the warmer weather is creeping in, it's starting to pop back up in addition. I only had mentioned it prior, in case I could try to connect dots between that and the lean codes. It's hard to try to narrow down one issue to tackle at a time, but I have Lady P's post above to try to test more for the 1121 issue, and the smoke to try to sort the others. I'll report back throughout the weekend to see what progress I hopefully make.
It's hard to try to narrow down one issue to tackle at a time, but I have Lady P's post above to try to test more for the 1121 issue, and the smoke to try to sort the others.
P1121 does not refer to the Throttle Position Sensor (TPS) that the link Lady P provided refers to. P1121 relates to the (accelerator) Pedal Position Sensor (PPS), which is also mounted to the throttle body but is a separate dual-trace sensor, so be sure you test the correct circuits.
Ah, that's true, I had forgotten I had referenced the other one earlier. Luckily the weather is calling for snow tomorrow which should make it so much better than if I had been off today when it was 65 degrees lol.
Well, mother nature decided to whip up a lot of wind today so I couldn't smoke the system as intended - I would never have been able to see where it would come from. I did however, change the intercooler pump. With the MAF off and unplugged, and nothing connected, I started the car to warm it up afterwards, bleed the system, etc. Just for kicks, since Torque was still paired and running, scanned for codes. Must be that it goes through checking for the MAF and Intake Temp circuits before then determining lean/rich conditions, as I got P0102 and 0112 errors, and nothing else. Checked the trims, and totally opposite of what they were. Put my hand over the intake at idle and wow, the suction on that tube lol. Anyway, tomorrow should be nice and cold and rainy but hopefully less windy so I can get this hooked up and tested and pray that wherever this leak is, it's not catastrophic.
didn't get much cooperation from the wind today but gave it a go. Looks like I have some coming from the front top end of the LH side of the engine. I'm guessing I might be looking at intake gaskets. I think I saw a little more on the passenger rear top end too, but hard to say, but I'm pretty sure I heard some air escaping near there anyway, either way. Time to look up more procedures I guess.
During my brake booster replacement, I found that I somehow had missed, or maybe it hadn't fully formed, who knows - but there was a giant split, about 4-5" worth on the underside of the vacuum line coming out of the throttle body. I wrapped the hell out of it with electrical tape, just to see if I could get ANY vacuum back at the booster (nope lol). However, it DID bring my trims down, and cleared my P0171/0174 codes. I've ordered another line in hopes I can make it work (a 25 dollar X100 line I'm hoping I can mold into shape vs spending 200 on a new X308 pre-bent), but at least it's narrowed it down. Strange, since I never could hear any air through there, and wasn't expecting it to be the cause of so much grief! Good news is that I found it, and that I can figure that mess out.
I also found a two-wire plug connector that has half-melted off the crossover pipe underneath, so I'm curious as to what that goes to. But as it's unrelated to this, I'll save that for another post.
03-27-2018, 04:07 PM
Strange MAF (?) issue
