and then as sure as sh#t now it just cranks and cranks and cranks and doesn't do a damn thing!

changed out ckps for one out of running car. no dice. Tach reading 200rpm while cranking.

What the H#LL gives on this bloody thing.

I'm going to kill it with fire.

 

Sometimes you have to go back and cover your bases .

Suggest going back to the basics and verifying fuel pump running .

Pull a plug to see if you have ignition .

Jumper the 2 white wires on the inertia switch .

Make sure you have a fuse in the security system slot .

The 48 pin plug above the fuel tank is engaged . This last connector can be tricky so don't try too hard and break the small locking ears off .

 

So I got back at it after my rant.

Fuel hose had come off in tank after replacing fuel pump to test it as culprit.

Good in that there isn't a new fault. Bad as it has changed not a thing.

On the up side I have fixed the fuel pump being ECU switched issue. the passenger footwel F10 fuse which I have checked at least 2 times was very barely visibly burnt out. It's listed as fuel pump relay coil fuse I believe. Replaced with new and presto. Key on and pump is energized as it should be.

So. That leaves the ever so slightly lumpy idle and lack of power/missing/hesitating/stalling under load or even throttle blip in Park.

Tps reads 11.4% at idle and sweeps neatly. Where else to look? What else to check.

 

So you have a spot of stumble under the bonnet , oh I mean't on the engine

The F10 fuse for the fuel pump relay closing control circuit by the ECU is tied into some other things to cover so it doesn't blow again . The 48 pin BT4 connector above the fuel tank is fragile and can break if tried to force too hard but if it is open it wouldn't pop the fuse , so I would recommend skipping that . Someone recently found his OBD 2 connector messed up . You'll have to ask " cdma " details on what he found

We'll have to find the rough engine running issue now .

 

That's interesting as when I was using my OBD bluetooth it was very slow to refresh if at all was missing values I expected to see. Maybe now the fuse is back it will yield more info.

But yes, I (we, thank you) need to find the rough running issue now. Did you see the video I took?

It idles ok. Will rev up slowly with minor hickups but ok, blip the throtle or stab the throttle and it stumbles and pops and misses. When in gear that stumbling will become a stall. When babying the throttle it will accelerate ok.

Not at all anywhere near the smoothness I'm used to from this engine.

I think I need either a diagram or pic of the vacuum hoses on the throttle body etc. It's either weak spark, timing, or vacuum. I feel like fuel pressure has been ruled out due to having tried 3 different pumps now and fuell sprays well at the rail.

When I had the rail apart all the injectors were very clean and the rail too.

My intuition says it's not the coils as I've moved those around. I suppose I could pull the coils off the x300 that IS running well and see if that makes a difference.

Does the XJR use any kind of MAP sensor to detect boost or does it just expect consistent boost as the supercharger is belt driven? Again seems like a vacuum leak... but that's just hoping at this point. Lol

Thoughts anyone?

 

Bluetooth has a slower refresh rate that other people complain about .

A quick check of the TPS may show something as you turn the butterfly shaft slowly the value with a meter on the Green / Pink wire should read 0.60 volts DC at idle stop and increase toward 5.0 . What you don't want to see is a bib or spike in the reading to 0.0 volts as you slowly twist through the throttle range . You have the keep the connector on the sensor under the butterfly with the key on but engine not running . You can strip some insulation off the wire as it goes over the to of the fuel rail for easier access . Verify the connector is on and locked in place and some connector clean might help .

The device you are using may not see this bib on the bad spot if it is present on your example .

If the ECU has a bad signal from the TPS sensor it rejects it and reverts to a less then optimal set of regulation data maps without a TPS value so the engine runs but takes a second to shift over to that mode , hence the misfire .

This is an easy thing to check covering a basic item of engine regulation .

Cheep coils can make the other electronics go nuts so do swap coils .

 

Will do. I have two regular xj40 TPS's I picked up today.

In case it's the TPS. Though I must admit, I'm doubtfull. A bad TPS has crossed my path quite a few times, resulting in either high idle or flat spots, never a "rev up fine slowly, but stumble all the way quickly" scenario...

will let you know.

 

X40 ( ? ) TPS for a X300 ( JLM12074 )

They are different ECU technologies and they may function differently in how it responds to a dead spot on the sensor . The test is free .

https://www.jaguarclassicparts.com/u...ally-aspirated

 

Sharp as ever. Although I don't know why I typed xj40. My buddy I got them off was working on one. These are both 4.0 aj16 TPS's. Maybe the 4.0 tripped me up.

So the question is: AJ16 4.0 TPS vs XJR TPS, same?

I need more sleep. I have two kids under teh age of 4

 

AJ16 4.0 TPS vs XJR TPS, same? Yes 4.0 and 3.2 liter engine the same also .

MAF and fuel Injectors , Not the same as supercharged are different .

 

engine still runs rough...


same skips and misses under load. any ideas? starts, runs, idles with a few bumps and burps here and there. Put it in gear accelerate slowly it's ok. Get further down then 20% throttle and it starts to bog, sputter and miss. Even more and it get's worse.

 

Could it be bad fuel and choked injectors?

 

error

 

Fuel is fresh. The rail has been out and cleaned.