95 Celebration throttle sticking half open!

Hello Everyone. As Im not driving my 95 very much due to winter weather and lockdown rules I am running the engine for half an hour whenever I remember. I did this yesterday and as I have an intelligent charger fitted it started first time and ran well with no problems until the temperature was at normal and 30 minutes had past. Before I turned it off I blipped the throttle as I usually do but the throttle stuck open at about half throttle. The bonnet was up so I just knocked it off by hand. I worked the butterfly a bit and the spring seemed fairly good but on starting the engine again and once again blipping it the throttle stuck once more. I am thinking maybe with lack of use throughout the year and freezing weather the butterfly is in need of a good clean and de-glazing. Could there be any other reason and if not should I remove the entire throttle body and service it. The engine is the AJ16 straight 6. It ran perfectly in the summer but did not get the usual amount of use due to the virus restrictions. Cheers. Richard.

Inspect the entire throttle linkage for binding, lubrication and throttle plate for cokeing.

Thanks for that. Should I remove the throttle body or clean it and lubricate it in situ? What is the best cleaner and lube? What parts will need to be removed in order to clean the TB in situ? Cheers. Richard.

Can you disconnect the linkage from the throttle body? If so, you can put a little tension on the linkage with your fingers while someone in the car gives it some throttle. That’ll usually tell you if the problem is in the linkage or the throttle body itself.

Thanks Kirbert. I will try that next weekend when a friend is here. I’ll let you know how it goes. Many thanks. Cheers. Richard.

I did dozens of these repairs and recalls to the AJ16 engine cars (XJ-S and X300)
Here are some TSBs for you.
17-12am2 Recall T493.pdf (228.5 KB)
03-1-15 Throttle Difficult to Open on Cold Engine.pdf (67.7 KB)
05-1-15 Intermittent High Idle.pdf (127.2 KB)
05-1-23AM2 Throttle Deposits_Sticking Closed.pdf (29.5 KB)

Thank you very much Motorcarman. These will be very useful. Cheers. Richard.

Hi Motorcarman
Thanks again for the pdf’s.
Can you tell me where you are based. I am in the UK.
I have read the basics of the Recall pdf and am wondering how I can find out if this upgrade has been performed on my car.
The idle speed is good and the choke seems to come off ok. No problem starting and the throttle sticking when I blip the pedal has never happened before.
I am wary of driving the car for fear of it sticking open while on the road however I am not likely to be going anywhere soon due to our lockdown restrictions. The car is garaged but not run often enough and the temperature here at the moment is freezing at night and not much higher in the short daytime. My friend owns the garage which has looked after my car since I got it 11 years ago and they have previously not found anything wrong they could not fix or repair. Before I posted on here I asked Steve my friend if he could come to mine next weekend and have a look. Maybe take the entire TB back to the garage and clean or service it. Is this a good idea or should any work be done with the TB in situ? At the garage they do seem to have every diagnostic piece of kit you can imagine and they never give up.
Which of the other pdf’s you sent do I need to download for this problem which I still feel may be down to lack of use and freezing weather and me over reacting as I have not attempted to rectify it in any way other than to knock it off by hand and close the bonnet. Sorry for this long text. Cheers Richard.

Whilst were looking at the throttle linkage, does anyone know of a suitable part substitution for the throttle return spring EBC3674? I don’t think it needs to be very powerful, but it does need a good range of extension.

I don’t know if the RECALL applies to any other country except the US (or maybe entire North America).

I am in North Central Texas about 40 miles Northwest of Fort Worth, TX. USA.

The TSBs are posted for info on what we did at the dealer to fix some of these issues.
I have seen people add ‘helper-spring’ from an XJ40 AJ6 engine to close the throttle.

I personally have modified the original spring by straightening the end of the spring a bit (ONE HALF TURN) and adding one additional turn on the spindle. Just cut off the extra bit of wire to tuck it into place to fit.

Whoa whoa whoa,hold on a minute.

The AJ16 throttle body is KNOWN to gum up. The best thing to do, the only thing to do, is to take it off the engine and give it a through cleandown. It’s held in place with four 10mm bolts, and even though it looks like it needs a gasket at the connection to the intake manifold, there isn’t one. (there is a coolant hose that goes in and out of the underside of the throttle body that is difficult to see. I use golf tees to block up the hose when it’s off)

Have plenty of carb cleaner on hand, and beware the TPS. Don’t let all of the carb cleaner collect at the TPS, perhaps take it off! Please measure the voltage on the TPS so you know it’s been put back exactly the same. If it’s reinstalled off by even a little bit, you’ll need to adjust it, in situ, or have it reset by a WDS/PDU/etc.

A sticky, gummed up throttle body is normal for the AJ16 engine. Let’s not jump to springs or anything else just yet. You’re gonna be surprised at what’s been collected there when you pull it off.

I agree with Veekay, do not go spraying carb cleaner in the your throttle body. Use throttle body cleaner and spray it on a rag and then clean the throttle body. I had a similar issue a few months ago. My culprit ended up being a faulty Idle Control Valve. Below is the link to that thread:

Thats great. Thanks Veekay and everyone else who has been so helpful with this problem. Cheers. Richard.

As I recall from the 4.0 '96 that we had, it is the only car I know of that dumps the PVC (crankcase breather) system upstream of the throttle plate - thus the inevitable fouling of the throttle body.