Background: A few months ago, wife came home with a "Restricted Performance" message. Pulled codes and determined that the MAF sensor failed. Ordered the replacement, installed and cleared the codes.
Everything seemed fine but then last week, had similar issue and decided to pull the MAF sensor connector to clean and double check the contacts. When I noticed that the MAF Sensor didn't say Delphi on the top, but I thought for sure I had ordered a Delphi (couldn't find a Denso in stock). Searched around and I still had the box it came in, and sure enough it was a Delphi box, looked up the number on the top of the sensor and it wasn't even the right type of MAF sensor. It was a Toyota one, so Amazon sent the correct Delphi unit.
Installed the correct unit, but to my surprise the car didn't run very well. Though maybe I shouldn't have been surprised because the wrong MAF sensor had been in there for a couple of months and might have messed up the adaptations.
I cleared the codes and took it for a drive cycle, and it seemed to be running beautifully so I put the car in the garage and foolishly thought "job done". Went to start it a few hours later, Engine Light and "Restricted Performance" almost immediately. Checked codes and now have P0171 and P0174. Also, if I try to start the car after driving it, it will start briefly but won't idle and stalls out. I can coax it to start by giving some throttle, but it's not happy. I've looked and listened for vacuum leaks, sprayed some MAF cleaner around and didn't detect any changes.

Suggestions of what to do next would be most appreciated.

Thanks!

 

The engine sensors are usually powered by a very controlled reference voltage from the EMS but the MAF sensor is not

on page 53 it is fuse F14 / 10 amp which requires the EMS controlled relay in the front power distribution box to be closed , the relay can be intermittent or have burnt power contacts inside

This will be point 134 circle E on page 63 and 53

X350 03.5/NA COVER (jagrepair.com)

 

Thanks for the suggestion, but I just tested and I'm getting 12V at F14 with the key on.

 

Try either the Toyota MAF or original.
I do not trust many Amazon suppliers.

 

The test you performed was probably under a no electrical load condition in a static sense and not a functional dynamic sense where a burnt contacts will trade voltage for a current flow

There should be a relay you can swap with

And then your issue is intermittent

 

Hi did you try smoking the engine for vacuum leaks... You might be surprised in what you find...At least you could fully eliminate vacuum leaks and move on.. What were your fuel trims during these issues??

 

A smoke test sounds like my next step. I imagine there is a way to cobble together a DIY smoke machine on youtube, so I'll commence searching.

 

There was a contributor in the X300 area that made a DIY smoke machine for manifold leaks

I'll look for it but I have things before then

See this one as there is some X350/8 discussion

Smoke machine hook up to 2003 XJ8 - X300 - Jag-lovers Forums

 

Was able to DYI a smoke tester with a paint can, 3/8" tubing, 1/4" air hose fittings, 3/8" to 1/4" bushings, and 4 o-rings (pics attached if anyone wants to see how), I used incense sticks to create smoke. You'll need an air compressor with a good regulator (1-2 psi) or a small air pump, As speculated I had some leaks -- two hose o-rings, a crack in the crankcase breather hose, base of the oil filler was loose, and the o-ring on the dipstick.

With a temp fix on the breather hose, and new o-rings, it so far hasn't thrown a too lean code. We'll see if that continues with more driving.

Thanks for the help!

 

Spoke too soon... when started this morning it searched a bit for idle, went up to about 1400 rpm, then settled in, but almost immediately Engine Light come on and Restricted Performance message.

Not sure what to do next.

 

Brillant, love the glove to give you a hand

 

LOL, It was what I had on hand, so to speak, but the glove it turns out is great for gauging the air volume from the compressor so you don't over do it.

However, I am back to where I started with Too Lean codes and Restricted Performance message. I thought for sure that curing the vacuum leaks would do the trick, but alas no.

Any suggestions?

 

Hi @Mac Allan ,

Which codes have you been getting, both initially and following the replacement of the MAF meter and repaired vacuum leaks?

-j

 

@Jacuar I can't remember the exact MAF related codes from the end of last year when I first replaced the MAF sensor, but I'm getting the following now:

P0171, P0174 System Too Lean Bank 1 & 2
P0101 Mass or Volume air flow range/performance problem

I have a IDS/SDD system if there is something I should specifically do or look for with that. Thanks for your help

 

If you haven't cleared the DTCs already, can you get the freeze frame for each logged fault?

I'm wondering if you have two different issues going on simultaneously.

-j

 

Apologies, how do I get the freeze frame?

Thanks

 

I think I have a clue, or least direction to investigate. The good news is that I can reproduce the 'bug' or error conditions in a consistent manner. Here is the sequence:

1. Clear codes to eliminate the Restricted Performance
2. Car starts and drives great, go for long test drive, no issues of any kind discernible, even under hard acceleration, high speed, low speed, etc. Put it on scanner, no codes thrown, no restricted performance.
3. Leave overnight.
4. In the morning, starts a bit rough, searches for idle, then rpms climb to 1500ish holds there for a bit, then drops to more normal range...
5. Check Engine Light come one, then Restricted Performance message.
6. Codes thrown -- P0171, P0174 System Too Lean Bank 1 & 2 Pending Code -- P0101 Mass or Volume air flow range/performance problem

So, what conditions change from the day before to the next morning? Two things came to my mind, the first is battery, the second is temperature related.

Tested for battery hypothesis. After sitting overnight tests at 12.1V, weak enough to confuse ecm? not sure, but left on charger overnight, and used engine start function of charger to make sure there was there was no voltage drop at start up, and it went through steps 4-6 like clockwork, so no easy solution, but at least weak battery is eliminated as the culprit.

Tested Coolant Temperature Sensor through the OBDII port, and it appears to register the correct temperature from start up to warm up. Thermostat is less than year old, and engine appears to come up to operating temp normally.

So, what other sensors or variables would change by sitting overnight?

@Jacuar any ideas? Anyone else with suggestions, or something for me to test and report back?

Thanks very much

 

There should be a freeze frame recorded when you get a confirmed DTC. This will record all of the conditions when the code was confirmed. I am mostly curious what the long-term fuel trims were, as well as MAF flow rate.


I have a similar temperature related problem. Almost exactly the same, in fact, without the RP (usually) and without the MAF DTC. I also get a rough idle, followed by increase RPM and then drop back down to a low and smoother idle. When cold my STFTs are >25% and my LTFTs are between 8 and 11%. As the engine approaches normal operating temperature, LTFTs increase to between 11 and 18% and STFTs drop down and hover around 0%. Once normal operating temperatures are achieved LTFTs are between 6 and 8% and STFTs are still bouncing around 0%. I wonder if you are seeing the same. I suspect, in my case, I have a vacuum leak until my engine reaches normal operating temperature. I have extensively tested for leaks using unlit propane and have found none. My next step is to do a smoke test when I have time, but I have no doubt that I have some small engine-seal leaks that need to be addressed and small o-ring leaks with the CCV and EVAP lines. Since it is only a problem when cold, I haven't made this a high priority, but it does need attention.

All that being said, I think we have similar problems, except the MAF problems you are having. When the ambient was really cold (ha, really cold for southern california, i mean ~32 degrees fahrenheit) it went into RP twice, but that was because as STFTs were approaching 0% the LTFTs had risen just over 20% confirming the DTC, i think because the engine took a little longer to reach operating temperature. The other thing is this apparent vacuum leak was clearly binary, as in, when the engine reaches ~185 degrees the leak nearly vanishes and LTFTs + STFTs are a constant +6% (I think 6% is my baseline collective vacuum leak, a separate problem from the cold temp issues). There have been several cases on this forum as well as on other forums that were very similar to this, but all but one person who posted them did not ever post a resolution. People have suggested EVAP purge valve, leaks that would seal up as temperatures rise, etc... But no unambiguous answers. The only one solved, that I saw, was on this forum (I can't remember whom), in which the CCV part-load breather (saucer shaped object on the bank 1 cam/rocker/valve cover, left hand bank when standing at the front of the vehicle) had a crack on the bottom side. The OP of that thread replaced it and these symptoms were resolved. I haven't had time to check mine, but will try to do so today, but I think it is fine. The binary nature of my problem suggests a temperature controlled valve, like the EVAP system controlled by the purge valve, but that doesn't seem to be the case with mine, as the problem persists when I remove the EVAP system from the intake and plug the orifices. Plus, my understanding is that the purge valve will only open at operating temperature, not when cold.

Anyway, long answers, but I am still searching for the solution for both of our sakes. You have similar symptoms, which I am intrigued by, but the MAF sensor problem needs to be isolated first. Your ECM needs to have an accurate reference for incoming airflow and temperature so it can calculate the correct fuelling for a given volume of air at a given temperature. If your MAF is faulty, then all measurements downstream are dubious, e.g., a lean condition is meaningless if your ECM doesn't know the true flow rate and temperature of incoming air. One thing you can do (where in CA are you?) is to go to a pull-a-part and get a Denso MAF. I will only use one from a wrecked car, because I assume it was running properly when crashed. Just make sure it is clean before you install it. A few shots of MAF cleaner will help. There are several X350s here in SoCal and probably some up in Elk Grove/Sacramento area. But if you are lucky enough to get a good factory MAF, then you can hopefully move forward in your troubleshooting. I assume your air cleaner is a factory style?

-j

 

With the battery area of concern clean and tighten the terminal nuts on the bus protection module in the trunk , they have a history of coming loose

There is a false bulkhead battery cable connection up front under the hood

At the engine start the EVAP and EGR will be closed and the IAC will be somewhere off of full closed , Smog pump will come on for maybe 60 seconds , and the O2 sensors will be heated through a heating element before the O2 sensors are used in the ECM closed loop by way of the coolant temp sensor getting hot enough

There is a EGR _ ERROR PID on your reader and the target is 0

You can blow through the EVAP valve to ensure closed and can be tested with a 9 volt battery

 

@Parker 7 I wanted to follow up on what you said, and I tested voltage at F14, while the engine was running and was only getting 3.7V, at F12 it measures at 4.0V, and interestingly 0.0V at F13. With ignition on, but engine not running there is 12V at all three. It's almost like the relay is working, but something is drawing all the voltage while it is running. If I'm reading the schematic correctly, F13 goes to the fuel injectors, but how can it ever run if it is measuring 0.0V at F13?

To say I'm confused, would be understatement.