TPS Adjustment
 

Hi all,

Due to my HE engine hunting ever so slightly when I am at neutral throttle postion holding a certain speed, (Throttle position dead still and slightly off zero), I decided to check and adjust the TPS as per Grants print out.

Holy cow that was frustrating and I may have a faulty TPS.

Took nearly 45 minutes to get the reading to near abouts 0.34v. As soon as I lightly tightened the holding screws with a handheld screwdriver the reading would move and I would have to do it again.

It seemed ridiculously sensitive and difficult to set and it makes me think the TPS is faulty. Is that possible?

Admittedly when I took her for a drive it did seem to have helped reduced the hunting somewhat and increased acceleration smoothness but I have only been put for a 5 minute drive.

It is like if you breathe on the capstan the voltage reading changes. I didn't like the sensitivity, makes me feel nervous it could change while driving.

Cheers
Craig

Frustrating; we've all been there.

I don't think your TPS is faulty. Even Jaguar tech literature mentions the sensitivity during adjustment and suggests using washers under the screws to help reduce movement during final tightening

Cheers
DD

Agreed.

Washers, common sense "firm" for securing the 3 screws, and beer, gotta keep the fluids up.

Some I set up waaaay back, took 2 or 3 shots to get it right, so you are not alone by any means.

When I fitting the XJ40 TPS to mine, that task got simple, coz that TPS is spring loaded to idle position, so the "lag" of the Bournes 3 leg is no more. Have not touched that thing in 12 years.

Ok So while doing all this I got another issue!

Now my fuel pump is whining loudly. Does that mean she is goneburgers or Can I rebuild it?

Also now when I stop at an intersection there is a very small lag which cuts the engine. If I hold 2% throttle down simultaneously while braking, then when I re-accelerate it wont cut out but with one foot she dies.

Is this a TPS symptom?

Cheers lads


Cheers

DAMN

Maybe pump, age is against it, BUT, change the main filter, behind the spare wheel, and clean the small plastic suction filter inside the small sump tank.

If its still noisy, new is needed. NOT big $$, same external pump as Commodore, BMW, Merc etc. About $140, depending on brand. I use Goss, or Bosch.

That other issue may be pump related, as the whining may be dropping pressure, and flow, fickle system we mess with.

TPS is not out of the thoughts at the moment, but that pump/fuel issue has taken top spot.

Cheers Grant I try that first

Define noisey? Just curious.. My pump sounds like a vacume sucking sand most of the time despite injector lube and a professionally cleaned fuel system. No issues though just a crackle.

As for cracker's issue a jug of injector lube and a few minutes at the redline might help quite abit. Also worth verifying readings on O2 sensor, coolant sensors etc. I had a similar issue car nearly stalling at red lights when you hit the gas, turned out the o2 sensors wern't even giving a signal.

New coolant sensors improved the matter to as the 30yr old OEM was giving crappy outputs to the various ecu's.

Pump now very noisy. Have already pt in 4 lots of injector cleaner over the last 4 months.

Will also look at O2 sensors. (Where are these mounted)

Thanks




Cheers

Come on Craker, 1984, we NO GOT O2 sensors, or Cats, so looking for them is wasting drinking time, HA.

Those "up there" got the full whack of rubbish back in the '70's, and we stayed sane.

CTS (Coolant Temp Sensor), I doubt it, coz if they go flaky the V12 stops with conviction. Again, same as Commodore etc, and I have the Bosch Part # here if you want it. Last time I needed one $23.

You have cleaned the inner bores of the throttle bodies????

Next item:

PCV valve, plugged into the backing of the B bank air cleaner, near the front. Pull it out, remove it from the pipe, plug the pipe end to seal the vac supply, and see if the engine behaves any differently. The springs go saggy with age, like us humans, and dont wok properly, and allow excess vac into the system, and engine hunting is one of the results. I ditched mine totally years ago, so forget some people still run them.

OK looks like i be busy next weekend. yeeha

Grant, What is the part number for the commodore pump? Is it the 5.7L LS2 Pump?



Cheers

Cracker,

GE034 is the Goss number.

Same as VN V6/V8 EXTERNAL Hi Pressure pump. The early V6 'Dores had a lift pump INSIDE the tank, same as the IN tank pump on the early XJ6 with carbies.

SEEEEE, nothing special about Jags at all.

When fitting the New pump pay particular attention to the +ve and -ve terminals ON the pump. Some brands have the "larger" terminal as the +ve, some have it as the -ve. The pump will work either way, but ONLY pump fuel when connected the proper polarity.. I got caught a very long time ago, and it has stuck in the grey matter.

OK,

Removed the pump & filter today.

Check out the muck than came out of the intake of the filter.

Is this really bad or to be expected? Do I have to rip my tank out or could it be because it has been in storage for 12 years, will it clean up and get better as I drive it more & more?

It is a GOSS filter so thinking it must have been replaced at some stage fairly recently and if so it is getting dirty FAST!!

Pick up the new pump tomorrow.

Cheers

https://cimg3.ibsrv.net/gimg/www.jag...e225e51370.jpg

Grant, I purchased the GE034 via Supercheap.

Do you remember if the terminals are the same as the Lucas or opposite?

Cheers
Craig

I would clean out the sump tank under the battery and renew the sock filter inside it. probably never been done, unless you did it! That fine dust certainly causes the pump to labour, but it does not look to me like a bad main tank, just years of neglect in cleaning and changing the sump tank filter.!

Cracker, oops Craig,

I am with Greg on that sump tank and sock filter.

New pump, Main Filter, and clean the rest, should be fine.

NO IDEA on that terminal, too long ago, and way too many beers, BUT, look at the terminals on the pumps,and alongside each post will be a + or a - symbol, the rest is elementary young Kiwi.

Ok I have replaced the filter and the pump.

Car runs great until she gets warm and then cuts in and out seriously. Almost as if the coil lead has been taken off for 2 seconds then put back on. All 12 pots die simultaneously.

Runs fine when idling, only happens under loads.

Any ideas? Could it be the TPS again or should I start with the coil?

Cheers

Decided to order this and try my luck. Looks like it has good reviews.

The Original TPS had a large dead spot so needs replacing anyhoo.

Jaguar Switch Kit, Pre-87 XJ-S Throttle P. - 03-2500

Pre-87 XJ-S Throttle P.
Sold Per: Each
Estimated Quantity Available: 0
Built-to-Order
www.xks.com

Craig,

I am assuming it idles OK when warm?, and cuts out at above idle revs?

Maybe TPS, but not convinced, and with the $$ involved, try a few things first:

1) CTS (Coolant Temp Sensor), on top of the LH (B) thermostat housing. Has a 2 pin injector style plug. Unplug is, take a paper clip, bend it in a "U" and plug it INTO the loom plug. This will "fool" the ECU (Computer) into thinking the engine is AT operating temperature. Place a rag for that plug to rest on, so it dont short out. It will only have 5v, but best to not tempt fate. If that sorts it, a simple CTS change, with a Bosch unit will fix that.

2) AAV, rear of the B cylinder head. Is it closing 100% when at operating temp. If it does NOT close as designed, the ECU WILL cut fuel, turn it ON again, off again, etc etc. See this attachment I have included.

3) TPS is going AWOL, sad fact. Got dead spots all over it and the ECU cannot get a "clean" signal.

The list continues, but those are prime from my years with these beasts.

Thanks Grant, Will try all of it!