I don't really know why no one mentioned this but if you are having to depress the accelerator to keep the car going then it is probably the idle control valve that failed. Things seize up if they have been sitting for 10 years.

Another problem could be a major vacuum leak under the intake manifold. when you get the car going can you hear a huge sucking sound coming from under the intake manifold?

 

Sound like 02 sensor bad, or like phil928 said, vacuum lines broke, take a can of brake cleaner and spray around the vacuum lines while the engine is running, the engine will rev up if there a leak in the lines, good luck.

 

No one has mentioned a coil problem yet. There are a dozen different things to test and verify here. I hope your tech is very 928 experienced or you are going to be spending a lot of money here. There are no cheap 928s.

 

again, in reading this post, lots of owners have the same problem....cant hold idle, wants to stall, need to feather throttle to prevent stalling, runs rich soot out of exhaust, hard to start cold, but starts fine warm etc etc etc...

then the diagnosis starts, and its all over the place, maf, isv, tps, throttle cable lubrication, intake leak, vacuum leak, temp sensor, temp sensor wiring, maf, maf wiring, o2 sensor, co2 calibration on maf, lh, fuel regulators and dampers, vacuum to fuel reguators, air filter upside down, stuck isv use wd40, etc etc etc etc

as i mentioned, no one really knows, we throw parts at it, and hope it eventually fine a cure.

 

You are a brave man hahaha, this is also a great way to check the condition of your ignition wires. Although you may not get a chance to repeat the experiment if it goes kaboom!

 

or, as was suggested a few times... there is a procedure in the manual that methodically addresses all of the potential causes and if you go through it from the beginning and don't take any shortcuts you will emerge with a solution and a smooth running car.

 

Like John already said: swap LH and MAF with known good ones. Yes, the MAF can do this. Especially the fuel smell points into that direction.
Theo Jenniskens
1992 928 GTS
The Netherlands

 

valley grounds.....i hear this talked about, but no clarification on exactly how many there are. 87s4.

i have 2 eyelets from the fuel injector harness, and i grounded them on one bolt next to drivers side throttle cable pulley.

there was exactly 2.

my other bolt for that pulley bracket on passenger has no grounds....

are there more grounds i forgot to hook up on my reinstallation? i am specifically referring to "valley" grounds rear top of engine.

 

There are only a few places that are to be trusted to work on 928's.

Ask on the 928uk mailing list - part of 928.org.uk (altho the website is down currently for maintenance - Angus posted on the list that he's doing something to it).

http://lists.928.org.uk/cgi-bin/mailman/listinfo/928uk

Places which are "safe" according to members of the 928uk list (i.e. won't screw things up and charge you to figure out how to fix their mistakes) include:

No.5 Garage in Acton (your closest)
Paul Anderson in Stroud (928spares.co.uk) - most commonly recommended
Loe Bank Motors in Bury
JZ Machtech used to be commonly recommended, but I did read their 928 specialist has moved on?

Your quote for timing belt sounds a bit light - the book time is 11-12 hours of labour, which doesn't leave much room for parts in their quote. For an idea on normal price, phoning one of the above and asking would give you a fair estimate as they'll know all the parts to be replaced.

Sounds like you've already chosen your garage tho' - in which case make sure they're replacing:

Belt (with Gates or Porsche belt - not Conti)
Two plastic bushings for the tensioner arm (these are IMPORTANT and often overlooked)
Cleaning and replacing the o-ring and cap, and refilling the belt tensioner (and not losing the 1mm thick spacer at the tip of it!)
Water pump (new, (e.g. made by Laso), preferably not a rebuilt pump)
Main tensioner roller
Idler tensioner roller

There's other stuff in there which can be a good idea to sort - like oil pump seal, and front main crank seal, but unless its leaking from there, I'd leave it alone. They will comment about an "oil leak from the front" but thats usually leakage from the tensioner.

You also want them to report (preferably with pictures) on the condition of the crank, oil pump and cam gears.

As for parts, lots of the UK guys use Roger (he's ROG100 here on Rennlist).

(I'm a brit in case you're wondering why some bloke in Oz is posting this.. )

 

Go here: http://members.rennlist.com/v1uhoh/underthe.htm
Under the drop down menu "Routine Checks and Maintenance" there is a selection: Under the Hood, the various views have a legend to id various parts.