Hi everyone, this is my first time posting.

I'll give you all of the story as some parts may or may not be relevant.

Yesterday I bought a 2001 XKR convertible, black paint, black interior and 20" BBS alloys, 86k full service history. The story of the car is it was bought by a car dealer/ collector in 2016 he put it in a shipping container and left it there until around 18 months ago. The car dealer is retiring and thinning out his cars so put it up for sale. I know car dealers like to spin a tale or two but everything that the guy said checked out.

The car is in very good condition given its history, no rust other than the typical surface rust on the underneath areas. After looking around the car the main negatives were some small amount of mould in the headliner smells a bit like a scout camp tent, the 20" tyres were practically new Avons but had perished over time and the big one... it would cut out when the throttle pedal was used but only when in motion. Along with various warning messages on the dash but hoped that a bad battery would rectify everything. Regardless to the issues it had and because my life is full of questionable decisions, I bought it. What makes this even more of a silly idea is it will be my daily driver / family car as I have a wife, two kids (7 & 6) and a dog. The dealer stated that it had no issues other than cruise control not working when he bought it.

A few days later it was delivered to my house on the same date the car was made 22 years prior and set about trying to get it in order.

I bought a new battery (Yuasa HSB019 Silver 900a and 100ah). After disconnecting the old battery I touched the negative and positive leads for 30 seconds and then left it disconnected over night. Following day connected the battery, the car started no issues aside what sounds like a tensioner pully squeaking the engine was spot on.

Sadly messages "INCORRECT PART FITTED" and "CRUISE CONTROL UNAVAILIBLE" were still lit and the red and yellow warning lights were illuminated.

I then read the codes which came back with

P1000
P1642
P1638
P1229
P0507
P0332
P0327

I cleared the codes, disconnected and reconnected the battery. The only codes that reappeared were P1229 and P1000.

I drove it very very gingerly to the petrol station put 30 litres of fuel in the tank, (needle was just touching red), took it for some new tyres, and then to the MOT station. On the way there I tried to push the throttle a little further than I had done, the messages on the dash went crazy No ABS, NO TRACTION CONTROL etc etc. The engine cut out as if I had turned it off (no spluttering or surging etc). I attempted to start the car up it turned over, started and the died until around 2 minutes past and it started back up. This time the only messages on the dash were INCORRECT PART FITTED and NO CRUISE CONTROL. I carried on the 6 mile journey very slow on the throttle peddle the car died in the exact same way a further 4 times.
Once at the garage asked the mechanic to do a scan using his Snap On system. During which he revvd the car to 2kRPMS for 2 minutes, the engine sounded perfect. He said that Ideally he would like to take it out and carry out the diagnostic as the car drove Overall he couldn't seam to find anything that pin pointed the problem but mentioned that he thinks the car hasn't liked being woken up after all this time and needed to relearn some of its parameters??
The mechanic had a look over the car and said it was in really good condition, whatever the problem was it wouldn't be a big one although it is causing a big problem.
..
I have had a look into the throttle body could see some carbon build-up although it wasn't caked up. I've wiped of most of it but the butterfly appeared not want to open when I pushed it (not sure if this was normal but didn't want to force anything.)

Today I have pushed the throttle pedal down, battery disconnected and pushed the butterfly valve, it took some force but it didn't feel like it was breaking just very stiff. I've now cleaned the whole visible area of the throttle body, disconnected most of the connecters and sprayed with contact cleaner. Cleaned the MAF. Reassembled reset battery again. No change in any of the symptoms.

My primitive OBD scanner is showing that when the engine is turned off the throttle is at between 5-7% pushing the throttle pedal down it hits a limiter of 3k rpms and 24- 27%.

So has anyone got any suggestions or do I bite the bullet and buy another throttle body, or is it possible a relay or module is at fault? I have checked all of the fuses in the car which were fine.

After reading some more forum posts I'm suspecting that the throttle body motor/solenoid is seized? However if this were true surely it wouldn't move at all when the throttle pedal was pushed when driving???.

Many thanks in advance.

 

Let's see if we can get you started.

The incorrect part fitted can be caused by modules being changed and not 'introduced' to the car: is there anything in the service hiistory? It can also be battery-related, but fitting a new one and the 'hard reset' are appropriate to address that.

The car does think there's a problem around the throttle body, as you state. Here's a snip from the DTC list for a P1229 code. I've included P1222 as it is referred to:



Ignore the P1000 for now.

Note the default actions that the ECM takes in response include inhibiting cruise (hence the message), and that it also disables the throttle motor. In this 'limp mode' state, the butterfly is operated directly from the throttle cable, and will only open to around 30°. See this snippet from 'SERVICE TRAINING COURSE 881 V6 / V8 ENGINE MANAGEMENT' which explains it better than I:

"
Limp Home Operation
If a failure in the throttle mechanism or control system occurs, the ECM defaults throttle control to the limp home mode.
• The ECM de-energizes the throttle motor power supply relay and / or deactivates the ECM internal PWM
motor drive signals.
• The throttle valve is operated mechanically from the drivers pedal and throttle opening is restricted to a range
from idle to a maximum of approximately 30°.
• The accelerator input shaft link lever is mechanically coupled to the throttle shaft levers, enabling the shaft to
be rotated against the unpowered motor and gearing.
• Due to the angular difference between the input shaft link lever and the limp home lever, there is no engagement
of the two levers until the input shaft has rotated approximately 60° from idle.
• When the link lever contacts the limp home lever, causing it to rotate, the throttle valve is pulled open by the limp
home spring. With the pedal fully depressed the throttle valve is open to a maximum of approximately 30°.
• On releasing the accelerator pedal, the throttle return spring causes the limp home lever to rotate to its stop at
the throttle idle speed position.
• If loss of motor power occurs when the throttle is open beyond the idle position, the limp home lever will close
to the point where it contacts the link lever. If the throttle has been driven closed (past the idle position) when
loss of power occurs, the limp home spring will return the throttle to the idle position.
• When the throttle is in limp home mode, the ECM adjusts the fuel metering strategy as necessary to control
engine power. At low throttle opening, fuel cutoff to individual cylinders may occur.
"


Do the $0 checks first.

• F9 (30A) in the engine management fusebox, and the relay itself here:
• Connector on throttle body, and wiring between the ECM and the throttle body

Check these and report back what you find.

 

1638 1642 and the incorrect part fitted christmas tree is high speed can going down can be a number of things.

as for the throttle motor circuit code. here’s how you diag it.

 

 

 

The rev limiter is correct. You should not be able to get passed 3k rpm in park.
Connect your OBD scanner, turn on your ignition and find the value for throttle position. You can then read out if the throttle body is functioning correctly. If you dont get 100% throttle with the accelerator pedal to the floor, but close, you can adjust the throttle cable.
Check the electric connector on the throttle body, there has been trouble with bad connections due to corrosion.

 

Thanks so much for your input.

To cut a long story short, I strpped the TB down and found the motor has seized, Stripping the motor I found that one of the two magnets had come free from the housing and preventing the motor from turning freely.

I have put it back together and it seems to be okay aside that I now have code P1647 for a 02 sensor. Im hoping I may have just knocked something as I was taking out the TB.

 

Great catch, and good to see it's a $0 fix

The HO2S connectors are on the top of the transmission so you may have disturbed one. The P1000 should morph into a P1111 once the emissions readiness cycle completes.

 

Well done....