Help - Mi Conversion Finished But Misfiring/cutting Out When Hot

[mat1227 1]

Chaps - I'm getting to the end of my tether with my 205 - can anyone help? I've done a search, and spoken to people on here before about this but now I know more and this seems pretty random.

 

I realised it was developing into a full on rambling post so I've taken the liberty of preparing a more concise version, for the knowledge-rich time-poor forumites amongst you

 

Short version:

* Car misfiring then cut out.

* Changed fuel, engine ran fine (stationary) for 10 min then once up to temp started misfiring in a large fashion and cut out completely.

* Would catch when I try to restart but won't idle; now won't even catch started just spins.

* Seems to be a hot misfire.

* Leads; dizzy; plugs were new. Ignition amp; coil; crank sensor known good, as I tested them on Paul's car.

 

What could this be? How can I fix it, because I'm going mad?!

 

Long version:

Spent months and months (about 6 weekends) with Paul (pug309twin40s) putting Mi lump in my 1.6. Exited, MOT time. Engine cut out on way back from MOT. Car was fine on way to MOT, failed MOT due to misfire and running rich - on way back went from misfiring to cutting out completely and not restarting within about 50 seconds. Fuel has been in the car since Glasto last year (12 months), we suspected dodgy fuel was to blame so when I got it back I drained the tank using the pump, shooting fuel from fuel filter into buckets.

 

Today I got hold of 15 litres of fresh super unleaded, put it all in and car started with a bit of a splutter but soon settled to a perfect idle. Problem solved I thought, mat was happy Occasionally it seemed like it was missing slighly now and then, but for something like 10-15 min was fine - sitting there idling happily. Would rev perfectly cleanly, very responsive. However once hot, it started misfiring heavily straight away - cut out and then wouldn't start. It's driving me spare and now I'm having bad thoughts about it. I've had a couple of tantilising drives to/from MOT etc and just want it on the road as it should be! Nearly there

 

What can I do? Why would a car only misfire when hot?

 

If anyone can shed any light whatsoever I'd be very grateful indeed. Mat

[KRISKARRERA 2 1 Cars]

Have you checked the injectors?

[mat1227 1]

Nope, how would I check them? Excuse the ignorance

[mat1227 1]

Just been out to try and restart the car after 50 min or so, should've cooled down but it won't catch. Starter spins, fuel pump running - misfires splutters and then nothing

 

[dan druff 0]

you need to see if your getting fuel pressure whilst cranking and if your getting a good spark also when cranking then go from there.

if the fault occurs when hot it could even be relay fault,is the wiring all correct ie all earthing points tight and correct .

on cars never assume a part is ok always check then check again.

not to sure how much coolant temp sensors affect starting on mi engine or even an air mass fault can affect fueling also when it misfires try and narrow it down to a cylinder

cheers

dan

Edited July 5, 2008 by dan druff

[mat1227 1]

Ok thanks Dan lots to look at there.

 

A couple of people have suggested the ignition amp/ignition module* could be at fault bearing in mind the fact this only happens when the car is up to temperature. Would it be worth replacing this?

 

* I presume these are different words for the same thing?

[jackherer 543]

Sounds like it could be the ECU coolant temp sensor to me, making it overfuel when hot.

[mat1227 1]

Sounds like it could be the ECU coolant temp sensor to me, making it overfuel when hot.

 

Thanks - would this be a case of trying a known good ECU?

 

Mat

[pug_ham 244 3 Cars]

Thanks - would this be a case of trying a known good ECU?

 

Mat

No, just a known good ecu temp sender but if you have a multimeter you can test them.

• 20'c approx 2500Ω
  
• 40'c approx 1200Ω
  
• 60'c approx 600Ω
  
• 80'c approx 300Ω
  
• 100'c approx 180Ω
  

Graham.

[mat1227 1]

No, just a known good ecu temp sender but if you have a multimeter you can test them.

• 20'c approx 2500Ω
  
• 40'c approx 1200Ω
  
• 60'c approx 600Ω
  
• 80'c approx 300Ω
  
• 100'c approx 180Ω
  

Graham.

 

Thanks Graham - in my infinite ignorance that doesn't mean a great deal to me but will ask a mate for a hand, failing that will pick up a new ecu temp sender. If that doesn't work sounds like ignition amp is next port of call

 

Cheers!

 

Mat

[pug_ham 244 3 Cars]

Sorry, should've explained a bit more, measure across the cts pins & those are the resistance values you are looking for at the appropriate temperature.

 

Graham.

[mat1227 1]

Ok, thanks

 

M

[paul205mi16 4]

Hi.

 

I had the same symtoms on my Mi16 conversion, It was eventually cured by these three things....Brand new (Bosch-from Pug dealer) Blue ECU Temp sensor

(the old one was a after marker job) Also-one of the Brand new sparks plugs seemed not to spark a well as the others, Swaped this for a old one and things improved, I then took it to a local garage got it on the gas analiser and they adjusted the AFM screw (Behind blue cap)

 

After that it's been great..First reading was about 7% on the analiser, Now its been set to around 1.5%...

[CaptainK 11]

I have a similar problem on my GTi6 conversion. Doesn't like starting at any time, especially when hot and occasional has a little misfire around 1700rpm to 2300rpm but only when under constant throttle and its hot. Let off, or hit the gas and its fine again.

 

Have changed the ECU temp sensor to no joy. Suspect its lambda probe for me, but the Mi16 don't have one as far as I know.

 

If it helps with starting I found this out about mine:

1) Cold: Put key in ignition barrel and then quickly turn it all the way to "starting engine". Generally starts first time. If I put it to first click or second click of ignition and then pause and start the engine, it won't start.

 

2) Hot: Reverse of above. Put the key to click 2 and then wait until the fuel pump turns off. Give it another second or two and then start.

 

If I don't do that it just turns over and so desperately wants to start and almost does, but just doesn't.

 

Good luck !

[mat1227 1]

Ok thanks Paul, K - it's not so much starting problems, just that it won't run at all once hot. Turns over but if it does catch on occasion runs really rough for literally a second then dies, even with lots of throttle. Cold, it's absolutely fine.

 

Sounds like I should replace ecu temp sensor first then go from there. Is it an easy job? Car's back at my mum's at the mo so can't go out and look

[paul205mi16 4]

Its a easy job, Just unplug the electrical connector,Then unscrew the Blue senser from the side of the thermostat and screw the new one in and reconnect the plug , Be aware there will be some water loss, So top the coolant back up, Jobs done.

Mine some times had problems when hot, But usully started from cold..Have you checked the sump for contamination from it over fueling??My sump ended up with around half a litre of fuel when I checked..So I would take a look and change if needed.(Fuel going down the bore past the piston and through to the sump)

Also, I would check the injector wires (2 wire's to each injector) and see if they are loose/making a connection or badley corroded too.

Defo need to get it on the gas analiser and adjust the Air Flow Metre!

[M@tt 77]

easy peasey to change just make sure you have the new one close to hand as you'll get some coolant leaking out when you remove the old one. You just need a suitable sized ring spanner or deep socket to undo the sensor from the Thermostat housing.

[mat1227 1]

Ok cheers guys changing sensor looks straightforward, then hopefully whoever's going to MOT it can have a fiddle with the AFM screw and get it on the gas analyser?

 

When it comes to fuel in the sump I've no idea; not sure how to go about taking a look either - sounds beyond me..

[paul205mi16 4]

Have a lookat the centre of the inlet manifold and you see a black cap where you would normally fill the engine with oil, Take the cap off by pulling and have a smell down the tube that goes to the sump. If there is petrol down there you would probably smell it m8..

 

Either do this or give it a oil change anyway, The Sump has a plug at the bottom of the engine, It's square shaped and you need a special tool (sort of like a allen key) Put a tray under and unscrew the key and the oil will flood out and probably go up you sleeves.lol

To fill just pour oil down the tube from the top where you removed the black cap, Cant remember how much oil you need, I would guess 5 ltr maybe, But some one on here will know or check Hayne manual or search function on here too.

[mat1227 1]

Ah thanks Paul I was imagining you had to take the sump apart or something silly. A sniff and an oil change sounds much more sensible now that I can do

[VisaGTi16v 1]

Fuel pump relay? They get very hot to the point where coming back from a sprint one VERY hot summer day 2 years ago my thing conked out on the M25. Coasted to under a bridge in the shade and left it to cool for a bit, was then fine until stuck in traffic again when it died again so had to pause for a bit longer. Replaced with a higher current spec one now so it runs cooler and so far no issue. Although this was only a one off so perhaps it was something else like the ignition amp......see how hot the fuel pump relay feels when you are having this issue

[mat1227 1]

Well if it's the brown one that clicks in the black box next to the ignition relay (very technical explanation..!) then this is sited somewhere pretty cool, it's sitting behind driver's headlight where the jack usually does and is protected by the black plastic casing too. So I'd be surpised if it got very hot, but I'll check regardless.

[VisaGTi16v 1]

No idea sorry, mines up by the bulkhead as its in a Visa not a 205 but it is black and about 7 pins if that helps heh

[returnofjim 0]

Check the condition of the hose from the idle valve to the inlet manifold (the one about 2-3 inches long), I had a similar problem on an mi16 when warm, after checking/changing everything electrical it turned out to be a split in the idle valve hose.

[mat1227 1]

Ok thanks Jim will do that sounds well worth checking.

 

Hopefully get a chance to have a look this weekend

 

Mat