Engine won't start when hot

[Allybingo]

Hi all

This is my first thread hope it all makes sense!

I own a 3b and have recently replaced the old cylinder head with a reconditioned one. The car seemed to be fine apart from a few tuning issues such as the engine shaking or missing occasionaly and exceleration not clean (holding back) this of course with only gentle exceleration (new cylinder head) So after three hundred miles i stript it down again and gave cylinder head bolts a nip, then put it all together again and it started first time.
I ran it for 5 mins at it seemed to run cleanly but when i turned it off it would'nt start again until the engine had completly cooled down. Ive checked all the sensors i can but all seem ok, the engine is still running fine but will only start from cold.
Can anyone help?
Thanks Alan

[Doug_RS2]

Is the distributor aligned correctly?

[Allybingo]

This could be it as i marked it up when changing the head. I had it runnining as advanced, but then brought it back a bit to its original posistion and now i'm having the problem, i thought it wouldnt even start if that was out?

[Doug_RS2]

I think you can really damage it if it is out. I would align it to factory settings to be sure. There are 2 marks on the dizzy that need to align - it is awkward to see but has to be spot on. I can't think what else would casue a 3B not ot start when warm - an ABY has the cam position sensor which is notrious for not working when warm (due to old age). Can't help naymore than that on the 3B

[Allybingo]

Thanks Doug

I'l look into it!

[WabTheKing]

check your HT leads for cracks on the storks going into the engine, i had the exact same problem on a 7A engine, it would run as sweet as a nut when cold, but when it warmed up the rubber expanded exposing the core of the ht lead which caused it to arc out and run like a bag of **** and would not start for love nore money, i am near stockport if you want to try my HT's (i have a 3B too)

[S2central.net]

Dizzy timing has to be spot on... That's where the hall sender lives and without an accurate signal from that the ECU doesn't know where cylinder #1 is... Do NOT try and fool the ECU by thinking you are advancing time with peculiar positioning of the dissy. ALL of the timing, fuel and turbo calculations are done in software on the ECU. There are no mechanically adjustable 'tuning' locations on the S2 engine.

Paul

[Allybingo]

check your HT leads for cracks on the storks going into the engine, i had the exact same problem on a 7A engine, it would run as sweet as a nut when cold, but when it warmed up the rubber expanded exposing the core of the ht lead which caused it to arc out and run like a bag of **** and would not start for love nore money, i am near stockport if you want to try my HT's (i have a 3B too)

Nice one

I'm sure i saw a crack on one but thought nothing of it i'l check it out and get back in touch!

Thanks

[Allybingo]

Dizzy timing has to be spot on... That's where the hall sender lives and without an accurate signal from that the ECU doesn't know where cylinder #1 is... Do NOT try and fool the ECU by thinking you are advancing time with peculiar positioning of the dissy. ALL of the timing, fuel and turbo calculations are done in software on the ECU. There are no mechanically adjustable 'tuning' locations on the S2 engine.

Paul

i marked it all up when replacing the head but if it is out its only out by a mm either way, could this still be the problem? The car has run ok with the dizzy set like this! I'm hoping it could be the split in ht lead 3 but when i looked at it it didnt look like anything that would affect running but hey i'm learning all kinds of new things!!

[audiman]

HT leads will make it worse when cold. I suspect it a temp sender of some sort. How did you check them? Which ones did you check. The dist. MUST be aligned correctly. That is the most basic setting for the enignes ECU.

Any fault codes?

[Allybingo]

HT leads will make it worse when cold. I suspect it a temp sender of some sort. How did you check them? Which ones did you check. The dist. MUST be aligned correctly. That is the most basic setting for the enignes ECU.

Any fault codes?

Should have some fault codes tomorrow which should shed some light on it!
However i'l check the ht lead going into 3 and also the dist alignment. if not one of these a temp sensor it must be. ive only been able to look for visible damage so far and all looks well!

[S2 Ant]

Just one lead being damaged would make it unhappy but it would still run as it has 4 others to keep it chugging.

[Doug_RS2]

You say you marked the dizzy? There are already 2 marks on it - use these marks instead off your marks - the dizzy could be mounted in any position to the head - it is the relationship of th euoter casing to the inner part that is important/critical.

[audiman]

Visual checks

They dont help on electrical sensors. They need checking properly with a multimeter. It may be telling the ECU that the coolant temp is 140 degs when really its only 20 degs. Also most of the time sensor failures in that way wont show as fault codes. Put the crank on TDC via the small hole in the block. Then check that the two marks are aligned.

[Floddy]

My guess would be that the hall effect sensor is in a bad shape. Starts fine when cold, runs fine, but doesn't start when the engine is warm.

One other thing, a bad ignitor module could give you the same problem. Had an old BMW that wouldn't start when warm, and a friend had the same fault on his 80Q.