faulty fuel pressure regulator

[Randell]

just posting this to assist anyone making a search in future...

for the past few weeks i had some problems with my car, not bad enough for me to take it into the shop, but it was annoying.. anyway it got worse

started with a rough, thumping, slightly hunting idle for the first 10 seconds when starting the engine cold.. would smooth out and be normal after that.

when i put it into gear (between P and D or R) the revs would sometimes drop to about 400, feeling like a near stall, and then pick up again. sometimes they'd spike when i put it back into P

hesitation off standstill (this was the really annoying part)

sometimes there was smoke under heavy acceleration

on the advice of a colleague i swapped the e.a.t. chip with the stock one, but the idle became rough as guts and it ran super rich at idle, which continued with the e.a.t. chip back in... ran it for a while and it was fine, but the next day the idle was hunting from 300 near stall to 1500. barely enough power to rev the engine. i checked the ICV (which was fine) i then started searching for vacuum leaks but a few starts later it wouldn't start at all

anyway, it turned out to be a failed fuel pressure regulator.. hope this info comes in handy for someone in the future!

[Michael999]

This sounds like what might be the beginings in my car.
I get the same hunting idle on startup, only about 5 seconds though.
And ive had a similar drop of power when put into gear about twice in the last week.
Some startups run very rich.

How much did the part cost, and where was it from?

[rob101]

I wouldn't have picked that at all, say was the smoke on acceleration black?

[gmannino]

I have that hunting idle problem also. But my car has a hard time starting up for the first time. After warm, it fires right up. Installed a fuel check valve but it still exist.

[Randell]

I wouldn't have picked that at all, say was the smoke on acceleration black?

pretty sure it was, i couldn't really see it unless someone's headlights were right behind me, but once i floored it in a tricky merge, looked back and saw an epic black cloud. other times i'd get a friend to follow me and i'd give it some stick and they'd see nothing, so it was weird.

the part was AU$165 second hand, the dealer would want an arm and a leg as usual, but i've seen them online for around US$80. it's a part that rarely fails.

i also sometimes get a hard start when warm, but it happens less than once a week or so i'm not sure if that has been fixed now.

[rob101]

i also sometimes get a hard start when warm, but it happens less than once a week or so i'm not sure if that has been fixed now.
Yeah thats classic fuel pressure regulator failure symptom, so it should have been fixed otherwise if it keeps going i'd be looking for a failed coolant temp sensor or a leaky injector. I am pretty sure hot start problems are caused by the car starting too rich. if your coolant temp sensor is gone then it may run more cold start enrichment (because it thinks the engine is colder than it is). I believe there are 2 sensors one for the gauge and the other for the ECU, but thats just what i gleaned from researching L-jetronic alot (for mine e28 has erotic idol, i mean erratic idle).