Tim Murphy

You should be

It's part of the Murf928 Stage 3 developement/ kit. It allows you to run 42 lb/hr injectors with stock fuel pressure and support 700 crank HP. Requires the ST to make it happen or chips in the case of the Murf928 Stage 3. The beauty of it is that it allows me to use the stock MAF. When you upgrade to Stage 3 you'll get one

Kevin Michael

But you never gave me a price on the upgrade..... Let me know (I'll be sitting down before I read your reply!) My state of tune is not optimum and maybe this will help.
Kevin

AO

$1,000,000

928SS

I noted the same thing. at 6k rpms they were off about 300 rpm... figured it didn't matter, as long as the timing and fuel maps were ok.

Tony

Thanks Rob. I think it just has to do with the signal and the way it is sent to the cluster then used by the gauge itself. My LM3 is tapped right into the EZK pin. I used a inductive clamp today also as a test on the LM3 and the gauge was still appx 200-300 off in the cluster ....again at the higher RPMS. I tend to believe the ST and my LM3.

928SS

I agree, and then I kinda wondered if I was shifting at the right spot if we just use the onboard tach and don't have some kind of correction mark to use as a guide. could be insignificant for me though, given my lack of driving technique

I also noticed a couple of inboard cyls that seemed to consistantly detonate/knock well before the others.. also the same cyls that have the common bearing failure, interestingly. the ST sure does provide some interesting insights.

John Speake

Hi Rob
I have found that different cars knock first on different cylinders to each other. There doesn't seem to be any regular pattern to it.....

heinrich

Why would that be, and is it similar on other 928's or just yours?

928SS

iirc, when doc brown pulls apart 928's for OH, the bearings and fire rings on the head gaskets consistantly get beat more in the inboard cyls. my guess is that they just run a bit hotter than the outside stuff, or the intakes feed them a bit differently. the oiling issue plays a role sometimes too, undoubtedly. I think this was covered in another thread or two around here years ago.

last time around I used a set of balanced injectors, still got 2 inboard cyls that consistantly were the "leader" of knocks when messing w/the timing. when I had the unbalanced set there were 3 cyls that were always the 1st to start knocking, 2 were the same 2nd time around. I'm sure a used unbalanced set w/30k + miles or goofy plug wires, plugs, etc could all lead to other results though.

prolly not a big deal, unless it's got sequential injectors w/individual egts to tune each cyl, most motors end up being that way to some extent. it's just that the ST is so accurate it's easy to see even small anomolies. kinda cool that way, but it does influence how one tunes somewhat. I used the "early cyls" as my tuning guide, although they seemed to knock several degrees before the others did, just to be conservative.

John Speake

Ineresting observations Rob. I can't remember which cyls were first in the queue to knock when I was SharkTuning.

I agreee about tuning the leading cylinders advance down until you get (say) less than 5 knocks recorded on a typical WOT 3rd gear run.

AO

I remember going out with Murph on one of his STer runs and #6 was knocking... not sure if it's related or not.

89 928 turbo

Greetings,

I have a question to pose to the group to see if anyone has come across this situation....

We have a RMT on a 1988 S4 running at 5lbs boost....it has had a previous hot start issue and Chuck has been methodically changing out parts....including the idle stabilizer and the throttle position switch.

He cold starts and the car runs fine....stops and upon restart, cannot get it to behave....after about 2-3 minutes of pedal fluttering, it sorts itself out and off he goes.

We had Thurston install a WBO2 sensor for sharktuning at the dyno session on Saturday.....one of the issues that the ST indicated was the TPS on the monitoring page....at idle it indicated "WOT", while cruising down the highway, it remained in "WOT" and upon acceleration the indicator moved to "Cruise" on the map.....we are going to pull it apart and do the usual checks, but I wanted to see if there was any other experience out there.....it seems like two wires are crossed, but can't imagine how....what are the typical failure modes for the TPS?....

comments?

heinrich

temp II?

Kevin Michael

Using an earlier model TPS maybe? I think I remember a thread on the pre 87 TPS was wired in reverse and could cause similar issues, or something like that.

89 928 turbo

replaced...