Dear all I have a x300 4.0l xj6 Daimler (1994) which I bought with known poor running. I am gradually working through issues. Main one at present is a severe hesitation to increase revs with heavy throttle change. If I very gradually increase throttle it will rev through full range but stomp on throttle and seems that the motor gets no fuel. I suspected tps and have not ruled this out but wondering whether I should be looking elsewhere? Any thoughts or suggestion? Thanks in advance matto

 

Have you scanned the car for codes?

 

You may have a bad TPS on the high end of travel range

The middle wire on the TPS connector will read 0.60 volts DC at idle and smoothly climb higher as you throttle up

You should not see your meter bip to zero volts through the travel range

You can check this with the engine not running but the ignition to the run position before the start position

I found on mine the TPS connector metal lock clip was missing so the connector was not securely connected

The Green / Yellow wire goes up and over the fuel rail and can be checked there if you nick the insulation

Do not replace the TPS until you have the understanding of it's adjustment criticalness

The fuel pressure is not easy to check but may have a underperforming pump

Easy things to do is to swap the relay with the ACC relay inboard of it and check the fuel pump connector on the pump itself for burnt sockets

The Fuel pressure regulator may be bypassing too much but hard to tell as they normally make a sound

They are commonly avail from the local auto parts store for around $ 65 US and they don't last forever as one justification to replace it

You can have dirty injectors and a dose of Cheveron fuel injector cleaner may be a easy try

Main Fuel filter changed ? someone found this to be his issue . it needs o - rings beforehand

The fuel injectors themselves have a basket filter in each of them but that involves more work

 

Not yet just waiting for my obd2 reader to arrive then I'm into it!! Cheers

 

Thanks Parker 2 - I suspected the TPS becuase it was very very dirty - I started at the spark plugs that were totally covered in oil pretty well to the top of th tubes - so I have ordered valve cover gasket set. When I got the car *last week) prior to cleaning oil from spark plugs the transmission shifts were very very harsh. I then cleaned out all the oil, re-gapped the spark plugs and cleaaned all the coils and this seemed to significantly improve the trans changes. Main issues now is the major hesitation on hard accelleration. Ill follow you guide with the TPS - fortunatley I found a full throttle body with TPS and stepper moter on ebay in AUS which is on its way - hopefully the TPS is good. There is a additional sensor on the air intake between the MAF and Thottle body - do you know aht that one is - just working back to the airintake at present. Just one more question there seems to be varying advice on the requirements for a gasket for the throttle body. Mine did not have one on dissassembly - should there be a gasket to the manifold ?? Many thanks Matto

 

The TB to intake manifold has no gasket , metal to metal

The 2 wire sensor is inlet air temp see page 54 and 86

http://www.jagrepair.com/images/Trai...20-%202000.pdf

At the idle stop the 0.60 + or - 0.02 value at idle is important not to disturb just yet with a parts swap

 

When was the last time you replaced oxygen sensors?

When was the last time you cleaned up the MAF? There’s a special spray you can pick up at the auto parts store.

I’m not sure the TPS will be at fault. I can’t recall hesitation at throttle as a past problem.

 

For the symptoms you describe, my first suspects would be blocked fuel filter or failing fuel pump (or both). Change the filter first as that's the easiest job.

 

Dear all

Thanks for input on this issue

Well I cleaned MAF, TB, TPM, all connections to Oxygen sensors, oil and water temp/press sensors, all fuses and cam sensors, cleaned all coils and especially to large amount of oil in spark plug tubes (gasket set on way!). Replaced the spark plugs with Campions and walla - no more hesitation.
Next Job valve cover gaskets.
Thanks again

Matt

 

Look for carbon tracking on your old plugs and monitor your new champions

This is different then the acceptable Arora in the Jaguar TSB and causes problems only on a loaded engine

You may have had higher resistance exotic plugs as the copper champians flow easier as the cylinder compression value goes up under load

Watch for the 2 D shaped cutouts on the rear of the valve cover and some form a gasket may be needed depending on the gasket molding manufacture

 

You mean 'voila" and not walla....

Glad it was an easy fix.

If you're replacing the camcover gasket, stick to the OEM. Unfortunately the more appropriately priced aftermarkets are significantly longer than needed and makes for a very poor fit.
Oh wait, you have an AJ6, not AJ16, never mind that last comment. I have no experience with the camcover gaskets for the AJ6.

 

Thanks Vee - I have the first AJ16 so the fit of the gasket could be an issue - got a set from British Parts so hopefully the correct fit !.

Cheers

Matt

 

I found that holding the main gasket with electrical tape worked well to keep it on the cam cover as you position it back over the engine..
Once in place the tape can be removed in one long piece with the gasket nicely positioned.
Just make sure you get the 'D' pieces at the back in correctly.

 

Matto1965,
Do yourself a big favor and buy a can of Berryman's B-60 "High Mileage" fuel system/combustion chamber cleaner. This is the very best you can find. It will clean better than any other on the market. (Berryman's has been at this for more than 100 years so they know what they're doing).
Run two bottles at once through a 23.1-gallon thankful. This will clean your fuel system and engines like the proverbial "dose of the salts" and make it purr as if it were a contented kitten. (It will even clean fuel screens and dirty fuel filters).
I use their products regularly (including maintaining the fuel system with their lighter B-12 formula). I wouldn't use it if it didn't work as I have claimed. (I never pour money down a rat hole if I can avoid it).