Over boost?

[Rikki Kitto]

Over boost is violent and throws you forward in the seatbelt; if it's a bit softer then its could be a spark issue.

Twice it scared the sh** out of me when it first decided to let me know it wasn't happy

[Rusty]

Over and above the boost leak idea:-

• Spark plug loose
• Oil in the spark plug recesses
• Degraded coil boots
• Degraded coil wiring inside the cover (I had this and had to resolve it).
• Power Output Stage (POS) on the blink
• MAF connector

Where are you in the country?

[jamie9048]

I belived it also was a ignition problem thats why I changed the pos amplifiers 3 years back this year I replaced the whole lot for five new pencil coils from a 1.8t and some leads from error404

what temp should the car run at mine goes upto and over 100 and stays there

[rynaqui]

I belived it also was a ignition problem thats why I changed the pos amplifiers 3 years back this year I replaced the whole lot for five new pencil coils from a 1.8t and some leads from error404

what temp should the car run at mine goes upto and over 100 and stays there

At that temperature at a constant I'd say the coils are overheating especially if they are not stock. Are you still running the cover over the coils? Does it start acting up as soon as you drive off or only when up to temperature?

[jamie9048]

yes but its the same as before with the old system and new 1.8t`s

what temp should the car be running?

[rynaqui]

You should remove the cover as the 1.8t or 2.0tfsi coils aren't made to run at such high temperatures and with the cover on this causes them to overheat.

Mine sits at 90 and goes slightly up with a bit of spirited driving, does your fan kick in at slightly above 90 degrees as it should? You should check a couple of things in the cooling system to avoid having headgasket issues as well just as a precaution. It could be a clogged radiator, pipe, may need a coolant top up (or change if it's not pink as it should be) or thermostat, MFTS.

If you could give us at least an indication of whether the radiator is properly bled, coolant is still good and pinkish in colour (not brown sludge!) and that the fan is kicking in when it's supposed to, we could eliminate a few potential causes of the engine overheating as well besides the boost or spark issue

[UrS4boy]

I belived it also was a ignition problem thats why I changed the pos amplifiers 3 years back this year I replaced the whole lot for five new pencil coils from a 1.8t and some leads from error404. what temp should the car run at mine goes upto and over 100 and stays there

You should remove the cover as the 1.8t or 2.0tfsi coils aren't made to run at such high temperatures and with the cover on this causes them to overheat.

I agree 1001% with ryanaqui. IF you've been running with the 20V Turbo plate over the 1.8T coil packs, you have been killing them and the missing/hesitation at WOT you are experiencing is the weakest one failing to produce the required spark at higher boost levels.

Temp should be around 89C.

Thermostat and temp info: http://forums.quattroworld.com/s4s6/msgs/21881.phtml

[jamie9048]

I replaced the water pump thermostat and timing belt and a new rad cap the coolant was replaced at the same time

the fault with boost has remained constant although Ive changed

coils and leads upgrade
plugs
coolant
w pump
thermostat...

I am happy to say I dont belive the fault is with the coils or plugs but I do belive my car is running hot
not sure if this will have a effect on the boost problem?
the aux rad was blanked off but Ive had it recored last week and will fit this weekend

[Rusty]

There's a sticky I did with pictures of where all the needles should sit

http://www.s2forum.com/forum/showthread.php?t=33953

[Monkeymagic]

Just pull the fault code then you will know if its ignition or boost cut.
Id suggest boost leak. Its sounds like its running hot to me mine sits about 80 to 90 even in summer. Its a 3b though.

[macspring]

My loss of boost was caused by a loose vacuum pipe in front of the drivers footweel going to the ECU.

Gernerally all of these faults turn out to be someting logical, so make a full list of all the things that people have said you should check, check out Dave's list of 'Things that will strand you at the side of the road' thread, and anything else you can find on here, check each one of them methodically and tick them off the list as you go through the list, and you're bound to trace it. A multimeter may help as there are voltages and resistances that you can check to ascertain if the sensors are working etc., to avoid the expense of replacing them on the off chance they might be faulty. Although a spare one of a few of them is no harm with these cars.

Assuming all sensors are fine, I'd say spray bit of electrial connector cleaner on all of the sensors connection points, especially the MAF and the TPS, not forgetting all of the electrical connections on the bulkhead, the four POS ones, the five small ones on the black metal bracket, and the two two big multi pin connectors on the RHS of the bulkhead, after that, I'd say it's a boost leak.

Use a boost leak kit, and also check / replace the small vacuum hoses, they don't cost much and get some new appropriately small sized jubliee clips to ensure they are properly tight. Old hose may look ok, but new ones will be for sure.

HTH.

Best wishes.

Post it up when you do find it.

[jamie9048]

first light in tree years


on its move for the door



new boots and brakes



paint time





back home



well im sad to say its owff with its head pulled the car out for a wash this morning and left her running, 10 min later the cooling system was running mad hot

i think this may be my running faults ive already changed the coolant thermostat water pump and belt

ive replaced the expansion bottle top...

ive tried every thing the last thing has to be the head gasket going to do a sniff test tomorrow night after work then start stripping her down

the engine was rebuilt by the last owner so maybe the head was not bolted down correctly or the head was not perfect/

[Ross]

Sniff test is worth while, but if it doesn't confirm a head gasket then check the flow through the radiator first. I recently replaced my radiator chasing an overheating problem, it was all scaled up inside after being left empty for some time and flowing about 1l per minute, causing 100+ running temps.

[Rikki Kitto]

I had a nightmaare with overheating, fan not kicking in, coolant system over pressurising and chucking it all out through the header tank turned out to be the MFTS on the water manifold changed it twice before sorting it now all is fine. Much cheaper than taking the head off so hopefully it might be the same

[Rikki Kitto]

PS I bought a brand new header tank and cap because I thought that might be the issue before we thought about the MFTS