VehiGAZ

Stuart - I'll be clearer and more certain in this post.

Those are the SAME SYMPTOMS I had when my LH failed two weeks ago. The injectors stayed open and flooded the intake, but I still had spark on both banks.

I think you should try to evaluate your LH next.

Manfred

I let my car sit for four days (usually a daily driver) a while back and the first time I started it I ended up flooding it. I was very nervous doing it but I held the gas pedal down and it fired up after about five seconds.

But.....I thought I remembered that you are never supposed to start the 928 with the gas pedal pressed--something about something exploding and causing dents in the hood????? Those that know what I'm talking about can fill in the blanks for me.

Dan

frustrated

John S, Remember my LH ECU with the weird spike you couldnt reproduce? Exact same symptoms until I fitted your replacement.

stuartph

Guys

Here is what I have tried today

with a fully charged battery I have cranked the car over for well over 30 seconds , nothing not even a cough

swap fuel pump relay and swap Lh realy with good other relays, try starting again nothing

looking in workshop manual it mentions removing Lh relay and bridging 2 terminals 87 and 30 and then checking volts at injector plugs, well I did this and have 11.9v on both terminals of the injector plugs?

John Speake

That's normal, one side of injectors are at 12v, the LH pulls them down to 0v to energise.

Were the plugs wet or dry after cranking ?

stuartph

The plugs smell of fuel and are sooty buy they are bone dry !!

AO

Obvious question, but needs to be asked. Do you have fuel in the tank?

stuartph

That's ok, yes I have and fuel pump is working and fuel pressure of 55psi on fuel rail gauge

AO

Do you have any starter fluid (ether) to spray into the intake? I keep a can just for these cases.

I wouldn't use much, just enough to see if it will cough and start, even briefly. If it does, that confirms it's fuel related. If it doesn't then it's spark related. We need assume you have air and compression.

John Speake

They're sooty from prebvious running periods, but it seems there's no fuel getting to them today.....

Was tach flickering when you were cranking ? Spark ?

stuartph

Maybe I'm billy silly but here is what I have found

I have kept maf and temp 2 unpluged but have had temp 2 bridged to avoid flooding, I have just pluged both back on and car will run but very very badly missing and lots of smoke, is it just able to run on the cold start fuel ?

stuartph

John

I did check for spark at the plugs and had one but when sitting in car and cranking no tach movment is seen

John Speake

Rather puzzling..... you can send me MAF and LH for testing. You will need to post them tommorrow.

jcorenman

Stuart, what does this mean? (from post# 21):

Two of the leads from each distributor cross over to fire plugs on the opposite side. Have the wires been off the engine since it last ran well? It might be worth double-checking that the plug-leads are wired correctly.

Temp-II was bridged how?? That is a dual sensor, one wire goes to the LH and the other to the EZK, both grounded to the block through the sensor shell. The best check for the temp-II sensor is to disconnect the battery, unplug the LH connector, and measure temp-II resistance at the LH cable connector (pin-13) to ground. It should read around 2400 ohms depending on temperature-- see the WSM (pg D24-14, in the S4/GT addendum for EFI). It is worth the time to methodically go through all of those various checks in the WSM, that will verify that the sensors are OK.

Also, an important test: with ignition on but without cranking the engine, listen carefully for the injectors clicking. If they start clicking with ignition on then that is a sure sign that the LH is toast. (The converse is not true: the LH can fail in other ways, so the absence of clicking-injectors does not necessarily mean the LH is good).

When cranking, the LH pulses the injectors with a fixed amount of fuel, varied with temperature. But the MAF reading is irrelevant until the engine fires. If the engine doesn't start immediately then it is quite easy to flood it, as noted.

If the sensors check OK, and the ignition wires are correct with spark at each cylinder, then it is probably time to try another LH, or try your LH in another car.

9284me

fuel filter,spark plugs,rotors and caps,and lhe LH ECU.