Mi16 Not Starting - Nearly There Though!

[eob 7]

Hey all. Most of you know I've been scavenging parts for my 205 on here for about four years, my freshly rebuilt Mi engine is in, the bodywork is done bar a polish and the interior is back from, eh, my mother who re-stitched the bolsters

 

The only thing is, it's not starting! Boo! Hiss! Etc

 

I made up the link loom and it all appears correct. The ECU seems to be getting plenty of -/+ in all the right places according to Autodata but...

 

1. There's no spark.

2. There's no fuel injection.

 

Just wondering where to start on the path to diagnosis?

 

Some pointers

 

1. The coil is getting plenty of positive current, I would also wager plenty of negative, it's earthed through the body of the coil correct?

2. The distributor cap/rotor are as new.

3. The HT leads are new.

 

Does the ignition system work independently of the ECU or does the ECU activate the ignition system somehow?

 

Really cannot wait to drive this so any and all suggestions welcome

Edited November 30, 2008 by eob

[Miles 331 1 Cars]

The coil doesn;t earth thou the body, it's seperate and depending on which loom you have the ign amp and coil + the power relay need this to work, But a good test is to check that the main power relay clicks when you turn the ign on and the fuel pump on clicks when you start cranking

[Mr_save 0]

Wich loom are you using? from a 309 or a 405?

 

mind that, me using a 405 loom i had to by-pass the fuel pump and relay,

 

and now when i turn the key it start itself. LOL...

 

also i remember that the ecu needs a positive more but i dont` remember where.. i have some electrical schemes if you need it!

[luggy 13]

I had a similar issue with my donor car before removal of the engine, turned out to be a faulty ECU.

 

http://forum.205gtidrivers.com/index.php?s...c=71025&hl=

[eob 7]

I have a hunch it's a faulty ECU but I just want to go through everything else first Both the fuel and power relays (thank you Pugtorque!) are working 100%. I've done the pin outs on the ECU feeds and while it's possible there's a wrong signal somewhere, it's getting fed everything it needs, ie. +/- in all the right places and all the signals from the CPS/AFM/TPS etc going to the right place. The injectors have a live feed but the ECU isn't pulling them to ground.

 

Turn it over, no spark, no fuel!

 

My hunch would be that it's either the CPS or the ECU.

[bensonmi 4 2 Cars]

I have a hunch it's a faulty ECU but I just want to go through everything else first Both the fuel and power relays (thank you Pugtorque!) are working 100%. I've done the pin outs on the ECU feeds and while it's possible there's a wrong signal somewhere, it's getting fed everything it needs, ie. +/- in all the right places and all the signals from the CPS/AFM/TPS etc going to the right place. The injectors have a live feed but the ECU isn't pulling them to ground.

 

Turn it over, no spark, no fuel!

 

My hunch would be that it's either the CPS or the ECU.

 

this sounds like the same prob i have except it has started for 2 dies then not again,i dont want to sound thick but what is cps ? how do i check it?

[DrSarty 90 1 Cars]

but what is cps ? how do i check it?

 

Crank Position Sensor - also referred to as a VR (Variable Reluctance) sensor, which creates pulses based on flywheel teeth whizzing passed it telling the ECU where TDC is in relation to everything else, aka telling the engine/ECU when to spark.

 

Best test - as is often the case - is a swap for a working one.

[bensonmi 4 2 Cars]

Crank Position Sensor - also referred to as a VR (Variable Reluctance) sensor, which creates pulses based on flywheel teeth whizzing passed it telling the ECU where TDC is in relation to everything else, aka telling the engine/ECU when to spark.

 

Best test - as is often the case - is a swap for a working one.

 

thats the badger!! il try that, might of damaged it when puttin gear box on

[luggy 13]

My hunch would be that it's either the CPS or the ECU.

 

Faulty CPS shouldnt affect fuelling

[GLPoomobile 958]

this sounds like the same prob i have except it has started for 2 dies then not again,i dont want to sound thick but what is cps ? how do i check it?

 

On the diagram I sent you it's the CAS (crank angle sensor) as per the wording used in CAPS.

[GLPoomobile 958]

Faulty CPS shouldnt affect fuelling

I'm fairly sure the ECU won't trigger the injectors if it's not getting a signal from the CPS/CAS, as without a signal it doesn't know the engine is turning over.

[bensonmi 4 2 Cars]

On the diagram I sent you it's the CAS (crank angle sensor) as per the wording used in CAPS.

 

 

diagram??? am i missing something here?

[GLPoomobile 958]

diagram??? am i missing something here?

 

Sorry! It wasn't you I sent it to, it was Jas-E and Veero! Just ignore me

[DrSarty 90 1 Cars]

Sorry! It wasn't you I sent it to, it was Jas-E and Veero! Just ignore me

 

PMSL

 

Foot, mouth etc .

 

Brilliant!

 

Does your fuel pump 'prime', i.e. run for 0.5-1.5 secs when the ignition is turned on, one place shy of starting?

[eob 7]

My fuel pump doesn't prime, no, which is what has me thinking the ECU is dead as every single Motronic ECU I've ever worked with primes the fuel system briefly when it 'boots' up

 

One thing that struck me, though, when I sitting in a Systems Analysis lecture in college, what the Mi16 205/8v 205 really needs is like... a flow chart... start at step 1, does your car have an engine? yes/no -> if no, you need to buy and engine, and then drill down and have people checking known bad components like tachy relays and the like.

 

I know, it's a pipe dream, but you see so many 'My car won't start' threads on here that I was reluctant to post a thread saying the same thing because I feel like I'm totally, I dunno, wasting peoples time because I'm too dumb to figure it out?

 

So... you think it's possible my ECU is borked?

 

PS. BTW, just in case anyone is mislead from posts before now, the ECU is everything to do with fuelling.

[DrSarty 90 1 Cars]

I CBA to read back through, so I don't know what ECU it is (i.e. BX or Mi), but I'm guessing it shouldn't really matter. There should be a single yellow wire exiting the main ECU multi-plug or near there, that should go direct to either the fuel pump or white wire 76 on the smaller of the 2 brown multi-plugs under the dash. You do not need a tachy relay.

 

Once we have your fuel pump doing what it should do we may be able to work from there. Admittedly it doesn't solve the no spark (yet) issue, but these cars have been known to have several things wrong at once you know.

 

Let's get you some fuel first.

 

If the above is not done, or has been done and doesn't work - with all other things such as power to the ECU being OK - then we must suspect a FUBARd ECU.

 

EDIT: Let's first test the fuel pump though with 12v and see if she goes.

Edited December 2, 2008 by DrSarty

[eob 7]

Hey Sarty, first up, thanks for the advice.

 

Luckily I'm not a total electronics n00b so I won't be replying with 'what's an ECU?' . I've double checked all the relays and the fuel pump, the pump runs fine once the fuel pump relay is grounded (ie. both the relay, pump and pump wiring are all good), the ECU is just not pulling the pump relay to ground. The ECU isn't pulling the injectors to ground either on cranking but I haven't verified the CPS

 

The ECU is from a BX GTi 16v, the loom looks like it's a 405 job as it's multicoloured

 

I've checked the pin outs on the ECU plug using Autodata and all the pin outs are in the right place bar one small earth wire which I don't think it needs anyway - Pin16 - (all the big thick +/- wires are there, Pin16 is just blank on my ECU plug from the factory).

Edited December 2, 2008 by eob

[GLPoomobile 958]

On my 405 2 row, pin 16 is an earth. It goes to the gearbox earth point. It also Ts off to the brown relay.

[eob 7]

Much appreciated GL

[jackherer 543]

So... you think it's possible my ECU is borked?

 

If you have neither fuel nor spark its much more likely to be the crank sensor IMO; I've never had a failed ECU but I've swapped loads of crank sensors. I carry a spare in the glovebox in fact, the CPS is the 16v equivalent of the tachy relay

[eob 7]

Those CPS's are pretty generic aren't they? Ie. find someone with a 106 and swap it over? Good news is I shipped the ECU off today to a friend with a working 405 Mi16 and he's going to try my ECU in his car so that's a start... If his car starts with my ECU, it's back to the drawing board, or the CPS.

 

"the CPS is the 16v equivalent of the tachy relay"

 

Wise words

[DrSarty 90 1 Cars]

You could've swapped your CPS/CAS/VR for another in the time it took to pack your ECU, and you could've had her running.

[jackherer 543]

Those CPS's are pretty generic aren't they? Ie. find someone with a 106 and swap it over?

 

I don't know about 106s (TU engines) but the newer XU CPS's from 2.0 turbos, GTI6s etc all work fine with Mi16s.

[luggy 13]

I'm fairly sure the ECU won't trigger the injectors if it's not getting a signal from the CPS/CAS, as without a signal it doesn't know the engine is turning over.

 

My mistake!

[jack1.9 0]

Those CPS's are pretty generic aren't they? Ie. find someone with a 106 and swap it over? Good news is I shipped the ECU off today to a friend with a working 405 Mi16 and he's going to try my ECU in his car so that's a start... If his car starts with my ECU, it's back to the drawing board, or the CPS.

 

"the CPS is the 16v equivalent of the tachy relay"

 

Wise words

 

 

Hi Eammon,

 

I gave that ECU to JK a few hours ago............ have you not got it running yet ?

 

C'mon man, get the finger out