DR

Hi Daryl,

>Dave, thanks for the tip on how to apply continues air pressure.

No problem, glad to help.

>As well I was loosing a very little by the rings, I could hear the air through one of the vent hoses,
>and that added to the difficulty of holding pressure and knowing for sure I found everything.

One word of caution, if you have the "charcoal system vent hose" (the one that goes to the small electric valve below/under the upper rad hose connection) hooked up be sure to crimp this closed if testing without the ignition switch on. With the switch off that valve is open and therefore creating a vacuum leak. I think my system is the only one plumbing this line in like the factory so it may not apply to your system. BUT, if it is plumbed into your system it will drive you crazy during vacuum tests unless you plug or crimp it closed.. I speak from experiance (Grrrr)!


>Dave, are you aware of any one who has a TS car and has >a slight idle roughness.

Only the ones I have read about here. I had some issues when I was experimenting with not using the Idle Stabilizer at all, but it was more of a cold idle issue.

> It’s minor and very easy to live with but I want to fix it if I can.
>I have some ideas as to why but I am not sure if this is a problem on all of the TS cars. >If it is then we know for sure it’s inherent in all cars and when someone finds a fix we will all benefit.

Once I am finished with all my Kits I should have lots of data because of all the different configurations I have tried and the issues of each and will gladly share it.

>What we are doing is shorting each spark plug one at a >time and observing the change in idle.

Try just pulling each fuel injector connector plug off one at a time to see if it changes anything. I find this much easier than dealing with the spark plug wires.

I would also suggest a fuel injector probe to verify injector pulses. Here is the one I use (link below) and it is the handiest gadget I ever bought. You just touch the tip of it to the injector body and it beeps and flashes for every pulse. I was so impressed we now sell them, but they are available lots of other places too.

https://www.928gt.com/ps-26015-30-el...ick-probe.aspx

Hope some of this helps, and have a Great 928 Weekend!

Tony

For all practical purposes we have Darriens car set up and running. His exhibits a very good idle as far as RPM....better than mine!..but when it gets warm, it too has that little bit of lumpiness to it as well. Minor in the big scheme of things. Would be nice to get to the root cause.

24lbs injectors...39-35psu fuel pressure at idle

First run 0-60mph...5.1sec..with a 2.4sec 60ft time. We have atleast 2-3 tenths on the table yet . Its a sub 5sec car.
Measured with my GTECH PRO RR. As not to hijack..More in another post later

heinrich

Good job. So Tony did you know the 951 boys .... they run 51lb injectors

Tony

How do they control the low end..idle etc?

heinrich

Maybe we can learn something .... they also have ridiculously low compression. Sounds like everything we wouldn't do. Yet ....

heinrich

Checkit -- 55lb http://www.gururacing.net/Injectors.html

Jim_H

It's about a supercharged 928, notta hijack

Daryl

Tony,
Congrats on getting Darriens car up and running. If and when you can find the time would you please do the shorting of each plug test after the engine is good and warm. It’s very easy pulling each wire at the distributor. If there is an issue I think it will be on the left side number six for me and number seven for Bill. I want to at least know what’s causing this before we start with computer mapping. I would really appreciate your help in this.

Anyone else running a TS please let us know if you are experiencing this idling problem or "NOT".

Thanks,

heinrich

Course they run Motronic. I was wondering if Garrity might have a thought.

FlyingDog

Pulling the injector connetors is what the WSM recommends for finding non-firing/injecting cylinders and it hurts less than spark plug wires. If you're doing a lot of injector checking, Dave's injector probe is very handy. I saw it at SITM last year, very cool toy.

FlyingDog

I've wondered how hard it would be to convert a boosted 928 to Motronic. The programming is much better known and it handles boost. The other OEM system I've thought about is SAAB Trionic. It is fuel injection, ignition, and a boost control in one box.

heinrich

Matt, I think Sterling has some experience in this regard, but I think he may have bad news for us.

FlyingDog

I thought he used Motec M48?

heinrich

yes ... and it was no walk in the park

Bill Ball

Just for the record, I have pulled the injector wires and plug wires individually and together. When the idle is lumpy, pulling either or both on cyl 7 does not affect the idle speed. On all other cylinders there is a drop. Pulling the injector wires is hampered by heat in the area. So you need leather gloves or some kind of tong to wiggle the wire plug off the injector.

I'm sure hoping John Speake is on to something when he speculates it is the injectors being run at too low a pressure at idle to get a proper stream when warm. Cyl 7 just happens to be the one on the edge in my car and it drops out.