jorj7

I have not been able to pass my car with the high flow cats, even when new. I had to install
known good stock cats to pass. Of course I made sure everything else was good first...
For my car that meant it passed the HC & CO with my broken up stock cat or the high flow
cats. With the good stock cats, it passed the NO also. Your car looks like it's a little further
away.

Hilton

Are the ECU chips correct '88 ones?

IIRC, the Autothority chips make the cars run way rich, and given the PO fitted an RMB, I wouldn't be surprised if he/she also fitted the Autothority chips too.

I'd open up the ECU's and look at the chips - if they're original Bosch ones there's a sticker on top of them with the Bosch part number.

If they're not original, you can burn some replacement chips using binaries from this site:

http://www.928s4.com/lh/lh_homepage.htm

(you can use '89 MY chips as direct replacements for '88 - I'd avoid using '87 as they don't support talking to the diagnostic tools).

Speedtoys

I will giggle if this is what it is..but like you said, who knows, given whats been welded on, beat out, and so on...so far.


And according to this post:
https://rennlist.com/forums/7670184-post2.html

The AutoAuth chips also increase idle to 775...and *gasp*..guess what my idle is??

Ya..higher than high 6s, mid-high 7s.

Hilton

Tiny intake leaks due to hardened gaskets, failed o-rings (e.g. flappy bearings, throttle bearings), or vacuum line issues may also cause the high idle - but I'd still open up the ECU's for a peek anyway. May as well work on exorcising all the PO demons

safulop

Dr. Bob told me that the Autothority chips don't really do anything below 3500 rpm, and given the smog check speeds, they should not be an issue. They basically force the system into open-loop under high throttle/rpm, I was told, which increases fuel flow and power under hard acceleration. My new 88 almost flunked smog too, due to high HC, so I'll be getting after that in the future, but other numbers were satisfactory and I have the Autothority chips. I have no symptoms to go by though, my car seems to run perfectly. Please update us when you make any progress.

-Sean

Speedtoys

Ya..will be a while.

Off to the 25hrs of NASA endurance race tomorrow.

Emickelsen

BUMP

Mine failed today to, but after some research i'm 92.8% sure its the O2 sensor. Two questions i couldnt find an answer to.

1. Obviously O2 sensors just go bad sometimes. How long should they last normally?

2. Is ther some way to test NO at home prior to paying a smog station way to much for so little work?

Thanks.

IcemanG17

couple thoughts....if you have vac leaks your idle will be high....what are the RPM in drive with the vehicle not moving? It should be 675rpm or so

Typically when I see #'s that are failing both HC & NOX that means dead or dying cats....find a known good stock cat and install that....typically that fixes it.....

For example Sharky would almost fail with high HC when it was tested with nearly cold cats....heat in the cats is your friend....so an italian tune up before smog testing is mandatory.....hopefully right before its pulled in for testing.....

Speedtoys

Hy HC and CO numbers are bad...with the new cats, my NOX numbers fell _well_ into passing range from clear fail at high speed..and barely pass at low speed.

Speedtoys

Update on this.

Just passed on the x pipe and highflowcats that came with it from rob Edwards 25 months ago, and we're used when I got them.




EIS intake passed for OEM without a blink. Air pump belt off. Sharktuned. $60 set of eBay 19lb injectors bought in 8/2010.

NOW it's time for Devek headers, 24lb injectors, more tuning...

karl ruiter

So, what do you think did the trick? Sharktuning?

Speedtoys

Well. It passed barely after the top end refresh was done. This was after 2 years of abuse, with the only material change in operation being the ST work.