My 172 Cup keeps dropping into limp mode?

[MarkCup]

It's happend about 10 times today, driving along as normal and with no warning or pattern as to why or when, the electrical warning light (below the fuel light) comes on and my speed drops down slowly until it steadys out at about 60mph. Engine refuses to pull above 2,750rpm.

There's no noticable noise or vibration, and at engine speeds below 2k throttle response and power are as normal...switching ignition off then on again clears it...until it drops back into limp mode again.

Car seems to be running fine as having driven 65 miles in it like this today, I've averaged 47mpg.

I'd guess there's a sensor somewhere throwing dodgy information at the ECU? Is there a usual suspect I should check, or does it need some Rentech love?

 

[Eckascliovalver]

Was happening to me a while back. Turned out it was an internal problem with the throttle body.

 

[Ali]

Bet it's that soddin sensor on the plenum! Was on my old one.

 

[Eckascliovalver]

Bet it's that soddin sensor on the plenum! Was on my old one.

Yeah when mine kept going into limp mode, someone said it could be that also.

 

[Schweppy]

I have had the same problem for ages!

Tried replacing throttle body, TDC sensor and cleaned Lambdas but still does it now, just not so much.

Been told to try Coolant temp sensor too.

 

[Schweppy]

Bet it's that soddin sensor on the plenum! Was on my old one.

Which sensor is this?

 

[Fred@BTM]

throttle body would be the first port of call

 

[MarkCup]

B****cks.

 

[chris_p]

I had the same problems only mine wasn't idling properly.
Turned out it was the throttle pedometer (sensor on the accelerator pedal).
Get it into a diagnostic machine mate

 

[Mark One]

certinally get it plugged in somewhere and see what it says. Alternatively buy an OBDII cable and software CD off ebay and plug in yourself.

If it is the FBW throttle, it's not going to be a disaster. They are quite easy to source and value is low as all the people doing conversions want Ph1 parts.

 

[clvs2222]

shwep, did you try the throttle pedal sensor? iv one here, its for sale in the for sale section

 

[Schweppy]

I have the same problem and fault code shows "Throttle pedometer circuit fault - inconsistency in tracks 1-2" any ideas on what i need to look at as i have already tried another TB.

 

[Mark One]

as above mate. throttle pot. Get a new pedal. 2 or 3 bolts and one plug

 

[MarkCup]

as above mate. throttle pot. Get a new pedal. 2 or 3 bolts and one plug

So it could be that simple? Fingers crossed.

 

[leeds_182]

Was the throttle body on mine.

 

[riz]

mine was lambda

 

[lemonnobby]

yeaa it could be the throttle pedal. we have also fitted ew plugs to some of them at work

 

[Mark One]

So it could be that simple? Fingers crossed.

that or Trottle Body. that was aimed at schweppy actually. get it plugged in and see what the OBD says.

 

[Icarus]

Throttle body or throttle pedal - specificaly there is a failure in one of the throttle position sensors or one of the pedal position sensors.

DBW relies on two lots of sensors at each end with both required to confirm the actual pedal position and throttle position. A failure in one of these will result in fail safe mode i.e reduced rev limit and allowed max throttle position.

Plug a fault code reader in and it will identify which end the problem is at.

Cheers
M

 

[SBV116]

Throttle body is first port of call mate!! Easy enough, they dont have to be coded or anything!!

 

[Icarus]

Throttle body is first port of call mate!! Easy enough, they dont have to be coded or anything!!

It could be throttle body (or rather one of the TPS sensors contained within it) or Pedal position sensor. The failure mode is the same for both. Hence the need to read the fault code to identify what has failed and avoid changing a component which may be good.

Cheers
M

 

[Schweppy]

It could be throttle body (or rather one of the TPS sensors contained within it) or Pedal position sensor. The failure mode is the same for both. Hence the need to read the fault code to identify what has failed and avoid changing a component which may be good.

Cheers
M

My code didnt say which end i dont think.

Just said inconsistency in tracks 1-2 ETC and something to do with throttle potentiometer circuit.

 

[andy_murray]

mines was the same as yours mate, showed up, turn the engine off for a few seconds, and back on it was all clear and good enought to drive for a few more days, it does start to get more regualar tho, and sometimes a right pain in the tits,

i put mine into renault and it was the throttle potentiomiter and i think it was 82quid fitted

 

[Tucker]

yeah renault can get it on clip and might be able to tell you what's up.

 

[MarkCup]

Right, thanks all.

I'll give Rentech a call.

 

[MarkCup]

Update:

New throttle body fitted...70 miles covered today, hasn't dropped into limp mode once.

On the old body, the same journey saw it go about 10 times.

Fixed for tomorrow :approve:

 

[jon_r]

See you in the morn Mark.

 

[rogers]

how much did u pay for the throttle body? do u have to have them coded? as i, iv got the same problem as you,

but mine came up throttle/pedel position sensor/switch circuit A

 

[Mike@Rentech]

they are not coded, you can fit new or used.

 

[MarkCup]

how much did u pay for the throttle body? do u have to have them coded? as i, iv got the same problem as you,

but mine came up throttle/pedel position sensor/switch circuit A

As Mike said, no coding needed.

Just 4x 10mm bolts, and an electrical connection...took less than 10 mins to swap over.

There's someone on here selling one for £35 I think...which is less than I paid for mine.