172 Cup suddenly developed a firing issue. Help!

[ex-Chinese Dave]

On Wednesday from cold my 172 Cup didn't fire after 4-5 seconds of cranking. On the second attempt it fired after about 5 seconds. It hadn't done that before and had always fired perfectly. So, off I went to have the car given a full service (belts, dephaser, fluids etc) and I picked the car up today. No issues regarding starting were noted by the guys who did the service (they have an extremely high reputation on CS) and the car started fine this morning when I collected it. I drove to work and it didn't miss a beat. When I started it after work I had the same issue, it needed 5 seconds of cranking and it took two goes to fire it. I drove to get some fuel and with the engine up to temp it still didn't want to fire as it did before Wednesday. Very odd!

Obviously the plugs have just been done. The battery seems ok (not noticed any problems but could it be a cause?) and it's connections look ok. I can hear the fuel pump prime the system before I start cranking the engine, too. I read on CS that the key can be an issue but not sure it would be that. The car idles fine, a little lumpy for the first few seconds but then perfectly normal.

I hear the TDC sensor (I need to look up where that is!) can be an issue so what do I check and how to do it?

Any ideas?

 

[Matt Cup]

Crank position sensor is here.

Post #16

Crankshaft sensor

Ive got a 172 w reg so its an oldie! ive had intermittant probs of not wanting to start... it finally died on me and had to get the AA out... he took 20 mins to find out it was the crankshaft sensor.. he removed it and cleaned it and returned it. I then took the car straight to the garage and...

cliosport.net

 

[ex-Chinese Dave]

Ok, so cleaning it is the first thing to do, right?

KTEC sell two of these, one looks like a copy part for around £46 and a genuine Renault item for £131. Which would you recommend?

EDIT: Is this it?

Renault Clio 172 182 Crankshaft Sensor - Renault Parts Direct

Renault Clio 172 182 Crankshaft Sensor - Renault Parts Direct - Renault Parts Direct is a web based service from our authorised Renault dealer.

renaultpartsdirect.co.uk

 

[Matt Cup]

You might need the bit of loom with a plug to splice into the original wiring if it hasn’t been changed before.

 

[TheBandit]

Hella and Febi do them for about £20 with loom, you can get a genuine one for £60 Renault Parts direct + £24 for the loom bringing it up to £90 or so with delivery

I have a Hella one as my backup, but not yet had to fit it so can't recommend it as such

EDIT: Some private sellers have genuine for about £20 on ebay

 

[ex-Chinese Dave]

You might need the bit of loom with a plug to splice into the original wiring if it hasn’t been changed before.

Ok. KTEC sell them with the wire and what appears to be one of those sleeves that need to be heated up to seal around any wire connections. That means that the old sensor is unbolted and its wires snipped, then the new sensor wires are joined to the loom and covered by the sleeve, right?

 

[TheBandit]

Ok. KTEC sell them with the wire and what appears to be one of those sleeves that need to be heated up to seal around any wire connections. That means that the old sensor is unbolted and its wires snipped, then the new sensor wires are joined to the loom and covered by the sleeve, right?

Yep, just making sure you get the wires the right way around 🙈

 

[ex-Chinese Dave]

Yep, just making sure you get the wires the right way around 🙈

I did think that....but they are the same colours so I guess you're joking, right? I'm crap with electrics btw.

 

[ex-Chinese Dave]

febi | 34970 | Crankshaft Sensor | bilstein group partsfinder | Official Catalogue for febi, SWAG & Blue Print Spare Parts

febi 34970 Crankshaft Sensor suitable for Dacia, Nissan, Renault

partsfinder.bilsteingroup.com

 

[TheBandit]

I did think that....but they are the same colours so I guess you're joking, right? I'm crap with electrics btw.

Only one way to find out ✂️✂️✂️✂️✂️

 

[ex-Chinese Dave]

Only one way to find out ✂️✂️✂️✂️✂️

Don't say that!!!

The tech info says "Connect them to the repair kit, if the original wiring harness has wires of the same colour, mark these wires before disconnecting to save yourself time and any incorrect joining of wires."

Yikes!

 

[npt]

Are you sure the pump is primming/getting power at the times it's failing to start, if it definitely is then I'd trust the crank sensor and wiring

 

[ex-Chinese Dave]

Are you sure the pump is primming/getting power at the times it's failing to start, if it definitely is then I'd trust the crank sensor and wiring

I can hear it priming for about a second when I turn the ignition on. It’s doing the same now as it had done for the last 4 weeks.

 

[npt]

Test the crank sensor and wiring, you'd need a multimeter and a helping hand, test the voltage at the plug and resistance of the sensor, or just change the sensor and wiring, cheap, easy to do and they are prone to fail anyway, hopefully it sorts the issue

 

[ex-Chinese Dave]

New part ordered. That’s my Thursday day off sorted.

 

[TheBandit]

Looking at the invoices I know the sensor has been changed on mine but I don't know about the loom. Looks like shrink tube on the black wire..., will find out when I next pull the airbox

My loom is cream/black and the Hella replacement is red/blue 🥴 did you go genuine?

 

[ex-Chinese Dave]

This is what I ordered…

Crank Shaft Sensor FOR RENAULT CLIO II 00->05 2.0 Hatchback Petrol BB CB | eBay

FOR RENAULT CLIO II. Number Of Ports:2. Vehicle compatibility. This is an original quality part manufactured by Febi Bilstein. Number of connectors:2. Weight [Kg]:0,060.

www.ebay.co.uk

 

[ex-Chinese Dave]

So, a little development. I noticed last night and this morning that when turning the key on the ignition before starting the engine, I didn’t really notice the fuel pump prime. It turned over first time, but didn’t fire. When I tried it the second time I had the fuel pump kicking, and the car started instantly. Thoughts?

 

[hopgop1]

So, a little development. I noticed last night and this morning that when turning the key on the ignition before starting the engine, I didn’t really notice the fuel pump prime. It turned over first time, but didn’t fire. When I tried it the second time I had the fuel pump kicking, and the car started instantly. Thoughts?

Pretty sure it's normal for them to not prime until 2nd click on of the ignition? Sure I've heard that somewhere, can double check on my car later.

 

[ex-Chinese Dave]

Just went back to the car about 2.5 hrs after running it. Hers what I did:

Turned key to full ignition position without turning the engine over (no sound of the fuel pump priming, just the usual buzz from the front of the car).
Turned engine over but it didn't fire.
Turn ignition fully off.
Turn key back to full ignition position without turning engine over (this time I hear the fuel pump prime)
Turned engine over and it fired.

 

[JamesBryan]

Yeah they don't prime until the second turn of the key.

 

[ex-Chinese Dave]

Yeah they don't prime until the second turn of the key.

Why is that? Surely if the car has been stood a while there will be no pressure in the system.

 

[Brigsy]

So, a little development. I noticed last night and this morning that when turning the key on the ignition before starting the engine, I didn’t really notice the fuel pump prime. It turned over first time, but didn’t fire. When I tried it the second time I had the fuel pump kicking, and the car started instantly. Thoughts?

Normal. Doesnt generally cause too much of an issue when intank fuel pressure reg is holding pressure ok.

With some remaps they prime every cycle

 

[JamesBryan]

Why is that? Surely if the car has been stood a while there will be no pressure in the system.

The fuel pumps are internally regulated, so there will always be pressure in the system, at least a little anyway.

The original pumps will be getting tired now, so yours is probably draining back a bit or a leaky injector.

 

[ex-Chinese Dave]

Another job on my ‘new’ 21 yo Cup lol

 

[ex-Chinese Dave]

Update on this....

Yesterday I had a spare hour so I thought i'd have a look at how the TDC sensor is changed as I've got the part on order. After seeing it was easy to get at I took it off and noticed the sensor part was blackened (obviously, as the car is 21 years old). I cleaned the end with a rag and used some fine sandpaper on the sensor part. I put it all back and tried to start the car. It started instantly, and this morning and this afternoon. Problem solved! I'll have a spare sensor and now don't need to change the fuel pump immediately.

Happy days

 

[Matt Cup]

Nice. The simplest fixes are always the most satisfying 👍