'tps' Problem - Case Notes

Just for the Forum record..........

 

(Edited ref confusion over fault codes)

 

CAR - '98 TT VVTI TIPT, imported June 03. 0do @ 4,426 miles (@6,900 km with full Jap service history, serviced @ 520 / 1,426 / 2,164 / 4,266 / 5,698 km) - Only obvious mech. mod prior to import = Apexi Dunk Megaphone cat back.

 

DELIVERY - odo @ 4,500 miles (JIC) Speed converter / delimiter (type unknown) fitted by Motormall, and Laserline alarm / immobiliser (Motormall ?) - MOT and 'service'.

 

June 03 to June 04 / 11,000 miles run - no problems except for the 'snow button'' coming on once in a blue moon when pulling away v quick.

(odo @ 7,940 miles - cam belt changed as over 5 yrs old.....odo @ 13,350 miles - 'A' service, no problems reported)

 

ODO @ 15,400 miles - Blitz Sonic fitted (VVTI spec - installed with inlet-cone pointing toward off-side front corner of engine-bay)

 

June 04 to June 05 / 7,500 miles run - random / intermittant fault starts.....

SYMPTOMS - coming to a halt at traffic-lights / rndbts / junctions, or sometimes from start-up when engine is hot, warning triangle and eng manag warning light comes on, revs go up to 1000rpm, no throttle untill last 20mm or so of travel....in every occurrence 'cept one, car is fine when turned off and re-started (once it took at least 6/7 re-starts before warning lights went out and car ran fine)....on at least two occasions, I felt it 'going' before it happened (when doing 30/40 more throttle movement was needed than normal)

OCCURRENCES - 8 times in total, spread over 7,500 miles run.

ODO @ 22,500 miles - 'B' service, garage obtained diag fault code (code number unknown / forgotten) that suggested a fault with the Throttle Position Sensor.

ODO @ 22,850 miles - new TPS fitted, test-drive fine, but fault happened on way home.

ODO @ 23,000 miles - car taken back in, same code logged, but garage couldnt replicate the fault, car running sweet for them....connections 'tween ECU and TPS jiggled while engine running, no probs. Throttle-body clean as Cliff Richard.

 

ODO @ 23,098 miles / 22nd July 05 - fault occurs again - OEM air-box with new Toyota panel-filter put back in.

NOTES -

The Blitz Sonic filter was very clean on removal.

 

ODO @ 24,000 miles / 26th Aug 05 - no problems since 22nd July 05........

NOTES -

At 26.08.05, wiring / connections for speed controller / de-limiter, odo and speedo have NOT been looked at so far.

I have been deliberately trying to force the fault to occur, fast blatting followed imm by loads of traffic noe-to tail / traffic lights / junctions etc etc, lots of hot traffic jams, lots of granny-peddling around at 30, lots of fast 40 mile runs, stopping the car and then waiting for 20 mins / half hour then re-starting and driving in town.....no probs since Sonic dumped.

Driving style day to day unchanged - mostly commuting, good run at the weekend.

Fuel has always been 80/20 mix between Otimax and Ultimate dep on where I am, but last few mths have been Tesco 99

Good concise write up Ewen - thanks.

That for the record is the same for me...if you feel it going you can save it via about 6secs of WOT...but this usually means breaking the speed limit! (6th gear WOT from 1500rpm keeps the speed down).

 

I can't try a stock air box and if it is intake temps that are the cause then VVTi's running pod filters may have to go to extreme's to reduce the charge temps.

Good stuff Exactly what you need to sort something like this.

 

So after refitting the stock airbox it hasn't manifested since?

 

Questions:

Are there any sensors that go in the stock airbox?

Did you disturb/remove/knock anything else to refit the airbox? Any dissassembly, anything you leant on, that sort of thing?

Has your driving style changed in any way?

Have you tried all-out to make the problem happen?

 

-Ian

....Mods please delete....

TPS???

TPS???

Throttle Position Sensor

TPS???

 

try persistently searching...

Its now been around two months since I put the OEM air box back on and Ive still not had the problem happen again, not a single blip............

Just a quick question, assuming heat-soak / under bonnet intake could be the cause - is there a logical explanation why, if underbonnet heat triggers the problem, why would the car start up again straight away and be ok if the underbonnet heat is the same ?

Just for information,

I've been logging engine temps versus intake temps.

with engine at 96c ....intake temps have been around 25-30c on the move.

at idle or slow moving traffic, engine is 96c intake is 35-45c.

Still have the throttle tipping issue though, & have noted that there is a warm start problem when engine temp is between 35-40c. If I don't catch it right 1st time......the bugger floods itself

John

ps. I'll only be able to log in from work for a while, my home pc blew it's psu yesterday:(

Is this a VVTi only problem or are there any cases of this manifesting itself in the earlier model?

 

(BTW i run a standard airbox set up.)

Is this a VVTi only problem or are there any cases of this manifesting itself in the earlier model?

 

(BTW i run a standard airbox set up.)

 

As far as I can tell from the various posts, this specific problem is on the VVTIs only......If I can work out a logical way of wording it, Ill post a poll to see if we can narrow the victims down a bit

How exactly did you fix the code 42 problem again??

'Fixed' is a loose term which really only applies to me in this case....

I only had the problem whilst there was a Blitz Sonic fitted, and on a hunch I took it out and put the OEM assembly back in....that was the back end of July and its been fine ever since.

It may be innacurate to universally label it as 'the code 42 problem', but in my case code 42 was the sole fault logged each time it happened.

 

EDITED TO CORRECT ERROR CODE. It seems that the garage that originally diagnosed the fault gave me the wrong code. Its an OBDII car so code 42 cant have been the code they retrieved. The actual code was P1120. Same fault description though.

The Code 42 is when the throttle tripped out cause the MAF's temp sensor got too hot....well this is the theory.

 

Hmmm just had a thought, the stock pipe is plastic and the Blitz one is metal....heat soak is going to be worse with the thick cast metal one....so we need a way of stopping the direct heat transfer from the pipe to the MAF via the housing/flange, but without ruining the way the MAF reads the airflow....how the hell do I do that then? Or should the whole thing be replaced with something less heat conductive....

THESE guys do a thermal barrier coating that might help to reduce the heat soak effect that occurs from metal pipework, i doubt it would look very bling though.

Here we go again

 

From 22 July 05, to 02 July 06, the original fault did not re-appear, in fact no problems whatsoever. Driving style unchanged - mostly commuting, good run at the weekend.

Fuel has been Tesco 99 since July 05.

 

 

ODO @ 29,100 miles / 02 July 06 - Last years fault occurs again, same symptoms as before.

NOTES-

Maybe coincidence, but it was an extremely hot day, and Id been pootling along at 40 for an hour or so when I got caught at a rail crossing....I was stationary in a queue for say 15 minutes engine running. I drove away, and slowed to take a bend, up came the warning lights and into limp home mode. Turned off and on again, fine since, until...

 

ODO @ 29,200 miles / 07 July 06 - MOT, new exhaust fitted. Same fault same symptoms, on way home.

 

ODO @ 29,230 miles / 10 July 06 - Happened again.

I've just reset the ECU and reset the TPS (ref Alex - full electics on, throttle hard to the floor for 10 secs). Will see how it goes.

After ECU and TPS reset last night, problem re-occured on way to work.

So....

Previous thoughts that returning to OEM air inlet sorted it, must have been pure coincidence.

Strange that problem went away for nearly a year and has come back suddenly, when all other parameters have stayed the same (problem started again before fitting of new exhaust).

Since last post, fault has occurred every day except one. Same symptoms.

 

Today I took car to Pete Twomley, a one-man band at Formula 1 Auto Electrics in Bournemouth (as recommended by Triton).

 

I've actually got three diagnostic ports. One on the engine (minus TE1 connection), a circular one under the dashboard which has various connections including E1 and TE1 BUT has no wires connected to it, and a third, true OBDII port right next to the boot release lever(see pic below). After no-go with the engine port, he successfully obtained these two codes...

 

P1120 Throttle / Pedal Position Sensor / Switch A Circuit Malfunction

P1121 Throttle / Pedal Position Sensor / Switch A Circuit Range / Performance Problem

 

He seemed happy due to the Toyota specific prefix 1. The last three digits tie-in with the (SAE J2012) OBDII codes and fault descriptions that Alex gave me....they also re-affirm my garages diag. last year.

 

Genuine or not, they certainly could apply to my specific problem. He cleared the ECU so that he can re-read any error code that comes up in the next few days.

That's great!

 

Now for the bad news...you can only get a new APP with a new Throttle and that is about £500. (Well that's what Toyota said last time).

That's great!

 

Now for the bad news...you can only get a new APP with a new Throttle and that is about £500. (Well that's what Toyota said last time).

 

Well, assuming its not the TPS itself, as that was replaced last year, it certainly looks like the APP or possibly a fault in the signals they both receive. £500 is a lot of money, but shit, if it fixes this for good Im happy. I'll drive it around and get another error code reading first though.

 

Better not go BPU till its fixed:)

I'd get an electronics man in to test the circuit before replacing parts.

 

Check the wires and pins from end to end...if you do still get the error then I think you'll need the new throttle.

I think the £500 inc a new TPS...but they may split it down for you....Speak to Steve manley when you are ready to buy as he gives this forum a discount. Have a search for his contact details.

I'd get an electronics man in to test the circuit before replacing parts.

Check the wires and pins from end to end...if you do still get the error then I think you'll need the new throttle.

I think the £500 inc a new TPS...but they may split it down for you....Speak to Steve manley when you are ready to buy as he gives this forum a discount. Have a search for his contact details.

 

Thanks Alex.

 

Both error codes refer back to the Throttle Position Sensor. Ones a circuit malfunction fault and the others a circuit range / performance fault. As its a fairly new sensor, I'd assumed it was either the connections OR the actual rotational mounting position of the sensor (I saw a post about this last year but cant find it). Today Toyota have told me there are actually TWO 'throttle position sensors', one on each side of the throttle body. The nearside one Ive had replaced last year, the offside one (more traction control orientated than throttle) I havent (£90). Toyota suggest the error codes may refer to this, second TPS. This Pete guy is up for trying to track down an electrical fault around the TPSs / throttle body area, but Id love to give him the gen from that thread about the nearside TPS position first.

As you look at the car from the front the TPS is right side and the APP is left side.

What is APP?

 

Alex, have I got one on my spare manifold?

The APP is the bit with the throttle cable attached. Actual Pedal Position.