Tony

Just a heads up and perhaps reminder of how easy these cars can flood and then be rendered unstartable.....even if you let them sit!

I just got done smogging my car. In order to do this i decided to put the cats back on. It passed fine. I came home put the car up on stands and swapped out my cats for my X pipe again for another year. While the car was up on the stands i released the tension on my flexplate as i do every year and took the opportunity to remove a bunch of wiring i had in the passenger footwell relating to the water injection system i had.

Long story a bit shorter , I got it all done, turned the key for the first time and it wouldnt start. It had a little bit of ignition then it died. IT was dead for 3 F'N days!!
This was the first start attempt after putting the Xpipe back on.

I had it in my head that perhaps i had damaged or disrupted some wiring or component when i removed the water injection wiring. So down that path i went...checking EVERYTHING...this pin on that pin...read that voltage ...continuity here...non there etc etc. I was at wits end as my wife will attest! Everything checked out ok. I thought there was no way in he!! it could be flooded since it sat for 5-6 hrs between crankings at times...as well as over night!! I decided to check the plugs anyway tonight as it had been a year and they were a bit damp..i cleaned them off reinstalled them and still no start. Rich smell of fuel...a bit of exhaust smoke and thats it. NADA

Searched a few things on here and thought maybe the SOB is flooded and was right from the get go. Back out to the car, pull the fuel pump relay, cranked it over with my foot to the floor. I watched the fuel rail pressure drop to zero then she fired up...POP POP..she quit. Ahh...Haaaa! I continued to crank with foot to the floor on and off for a few minutes time. I replaced the fuel pump relay turned the key and as soon as the rail pressurized she fired up..belched a little smoke and settled into a smooth idle.

So.........no start..smell of gas..and what seems intermitent igntion.
remove the fuel pump relay
crank with foot to the floor...several times.
replace relay and start.

They flood very easy and will stay that way for a long time...even sitting overnight!
Simple in the end!

AO

Tony,
Glad you found your issue. I can't help feel that there was something else at work here. Just before I discovered the issue with my heads, I had a similar no-start / rough runnung issue from coolant in the combustion chamber. Perhaps you cycled the water injection or the plugs were a bit fouled to begin with? Anyway, it's a good thing you got it running again.

Tony

The water injection tank isnt even in the car anymore and its been unhooked for nearly a year. So that wasnt an issue. Ive never had any visable white smoke either so Im pretty sure my heads are holding their own...although im sure my days are numbered.
It was just really odd that this happend after swapping the Xpipe in for the cats on the first start attempt. I hadnt unhooked the battery so perhaps it had to do with the "zero" back pressure that the X pipe offered compared to the cats and that threw the mixture out long enough during startup to flood it.

My injectors dont leak as i have never had a start/flooding problem before.
Anyway, took it for a minor thrashing last night and runs like a scalded cat! Amazing...i love it. Im going to hook it up to a ST next month and perhaps swap in the 42 lb injectors. Im going to check and see how it responds with the ST and 30lbs first.

did you get the pics AO?

SQLGuy

I've got an '88 S4 and have had the same thing happen to me a few times. As you describe, it's really tough to get it started once it floods. There seems to be that first catch, when it's in this mood, and if you don't give it a bit of gas at that point, you can crank 'til the cows come home (or, more likely, 'til your battery starts complaining), without anything more than the slightest cough and a really strong gas smell.

Mine's did this this morning again. I put the battery on a charger, then came home for lunch and tried again... no luck. Then put it back on the charger and tried again after dinner. Still nothing but that first cough. After searching and reading Tony's post, I decided to try a variation: I pulled fuse 42 (fuel pump), and cranked it, foot to the floor. This quickly resulted in a second or two of running. Put the fuse back in, and it flooded again. Went through this cycle one more time, and this time gave it throttle just at that first cough after putting the fuse back in, and it picked up just fine and went into a nice idle.

I'm sure there's some better explanation than just "S4's flood easily." I'm thinking that maybe a weak battery or a questionable temp sensor is providing too much after start enrichment or too wide of cranking pulses to the injectors. Anyone had and solved this issue?

Thanks,
Paul

Mrmerlin

if you think you may have flooded the engine simply hold the pedal to floor and crank it, till it starts.

Paul you might consider checking your injectors , they may need cleaning and or replace them with the 4 hole type,
also inspect the dampers and the FPR for fuel in the vacuum lines, it is not normal for the S4 to flood,
also make sure the battery is fully charged a low battery will turn the engine over but cause a weak spark this can lead to fouled plugs,

NOTE dont try jump starting as you can damage the alternator or the engine computers

NOTE holding the pedal to the floor will not add more fuel till the computers see the engine running

Koenig-Specials 928

I learn **** everyday from this family. I didn't know that and was always told not to touch the gas pedal on an injected car.

This is a really good post, I've been there and felt the pain of thinking something more serious is wrong with the car (especially after working on it).

Thanks guys.

Mrmerlin

Mee Too!

SQLGuy

That's what I tried the first and second times. It did not help.

I've heard people say this before, but I have not heard anyone explain a mechanism by which such damage can occur. Can you explain this?

I would have thought so too, but apparently not on my car. Maybe I should check that the WOT switch is closing correctly. Thanks for the information, though. It's good to know that LH Jetronic is supposed to have a flood clear mode. I have used Megasquirt (actually Microsquirt) on a motorcycle project and knew that that code had it... I was thinking/hoping that Bosch should have added such a thing even though L/LH is a much older system. OTOH, I read through the L-Jetronic manual and didn't find a mention of it.

auzivision

Thanks for the heads up. Mine has been sitting on stands for 4 or 5 months. Went out to fire her up the other day and baarrooomng... fired right up. Hans joke that it fired quicker than my truck that I drive every day. Maybe it’s that 044 pump you are running… or is that 440?

AO

I had an '87 that would do this too. Turned out the Temp II sensor (the one on the passenger side of the water bridge under the oil filler) was not grounding properly. Once I resolved that, I didn't have any starting issues.

The Temp II sensor tells the LH to add fuel if it's cold. If the sensor is not grounded or has failed, the LH will go full rich. and it doesn't take long to flood the car. Holding the pedal down all the way and cranking is the only way to clear this (aside from letting it site for 24 to 48 hours). On my '87 it would take as much as 30 seconds to a full minute to clear and start. Also remember, Once this happens, the plugs are likely to be fouled... so the more it happens, the harder it will be to start.

Use the link in my signature to follow the LH/EZK diagnostics. In there you will find out how to diagnose the Temp II sensor. Remember when checking resistance, you check from the lead to ground... NOT between the leads.

dprantl

A 100% foolproof method that only takes 30 seconds to do when a 928 is flooded is to remove the fuel pump fuse and start the car. If it really was flooded, it will start, run for a couple of seconds, then die. Reinsert fuel pump fuse, start again and you're done. If you are really fast, you can reinsert the fuse while the car is still running

Dan
'91 928GT S/C 475hp/460lb.ft

AO

But if the Temp II is bad, it will just re-flood (unless you hold your foot down.)

dprantl

Yup. That's exactly what happened to my car a couple of years ago. New TempII sensor fixed it right up. With larger than stock injectors, the flooding is seriously magnified too.

Dan
'91 928GT S/C 475hp/460lb.ft

SQLGuy

Thanks. I checked that sensor, and it's .1 Ohm from its base to chassis. 3K Ohm from one sensor terminal to chassis, and 2.8K Ohm for the other terminal to chassis. Doesn't sound like this is the culprit, in this case.

By the way - I couldn't find a 928-specific manual or article, but I did find this on a Saab tech site discussing LH Jetronic: "If the accelerator is floored when the engine is started at temperatures below -4F (-20C), the ECU issues an order to reduce the amount of fuel injected into the engine. This prevents the engine from becoming flooded. In the LH 2.4, 2.4.1, and 2.4.2 only, repeated attempts to start the engine will cause the enrichment cycle to not be activated. This prevents exceptionally generous enrichment and a consequently flooded engine."

Anyone know what version of LH an '88 would be running? It was not below freezing when I was trying to start my car.

dprantl

There are two versions of LH in 928's. '84 - '86.5 is LH 2.2 (in '84 EuroS only), and '87 - '95 is LH 2.3.

Dan
'91 928GT S/C 475hp/460lb.ft