Hot starting issues - 4200

Chris155

Chris155

Member
Messages
196
After fixing the gearbox oil leak and rear arms, the car has thanked me with a new problem. :rolleyes:

I made a 10mile trip, stopped for 5min, got back in the car and it took a while to start. It wouldn't fire initially, but eventually fired on the 2nd try with some reluctance. At the same time, the hi-speed radiator fans were running despite it only showing 70 odd deg on the gauge.

I had to stop again after another 7 miles and had the same issue.

I think the high speed fans had been on the whole time as the engine did not get up to temp.

The gauge reading appears to be correct as the cabin heater wasn't blowing anything but cool air.

After arriving home I found the same problem was still present, fans on, engine temp low, reluctant to restart. One point worth noting, the fans did not turn on with the ignition, only after the engine started.

I turned the battery off and back on and it cleared the problem. It started cleanly with the fans off and ran up to temp properly.

I'd say the engine ecu is thinking the engine is either hotter or colder than it actually is.

If it was an Alfa I'd be thinking engine temp sender - they have 2 circuits, one feeding the engine ecu, the other the gauge. But if it had failed, then turning the battery off shouldn't make a difference.

I've obviously been poking around at the fuses and relays in the boot recently. I've also topped the coolant up - it was low but I don't think it has a leak, probably just blew some out of the pressure cap.

But, are there any coolant bleed valves I should check?

Anyone have any ideas?

Thanks.
 
Chris155

Chris155

Member
Messages
196
Ah right, I see where you're both going with this. Yes, it did feel like the engine had flooded when I was trying to start it.

Would this also affect fuel consumption? Id did seem to eat a lot of fuel, but I put that down to me being a hooligan.

But how does that relate to the high speed fans being on permanently? - This does appear to be linked.
 
Zep

Zep

Moderator
Messages
9,230
What sort of MPG are we talking about? Low teens would be pretty normal when pushing on.

In theory the carbon canister purging shouldn't impact the MPG much. If there are issues this normally manifests itself as sluggish starting, and no initial blip on starting. If you think the economy is poor, you would need to look at the long term fuel trims and also the lambda cycle time (you get a CEL when the lambda cycle time is over 1.5 seconds but they do run worse before this threshold is reached).

The temp sender is a single circuit one, so if the gauge is right then the sender for the ECU is too. The fans running at high speed is probably the resistor and not related - there is an Alfa alternative in the alternative parts thread. When at speed in cooler outside temps the gauge will generally read a little low, the sender is on the return to the engine at the water pump - I changed a thermostat to try to rectify this, but it didn't make a jot of difference.
 
Chris155

Chris155

Member
Messages
196
MPG - Don't know, it's the "higher spec" GranSport, which lacks a trip computer. And SatNav. A phone, decent stereo, etc. But it does have nasty, plastic climate control knobs....

Anyway... I think I did around 50-60 miles, so higher than I thought initially.

Yeah, 2 pin sensor. They were only running whilst it was having a fit. So it's not a resistor or relay control issue. And I'm 99% sure it's related to the hot start problem - disconnecting the battery solve both problems.
 
doodlebug

doodlebug

Member
Messages
917
I had exactly this problem in my 4200 Coupe except in my case it was occasionally intermittent. Initially the fault codes pinpointed a faulty engine temperature sensor which I replaced. The car seemed to be OK for a couple of weeks but the problem returned and the faulty temperature sensor was replaced again but the problem still persisted. Note that at all times the temperature gauge seemed to register the correct temperature.

Both Grimaldi and Lancaster Maserati were unable to fix the fault. Rob Grimaldi suggested it may be the ECU but I didn't want to go to the expense of changing it to find it didn't fix the problem, so I just put up with the hot-starting issue and the engine fans being on all the time.

A few months later while driving the car I noticed the temperature gauge was staying at around 40° and the heater seemed to take a long time to get up to temperature, so I suspected the radiator thermostat was fubared. I got Grimaldi's to change it while it was in for service, but the gauge still showed the same low temperature. After some investigation, Rob temporarily swapped the gauge ECU and all the gauges now worked correctly. Surprisingly, the fans also ran at normal speed and the car hot-started perfectly.

Neither fault has returned since the gauge ECU was replaced two years ago and the fuel consumption has returned to normal.
 
Gp79

Gp79

Member
Messages
1,398
I have also had the exact same symptoms with the hot start issue.

I replaced: thermostat, engine temp sensor, wash / purge valve, carbon canister.

Not happened again for over 2 years now.

Coolant bleed valves are on front cover here, same on other side: 60360
 
midlifecrisis

midlifecrisis

Member
Messages
16,189
I was going to say the MAF is goosed. If you disconnect it the car will still run but in a 'default' mode. try that if the above fails. Let us know how you get on.
 
GeoffCapes

GeoffCapes

Member
Messages
14,000
I had this on my 4200, and changed the engine temp sensor like has been mentioned above and didn't have a problem afterwards.

But as has also been mention it could be one of a number of things.
 
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