4200 hot starting issue - please help.

[BP72]

Hi

I purchased a 53 plate 4200 Coupe CC a few months ago and I absolutely love it!

Unfortunately, out of the blue, it has developed a hot starting issue. I wondered if anyone had encountered a similar problem?

Symptoms are:-

Laboured starting unless attempting to start from cold. At first I thought it was the immobiliser but the car does eventually start. You have to give the car a dose of throttle just as she seems close to 'catching'.

The car is 'hunting' at idle. Performance does not appear to be impaired 'on the move'.

There is a smell of petrol outside the car upon starting.

I should say the car was serviced only a few months / 1000 miles ago and this included a change of the spark plugs. I have been doing quite a bit of commuting in the car and wondered if she just needed a good blow out. Neither that, nor a change onto V-Max fuel has improved the problem.

Other than this she has been utterly reliable. Any advice would be appreciated.

Cheers



Bryan

 

[2b1ask1]

Hi Bryan,

Some of the more hands on guys will be along to advise later but some have a sore heads this morning too.... Patience and great advise will flow!

My 2p worth says it is temperature sensor related as it sounds like the motor is interpreting itself as cold and giving a richer mixture as if a cold start, effectively flooding it hence the fuel smell.

 

[conaero]

Yes my thoughts too. The car is overfuelling probably due to the sensor not telling the ECU that its hot. Then what happens is basically your flooding the engine.

The other thing you want to check is the TDC crank sensor, notorious for hot starting issues. It's cheap enough to just change, bit fiddly to do mind.

Have a look at the air flow meter too if none of the above remidy it.

 

[Ambient69]

If non of the above sensors. On another car I had the same issues which turned out to be failed ignition coil packs.

 

[BP72]

Thanks guys - that's great! I might just pop it to our local garage then - the specialist is some way away.

 

[SimonM]

had a similar issue - was an air flow sensor with inexpensive fix so that might be a good place to start- as you likely know you might end up paying for a "non specialist" half the hourly rate for twice as much time to figure it out

 

[ecarca]

I have the same kind of problem BP72 was talking about. My MAF is unplugged so it is not the issue since the car does not run good with the MAF plugged (have a thread about that).

Could it be coil packs? I think some of the coils were changed already (I found 2 in the trunk when I purchased the car)...

Not sure where it comes from but all of this could take me back to my misfires/MAF issue...

 

[CraigWaterman11]

I am interested in this as well because from time to time the forum members car in New Hampshire I am working on has a problem with hot starts.

If it was a coil issue wouldn't there be a CEL for mis-fires?

I fully follow the rationale for the crank position sensor, I think it's also called the Engine RPM sensor for the Mas. I've had this problem on a few cars, Mercedes etc. did the same thing, car would turn over but not start. It also wouldn't store an CEL.

Ambient Temperature sensor I understand it's under the driver's side mirror in the U.S., passenger side in the UK? But this is for the A/C system correct? The "E" shows up in the display when it malfunctions? I was pretty sure the MAF meter gave the values to the ECU relative to aspirated air correct? I could be wrong. It could communicate that information in a way the ECU chooses other functions as well? The gentleman's coupe I am working on does have a problem with that sensor at times.

I checked the fuel pump relays, and also it's not the immobilizer for sure. I don't think the cam position sensors would cause it not to start though it would cause it to run terrible.

 

[CatmanV2]

100% sure the outside temp sensor has nothing to do with what the ECU does. There have been plenty of failures of the sensor, and no one had a car that wouldn't start.

Are you sure your 'E' indication is the sensor? There are a whole suite of errors that can be it:

https://www.flickr.com/photos/catmanv2/11771176395/in/set-72157632035786271
and
https://www.flickr.com/photos/catmanv2/11771427093/in/set-72157632035786271/
C

 

[CraigWaterman11]

Chris, I agree with you that's why I was looking for clarification because the outside ambient temperature sensor was mentioned. I was confused. I mean in some turbo cars it does use this but.....I didn't think it did for the 4200. Honestly I don't know. I've never heard it causing a hot start issue. But again, that's why I asked.

 

[CatmanV2]

Personally I'm convinced it's three faults, but I've been wrong before

C

 

[2b1ask1]

Mine has done this to me twice; both times I had only switched it off for a few seconds and realised I needed to restart. It simply spin a over for about 20 seconds and eventually creeps into life it won't pick up or Rev till it figures itself out a few seconds later.... Weird it is I just think it has not shut down. Both times it has been a hot engine and sub-zero outside.

 

[gingeh721]

Well mine does this every now and again, mainly when I've driven a short distance which hasn't allowed the engine get up to full working temperature.

I've changed the Maf centre for a genuine Bosch one and I've also changed the outer temp sensor as it was intermittent. The problem still occurs. I have a new coolant temp sensor and a TDC sensor ready to change when I can be arsed. I plan on getting some new fuel relays too which take a min to change.

Out of all the threads I've read, one of these has solved it for someone.

 

[ecarca]

If it was a coil issue wouldn't there be a CEL for mis-fires?

In my case no because I run with the MAF unplugged. The misfires CEL won't trigger if you have a MAF related CEL before. I assume I have the problem of misfires though
This said, I am not sure if a faulty coil problem would cause an issue in the higher RPM range or not. If yes, then mine is not a coil problem. I checked the replaced coils are on Cylinders 5 and 8, I happened to have most of the misfires on bank 1, I might try to change the 4 coils there but I am not sure if it would help. I measured the resistance of the coils that were replaced (still have them). Maybe one of these days I will compare it with the coils on the car...

 

[ecarca]

Mine has done this to me twice; both times I had only switched it off for a few seconds and realised I needed to restart. It simply spin a over for about 20 seconds and eventually creeps into life it won't pick up or Rev till it figures itself out a few seconds later.... Weird it is I just think it has not shut down. Both times it has been a hot engine and sub-zero outside.

Yes, exactly my symptoms. On these 2/3 days it happened, the outside temperature was in the 1 to 3°C range.

I noticed the ride is not very smooth in the first 30 meters drive in these temperatures as well. I so far attributed this to the cold transmission, not sure if I am right or wrong.