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gtt dave j esprit

TPS not able to open full

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Hi,

TPS set at 0.49 - 0.51 volts, When throttle fully down its only showing a reading of 2.81 volts. and giving little over 40% .

Why could this be ? have old and new tps both reading the same.

Any ideas help much apperciated

Cheers regards dave.

having problems getting more that 2.81 out of tps. after setting it at 0.49-.51 , it will only read up to 2.81volts.

The temp sensor that runs thru the same curcuit, just been replaced after that was messing up.

Do you understand much about how the curcuit works.

Yesteraday it was fine one min , then the next it was poor again, it fix itself for a while , then returned to only being able to get just over 40% throttle ?

If you cant help dont worry thank you once again.

Dave

PS, "My veiw" It also seem by the look of a lot of poor running Topics/threads people seem to struggle to fix the culprit, that must leave a vast majority of esprits turbos off the roads no.gif .

Edited by gtt dave j esprit

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The tps is a potentiometer and uses pins c5 c12 and c15 on plug 3 so must be 5v+ 5v- and reader from resistance circuit.To read pd from ecu with voltmeter it must be across pin c5 and either c12 or c15 i would think.

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Voltage between pins J3C5 (signal gnd) and J3C12 (reference voltage) should be approx. 5.00v

Voltage between pins J3C5 (signal gnd) and J3C15 (signal voltage) should vary smoothly between approx. 0.45 - 0.70v and 4.50v when going from closed to open throttle.

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Same car bob, the voltage at c5 c12 4.85v but freescan only showing 2.38v with pins A and C shorted.

Edited by mick

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Mick, when you say 'same car', do you mean yours or Dave's?

Assuming you mean Dave's, I'd check the resistance of the wiring between the TPS and the ecu next. If the voltage drop isn't caused by the wiring/connectors then the next suspect is the ecu itself.

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Derek, Me and mick both trying to suss out the same probs, on the same car. Sorry for any confusion.

Have a look at other topic about same thing, Maybe it might say or show somthing you havnt seen or been told.

Next look at ecu being at fault you say, We sent ecu away for testing and came back with no problems ? mabey it might not have shown a prob yet it has one!

Would any wires to or from ECU cause these symtons.

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Yes, the wiring could be causing the problem. Also, whilst checking the resistance between TPS and ecu connectors wiggle the connectors and flex the wiring itself to check for breaks.

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The wires or connections dont seem to be the problem on the tps side got a new tps also, maybe having non genuine temp sensor is causing problem, thats on order asap.

Is there wires that feed the ecu from the ignition curcuit that could be causing problems, also what earths are there ect.

dave

Edited by gtt dave j esprit

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You'll need a multimeter that measures resistance. Disconnect the connector from the TPS and the J3C (green) connector from the ecu, measure the resistance of each of the wires, i.e. between pins A and J3C12, pins B and J3C5 and pins C and J3C15. All should be reading zero, or very close to zero, ohms.

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Hi derek

Continuity check as close to short as multimeter can measur

source voltage at tps plug 4.98v so no voltage drop there. Im increasingly becomeing suspect

of ecu's reading of the data as occasionally weve had 4.5v on freescan then it drops to 2.8v after

a run. Maybe an intermitent fault thats getting more permanent?

Edited by mick

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Did you wiggle the connectors and flex the wires whilst doing the resistance check? It might be worthwhile repeating the check after a run too. That all said, it's looking more like an ecu problem, maybe some component breaking down when warm.

I don't know if there is anyway of verifying that the same +5v ref voltage is applied to all the sensors but when you disconnect the coolant sensor does Freescan show that as approx. 5v even though the WOT TPS voltage is showing less than 3v?

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The temp sensor is supplied from the same 5v source as tps (same pin on ecu c5) I dont know of a check like shorting out tps to get 4.5v on freescan

Ive rewired tps so thers no harnes or loose connector probs.(everything reads the same before rewire and after to double check i put it back to normal

through the harness)

I spent 61/2 years in navy as a radio electrician but this has got my head going in full spin.

100% confident its not wiring fault, think its ecu reading error.

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Pin J3C5 is the signal ground, you cannot short this out to read the reference voltage. The ECT sensor voltage is measured internally from within the ecu so disconnecting the sensor should result in vRef being displayed in Freescan.

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Thats not what i was saying. Ground from ecu via c5 is 4.98v as measured on volt meter. The manual says disconnect plug

short connection A and C freescan should read 4.5v 100%. Its only reading what we can get with plug connected

and flooring the throttle.

Edited by mick

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You are losing me, I'm not understanding what you mean.

By checking the ECT sensor voltage I was trying to find out if the low voltage problem was confined to just the TPS or if it affected other circuits.

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Check out this topic i started about wiring on alarm/immobiliser/radio. http://www.thelotusforums.com/forums/index.php?/topic/32510-ignition-wiring-and-radio-wiring-on-se/page__gopid__297994&

am looking and wiring is messed , found a prob and maybe more. dont seem to be able to upload pictures at present.

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Hi derik

the source voltages are correct all systems work its just the return reading is not corresponding to the tps positition.

I think theres something wrong with the reading circiut of ecu.

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Thanks to all who have advise and insight to this long running problem, especially dermot for his freescan analyasist.

After rewiring the tps and temp sensors the prolem was with the ecu.

words of warning dont use a generic temp sensor they only read 50% pay the extra £7 and get the lotus one.

Sent ecu for test at power steering, came back no fault for £100

Hence 12 months and loads of hassle

sent ecu to bluestreak they found intermitent fault due to board flex(causes dry joints) car ok now.

So if you go all the options and still have problems its the ecu withhard to find intermitent probs.

highly recmend bluestreak too test your ecu.

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