Hi,

 

I have been looking through the forums to try and find any advice, or people with a similar issue. I have found various threads but nothing that seemed to quite fit this. 

 

Engine is a 1.2 BME code 2006

 

Essentially the car starts, runs for up to 30s and the dies a lumpy death. This is with no foot on the accelerator and just from a turn key start.

If you put your foot on the accelerator the engine will pickup up briefly, but will then return to the same lumpy death.

There are no warning lights on the dash - all seems to be normal up until the point the car dies.

 

The code issue appears to point to a crank shaft sensor. The car has been in to the electricians, they have changed various parts - cranks, cam, lamba, oxygen sensor etc., Different throttle body, different ecu. - nothing has made any difference.  

They decided that the issue must be the timing chain and that something is out there. The timing chain has now been done - thanks to the posts on this forum for some great pointers in that process.

 

Nothing seems to have helped. 

 

I have put a link in to a video of the engine starting, and then dying in case that helps:

 

https://photos.app.goo.gl/rowmoTdZaW4mdCnD7

 

 

Thanks

John

Has a compression test been done before or since the timing chain was replaced?

56 minutes ago, Wino said:

Has a compression test been done before or since the timing chain was replaced?

 

I would have to ask the garage and my brother (who's car this is) about before the timing chain was replaced. I have just carried a compression test out, and all are reading 12 - 12.5 bars.

 

Doesn't matter about before then; that sounds OK.

 

Is it still showing a crank sensor code?

 

Sounds like something's suffocating it shortly after it starts going.  If you watch the throttle butterfly, leaning over to look down onto it, does it close completely just before it starts coughing?

 

 

From the video sorta looks like when my car had a faulty coil and MAP sensor a year ago. 

I don't have a means to check the codes here - I may be able to get hold of someone who can.

 

In terms of the butterfly its mostly closed through out until it really starts coughing, then it opens fully just before dying.

 

I have checked that the spark plugs are sparking - I will find out if anyone has mentioned the MAP sensor in looking into this.

54 minutes ago, juanse_2691 said:

From the video sorta looks like when my car had a faulty coil and MAP sensor a year ago. 

Well, I have just unplugged the MAP sensor and the car starts, idles and revs - so looks like that's the culprit. 

So got a part number will order a new map sensor and hopefully all will be good. 

 

Thanks for the pointers and ideas!

That hissing noise just before it dies makes me wonder if the exhaust is blocked. Worth checking. I once had that happen on a Vauxhall Astra.

 

EDIT: Just noticed where you said it runs with the MAP sensor disconnected, so can't be the exhaust.

Edited 29 March, 20215 yr by TMB

Be sure to get an original MAP sensor. My experience is that pattern ones don't seem to last long. If I were you, I'd be looking for Polos and Fabias at the breakers nearby to get the sensor out of one. 

46 minutes ago, juanse_2691 said:

Be sure to get an original MAP sensor. My experience is that pattern ones don't seem to last long. If I were you, I'd be looking for Polos and Fabias at the breakers nearby to get the sensor out of one. 

OK, thanks will take a look and see what I can find.

Hi All, 

 

So I put the new MAP sensor in place, and started up, and the same issue presents its self, un plug the MAP sensor and its all good again. 

 

So this leads me to think that there is either a wiring issue - or a problem with the ECU itself? 

 

So the other question is how safe is it to drive with out the map sensor - my understanding is this is helping the ECU determine when to spark, so it may be a little rough without it?

 

Thanks

John

No, not much to do with spark timing, that's the crank sensor. 

MAP sensor measures air pressure and temperature in the intake manifold, which aids calculation of fuelling quantity (injector duration).

 

Doubt there's anything wrong with the engine ECU, can help you with wiring info later.

Edited 6 April, 20215 yr by Wino

Looks like I was partly wrong and you were more correct than I thought. This from the Self Study Programme on these engines:

 

"Intake air temperature sender G42 and intake
manifold pressure sender G71
supply signals to enable the engine control unit to be
able to compute the necessary injection time as well
as the ignition timing point."

 

I guess in the same way as vacuum advance used to modify distributor function back in the olden days.

 

I'll check the wiring info now.

Are you entirely certain that there are absolutely no faulty coils and/or plugs at this point? What happens if you run without cabin fuse #9 (lambda probe)? 

 

You need to read the codes either way, hopefully with VCDS or something similar.  

Pin 1 at MAP sensor connector - brown wire, earth for temp and pressure sensors, to/from engine ECU pin 83, shared with a few other sensors,

Pin 2 Green wire, temperature sensor high side, to/from ECU pin 93,

Pin 3 Red/green wire, 5V supply for pressure sensor, form ECU pin 96, shared with other sensors.

Pin 4  brown/white wire, pressure sensor output to ECU pin 95.

 

Thanks I will look at the wiring as soon as I can. 

 

The car is at least driveable now, so that it can get to a garage to check for codes. What is odd is that with the MAP sensor unplugged the car runs and drives, its likely to stall when you take your foot off the the gas to quick. BUT the engine warning light is on. If you plug the MAP in you'll be lucky if it runs for 30s but there are no warning lights on the dash.