More old knowledge from the archives...

the customary way of getting good plug readings at WOT without
the subsequent cool down affecting the reading is to cut the ignition
at WOT and coast to a stop

water introduced to the combustion chamber is an effective carbon
cleaner. with a MAF to consider, introduce the water through the
power brake booster vacuum line.

 

I listened to the sound file (just love the supercharger whine) but the clattering/rattling sounds to be too intermittent and random to be detonation.

Dunno.

 

I am 99% sure it's pinging.

Anyhow, I was still wondering about the P1235 code and I came across this thread https://www.jaguarforums.com/forum/x...l-pump-112173/

Which kind of takes the sting out of putting in new pumps.

Still waiting on the new fuel pressure sensor, end of next week I guess...

One thing is for sure, when the car is running properly i'm going to leave all the cabin filter & noise-insulating shrouds off, the sound in the cabin is nuts!

 

Another thread related to the fuel pressure sensor

https://www.jaguarforums.com/forum/s...s-power-77995/

Interesting that you are able to just unplug it and somehow the system is able to maintain the correct fuel pressure....

"I still was not sure it was the sensor but finally came up with an idea. I unhooked the sensor and let the plug hang. Then drove around again with the fuel pressure tester on the windshield. Much different! The pressure stayed around 45-65 psi with some variance as the RPM's changed. Never went to 90-100 psi and never dropped below about 45 psi.Car drove with pretty much full power again. Of course a constant check engine light but I expected that."

And yeah, wish i'd found that thread earlier, Ford p/n on the sensor, 3R3E-9F972-AA, much cheaper of course...

And this is interesting '03 ST170 driving me mad, but not driving...

"if you hit the rev limiter too often or your traction control kicks in while you're up high in the RPM range, it'll attempt to cut power by removing fuel pressure (dropping fuel pump voltage). The problem with this method is that a lot of times in these situations, the fuel pump cannot react quickly enough to the demands of the computer and you end up with over-pressure (70psi) which blows the FRPS's internal diaphragm, rendering it useless and causing it to give a faulty reading of current fuel pressure, then the computer has incorrect data to make decisions with, causing the car to run like ****."

I will certainly be dissecting the old sensor to see if there is internal damage to the diaphragm.

Also interesting to hear that "The exact same part used on my ST170 is used on 2003+ V8 Mustangs in the States. These sensors blow regularly which is why they were improved. They're sold seperately at Ford or Ford spares places from $60 - $90." so i'd better be getting the new and improved version from Jag...

EDIT

Another thread for bad fuel pressure sensor https://www.jaguarforums.com/forum/x...ighway-119205/

And another https://www.jaguarforums.com/forum/s...3-p0191-85703/

 

I wonder if oil from the filter has gotten to MAF. I have removed the K&N filters from three of our vehicles.
The paper filters just work better.

 

Hi Panelhead,

Welcome to the Jaguar Forums! It's great to have you with us, and thanks for contributing.

Since we're a friendly group, please visit the New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum and post an introduction so we can learn something about you and your Jaguar and give you a proper welcome.

Also, please add your Jag model and year to your signature line so others won't have to ask. It's easy to add the info to your signature using your user Control Panel. Hover your cursor over your username in the upper right corner of this page, and in the dropdown menu click on the first option, User CP. In your Control Panel, find Edit Signature under Settings & Options in the left hand column. Add your vehicle details to your signature and save, and you're all done.

Cheers,

Don

 

Welcome to the forum.

There is already a discussion about K&N's going on in another thread https://www.jaguarforums.com/forum/x...ilters-119498/ we are not going to have that discussion in this thread.

The MAF on this car is fine.

1. It was cleaned a couple of weeks back, no residue came off it, as opposed to the first time it was cleaned a year or so ago where a heap of yellow/brown residue came off it.

2. The question of the MAF readings from 300 to 330g/s over the that rev range was also clarified as being normal, based on previous measurements from other 4.2L Supercharged cars, and this one, over that rev range and dynoed power output.

I wasn't going to update this thread again until the mechanical fuel gauge was installed and the replacement fuel pressure sensor on hand. But might as well mention it now.

I had made some observations of the Long Term Fuel Trims a few weeks back when this all started, using the datalogger in the IDS/SDD. The LTFT's at idle with a warm engine were close to 0%. I only checked them a couple of times with IDS/SDD because it was a PITA to get it all loaded up.

I got my Android Tablet with Torque Pro working with a new ELM module.(actually it was the ELM327 that was the problem, the pins on the plug had pushed in so poor connection to the OBD socket in the car)

Well, after putting in new upstream O2 sensors (and plugs & coils), we now have this;



Same conditions, at idle, engine warmed up. The LTFT's are a mile off.

Following the assumption of the FPS being shot / reading high, I'd say that low fuel pressure is causing the ECU to add more fuel to acheive the demanded AFR. Which would explain why the car was running so rich and fouling up the plugs/tailpipes.

Will confirm this with the mechanical fuel pressure gauge, or the new fuel pressure sensor, whichever arrives here first...

 

As you rev, still parked, what do the trims do?

 

Seems i've lost all the screenshots off my tablet...

I did hold it at 2000rpm in neutral to see what happened with the LTFT's, they did change, but don't ask me if can remember what they did exactly...

Will try again tomorrow if I have time...

 

Cambo,


I am thoroughly enjoying this thread even though my knowledge of the subject is superficial. One thought - In the old days we were cautioned against WOT operation of cold or rich running engines. The caution related not only to excess engine ware but also glazed plugs.
It seems to me that you need to get to the bottom of the rich condition before WOT operation (curb your enthusiasm). BTW it's something, curbing enthusiasm, I have never been able to do myself but I wonder if you could have glazed plugs under a coating of soot?

 

I already did about 4 more WOT runs than I wanted to, and there won't be any more until the mechanical fuel pressure gauge and the new fuel pressure sensor goes in. In the back or my mind I have been wondering, how much damage has been done to this engine...

When this is all finally resolved, we can sit back with the wisdom of hindsight and say "yes of course, it's so obvious what the problem was"

In fact I am very sure that I will get an "i told you so" from Plums about needing to put a mechanical pressure gauge on the fuel rail. Well at least I eventually found a way to do it that does not require a hacksaw EDIT: No i didn't!!!!1!!

If nothing else it's been a great learning experience, i've replaced a heap of parts that would have eventually needed replacing anyhow / were on the to-do list, I bought several new tools (and made one, so proud!), found a solution to a stupid problem, got my IDS/SDD back-dated so it works better, got my Android tablet working properly with Torque, and the best bit is that if this ever happens to anyone else, they won't have to go through all this crap again...

 

More learning experiences....

The fuel line that has the quick connect is not the feed line to the fuel rail. It does not hold any pressure at all. The other line is the pressurised one. And there is no way to get into it without cutting... So waste of money buying the special fittings, will have to send them back...

It was suggested that I had a vacuum leak because of the LTFT's at idle. So I had a spray with some MAF cleaner at the PCV line, and the engine stuttered after a spray around the throttle body. When I changed the throttle body last year, I re-used the old gasket, which you are not supposed to do.

So I pulled it all apart, and put in a new gasket. Got it all back together, and the LTFT's were still sky-high, and spraying around the throttle body also caused the stutter...

At wits end, I decided to put in the new fuel pressure sensor. Here I got a surprise, the rubber hose on the sensor is in two parts, a bend which is on the sensor, and it connects to another tube with a little barbed fitting, that then (must) go on to the intake elbow before the supercharger, so the pressure sensor actually has a vacuum line attached to it, not boost pressure. When I was pulling the tube off the sensor, the whole thing came off in my hand, it pulled out of the barbed fitting further down the line. Helloo vacuum leak.

So I put in the new sensor, and put cable ties around the joints at the barbed fitting.

Started it up, and let it warm up. The STFT's were like -18.5%. The LTFT's slowly fell back down to 0% from +19.5%, and the STFT's slowly went back up 0%. It settled with the LTFT's at -2.5% and the STFT's at 0%. I would say it went below zero because of the heat in the engine bay, it stood idling for about 20mins.

With the new fuel pressure sensor in, it was showing 55psi at idle.

I thought that was it, all fixed, time to go for a drive....and.... it still pings.

Fuel pressure peaked at 70psi, detonation above 5000rpm....

Moscow Leaper had mentioned that the PCV valve could be a problem, and I could really hear some sucking sounds through the PCV hose that runs from the valve back to the throttle body.

So I took off the PCV, and air will pass both ways through it. Which is apparently a problem...https://www.jaguarforums.com/forum/x...-valve-134269/

Tried to blank off the PCV with some plastic sheet. The sucking sounds were gone! I gave it a little rev and there was a distinct "pop" as the plastic sheet popped under the vacuum through the PCV hose, just put a hole in the plastic... oops.

But now, the fuel pressure is showing as 65psi via OBD, at idle...did the sudden surge of air through the PCV hose cause actual damage to the brand new sensor?

I am ready to burn this car to the ground...

New PCV valve will arrive next Wednesday, because everything is closed here for Easter...

EDIT

So this got me thinking about an oil catch can. And I found this thread in the XF section https://www.jaguarforums.com/forum/x...an-yet-138452/

These comments jump out at me:

I changed the oil just before new year, put in a full synthetic... and I only noticed the detonation in February, after hardly driving the car...

There is a heap of vacuum on that hose that runs from the PCV to the throttle body. And this engine is pretty old now. It seems to fit together that crankcase fumes would have a lot of oil. With the failed PCV it's sucking a lot of vapour from the crankcase, the synthetic oil vapours are causing the detonation?

There are cheap-enough catch cans on ebay that have an OEM look to them, I am seriously considering this now.

 

You'll have to remember to come back to that in case it really did pop the sensor.

A catchcan won't cure existing combustion chamber deposits.

This would be one of the times where SeaFoam is the right thing to do.

With a MAF system, the seafoam is introduced via the power brake booster hose.

Speaking of PCV and a recent oil change ... is the 710 filler cap fully seated
as well as the 710 dipstick?

 

I am not competent enough to bring any useful contribution to this issue but I wish to thank Cam for this fascinating report and all the contributors for their knowledge and ideas' sharing.
This also reminds me of another recent lively thread to identify the causes of a frozen 4.2 SC engine.
Thanks to this invaluable forum.
All my wishes to Cam to finally get it sorted out

 

Well... it's good news that you found something that needed fixing! Stick at it, you'll get there.

 

No. The other poster's understanding on this topic is very misguided.

 

Just looking for any possible explanations to the problem i'm having...i'm not a mechanic, I know just enough about cars to be dangerous... LOL

For sure it's better to have a PCV system functioning as it was designed to, as opposed to mine which is currently not functioning correctly. At least when it's working properly it can be ruled out as a factor in the detonation.

Like Plums said, I think it's time to look at carbon-cleaning.

 

I think it's time to see IF there is carbon and enough to cause any sort of issue. You may wish to review this video


before spending money on the much worshipped Seafoam. Despite the reviewer's enthusiasm, the product didn't really do much. The same or better could be accomplished with plain water.

 

There are a couple of workshops here in Sydney who have a "proper" setup for carbon cleaning.

Carbon Cleaning and Hitech Auto Electrician they are not exactly local, but I can't find anyone close to me.

I couldn't find SeaFoam here, but Liqui Moly has something similar

PETROL ENGINE INTAKE DECARB | 2733 | LIQUI-MOLY - AUSTRALIA

Interesting that these products only talk about cleaning the upper intake, not actually cleaning the combustion chamber.

In any case with the volume of smoke that comes out, I can't do it here at home. Depending on what a Motorvac service costs, I will consider it.

But...

One question has not yet been answered: Why is the ECU not pulling things back when the engine is detonating? Surely the whole point of having knock sensors is that when a detonation is detected, the ECU responds...

According to the Torque App "fuel status" at WOT it changes to "Open Loop Monitoring Knock Sensors"

Are my knock sensors working properly?

There are some pin-point tests in JTIS to check the Knock-Sensors. Section O for right hand side.

O1: Check KS Sensing Circuit for High Resistance
O2: Check KS Sensing Circuit for Short to High Voltage
O3: Check KS Sensing Circuit for Short to Ground
O4: Check KS Ground Circuit for High Resistance

And the same for the other side as well, but these are "P"

The pinpoint tests are called up if you get a DTC for knock sensor issues, which I do not have. But I wonder if it could be that the knock sensors are electrically OK (so no DTC's), but just not functioning or not actually hearing the detonation.

I would like monitor the knock sensors, preferably by OBD either with Torque or using the IDS/SDD, but for the life of me I cannot find any function to do that. There does not seem to be any option in the datalogger of the IDS/SDD to monitor the knock sensors.

They are just 2 wire, I have read here and elsewhere that they are basically just a piezo crystal microphone, so the signal is a frequency output, I don't know how I could read that & tell if it's "good" or not.

An interesting article here about how knock sensors work, and some suggestions on how to test them http://www.wellsve.com/~wellsmfg/sft...12_i2_2008.pdf

So a "mechanical" test would be to monitor the ignition timing while hammering away at the engine with a metal screwdriver?

Another thought, and based on the controversy it caused, I want to point out that the would be for DIAGNOSIS PURPOSES ONLY is to fit some external sensors and see if there is any change in the way the ECU responds. i.e. like this https://www.jaguarforums.com/forum/x...charged-93580/

As you know, the knock sensors are buried away in the valley of the engine, so swapping them out is no small task...

 

from my knowledge (coming from other brands) knock sensors are generally set to only take out X degrees of timing i.e. they may only be able to retard 20* max, in case they do go nuts. Too much constant retard and you will overheat an engine.

So one possibility is that it's taking all the timing out the sensors can, and still detonating. Or, a wacky sensor not reading knock would also let it knock without properly retarding at all as you discerned.

*in the early days of turbocharging miatas, we used to use aftermarket knock sensors like the J&S system. The test to check they were working was to knock the block with a wrench and see if the display lit up showing taking timing out, so yes, that is legit, but you need a way to read it as you figured out.

Sorry, not a lot of help, but you're thinking is legit.