Mk 2.5 1.8 Sport Starting Issue

Technical Area Engine, Transmission, Exhaust etc
2

Good evening,

I own a 2001 MX 5 2.5 1.8 S-VT sport. 

Unfortunately, a few weeks ago the car suddenly stopped/stalled and failed to restart. I am now at a loss as to what will resolve this. 

 

The symptoms when attempting to start the car are as follows:-

       1) Turn key - Engine will crank and upon initial crank will fire once or twice.

       2) The engine will continue to crank until the key is released, however no further firing of the spark plugs will occur.

       3) After the key has been positioned to off, the symptoms then repeat as per step 1 when attempting further restarts.

 

When the breakdown occurred I had the vehicle recovered and allowed the recovery garage to carry out the initial repair/fault finding. 

Their findings/actions were as follows:-

       1) Coil packs and spark plugs replaced.

       2) Plugs found wet so fuelling is not an issue.

       3) Garage found crack on crank shaft sensor - sensor was replaced and set up correctly.

       4) Engine timing was checked with no anomalies found.

       5) Garage checked feeds to coil packs and found signal dropped off after initial start.

       6) Garage recommended ECU change.

At this point, I decided to have the car returned home whilst I worked out my options.

 

Fortunately for me, I came across rhino666 who offered advice and the many options available to me. After a discussion with rhino666, I obtained a working ECU from him but unfortunately, this failed to resolve the problem. 

At this point I did manage to identify a fault code of P1345 - ‘No CMP or SGC Signal’. something I had not managed to read until this point.

After further discussions with rhino666, we decided to try a replacement Cam position sensor, however this has also failed to resolve the issue, with no changes seen.

We are currently looking at checking the continuity of the wiring to and from the Cam sensor and crank sensor to try and determine if a possible wiring problem is present.

 

If you have any experience or advice please post. I’m almost out of ideas.

Many thanks for taking the time to read my post.

 

Thanks again Ryanjc83

 

3

It would be very helpful if others could contribute here please.

We have proved by replacement that the issue is not connected directly to ecu function or the cam sensor.

On that basis I can only suggest that the P1345 code generated relates to a timing issue or possibly a wiring/connector fault.

Not sure if the VVT could be involved - suspect not?

Is it possible to remove the top plastic cam belt cover and successfully check cam pulley alignment(timing) at TDC without removing cam cover?

Thank you      

4

Have you tried a MAF sensor?

5

Hi Rob

Thanks for that. I did talk about the MAF before the P1345 code came up but no as far as I know it has not been tried…yet:-)

Is there any way to tell by just unplugging the MAF as with the MK1 1.6 or would he need to replace?  

 

 

6

Missed the bit about the fault code so probably not a MAF. The pick up for the sensor on the back of the cam isn loose is it? Damaged teeth on the crankshaft sensor pick-up plate?

7

After your suggestion of a MAF I did a search on P1345 code and MAF - there is some possibility as apparently like the MK1 1.6 a faulty MAF can suck voltage from other areas. Hoping it has been interfering with the cam sensor operation. Anyway it really is the last component part to try out so posted first class this morning. I believe the pickup plate and 4 teeth for the crank sensor was checked when sensor was replaced? 

We will report back when this is finally sorted.

Not considered the pickup for the cam sensor - that would make a lot of sense. If you are reading this Ryan worth removing the cam sensor to check pickup and also have another look at the crank pickup plate too. Nice day for it unlike yesterday.

Girlfriend has taken MAF to PO already but if not needed send back with the other parts when all sorted.   

8

Good afternoon and thank you for all your advice and support, particularly to rhino666 for his endless conversations that he must have found frustrating (with respect to me being an amateur mechanic).

 

In the last few days, whilst waiting for the delivery of the MAF sensor I decided to check the previous items that were done by the garage. I started with the timing, which is by far the most mechanical job I have undertaken (all be it with verbal advice from rhino666). However all markings lined up correctly and in my limited experience, I believe the timing to be correct.

 

The garage originally concluded that the crank sensor was damaged and loose. So I also investigated the trigger plate for the crank sensor. I have subsequently discovered that one of the little nipples are missing and another one has a slight indent. It is now my belief that this caused further damage to the trigger plate (it is possible that it was something else, however, I have no further explanation).  I now believe this to be the reason for the failure to start. This will be replaced in due course and an forum update posted accordingly.

 

I have attached photographs of the damaged trigger plate for others to review if required (please let me know if it cant be viewed as I’m new to this forum but will be using this from now on).

 

Obviously the car is not running at the moment, but I hope that, once its back together, I will have no problems.

 

Again, many thanks for all you help and advice

Ryan

 

9

When you replace the trigger plate make sure that you fit the new one in the same front/back orientation as the old one. It’ll fit either way but the tags are offset to the mounting holes.