Heh guys. Sorry I have been slack and not been on the forums in a while. That is not to say I haven't been busy with the ole Blue Goose though. She is been playing up starting to show her age! In particular James (34by151) and I have been trying to narrow down an issue with her unable to maintain idle.

It started with her in traffic once the engine was warm. I would be stopped at a red and then as I go to pull away she can't seem to maintain 750 RPM idle speed and starts to drop and chug away until I can get up to speed.

It also would happen if I was parked somewhere for like 10 minutes after getting her up to normal running temp, and then tried to take off.

Highway driving is/was fine. It has the air running through it and seems happy.

So, there began the journey.

* First thing we did is do the world famous Grant Francis Cold Air intake mod. Although improving the system, the symptom still remained.

* Next was the biggest job of all. Replacing the water pump. We pulled it out. It was full of crud and the bearings were average all though probably acceptable just. Anyway, new one installed. Symptom still remained.

* Next we started to tackle the Auxillary Air Valve to close out going through the cooling system. Evidentally we found the piston stuck closed. The Great Wizard Grant kindly offered me to send it down to him and rebuild if for me which he did successfully. Cheers again Grant Unfortunately after install the problem still remains. (Yes I set it at 750 PRM via adjustment screw when the engine was up to normal running temps).

* Next we started looking at the ignition system. We found oil leaking from my coil near the cap stan. Sure enough the top screw was a little loose and we thought we had nailed it. We did the research and changed my car from a dual coil set up to the widely accepted single coil set up. Unfortunately the symptom remains.

This leads me up to where I am currently at. This may not necessarily be a bad thing but the situation has gotten worse. When I try to back her out of the drive way, after say about 1/4 normal running temp, she will display the same symptoms.

I haven't changed the spark plugs since I have owned the car so I am doing that next as a matter of maintenance as well as the vac advance connecting to the dizzy.

I have a good manual on the XJS HE Fuel Injection system and we have a few thing we want to try as regards to tweaking the ECU etc. (Oh yes and we blew out the vaccum line with compressed air going from the ECU to the engine bay.)

So along the way we havent fixed the fault but slowly improved some things that would of failed along the way. I have a feeling we are close but I would value your guys opinons as always. Maybe there is something we havent covered?

Anway appreciate any advice you guys can share.

Cheers

After cold air intake mod:


The old AAV getting pulled out:


Coil leakin' oil (heh that ryhmes)


Coil number 2 in the dual coil set up. Note my ignition amp has been moved to the front of the car as per the common mod.


The New Coil ready for install (DAC6093 equivalent)

 

Paul,

Sent you an email, as the infor is too big for here.

As usual, keep the thread updated for others to benefit.

 

Paul,

I am having a similar problem, maybe the same?!?!

When my car gets to operating temp it will start but not idle. It will drive fine after I get it going and then run good even at a stop light. It seems to be only when I start it after it sits for a little while after being driven.

Starts and idles fine when cold!!

It'll start and then the idle drops to zero and it dies. If I keep it running using the gas peddle it'll take off and then drive fine.

Is this the same problem you're having or does yours idle fine when you start it at operating temp. Just trying to get an idea of your problem and I'll watch the replies to see if I might have the same issue.

Now I'll sit back and wait for the smart guys

Terry

 

Cheers Grant. Thanks for the email. I will definitely update the forum as I progress

Terry,

Mate that sounds 100% exactly like my symptom.

Tell me, is your 1990 XJS a Marelli Engine?

I have just recieved some very wise council from the Great Wizard and I have some new areas to look at:

CTS - Coolant Temp Sensor
TPS - Throttle Position Sensor
Full Load Throttle Vaccum Switch

I am currently at work at sea so I am doing all my research out here and getting the necessary parts ready.

I will update as I go. Hopefully we can get two XJS's sorted!

 

Grant, can you post a link to your info?
I now have hot start problems since changing the AAV and CTS; it's better than suddenly stopping and then not starting at all though which it was doing before.

 

Hi Steve

I'm sure Grant won't mind if I paraphrase what he has me on next:

He is thinking between the CTS and TPS as well as the Full Load Throttle Vaccum switch as places to look. Seeing how you said you replaced your CTS looks like the latter two might be good for you to check.

On the Full Load Throttle switch grant says:

As for the TPS please find attached write up from Grant.

The Wizard never fails to deliver!

Picture of the Full Load Throttle Vaccum Switch:

 

Steve
My money on your B bank fuel pressure regulator. Happened to me recently, no actual failure symptoms from the FPR, but I think as it gets hot it somehow stops working properly.


Paul, fuel pressure also worth testing in addition to the WoOz's list
Greg

 

G'day Greg! Good to hear from you mate.

Yes James (34by151) has said the same also. Once we have ruled out cooling and ingition system we will move onto the fuel system. It has been an epic battle but I think we are getting close...

 

Paul,

Yes I have a Marelli car. I have about 500 miles on new plugs, wires, dist cap, rotor. New FI harness and injectors cleaned and flow tested. Runs good other than the idle issue. A PITA for around town use, not to mention embarrassing.

Terry

 

Yes I know what you mean about embarassing when it does it at the traffic lights lol!

Well I have a pre Marelli system (H.E) so I am not sure what differences we share in regards to this idle issue however symptoms are the same.

I would wait for the advice of some of the other fellows and see what they come up with. I'm sure we'll both get them sorted!

 

Thanks for that.
Law of sod that CTS, AAV and FPR (Crikey, I'm speaking in letters!) all go down at the same time but I guess that they are all the same age.
The car started faultlessly prior to having to change CTS and AAV.

 

Paul, just to clarify a few points.

A few things along the way that you missed in your post
We checked the vac hose to the ECU and blew it out for good measure
Confirmed you have the 6 ecu and have lined up a 16 for latter on
Confirmed you have no O2 sensors

Added to the list for latter on adjusting the ECU and checking the sensors TPS
We also checked the full load switch and actuator, but maybe worth doing again

We checked the Temp sensor. If you remember it was disconnected.
We checked it cold and hot then reconnected it.
These are cheep so no harm popping in a new one to be sure

Also to recap we have gone right though the intake air and cooling systems. We ale half way though the ign system (plugs, leads and vac advance to go)
We are also part way though the ECU (TPS and adjust fuel to go)

Things to do next, finish off going though the ECU and VAC system before moving onto Fuel

We can jump from one thing to another but I find that only confuses the issue.
Personally I like to rule things out methodically, system by system
That's how we have approached it so far and found a few things along the way (AAV, coil and water pump) that are not the cause but on the verge of causing new issues.

If there is a better way of approaching it or something we missed im all ears

Cheers
34by151

 

I 100% agree. Also, I never mind changing pieces on the car, as on any 30 year old car even things that have not failed and are more than 10 years old soon will, and what you are really doing is preventative maintenance, - essential if you want a reliable vehicle. And you have a known working spare for emergency and testing purposes!
My FPRs I changed preventatively in 2001, and b bank started to go home last year, so cannot grumble.
Greg

 

I cannot see the AAV as the problem, Steve, but the CTS could easily be a bit odd. Check the plug for electrical continuity, and swap in the old CTS or just try another new one.
Still does not rule out the FPR though!
Greg

 

I'll order a FPR today; just have to decide whether I want to pay £40, £65 or £88!
Can't figure out some of the suppliers prices; rip off springs to mind.

 

Thank you Greg and James. I appreciate the help.

James yes I think we did check the full load switch come to think of it. I recall one of us laying over that side of the car with multimeter in hand, you also checked to make sure it was sucking too correct?

Thanks again for filling in the blanks for me!

Well next steps for me, after I have ordered the parts and return from sea, is to finish off going through the ignition system. That will close that and the cooling system out as you have said, and won't hurt even if they are ok!

Hopefully I will be back on the road in the next few months, I miss the ole girl!


Picture of my ECU which is the older 6cu version:


Pics when James and I swapped out the Water Pump:


Nice new pump:

 

Hi Steve

They've got some really nice ones on Amazon for about £20 that even come with their own Fuel Pressure Gauge.

https://www.amazon.co.uk/s/ref=nb_sb...re%2Caps%2C179

 

The same problem, only when the outdoor temperature is more than 25C (77F), Fuel in the fuel tank is less than a quarter, and air conditioning is switched off (no fuel cooling). And I hear a buzzing gasoline pump, idle speed drops to 500rpm.
I think it is boils fuel in the injector rail.
As soon as the air conditioning on, 5 minutes later all is well. Cooling the fuel is required.

 

We're all here, HELLO !!!

 

I got the D Manners 40 quid job, maybe 35, cannot remember. Perfect, fits perfectly too.
Greg