Ive got 42lb injectors in my S4 and on certain days/condtions if it doesnt catch right away it will not start...for a long time. Ive since wired in a switch to turn off my fuel pump....when it floods or i see the first sign of flooding/no start, i turn of the pump, continue to crank , i watch the fuel pressure drop on my gauge,...it clears itself and starts right away and i trun the pump back on. Switch sits down by my parking brake lever.

starting my car in the summer is sometimes like starting a IO-520 airplane engine! I still neeed to tweek my cranking fuel map. If your off just a little with 42lbs its not forgiving.

 

This happned to me last week!
I started it and it caught after a couple cranks like always but I must have turn the key back to soon because it died right after I thought it had started. After that it would crank fine, but would not catch. I tried for a while with nothing. Then I tried putting the pedal down and it started again! It ran rough for 10 seconds then started running smooth again and was fine. I have not had it happen again since.

 

Tony,

That's a great idea, even with the new battery my car sometimes doesn't want to crank at full speed when it's really cold out and I haven't driven it in a while.

Ken,
I hope you don't think this thread was intended as a knock on your chips. I thought of it as more of a PSA than any kind of negative post. I just wanted to point out what happened and why and what I did to fix it so no one else has to wonder about it.

Still a huge fan and in this cold air the setup is lots of fun. The other day I went to pick up my daughter from school and before the tires were fully warmed up I went around a turn and let out the clutch. The roads were cold too and the back end let go a little as I came around. The tires chirped a bit as they let go and I slid through the perfectly dry intersection with just a hint of a wiggle for the other drivers to see as I accelerated through and away from them. I still get that silly *** grin when I let out the clutch.

 

I'm sorry, but this statement just flies in the face of logic.

If the fueling is the same, then it shouldn't get you in trouble any faster or slower than the stock setup.

The fact is, you're adding a lot more fuel on start up. And if it doesn't start, it floods. That's the reality. I would think think that this could be fine tuned with the 24# injectors, but perhaps this is a limitation of the 85/86?

I've only had my GT with 42# injectors flood on me once that I can remember and that was due to a weak battery (well there were a couple of times when I was trying to use the PEMs and a non-Speak rebuilt LH, but that was a different issue). IIRC I zero'd out much of the cranking map and the warmup map. It's still quite rich upon startup as evidenced by the black soot on my garage wall, but rarely floods.

 

If the cranking fuel map is set correctly and all electronics are working properly, there should never be a flooding issue. I have only had a flooding issue once with 42lb injectors, and that was when my TempII sensor was faulty.

The 928 warms up very very fast for the first few seconds when it is cold out. You need to turn on the ignition, look at the coolant temp and figure out where on the cranking map you are, then start the car to make sure you are working with the correct cell.

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

 

The following, underlined, text was mistakenly left out of the original article.

"With my chips, fueling while cranking is about the same as with the stock chips. 55 psi and 24# injectors just gets you into trouble, faster if there is a problem. EG. faulty sensors or insufficient cranking amps.."

 

Yeah... I guess you're right. If there is a problem the larger injectors and higher fuel pressure could add even more fuel than a 100% bone-stock setup and cause a larger, more pronounced problem. When i read your statement I was only thinking of the cranking map in isolation. Sorry for mis-construing your statement.

 

Go back to yer llamas!!

The S3 comes stock with 24# injectors which is one reason it outclasses the S4 and GT stock, the only real change is higher fuel pressure. Here lies the problem if you have leaky or weak injectors the higher stactic pressure will push more fuel into the engine causing the flooding on short start/stops.

 

If you are going with improved chips and higher fuel pressure, I would think its reasonable to at least have the injectors tested and cleaned. A set of newer style injectors can be had at a minimal expense. Are you sure your flooding isn't being caused by a defective injector(s) ?

 

Tony,
Get the specs on your injectors for opening time at 13V and adjust that in STII.

I have 60# injectors and have no issues with flooding, even if the battery is a little weak.
Also pull a ton of fuel out of the cold area. I found its far too rich at factory levels.

 

Mine did it, and Stan just replaced most of my fuel system including the injectors a few months ago.

 

OK, if the battery is weak, that excuses it. But if it does this otherwise and the plugs risk fouling, then the fuel map for starting and idling needs a bit more more work.

 

My car has flooded on me twice. Once in stock config and once after I went to the S300, 55psi, Ford type III set up. So in my experience my car behaves the same during start up. Both times it happened when I released the key just as it started to catch but wasn't quite started.

 

In 12 years the only time the car failed to start properly was when the LH failed or the battery was dead. If you bump the fuel pressure and injector size then downward adjustment of the starting and warm-up enrichment maps to prevent overfueling should take care of this unless they are too far out of range.

 

On my 84 USA automatic I found it gets MUCH harder to start once the battery gets even slightly low....my guess is its a voltage-coil-spark issue..... I installed a new battery and it fires up right away....