G/box: 850 Auto: Orange flashing arrow - T5R auto - Help

[Pupbelly]

Originally Posted by Laird Scooby

If the hesitant running is predominantly on a light throttle, that usually points towards the TPS - not having the exact details of your car i had to make a guess so double-check this is the right one :

https://www.ebay.co.uk/itm/303887175352

Fairly straightforward to fit, unplug, undo the screws and remove then to fit the new one, "Haynes it" - in other words refitting is the reversal of removal. Clear the ECU memory after to clear any fault codes and/or fuel trims it has memorised from the old (potentially) faulty TPS. You could also read the Bosch part number on the side of the current TPS, likely it starts 0 280 xyz abc where xyz and abc arethe digits that denote the exact part number, the 0 280 denotes fuel group.

Then type the Bosch part number into the ebay search bar and see what you find.

I did a quick eBay search and came up with the same part which is in my watchlist

The drive to work was fine and had a few heavy foot moments - just to see if I could wake the car up a little ......still felt lazy though! Last night before I cleared the code when I got home, the car was clearly running rich as the exhaust smelt very "sooty" when running as though it was over fuelling.

I had a look at the throttle body and it appears clean - I've seen worse. Suppose I should do a "click" test to see if the throttle position sensor is activating.

Could it be anything do do with me running it on Super Unleaded and its 'adjusting' to it? Or maybe I'm just being unlucky? Bloody annoying having behaved fine for the 2 1/2 hour drive home after picking it up

[Laird Scooby]

Originally Posted by Pupbelly

I did a quick eBay search and came up with the same part which is in my watchlist

The drive to work was fine and had a few heavy foot moments - just to see if I could wake the car up a little ......still felt lazy though! Last night before I cleared the code when I got home, the car was clearly running rich as the exhaust smelt very "sooty" when running as though it was over fuelling.

I had a look at the throttle body and it appears clean - I've seen worse. Suppose I should do a "click" test to see if the throttle position sensor is activating.

Could it be anything do do with me running it on Super Unleaded and its 'adjusting' to it? Or maybe I'm just being unlucky? Bloody annoying having behaved fine for the 2 1/2 hour drive home after picking it up

Unless i'm very much mistaken, the throttle position sensor on your 850 will be a potentiometer so if it clicks it's definitely broken!

Super unleaded will be better as yours is turbocharged but if (as i suspect) the first part of the throttle pot is worn, it may not be getting the idle signal correctly and still "thinks" you're driving. As the engine speed has dropped, the ECU will usually try to add fuel to bring it back up to speed or at least the speed that would correspond to what it's reading on the TPS.

That said the Lambda sensor and catalytic would soon tell the ECU something isn't right, the ECU would see the Lambda sensor is responding but that the TPS didn't match engine speed and mixture and throw a TPS warning code. Also if it is running rich, that would make the cat work harder which would give a rotten egg smell. There are some other scenarios but the most likely (especially given the fault codes) is the TPS but if the mileage is ~100k and the Lambda sensor is original, it will be due for changing soon anyway.

[Pupbelly]

Originally Posted by Laird Scooby

Unless i'm very much mistaken, the throttle position sensor on your 850 will be a potentiometer so if it clicks it's definitely broken!

Super unleaded will be better as yours is turbocharged but if (as i suspect) the first part of the throttle pot is worn, it may not be getting the idle signal correctly and still "thinks" you're driving. As the engine speed has dropped, the ECU will usually try to add fuel to bring it back up to speed or at least the speed that would correspond to what it's reading on the TPS.

That said the Lambda sensor and catalytic would soon tell the ECU something isn't right, the ECU would see the Lambda sensor is responding but that the TPS didn't match engine speed and mixture and throw a TPS warning code. Also if it is running rich, that would make the cat work harder which would give a rotten egg smell. There are some other scenarios but the most likely (especially given the fault codes) is the TPS but if the mileage is ~100k and the Lambda sensor is original, it will be due for changing soon anyway.

Hi Dave,

Ah ok, I thought the throttle sensor would click like a micro switch when it activated (I'm thinking like on the Impreza!). The exhaust smelt like it was running rich and the tickover was at circa 1000rpm again which is a little too high. It smelt like a decatted car which surprised me a little because as you say the cat should go 'eggy'.

There were no engine management lights on the dash, the only indicator is the flashing orange light which seems weird.

The car is on 173k but has seen very little use in the last few years so i wonder if its in shock! Is it worth having a blast of carb cleaner to see if the throttle body flap isn't sitting flush? It looks ok and there's no slack from the accelerator cable to flap movement.

This all seems to have happened since I started faffing about checking vacuum lines, and checking this generally. Should have left it alone but I want to get to the root of the perceived low boost / lack of pace thing.

The car is in lovely condition and is all very original and not messed with but has had regular maintenance. Very frustrating!!

[Laird Scooby]

The lack of play in the throttle cable could be a problem, usually i'd expect a little slack in the idle position and yes, some carb cleaner sprayed around the throttle body would likely help as well. There should also be an AICV (Air Idle Correction Valve) that could probably do with the same treatment as the throttle butterfly.

From what you say, i think it may take some time to settle down to doing what it should, also what are you cmparing it to in terms of performance?

[Pupbelly]

Originally Posted by Laird Scooby

The lack of play in the throttle cable could be a problem, usually i'd expect a little slack in the idle position and yes, some carb cleaner sprayed around the throttle body would likely help as well. There should also be an AICV (Air Idle Correction Valve) that could probably do with the same treatment as the throttle butterfly.

From what you say, i think it may take some time to settle down to doing what it should, also what are you cmparing it to in terms of performance?

I'm probably not explaining things too well but there's no play or slack in the cable, and the rose jointed pivots etc. I'll maybe have a blast of carb cleaner and a delicate wipe with a cotton bud.

My comparison is a 300 bhp Impreza Wagon which of course is an alive and "on it" beast, but I would have expected the T5R to have a certain surge and power delivery to it after reading posts about how manic they can be. Mine doesn't have the ability to create wheelspin (not that I'm that sort of driver but a good hoofing of the throttle doesn't provoke a rapid launch in any way)

[Laird Scooby]

Originally Posted by Pupbelly

I'm probably not explaining things too well but there's no play or slack in the cable, and the rose jointed pivots etc. I'll maybe have a blast of carb cleaner and a delicate wipe with a cotton bud.

My comparison is a 300 bhp Impreza Wagon which of course is an alive and "on it" beast, but I would have expected the T5R to have a certain surge and power delivery to it after reading posts about how manic they can be. Mine doesn't have the ability to create wheelspin (not that I'm that sort of driver but a good hoofing of the throttle doesn't provoke a rapid launch in any way)

There should be a little slack in the throttle cable so the butterfly can actually reach the idle position - beginning to wonder if the previous owner couldn't read the faults and decided the idle was too high or low and adjusted the free-play i the cable out so the cable was tight in an attempt to cover the fault.

If the ECU is sensing a fault (such as the TPS) there is every chance it will put it into Limp Mode which means it uses a substituted value based on other factors to "make an educated guess" at the fueling etc but at a reduced performance level.

The Impreza should be a reasonable comparison to an 850 Turbo-R, they were both quick performers. If the 850 is nowhere near it, consider the turbo may not be producing boost (stuck wastegate perhaps) but i'd be inclined to renew the TPS first to rule that out as being part of the problem.

[Derek UK]

Have you checked all of your vacuum pipes, especially at the "tree". Air leaks can cause the computer to think that the mixture is weak and therefore erichen it to correct it. This may end up as you having a rich smelling exhaust. You have given a good run, you say, but how was the fuel consumption?

[Pupbelly]

Originally Posted by Laird Scooby

The Impreza should be a reasonable comparison to an 850 Turbo-R, they were both quick performers. If the 850 is nowhere near it, consider the turbo may not be producing boost (stuck wastegate perhaps) but i'd be inclined to renew the TPS first to rule that out as being part of the problem.

The T5R is nowhere near the impreza at all, it just feels fat and lazy. The boost gauge indicates negative boost / vacuum and will swing to a 1/5 or so in to the white if you give it full kick down, and then it just accelerates like a 2.3L car no hint of boost surge whatsoever and no sound of the turbo spooling.

I have replaced the vacuum pipe from wastegate to yellow(?) on the BCV and replaced the blue line to the air box trunking, I've yet to do the red(?) one which is tucked under the turbo - time has been short this week for major tinkering. The turbo has has a "rebuild" supposedly, it looks like a recent turbo control valve at a guess judging by a shiny part on the side of the turbo.
What is surprising is, considering some turbo work, the vacuum line from the wastegate to the boost control valve was original i.e. old, crusty and I had to cut it from the metal outlet on the wastegate!

Is there a way to check or establish if the boost control valve is functioning?

[Pupbelly]

Originally Posted by Derek UK

Have you checked all of your vacuum pipes, especially at the "tree". Air leaks can cause the computer to think that the mixture is weak and therefore erichen it to correct it. This may end up as you having a rich smelling exhaust. You have given a good run, you say, but how was the fuel consumption?

The tree looks new-ish or just in good nick. I think there's only one line off the tree which I think goes off (via white/creamy coloured) thin gauge pipe towards the passenger side headlight an disappears. I'm sure the remaining branches are plugged with black domed caps.

It was showing (from memory) 29. MPG something after a 1 1/2 run back on the M3 / M25. It was a steady run back only at say 70 mph as the missus was following behind and I was told not to speed off noting this was a fresh start i.e. the battery had been disconnected so the car was learning its numbers from being reconnected.

[Pupbelly]

I'm sure the car should be just fine but something is clearly not right and it is holding back in a big way which is spoiling the excitement of getting the car.

Any pointers are appreciated, however I don't have additional boost gauges, vacuum testing bits of kit or smoke kits etc. I am handy with the spanners but its a case of where to look without just chucking money at it.