Disconnected sensor on Peugeot 205 rallye TU24

[Derek 205 Rallye 0]

Hi All!

 

First post on here, I've just bought a LHD 1.3 Rallye from Spain, and I'm going through the process of getting it spot on before registering it in Portugal. It's pretty good already having had a rebuild some years back, but is clearly running very rich and doesn't idle well at all. (I've bought a refurb kit for the Webber DCOM's as a starting point...) It also had a lot of GTi interior parts used in the rebuild which I am or already have swapped back (windup windows, dashboard air vents, door cards etc...)

 

It's fairly standard under the hood, OEM airbox etc, but I notice it has a sensor on a bracket just by the airbox, which is disconnected. No-one seems to know what this sensor is, some people have suggested it might be a knock sensor that somehow retards the ignition timing (if so, would seem an odd place to put it, hanging on a bracekt!) Many Rallyes I've seen don't have these, mine is a 1989 car. Picture is a library photo, not of my actual engine, but the sensor I'm referring to is circled in red. What is it? Any ideas?

 

Thanks a lot, hoping these forums will be a great source of info inthe coming months!

[SRDT 182]

It's a temp sensor to keep the fan running for a while and help with hot starts, it should work at aroud 50-60°C.

[Derek 205 Rallye 0]

Ah great! I assume it's the sensor marked M863 - "Temperature sous capot" - (Temp under the bonnet?) Glad it's nothing more fundamental.

 

It might well help reconnecting it, given the car will be in a hot country.

 

The two connector blocks M884 and M733B - where can I find them under the hood? I can probably just make up my own loom and reconnect it.

 

Thanks again.

[SRDT 182]

The plate may not be the original one and not all cars had this at first so it's better to start on the fan side an see whant you can find.

[Derek 205 Rallye 0]

Ok, made some progress with this while taking bits out to clean it up... Think I've found the original loom to the sensor that had been disconnected and just tie wrapped up under the relay box. It's the correct length and has the two spade connectors on it, except one of them is disconnected.

 

In the relay box by the front Left headlight I've found what I think is the relay M733B shown above, and also an empty relay block for M884. The wiring connections all correspond, and one end of what looks like the wound up long loom from the under bonnet temp sensor does indeed connect to the correct pin for the relay (pin 1 in M733B). The only thing is I am unsure what type of relay I need to plug into the empty relay socket (M884) - the blue one in the photo below. It only uses 4 pins. Is it a normal relay? The symbol on the wiring diagram is slightly different, showing a square pulse.

 

Also the yellow wire below that comes from pin 1 of M884, and connects to pin 4 of M733B, but it also connects to H706, which I think is the ignition barrel/steering lock. Where do I connect that to? Is there a wire in from the ignition switch into the relay box?

 

Many thanks, think I am nearly there. I'd like to connect it back up so it's as close to original as possible. I assume the fan only runs when the ignition is on also?

 

Many thanks!

 

 

[Derek 205 Rallye 0]

This is the relay I am trying to identify - is this just a normal relay? That switches the fan on when the under bonnet temp sensor reaches the required temp? It's the square pulse symbol on the wiring diagram which is making me think it's not a normal relay... The connector block is there in the loom (photos above) but there is no relay in it.

 

Also, any idea what the other 2 relays are for?

[SRDT 182]

Temporisation means there is a timer inside.

For what I found this relay should be blue and it should be on when there is +12V on pin 1, when there is no loger +12V it will stay on for 12 more minutes.

[Derek 205 Rallye 0]

Thanks that's good information, of course, a timer! I should have guessed as it is designed to run the fan after the engine switches off...

 

Any idea where I might find one? They don't seem to have any on any of the usual Peugeot 'Youngtimer' sellers, is it something I could still get direct from Peugeot?

[SRDT 182]

I have seen used blue relays that are probably the right ones but you could also buy a brand new universal timer relay.

[Derek 205 Rallye 0]

Happy to say the car is finally through the import process!

 

Now I can drive it, I've noticed it's pretty flat and also really struggles to idle until it's warm, misfiring and also popping out the silencer when trying to start it. It is still also running very rich, and the carbs have been rebuilt.

 

We've replaced the (cracked and leaking) rubber carburettor supports with a CNC'd aluminium block. Where would you start the trouble shooting? I'm thinking easy stuff like HT leads and plugs first, but could it be the timing belt is a tooth out? I'm thinking especially because it often pops out the exhaust when trying to start from cold, but don't know if that's normal for these cars and just how aggressive the stock camshaft is. I also don't know of course if it's the original cam, but all the way up to 7000rpm it never really clears,  seems to be running rough.

 

What else? Coil producing weak spark? Distributor (it's the original one.) I've seen some solid state after market bluetooth programmable coils for these cars so you can programme your own advance curve, but they're not cheap...

 

Thanks all.

[SRDT 182]

How is your CNC'd bock? You can have problems with the carbs floats if you are 100% rigid. It's better to have big O-rings and special washers:

[Derek 205 Rallye 0]

Yep I'd read about that, percolation problems with vibration and resonance of the floats. But the symptoms were there before and after we swapped it over, so I don't think it's that. I think it's something more fundamental... Also as it causes very difficult starting, then down on power once its warmed up. I've done a compression test, all 4 cylinders were absolutely identical at 110psi, lowish I know, but it was a nasty cheap gauge and the engine was cold (and the cylinders were very wet with fuel.) This also made me wondering about the cam timing as all the cylinders were a but low but all the same...

 

Also the return pipe T-piece to the tank was originally plugged with an aluminium bung, and it was suggested that it was causing an excess of fuel pressure and flooding the float chambers. So I drilled it out, but that has also made no difference. (Photo attached of that and the CNC carb mounts.) I now reinserted a bung with a small 1.5mm hole in it, apparently the T-piece and return to the tank was there to bleed vapourlock back to the tank, so it needs to be there.

[welshpug 1,661]

really you need a specialist to check the fuelling with a wideband Lambda gauge, be it with a welded bung or a temporary clamp in the tailpipe type.

 

 

where you would find that in Portugal I have no idea, but you aren't far at all from Estoril so there must be someone out there

[Derek 205 Rallye 0]

Thanks, the car spent a month with a 'specialist' near Estoril after I'd done most of the work, he installed the CNC carb mounts, he improved the idle as he found a leak in the distributor vacuum hose, but this is as good as he could get it sadly. We were originally setting up the idle lean for the CO² test until we discovered they don't actually measure idle CO², they measure it on a rolling road under load for the import test. So he set the idle back up again.

 

Could a timing belt out cause any of these symptoms? Constantly wet plugs, hard starting, a lot of fuel in the exhaust? I was thinking bad valve timing could be the culprit of unburnt fuel, backfiring and generally poor performance. Trouble is over here the car can sit with an 'expert' for months that doesn't actually know the car any better than the owner. So I was going to try and sort it myself. Timing light plugs and HT leads on the way first, and I'll try to check the cam timing from the manuals which I have.

[Thijs_Rallye 87 4 Cars]

Albeit in Dutch, the manual might help. The DCOE's and DCOM's aren't renowned for their easy cold starting properties. The 1.3 rallye has an extra solenoid which increases the ignition timing with a cold engine.

 

As with most issues, start with all the basics, so it will help if you check the cam timing and valve clearances. Where the throttle shaft seals replaced as well during the rebuild? Have the butterfly valves been realigned after aforementioned rebuild? Also the progression holes often have a tendency to clog up which also makes it a pita to drive and cause hesitations.

 

Aanvulling_205_Rallye.pdf

[Tom Fenton 1,542]

Those CNC mounts are not the right thing at all to mount the carburettors, but the issue is elsewhere from your write up. Going through the fundamentals e.g. cam timing and valve clearances is a good move, but it sounds to me like it needs to go to someone that knows how to set up the carburettors. It also needs the correct carb mounts, sometimes called Misab plates. It looks like you could maybe use these in conjunction with your cnc adaptors to give the movement needed.

[DamirGTI 342]

I worked on a TU24 few years ago ... you need to play a bit with the carb adjustments - jets and emulsion tubes (feel free to wander a little bit off from factory spec - aka experiment) , and synchronize .

 

But first thing clean up and replace all the gaskets/diaphragms on the carbs , set floats etc.

 

We had also similar alu. CNC carb mounts with bakelite strips in between , no problem with those .

 

After some trial and error , trying different jets and emulsion tubes , adjustments via screws , i managed to make it spot on .

Started up straight away and pulled/accelerated cleanly without "flat spots" .

 

I've also some documentation for Rallye in French if you want .

 

One important thing - what ever you do , do not fit NGK spec. spark pugs on this engine ! only Eyquem (there's specific spark plug for TU24)

 

D

[Derek 205 Rallye 0]

That's all really useful info, thanks Gents! I wasn't aware of the cold start solenoid increasing the ignition advance... Maybe that might be a clue as to why the engine idles better once it's warm. Is it a notably fallible part? What temperature does it switch off, and is it integral to the distributor itself? I've seen the aftermarket solid state programmable distributors. They're not cheap but I'd be interested in any first hand experience of them? Time to order a decent timing light, not had one since I raced Formula Ford... Perhaps of the solenoid is suspect that might be affecting both idle and running under load also.

 

I have ordered a set of 'misab' plates, they're cheap enough. The throttle shaft seals weren't replaced, no, but the carbs were balanced when he was trying to prep it for the inspection.

 

Edit: As for the plugs, they are indeed Eyquem plugs.

Edited May 22, 2023 by Derek 205 Rallye

[Wallby 47]

Lots of good info here!

 

What's the deal with the Eyquem plugs? I've always used NGK on mine so would be good to give these a go. What's the part number?

 

Any ideas on how to clean up the progression holes? If I remember right they are under a bronze cap? Just got mine back together after a few years so things need adjusting/fettling to perfect.

[Thijs_Rallye 87 4 Cars]

1 hour ago, Derek 205 Rallye said:

I wasn't aware of the cold start solenoid increasing the ignition advance

It's inactive from 15°C onwards.

 

1 hour ago, Derek 205 Rallye said:

I have ordered a set of 'misab' plates, they're cheap enough.

Don't forget to order the springs and locknuts as well, since they are not included afaik.

 

1 hour ago, Derek 205 Rallye said:

The throttle shaft seals weren't replaced

Might be worth checking with some brake cleaner and a running engine.

 

But check all the basics first otherwise you will keep chasing your tail since carb's are not very forgiving in that regard.

[Thijs_Rallye 87 4 Cars]

4 minutes ago, Wallby said:

Any ideas on how to clean up the progression holes? If I remember right they are under a bronze cap? Just got mine back together after a few years so things need adjusting/fettling to perfect.

The mixture screw is indeed located under the bronze cap, which also is near the progression holes. Easiest way is dismantling the carb and use some decent carb cleaner and compressed air cleaning all channels / mixture screws. When you blow some brake cleaner in a channel you will quickly figure out what goes where as soon as all jets and set screws are out. (Good!) Carb cleaner is nasty stuff, try to avoid skin and eye contact.

[Wallby 47]

2 minutes ago, Thijs_Rallye said:

The mixture screw is indeed located under the bronze cap, which also is near the progression holes. Easiest way is dismantling the carb and use some decent carb cleaner and compressed air cleaning all channels / mixture screws. When you blow some brake cleaner in a channel you will quickly figure out what goes where as soon as all jets and set screws are out. (Good!) Carb cleaner is nasty stuff, try to avoid skin and eye contact.

Sorry, I meant the bronze plug, I know where the mixture screws are. I don't think there's an easy way of getting those plugs out to check the progression holes that way? 

[SRDT 182]

The cold start ignition advance is an old trick, I think Jaguar used something similar on the V12 to get it up to temp faster and cut on emissions.

As long as there is no leak it's not really a problem to have it removed or nonfunctionnal, at least not like whant you're experiencing.

 

 

[DamirGTI 342]

True , i broke off one of the plastic outlets on the solenoid on our Rallye , and as we couldn't find new nor replacement one i simply discarded it after some research about what it does - makes no difference with or without it , just sort out the vacuum hoses .

 

 

D

Edited May 23, 2023 by DamirGTI

[DamirGTI 342]

16 hours ago, Wallby said:

What's the deal with the Eyquem plugs? I've always used NGK on mine so would be good to give these a go. What's the part number?

 

NGK specified plugs for Euro Rallye 1.3 in our case created no start condition when installed .. spark was present upon inspection out from the cylinders , but something happened whilst screwed inside the head/cylinders cause of pressure/turbulence whatever - engine simply didn't want to start/ignite the mixture , not even a cough , not even on start spray , was flat out dead .. after a few hours of "wtf ?!" pulled the old Eyquem plugs from the trash can and it fired strait up , tried NGK's again just for s*its and giggles - no go .

 

Eyquem Rallye specific plugs are : FC82LS3 , or by Peugeot number 5962 K3 .

 

D

Edited May 23, 2023 by DamirGTI