Could anyone offer possible solutions/problem to some hot restart issues. Car runs fine up from cold but when hot can then not restart well, will not idle then stall when pulling away. Will restart and keep going with a few revs on but can soon drop out again. Seems down on power during this all going on. Once cooled off all normal again. Had time on a diagnostic at specialist but shows no fault codes so have little idea where any fault may be. Oddly at times temp gauge may show full hot even after been stood for a bit. Sensor issue or something sticking? Anyone had a similar issue and found a cure? Any guidance would be appreciated. Cheers

Hi kev. 
what car and engine is it?

I had an issue similar and it turned out to be the cam timing sensor on the pulley on an e36 petrol engine.

car wouldn’t see the sensor and wouldn’t start when it was hot, also lots of misfiring.

also, I cracked my thermostat housing which caused overheating and non starts and stalling. 
 

I fixed it by getting a new car😞

Hi Stu thanks for the reply.  It's the 6-cylinder 2.2 litre version. I had a 4-cylinder 1.9 twin cam Z3 a while back which had the same cam sensor issue with the mis fire.  Does not seem the same on this car with no mis fire on the 6-cylinder and just had a new water pump and rad so no overheating. Maybe worth fitting a new cam sensor if the 6-cylinder has one. Regards 

Hi Kev

I agree with Stu, my Z3 (2.0 litre 6 cylinder) did the same when the Cam Sensor went faulty.
You could change it to see if it makes a difference but I believe you will have two of them fitted, one for the inlet and one for the exhaust camshafts.
Other considerations could be the Vanos units playing up, seals gone and poor oil quality?
Check also if the fuel filter has been changed as if not then this can affect running as could the ignition coil so worth checking the plugs for condition and gaps

If the water pump has been replaced then there may some air trapped in the system, from memory there are some sneakily hidden bleed screws in the cooling system so worth measuring for cool/hot spots in the cooling system with an infrared temperature gun and bleeding the system if necessary

Here is my two pence worth 🤣

The sensors are easy enough to check with a multi meter and as they are not throwing codes the issue may be elsewhere. Check the thermostat and temperature switch as your temp gauge is measuring sometimes over hot it could be fuel evaporation. A check with an infra-red thermometer should tell you what is going on when up to temp and the issue is there. If it is above 90 c that could well be your issue. 

There is a temperature switch at the bottom of the Rad plus the thermostat in the housing. On my E53 4.6is I fitted a lower value thermostat 80 c to keep things cool.

Have you also checked if the Pusher electric fan is operating, on start up the fan should self-test by spinning up.

Dave

 

Thanks Trevor, Dave the advice is appreciated. The issue was around before the water pump and rad swap and had a new fuel filter fitted a while back thinking that might be part of the problem.  Others are mentioning the crankshaft position sensor, idle control valve or split somewhere in intake as possible sources.  Will check cam sensors are a start point. Cheers Kev.

You guys ever figure this out? 

yes - changed out both cam sensors - exhaust side one had engine oil inside- and all been well since

13 hours ago, KevWils said:

yes - changed out both cam sensors - exhaust side one had engine oil inside- and all been well since

Glad that sorted the issue....cheap fix and worth carrying a spare as I seem to recall they are the same both sides?