4200 CC : Problem starting when engine hot

[tonycharente]

I would disconnect the tube from the purge valve as you have done and plug both the valve and the tube.

If your hot start issue disappears, then you will know. If not, it rules it out.

Thank you Zep. Sounds like a good idea - could save me replacing the carbon canister for nothing. I left the purge valve in place (and still connected to the carbon canister) so I just need to plug the valve. I think I should reconnect the electric plug, to avoid throwing up an error code?

 

[Oneball]

I can come up with all manor of reasons none of which I know for sure. But perhaps it isn’t the thermostat, maybe it’s a wiring or ecu issue things which would definitely affect starting.

My logic is you’ve got a definite fault (running cold) that should be an easy fix if it’s thermostat or fan. Get that sorted and see what happens to the difficult problem. Plus it’s doing your engine no good running around cold.

 

[tonycharente]

Update...
In preparing to plug the purge valve as suggested by Zep I used some rubber hosing with better hose clips and I so thought I'd try measuring the vacuum leakage again, both of my purge valve and of the Mityvac itself, this latter having previously itself been the subject of a slow leak. It turns out that the leakage of the Mityvac itself was down to leaks from the supplied clear plastic tubing (despite my using clamps) - it now only drops 2 or 3 PSI even overnight. So I remeasured the purge valve leakage rate yet again. There is still a small leak, but less than I had thought - a drop of around 10 PSI over 1.5 hours. Could that rate be enough to cause my hot start problem?

Anyway, taking on board Zep's suggestion, my next step is to try the car with the purge valve and the pipe to the manifold plugged to see whether this resolves my hot start problem. As my hot start problem is very intermittent, and as I only drive the car about once a week, it may be months before I start to feel that this has cured it. I do hope so, but at least if it it hasn't I'll have saved replacing the carbon canister and/or purge valve for nothing.

Watch this space...

PS for Oneball: Thanks again and I totally agree that I should replace the thermostat, but as I really really really can't see why its potentially not closing properly should be causing a hot start problem I shall leave it until next time I'm buying Maserati parts.

 

[Tedwud]

Update...
In preparing to plug the purge valve as suggested by Zep I used some rubber hosing with better hose clips and I so thought I'd try measuring the vacuum leakage again, both of my purge valve and of the Mityvac itself, this latter having previously itself been the subject of a slow leak. It turns out that the leakage of the Mityvac itself was down to leaks from the supplied clear plastic tubing (despite my using clamps) - it now only drops 2 or 3 PSI even overnight. So I remeasured the purge valve leakage rate yet again. There is still a small leak, but less than I had thought - a drop of around 10 PSI over 1.5 hours. Could that rate be enough to cause my hot start problem?

Anyway, taking on board Zep's suggestion, my next step is to try the car with the purge valve and the pipe to the manifold plugged to see whether this resolves my hot start problem. As my hot start problem is very intermittent, and as I only drive the car about once a week, it may be months before I start to feel that this has cured it. I do hope so, but at least if it it hasn't I'll have saved replacing the carbon canister and/or purge valve for nothing.

Watch this space...

PS for Oneball: Thanks again and I totally agree that I should replace the thermostat, but as I really really really can't see why its potentially not closing properly should be causing a hot start problem I shall leave it until next time I'm buying Maserati parts.

I had the same issue as you, running at 75C constantly and hot start issue.
I have replaced the thermostat and it was stuck open. I have also bought the ‘Washer valve’ but haven’t fitted it yet.
Touch wood, but my hot start issue hasn’t happened since the thermostat replacement. The only slim connection I can think of is that the engine is now running at the appropriate temperature when hot, therefore the air/fuel mixture is correct on hot starts. Maybe it’s over-fuelling with a stuck thermostat?

 

[tonycharente]

I had the same issue as you, running at 75C constantly and hot start issue.
I have replaced the thermostat and it was stuck open. I have also bought the ‘Washer valve’ but haven’t fitted it yet.
Touch wood, but my hot start issue hasn’t happened since the thermostat replacement. The only slim connection I can think of is that the engine is now running at the appropriate temperature when hot, therefore the air/fuel mixture is correct on hot starts. Maybe it’s over-fuelling with a stuck thermostat?

Many thanks Tedwud. What I can't get me head round is why the engine management should cause difficulty in starting when hot just because the engine is running at 75°C instead of 90°C. Surely it should all the time be adjusting the mixture to suit the temperature? Anyway, for now I'm going to see what difference shutting off the purge valve (and thereby the carbon canister) makes, if any. If the car is still sometimes hard to start when hot I shall take all the readings previously discussed whilst it's refusing to start. If that doesn't point me in the direction of what needs changing, I'll certainly change the thermostat. And if it points me towards a different part to change, I'll still order a new thermostat whilst I'm at it.
Many thanks again
Tony

 

[tonycharente]

This morning I received an email from the website informing me of the following response from Doodlebug:-

On my car, the engine block temperature sensor was changed twice and the thermostat was changed but it was still faulty. It was the Interface CAN for the Instruments Panel (Maserati Part Number 196622) which caused the faults you are experiencing. The gauges report the incorrect engine block temperature to the engine ECU which sends incorrect fuelling information to the injectors.

Hope you get it fixed soon, it used to drive me nuts.

Strangely I cannot see this post once I actually open this topic.

However Doodlebug had posted a related response on another topic
"POTENTIAL COOLANT TEMPERATURE ISSUE"
so as I couldn't reply to him on my own topic I replied to him there, (below) to which he has already replied (further below).

Potential Coolant Temperature issue tonycharente said: Hello Doodlbug, I am replying here to your helpful post on my 4200 CC : PROBLEM STARTING WHEN ENGINE HOT topic since strangely although I received an email from the website giving me your very helpful reply when I go into my post there is no trace of it. Is it the same for you? If so perhaps you could repost your reply to me and I'll then repost my reply (below) so as to maintain the replies chain. I've spent some time looking into part number 196622, worked out where it must be on my LHD car (up below the steering column), and managed to locate it. On my facelift (MY2006) it's actually part number 219367. (On the Scuderia Parts diagram 219367 is shown as being for 2005-2007 coupés, whereas (strangely also...) 196622 is shown as being for 2002-2004 coupés and 2005-2007 spyders - how weird is that? Perhaps the spyders didn't get the same facelift features?) They are both shown as being "INTERFACE CAN FOR INSTRUMENTS PANEL", and both are item 1 in the respective diagrams. Now here's my query. Does the temperature sender sends its signal via the "INTERFACE CAN FOR INSTRUMENTS PANEL", which then (a) sends a temperature to the temperature gauge AND (b) also sends a temperature signal to the engine management which takes account of it in deciding the petrol mixture? That is to say that my true engine temperature higher is than the reading on the temperature gauge due to the problem with the INTERFACE (196622 or 219367)? Once you had your new 196622, did your temperature gauge then read closer to 90°C,please? Anyway the good news is that for once the part is readily accessible, which makes a very nice change. The bad news is that it may not be available new ("AVAILABLE TO ORDER" on Scuderia Parts. I plan to still go through the steps in my post to see what happens - and if that doesn't lead me to the solution I'll most certainly try to buy a 219367. Thanks again for your helpful reply, Tony ** Hi Tony, I'm not sure what happened to the post but the one you have quoted is still there. I don't know the communication protocol used by the Instrument CAN Interface, but the car had the following symptoms. It would start normally from cold. The radiator fan would always run immediately the car was started, whether or not the engine was warm. The temperature gauge never indicated higher than about 70°C even on very hot days in slow traffic. The car would be very difficult to start from hot and there was a strong smell of overfuelling. Occasionally, the Check Engine light would illuminate. Checking the fault codes showed an engine temperature sense fault. After replacing the Instrument CAN Interface, the temperature gauge reads 90°C in normal conditions and higher if stuck in traffic, where the radiator fan will come on. The radiator fan only comes on if the temperature is well above 90°C. It no longer comes on if the engine is cold when it is started. I no longer have hot start problems and the Check Engine light no longer stays on once the engine is started. I hope you get it fixed soon. It took one main dealer and two independent garages a total of 4 attempts to cure it after they tried changing the temperature sensor and the thermostat.​

Given that Doodlebug's suggested solution is clearly highly relevant,I thought it useful to post all the above here.

Has anybody else changed their 196622 or 219367 I wonder, and with what outcome ?

Thanks, as ever, to all,
Tony

 

[Oneball]

“The gauges report the incorrect engine block temperature to the engine ECU which sends incorrect fuelling information to the injectors.”

Should be easy to confirm that by measuring actual coolant temp with a thermometer and comparing it with the gauge reading or reading sent to the ecu using actual data from OBD.

 

[tonycharente]

“The gauges report the incorrect engine block temperature to the engine ECU which sends incorrect fuelling information to the injectors.”

Should be easy to confirm that by measuring actual coolant temp with a thermometer and comparing it with the gauge reading or reading sent to the ecu using actual data from OBD.

Excellent suggestion, thank you so much Oneball! This morning I took the car for a run to take various data stream measurements with my Launch. To my delight I found that my temperature gauge seems to be under-reading. With an outside temperature of 13°C, driving very gently my Launch showed 83.4°C, the gauge more like 75. Stopped and ticking over for a while, the gauge went up to 90°C and then 93°C, for which the gauge read about 86 and 88 respectively. This is really good news, as I am hoping this means there is nothing wrong with my "INTERFACE CAN FOR INSTRUMENTS PANEL". This is especially good news as although for once this looks to be dead easy to replace, Maserati have obviously recognised this by making the part no longer available !!!

 

[tonycharente]

Interim report...
This morning I took the car for a run to take various data stream measurements with my Launch and to make sure no codes came up due to my blocking out the purge valve (and indeed to make sure the car still ran normally with it blocked out). No codes, ran perfectly normally and no problem restarting from hot despite my trying to replicate situations where it had happened previously. So far so good... ...but very early days yet.

 

[tonycharente]

It will be a few days before I take the 4200 out again, so I'm sitting here pondering the meaning of the various Launch data stream readings I took yesterday. Any ideas about the following readings, please?

CANISTER PURGE VALVE : 0%
CANISTER FILLING FACTOR : Minus 4.05
(I have blocked the hose linking the Purge Valve to the Inlet Manifold, and the Purge Valve's electric plug is plugged in).

Also given that since blocking off the Purge Valve the car hasn't yet failed to restart with the engine hot, (very early days yet but I'm hoping it stays that way !!!) I've been unable to read the Launch data stream rpm as has been suggested. Is there any other way of testing the Crank Position Sensor, with my Launch or otherwise, please?

Thanks to all,
Tony

 

[Masernico]

This morning I received an email from the website informing me of the following response from Doodlebug:-

On my car, the engine block temperature sensor was changed twice and the thermostat was changed but it was still faulty. It was the Interface CAN for the Instruments Panel (Maserati Part Number 196622) which caused the faults you are experiencing. The gauges report the incorrect engine block temperature to the engine ECU which sends incorrect fuelling information to the injectors.

Hope you get it fixed soon, it used to drive me nuts.

Strangely I cannot see this post once I actually open this topic.

However Doodlebug had posted a related response on another topic
"POTENTIAL COOLANT TEMPERATURE ISSUE"
so as I couldn't reply to him on my own topic I replied to him there, (below) to which he has already replied (further below).

Potential Coolant Temperature issue tonycharente said: Hello Doodlbug, I am replying here to your helpful post on my 4200 CC : PROBLEM STARTING WHEN ENGINE HOT topic since strangely although I received an email from the website giving me your very helpful reply when I go into my post there is no trace of it. Is it the same for you? If so perhaps you could repost your reply to me and I'll then repost my reply (below) so as to maintain the replies chain. I've spent some time looking into part number 196622, worked out where it must be on my LHD car (up below the steering column), and managed to locate it. On my facelift (MY2006) it's actually part number 219367. (On the Scuderia Parts diagram 219367 is shown as being for 2005-2007 coupés, whereas (strangely also...) 196622 is shown as being for 2002-2004 coupés and 2005-2007 spyders - how weird is that? Perhaps the spyders didn't get the same facelift features?) They are both shown as being "INTERFACE CAN FOR INSTRUMENTS PANEL", and both are item 1 in the respective diagrams. Now here's my query. Does the temperature sender sends its signal via the "INTERFACE CAN FOR INSTRUMENTS PANEL", which then (a) sends a temperature to the temperature gauge AND (b) also sends a temperature signal to the engine management which takes account of it in deciding the petrol mixture? That is to say that my true engine temperature higher is than the reading on the temperature gauge due to the problem with the INTERFACE (196622 or 219367)? Once you had your new 196622, did your temperature gauge then read closer to 90°C,please? Anyway the good news is that for once the part is readily accessible, which makes a very nice change. The bad news is that it may not be available new ("AVAILABLE TO ORDER" on Scuderia Parts. I plan to still go through the steps in my post to see what happens - and if that doesn't lead me to the solution I'll most certainly try to buy a 219367. Thanks again for your helpful reply, Tony ** Hi Tony, I'm not sure what happened to the post but the one you have quoted is still there. I don't know the communication protocol used by the Instrument CAN Interface, but the car had the following symptoms. It would start normally from cold. The radiator fan would always run immediately the car was started, whether or not the engine was warm. The temperature gauge never indicated higher than about 70°C even on very hot days in slow traffic. The car would be very difficult to start from hot and there was a strong smell of overfuelling. Occasionally, the Check Engine light would illuminate. Checking the fault codes showed an engine temperature sense fault. After replacing the Instrument CAN Interface, the temperature gauge reads 90°C in normal conditions and higher if stuck in traffic, where the radiator fan will come on. The radiator fan only comes on if the temperature is well above 90°C. It no longer comes on if the engine is cold when it is started. I no longer have hot start problems and the Check Engine light no longer stays on once the engine is started. I hope you get it fixed soon. It took one main dealer and two independent garages a total of 4 attempts to cure it after they tried changing the temperature sensor and the thermostat.​

Given that Doodlebug's suggested solution is clearly highly relevant,I thought it useful to post all the above here.

Has anybody else changed their 196622 or 219367 I wonder, and with what outcome ?

Thanks, as ever, to all,
Tony

Hi Tony

you're reporting strong fuel smell as well. The hot start problem is very often caused by a failing valve no. 180173 . Also termed as "role over valve" => Nr. 3 antievaporation device.
The valve is important if you drive uphill and/or doing fast accelerations. If the valve is leaking your carbon canister will be filled up with fuel. That cause the strong fuel smell and unwanted enrichment of the A/F mixure which leads to the hot start effect you experianced. Had same problem on m 2003 MY Spyder. The fuel smell you're reporting is a strong indiator for this problem. Problem happened in my case espeacially after some short uphill accelerations.

By the way the valve is a BMW part. BMW no. is 16131183279. It's not anymore deliverable from BMW as well what I know.

Best regards from a Maserati driver in Austria

 

[tonycharente]

Hi Tony

you're reporting strong fuel smell as well. The hot start problem is very often caused by a failing valve no. 180173 . Also termed as "role over valve" => Nr. 3 antievaporation device.
The valve is important if you drive uphill and/or doing fast accelerations. If the valve is leaking your carbon canister will be filled up with fuel. That cause the strong fuel smell and unwanted enrichment of the A/F mixure which leads to the hot start effect you experianced. Had same problem on m 2003 MY Spyder. The fuel smell you're reporting is a strong indiator for this problem. Problem happened in my case espeacially after some short uphill accelerations.

By the way the valve is a BMW part. BMW no. is 16131183279. It's not anymore deliverable from BMW as well what I know.

Best regards from a Maserati driver in Austria

Hello Masernico,
Thank you for your suggestion. I couldn't find 180173, but I think you must have meant 180573 Rollover Valve. This is available but is rather expensive. Also it wasn't me that reported a strong fuel smell, so for now I'll just add it to my ever growing list of possible causes of my hot start problem.
Please see my next post for a summary of "where I'm at".
Thanks again
Tony

 

[tonycharente]

Hello all,
UPDATE,
Having plugged off the Purge Valve I've done my best to simulate the situations where the engine has failed to start from hot shortly after shutting it down, so far without "success", which is of course good news. However it's by no means conclusive since my failure to start from hot didn't / doesn't happen very often.
On Thursday just gone I ordered the following parts that are relatively easy to replace (compared to changing the Crank Sensor):- 180861 (Washing/Purge Valve), 220074 (Fuel Vapour Filter), 230890 (Thermostat) and 137873 (Gasket for the Thermostat). They are due to arrive on Tuesday. I shall then start by comparing the vacuum retention of the new Purge Valve with that of my old one, and then fitting the new one. I'll then need to try umpteen times to simulate the situations where the engine has failed to start from hot shortly after shutting it down, in the hope that this alone has cured my problem. Fingers crossed...
Tony

PS For those that have changed the Crank Sensor, did you also replace the manifold gaskets or were they readily reusable, please?

 

[tonycharente]

FURTHER UPDATE : BAD NEWS
After testing my new Purge Valve vacuum retention and finding it to be better than my old one, I was quite optimistic about having solved my problem, and I would just have to do umpteen successful outings to prove it. Unfortunately today I had another fail to start when hot, so my work so far has been of no avail, except that I have eliminated the Purge Valve. I was also able to ensure that neither using my spare key nor locking and opening the door using the remote made any difference. I had my Launch set up to read engine revs, as suggested, but did not get "0" as a revs reading whilst trying to start the car. I did get some very unlikely readings though - 6848 and 8064... ...perhaps alternative signs of an iffy Crank Sensor? I did also try to sniff the exhaust pipes for the smell of petrol, but as I was on my own this was hard to achieve - there certainly was no strong smell of petrol by the time I lept out of the car and round to the back. As usual the car did eventually start and then drove perfectly.

I have ordered a new Crank Sensor but it is not due to arrive until next week.

Meanwhile I shall try replacing the Fuel Vapour Filter (220074, bought already) as it has never been replaced, just in case that is my problem. Watch this space...

 

[Bails848]

Hi Tony, I've been reading your thread with much interest, mainly because I have been experiencing exactly the same symptoms of the hot start that you've been having. In fact it is spooky, it's as if you've been driving my car!

I decided to start by replacing the thermostat and while I was in the area, replacing the coolant sensor.
I wasn't very optimistic that this would work in curing the hot start issues, but as others on this forum had had success doing this I thought it was a reasonable place to start. The coolant was never getting above 75 degrees and I've been stranded on a busy petrol forecourt about 3 times, which is extremely frustrating and embarrassing! Then all of a sudden it starts after about 10 minutes as if nothing was ever wrong!

I changed the thermostat and coolant sensor myself, and got plenty of cuts and bruises to show for it.

I've been testing the car since, many times driving exactly the same routes where I had previously had issues and not once has the car failed to start when warm or hot. I actually can't believe that the thermostat/coolant sensor would make such a difference, but it has. I was finding that on most short trips I would have an issue starting a warm/hot engine, and since replacing these two components the engine get up to about 85 degrees quite quickly and re-starts every single time. I've done at least 30-40 re-starts where I know it would have been a problem before.

Hope you track down and solve your issue. Your thread has been very helpful to me.

Ian

 

[tonycharente]

Hi Tony, I've been reading your thread with much interest, mainly because I have been experiencing exactly the same symptoms of the hot start that you've been having. In fact it is spooky, it's as if you've been driving my car!

I decided to start by replacing the thermostat and while I was in the area, replacing the coolant sensor.
I wasn't very optimistic that this would work in curing the hot start issues, but as others on this forum had had success doing this I thought it was a reasonable place to start. The coolant was never getting above 75 degrees and I've been stranded on a busy petrol forecourt about 3 times, which is extremely frustrating and embarrassing! Then all of a sudden it starts after about 10 minutes as if nothing was ever wrong!

I changed the thermostat and coolant sensor myself, and got plenty of cuts and bruises to show for it.

I've been testing the car since, many times driving exactly the same routes where I had previously had issues and not once has the car failed to start when warm or hot. I actually can't believe that the thermostat/coolant sensor would make such a difference, but it has. I was finding that on most short trips I would have an issue starting a warm/hot engine, and since replacing these two components the engine get up to about 85 degrees quite quickly and re-starts every single time. I've done at least 30-40 re-starts where I know it would have been a problem before.

Hope you track down and solve your issue. Your thread has been very helpful to me.

Ian

Thank you very much indeed for your input. As you will see from my next message, replacing the thermostat is next on my list. Your message has given me new hope that this just might work !!! How did you gain access to the thermostat in order to change it, please?
Thanks again,
Tony

 

[tonycharente]

TODAY'S UPDATE
As planned I replaced the Fuel Vapour Filter - hardest bit was removing and replacing the trim in the boot - the actual Filter was dead easy to remove and fit back. Although I could see no real reason why changing this Filter would have any impact on hot starting problem, I was optimistic that it might do since when I weighed the old one versus the new one, I found that the new one weighed nearly 400 gms less than the old one (1893 gms vs. 2279 gms). This morning I did my test run again and.... .... the car failed to restart whilst hot. So that's another item eliminated.

My new Crank Sensor arrived today. However I had failed to order a pair of manifold gaskets, so I have just done so. Meanwhile I intend to replace the Thermostat, which I had already bought. I had been pondering whether or not to skip doing that and jump straight to changing the Crank Sensor, but this looks to be such a pig of a job that I thought to try changing the Thermostat first. The input (see above) from Ian has served to make me want to try this even more.

For anybody stll reading - "Watch this space".
Tony

 

[Mr S]

I had a very similar issue to you, and ended up changed the coolant temp sensor, evap box, and purge valve, but also the rocker cover gaskets. Not much help as i changed all these during the lockdown, so didnt do much testing, but id put the rocker cover gaskets on your list. Never done them before, but followed a couple of the guides and did it fine with taking my time. No hot start issues now.

 

[Bails848]

Thank you very much indeed for your input. As you will see from my next message, replacing the thermostat is next on my list. Your message has given me new hope that this just might work !!! How did you gain access to the thermostat in order to change it, please?
Thanks again,
Tony

Hi Tony,

Please bear in mind that I’m very new to Maserati, only owned it 2 months, so others are far more qualified than me to offer advice and probably a better way of doing it, but happy to tell you how I did the job.

So…. front drivers wheel off, arch liner out, undertray removed. The coolant sensor was hard to get at, needed at least 4 socket extensions to get a decent swing on the ratchet, but quite straightforward to do.

To do the thermostat I took off the bottom hose completely and could just get a hex socket on two of the three thermostat housing bolts from underneath the car. The top bolt is harder to get at with less room so had to use an Allen key and very patiently work the bolt out 1/4 turn at a time. This bolt was the hardest part of the whole job for me. Under the bonnet I took the top hose off at the radiator and then removed it still attached to the thermostat housing from underneath. It’s ultra tight for wiggle room but it will come out.
it’s not a hugely complex job, just no room to work and covered in cuts and bruises all over my forearms!! Need decent hex socket and Allen key. 5mm from memory.

I honestly didn’t think this would solve a hot start problem, but it genuinely did, and I’m now much more confident going to a fuel station or making any journey requiring a hot start. It has not let me down since.

Good luck with your car, I hope you get it sorted.

Ian

 

[tonycharente]

Hi Tony,

Please bear in mind that I’m very new to Maserati, only owned it 2 months, so others are far more qualified than me to offer advice and probably a better way of doing it, but happy to tell you how I did the job.

So…. front drivers wheel off, arch liner out, undertray removed. The coolant sensor was hard to get at, needed at least 4 socket extensions to get a decent swing on the ratchet, but quite straightforward to do.

To do the thermostat I took off the bottom hose completely and could just get a hex socket on two of the three thermostat housing bolts from underneath the car. The top bolt is harder to get at with less room so had to use an Allen key and very patiently work the bolt out 1/4 turn at a time. This bolt was the hardest part of the whole job for me. Under the bonnet I took the top hose off at the radiator and then removed it still attached to the thermostat housing from underneath. It’s ultra tight for wiggle room but it will come out.
it’s not a hugely complex job, just no room to work and covered in cuts and bruises all over my forearms!! Need decent hex socket and Allen key. 5mm from memory.

I honestly didn’t think this would solve a hot start problem, but it genuinely did, and I’m now much more confident going to a fuel station or making any journey requiring a hot start. It has not let me down since.

Good luck with your car, I hope you get it sorted.

Ian

Thank you Ian, that's very helpful. It's really cold here every day at present despite being down in the Charente, so I might leave it a while. I'm used to getting cut hands and forearms though - comes with the territory once you turn 70 !!!
Tony