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First, apology for overlooking where you said earlier about the fuel pressures.
Well, then the MAF is probably not in play, so that's another check mark to narrow it down. But the status of OL vs CL is the OL is when the system is getting to operating temp and once there it hits CL barring any encumbrances like a faulty part.
No need to apologize. I posted before that the MAF numbers were good. Well, I'm going to have to check that again because the fuel trim problem is resolved. Cranked her up this morning from dead cold to drive to work. OL numbers were good...went to CL much faster today (before Engine Coolant Temp (ECT) reached 95 degrees). LTFTs went up just like before. After about 5 miles, while sitting at a stoplight I noticed that all the fuel trims were good.
I did only two things last night so I'm assuming one of them fixed it. I removed the connector off of the TPS...cleaned it and put it back on. I did this because I was chasing a buzzing sound under the hood with the engine off and just the ignition switch on. The buzzing sound stopped when I disconnected the TPS. When I plugged it back in it did not start buzzing again. When I turned the ignition off and then back on it started buzzing again. I have no idea if this is normal or not.
The second thing I did was replace the MAFS with another one I had. So, since I did two different things I will have to go back to the MAFS I had on it to see if the problem comes back. I will compare the MAF numbers between the two.
The car seems to be running exactly the same as before. She still has a bit of an idle problem so that is definitely something different. I started another thread about the idle issue.
I put the original MAFS back in and the problem came back. Don't understand it because the numbers are not that bad.
Full operating temp both test. Readings in g/s
............................Good.......Original
Park...Idle ............4.28...........3.85
Park ..2500RPM....14.5..........14.25
Drive...Idle............5.2.............4.5
Drive...1500RPM....32.1..........32.0
One thing I noticed while taking the readings is the idle numbers change a good bit when the AC turns on. The above numbers are with the AC off. With it on they are 5.1 and 4.73. The idle speed doesn't seem to be changing enough to do this so now I'm starting to suspect a weak battery or voltage regulation problem. I will check that and post findings. But the bad fuel trim problem on this car is FIXED.
Last edited by 2001 White XJ8; Feb 10, 2020 at 03:35 PM.
I don't trust MAF's, they are a fickle item...kind of takes after the fairer sex.
Check the pins on the connection in the TPS harness....here's someone's account with the TSB... http://www.jagrepair.com/ThrottleBodyPlugs.htm
I don't trust MAF's, they are a fickle item...kind of takes after the fairer sex.
Check the pins on the connection in the TPS harness....here's someone's account with the TSB... http://www.jagrepair.com/ThrottleBodyPlugs.htm
The symptoms of your rough idle are quite similar to what I’m experiencing... Have you solved it? If not: have you checked your Throttle Body opening percentage at idle?
No,not yet. I've been giving the ECU time to completely relearn. The wife has been driving it lately so I don't even know if it has improved. Still have to check the TPS contacts for the above TSB as well. The throttle position percentage PID in the live data seemed to be very low to me. Would like to compare it to another X308.
Jack,
Drove the car today and nothing has improved. It seems to have the exact same symptoms that yours does and it is also Ironic that we both just solved P0171/174 lean issues.
The idle drops below 600 when coming to a stop and the engine sort of shutters. The idle always comes back up but it does the shutter nearly every time. No codes. Good fuel trims TP percentage seems low but maybe that is how it is supposed to be.
Are we sure the O2's are all good? Here's my install thread from the How To, make sure you have the correct O2's. Though that low idle shudder sounds more like a vacuum leak. https://www.jaguarforums.com/forum/x...cement-195018/
Like I said in an earlier post, Ford components tend to have "hard" code issues.
Are we sure the O2's are all good? Here's my install thread from the How To, make sure you have the correct O2's. Though that low idle shudder sounds more like a vacuum leak. https://www.jaguarforums.com/forum/x...cement-195018/
Like I said in an earlier post, Ford components tend to have "hard" code issues.
For review....
Fuel trims good. Smoke test good. No codes. O2 sensors correct. Is there something I should look at in the live data? Do you know what the TP percentage should be at idle?
If it's running CL (closed loop) with a hot engine parked, at idle, LTFTs within about 5 of zero, all OBD monitors happy, then it's all good and the TPS is irrelevant really.
What exactly am I looking for in the live data to make sure the O2 sensors are happy? They obviously are happy enough to not throw a code. Also, just for S and Gs what TP percentage should I see at idle? It seems lower to me than other cars I have compared it to.
To explain the symptoms maybe a little better...... I was in a long line of cars yesterday at a 4 way stop. Every time I moved my car forward and stopped it did the stumble or shutter. AC on or off didn't matter much. Pulling in to a parking space while turning makes it do it worse. The pull of the power steering drags it down even more.
You state when you turn the wheels your idle gets worse, this really sounds like a vacuum leak.
Since you recently had the 171/174 issue, I suspect moreover the simplest scenario, possibly along with a vacuum leak....fuel filter...just make sure you've covered these other areas...
Ok, I found this on Jagrepair.com with fuel trims and no codes with poor idle....So I took a hunch and elected to replace the purge valve. I had no codes and no other indications leading me to it.
See the fuel trim readings.
This is the Old Purge Valve at idle Bank1 - 3.1 Bank2 – 6.3
This is the Old Purge Valve at Driven Bank1 – 1.7 Bank2 – 2.8
This is the New Purge Valve at idle Bank1 - -0.9 Bank2 – 2.8
This is the New Purge Valve at idle Bank1 - -1.4 Bank2 – 0.7
I did the part and full load breather. I've also fixed all the vacuum leaks. I did this by smoke test. It even holds the 1 psi of pressure for a while. Only possibility of vacuum leak I can think of is one that only occurs when engine is hot versus cold. But I went over the engine with starting fluid. So pretty sure I don't have a vacuum leak. But the TSB you sent me about the adaptations makes sense. JacksJag is having the same problem with his. And his is also after fixing a lean condition. I'm going to perform the TSB and let you know.
