pumpedTSI

My 89 S4 was running perfectly when I parked it a week ago.....started up on the slightest turn of the starter with a strong idle. Fast forward a week.....went out to start it today and she cranked over fine but "seemed" to start on 4 cylinders and had a lumpy idle.....wouldnt rev, never came on with all 8 cylinders and died. Cranked over a few more times with same lumpy idle result. Eventually she cranked over but just wouldnt catch so I figure she may be flooded so I let her sit for a few hours. Upon my return she cranks strong but no attempt to start at all even with a shot of ether so I assume no spark/fuel. I check for fuel and pump runs with fuel at the rail. Thing is I get no pulse at the tach when turning over...I have changed the injection/ignition relays but no avail. All fuses are good. The problem seems to be spark.....with no tach pulse would this point to the CPS?
Any ideas welcome.....the car ran perfect prior to this.

Mrmerlin

how many miles and has an intake refresh ever been done?
auto or stick?
have the computers been rebuilt ?
Did you pull the vacuum line off the front damper to check for fuel?
when was the last time you cleaned the grounds or battery terminals?
Post pictures of the engine for a better diagnosis

pumpedTSI

Stan,
how many miles and has an intake refresh ever been done? 80k PO apparently did TB/WP just over 2 years ago.
auto or stick? Auto.
have the computers been rebuilt ? No idea.
Did you pull the vacuum line off the front damper to check for fuel? Yes, I have fuel.
when was the last time you cleaned the grounds or battery terminals? about 6 months ago when I got it. All fuses are good and relays switched with known good ones for testing.

Mrmerlin

OK posting a picture of the engine would be a good idea now.

a TB/WP is not an intake refresh.

Computer could be on the way out.


If you have fuel in the vacuum line, thats not good.

Then you need to figure out where its coming from.

You will have 3 choices.

The front center damper.

Remove the air cleaner lower and then check
The driver side rear damper,
or the passenger side rear fuel pressure regulator.

NOTE if fuel is coming from any of these 3 parts then it would be wise to replace all 3 of them
NOTE the front damper and RR FPR look the same and if they get swapped the engine will not get any fuel

To start a car with a flooded intake,
I would first suggest to remove the MAF and inspect the plenum for a puddle of fuel,
have a helper hold the throttle open while you use a flashlight and mirror to look.
Use a rag to soak up the fuel if any is found.

If no puddle of fuel then you should be OK to hold the pedal to the floor and crank it till it starts.
Make sure the battery is fully charged before attempting this,

dr bob

Things that cause these particular no-start symptoms:

-- Relay-relay-relay lead off the effort. These are the injection (LH), ignition (EZK), and fuel pump relays. You hit two of the three so far.

-- Have someone crank the car while you listen for the fuel pump running under the rear bumper.

-- Have someone turn the key to 'run' but not to 'crank' position while you listen with the hood up for chattering injectors. This is a common symptom of LH controller failure.

-- If you crank and there's no tach movement at all, the Crank Position Sensor may have failed. The sensor is at the top of the valley at the rear of the engine, point towards the flywheel. Black squarish cover with a cable coming out., held down by one small bolt. Cable terminates by the passenger side fuel rail under the cover. This sensor can be changed after the air filter housing is removed. It can be a chore getting the old one out. Look at the connector too, they get crumbly and fall apart. But... your statement that it sort of ran like on four cylinders would point me away from this as a probable cause. If you have a timing light, check for spark while cranking -- failed CPS means no spark at all.


My nickel is on the fuel pump relay. Cheap, easy to check, and a weak relay gives poor to no fuel flow.

pumpedTSI

Stan,
there is no fuel in the FPR vacuum line or anywhere other than where it should be. Not sure why she would need an intake refresh when she ran fine a few days ago. There is no spark but I have fuel.
She will not fire even with ether so Im pretty sure its no spark and no pulsing at tach during cranking which is pointing me towards CPS/Coil since all fuses are good and relays swapped for known good relays...........trying not to overthink this or complicate it when she was fine a few days ago. Battery is on tender and fully charged.

pumpedTSI

Bob,
she ran lumpy on 4 at the beginning but then after cranking on/off for a few minutes she just cranks.....absolutely no ignition at all even with starting fluid which should solicit at least a puff/backfire of some sort....nada so Im thinking no spark BUT have not confirmed that other than my presumption based upon the starting fluid results and the non bouncing tach needle.....am I way off?

jeff spahn

Put a tester light on your spark plugs also and be sure you still have spark. something I didn't see mentioned in the replies to you were: Coils and ingnition amps. They can die, even when new and give you 4 cylinder running and/or then no cylinder running. How do I know. Happened to me on a fall leaf drive. All new parts with less than 100 miles on them and they failed. They were generic. Replaced with Bosch parts. Several thousand trouble free miles since.

John Speake

If the fuel pump runs when cranking then that means the LH is getting an rpm pulse from the EZK ECU on pin 1 (12v square wave). But the tach should also work as it is driven from that same signal.

So something doesn't stack up . Unless the tach has suddenly gone U/S. Please confirm that the fuel pump does run when the engine is cranking, as already suggested by Dr Bob.

pumpedTSI

Thanks for the input guys.......cant really do much troubleshooting since its been pissing rain for a week or so here which is a rarity. Apparently it "may" let up by tuesday.....Ill keep yall informed...

BTW John......since she wont fire on starting fluid shouldnt that point to lack of spark irregardless of fuel pump run or not?

ammonman

If there is combined lack of spark and no fuel pump then it points more toward a bad crank position sensor as both are dependent on this signal.

Mike

worf928

How did you determine this? How do you know you have fuel flow?

I ask because it is uncommon on a 928 to have fuel flow and no spark. If your observation that you have fuel flow is in error it will lead us down the wrong track.