Engine Probs/Revs on start Up/Won't start/Management light

[john.med]

OK, I've just done a search and had a read. But I'm still uncertain what's wrong with my 172.

A few weeks back I started my car and it was fine till I tried the throttle, which didn't respond. Idled normally just wouldn't respond to the throttle. Switched off and on again, all was fine. No warning light.

Happened again, so I put the diagnostic tool on it, no faults.

Today having sat for 2 days it wouldn't start, the car had electricity, windows and interior lights were fine. The engine turned over quickly but wouldn't start. The engine management light was on. It started with jump leads.

Went for a good long blast, everything was fine, no warning lights, plenty of power.

Switched it off and on again, the engine management squiggle came on and the engine revved from 2000 to 2500 and again wouldn't respond to throttle.

What do I do, because whenever I put the diagnosis tool on there's no fault!

Do I just replace the throttle potentiometer, lamda sensors and or coil?

HELP! and sorry for the essay.

 

[mini-valver]

I'd go with Throttle body personally dude. There's plenty about and cheap enough. Just check the wiring plugs are clean and well connected on both the pedal and TB first.

 

[john.med]

cheers dave. I'm just really unsure about replacing stuff one by one. Can prove expensive. One thing i have noticed is the sensor that enters the plenum is a bit insecure. Everything else seems ok.

 

[john.med]

just managed to get a fault code off the car: P0110 01/01 IAT SENSOR CIRCUIT MALFUNCTION. What's all that about?

 

[john.med]

just managed to get a fault code off the car: P0110 01/01 IAT SENSOR CIRCUIT MALFUNCTION. What's all that about?

 

[john.med]

the temp sensor had disconnected. That was the fault code. But i'm still having weird revs and no throttle response. I'll check the throttle body over in a mo. How much would i get one for, is used ok?

 

[gtruk]

go look on ebay seen a few cheap on there. Used is fine.

 

[john.med]

my mate works for reno, best price he can do me one for is £190. He's 200 miles away tho. He said to clean it first with brake cleaner. And advised against 2nd hand. But hey, needs must. Thanks for the help chaps

 

[mini-valver]

Dont pay 190, lol. You can try cleaning it but unless its really s**t up, I cant see it maikng a massive difference.....

 

[john.med]

i just cleaned it but it wasn't so dirty. Surely the throttle is closed at idle? Would the throttle body really make the car idle badly? I've sourced a few used ones. Just not convinced it would cure it dave...

 

[mini-valver]

If you have a scrapyard near you, they'll let you buy it, try it and return it if its no good! The throttle is close at Idle yeah but as its fly by wire, it tells the ECU what to do and if the unit is faulty, it'll send mixed signals.....

 

[john.med]

Ah, that explains it Dave. I think I'll buy one from a lad on here

 

[mattjk]

Yeah, sounds like an electrical fault, could also be the sensor ont he pedal but more likely the TB

 

[john.med]

I did have an accelerator pedal fault recorded absolutely ages ago... Ah feck I'm gonna be replacing loads of things one by one!

 

[mattjk]

Hmm its most likely one or the other lol sorry cant be more specific.

 

[john.med]

if i disconnect my accelerator pedal and start the car i prompt the revving fault. Could it be the pedal that's duff? Or does that prove nothing?

 

[john.med]

ok just and update. I fitted and calibrated a mint throttle body i bought from Has off've here. Test drove it last night, was faultless. This morning, the black beauty wouldn't start. Turned over on the starter like a trooper, but wouldn't start until 5th attempt! I've a new throttle pedal in the post, but i'm thinkin something else is at fault... Not good.

 

[BRUN]

does your TDC sensor have a blue connector ?

 

[john.med]

Where's the TDC sensor and how much will it cost me?

 

[john.med]

Just cleaned up my TDC sensor, fiddly little fecker, will see how I get on.

 

[BRUN]

is the wiring connector on it blue ?.....and part of the problem can be the connector, not the sensor itself

 

[Has]

is the wiring connector on it blue ?.....and part of the problem can be the connector, not the sensor itself

Does the blue signify anything? Were they a batch of faulty ones?

 

[john.med]

Non blue were early I gather. Blue were later. Brun, mine wasn't blue, no.

 

[BRUN]

if its blue then its been fitted with the replacement modified one which requires a new loom aswell, about £50 inc vat for both of them

you cant fit the new sensors without the loom, and nearly all Renaults have now got revised TDC sensors, id say nearly all that are 10 years old or less, you wont get the new type from a factors, only OE

they are the most common cause of starting issues, usually the vehicle will turn over but it wont fire up

reading your past problems it wouldnt cause the none responsive throttle but it may solve starting problems

 

[BRUN]

did you sort this ?

 

[john.med]

Yeah Brun, cheers for asking. I fitted a 2nd hand t/body and fly by wire pedal and cleaned up my TDC sensor. Car's been fine since.