Erik N

Overinflate the rear tires at least 10psi past their limit for your test... make them super-hard rocks. Way less rolling resistance that way. That has worked for me 4 or 5 times on various cars and trucks back in sweet Cali.

Charley B

never heard of that one.

blown 87

That is true, and I have seen three way converters work great on HC and do nothing on Nox.

Speedtoys

Ive heard it..dunno how much it really helps..

Erik N

FWIW, My wife took in her '88 300SE into a shop that I had had luck w/ several times before for a pre-test and it totally failed. Then I told her to get the car super-hot before the re-test... still failed. Then I inflated the rears to about 55psi (up from around 34) and took it in and it passed at mid-margin levels. That was in Vacaville, CA.

Speedtoys

*nods*

I think I'll go to my friendly shop..and do maybe 3 runs:

1) As-is
2) Adding tire pressure
3) Adding a can of "pass smog" snakeoil in a can (then drive up highway a few miles and back)


..see what I get.

Bill Ball

Charley: I have the stock cats off the car. You can try them if needed. I passed last time I used them.

Hilton

Your car is running lean - hence high NOx

How old is your MAF in the 88? As MAF's age, they tend towards lean, and eventually go far enough out of whack that the O2 loop can't compensate.

I'd start by swapping MAF's with the GTS, disconnecting the battery to clear MAF calibration data from the O2 loop, and driving the car for 10 miles to re-calibrate the new MAF, and to get it nice and warm. Then have the test center do the test with the gear lever in 2nd (928's typically run rich higher up the rpm range, so forcing it to keep in a lower gear helps).

Charley B

Thanks Bill, I'm going to follow suggestions here and give it another try. If no go, I'll take you up on that.

Charley B

As far as I know the MAF has never been touched.

I had asked him to run in a lower gear but he said thay are not allowed to do that. I didn't know enough to argue with him.

jeff spahn

By cheap I think it was meant as "non-premium" with a low octance number. Higher octane fuel will burn more evenly.

I lifted this from Wikipedia. Octane rating does not relate to the energy content of the fuel (see heating value). It is only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Where the octane number is raised by blending in ethanol, energy content per volume is reduced.

Speedtoys

Ya..I miss track-mixing fuel down to about 65-70 octane for the old racecar.

Made about a 1.5-2sec lap difference...

Then they changed the fuel rules...BOOOO!

Iwanna928

Get out of Cali and move to GA so we can play. Plus you can buy a mansion and live like a King here compared to what you are use to!

Good luck with your test!

Speedtoys

Nah..wouldnt like the pay cut.



Costs more..but..pays more.