87fbird

but the only problem i had was that my NOx was a little high on the 25mph test, the max allowable was 706 and I measured 755, what should i check out to fix it, I think it might be my timing because its set at 6 degrees BTDC

paulo57509

Please post all the other measurements and max allowable for both 15MPH and 25MPH.

87fbird

first off id like to include that my gas cap was bad, now here are the results

15mph test at 1580 rpm:

CO2 meas. 13.50
O2 meas. 1.74
HC Max-108 Meas.-48
CO% Max-.71 meas.-.13
NO(PPM) Max-767 meas.-755

25mph te st at 1508 rpm:

Co2 meas. 13.43
O2 meas. 1.93
Hc Max-83 meas.-28
CO Max-.58 meas.-0.10
NO(PPM) Max 706 meas.-775

87fbird

any help would be great...

Rayvan

EGR valve is not working as well as it should. Replace it, and clean out all the EGR passages.

paulo57509

Forgot to ask....what kind of engine is in your car? Carb? TBI? TPI?

87fbird

its a tpi

87fbird

also my car was staling on the dyno a lot, but i think it because ive been havin this issue with my car stalling when you first start it up and put it in reverse or drive, so you have to keep the rpms up to get going, then after you have been driving it awhile its fine and doesnt stall, but this doesnt happen when its cold so i have no idea whats causing this I think its either a vacuum leak,the IAC valve isnt working or something with the transmission

paulo57509

From your test numbers, I'm going to say it's either mixture (lean) or your EGR system.

You can't tell from the test numbers if you're running lean because the AIR pump is pumping air into the catalytic converter so there will be a reading of excess of O2. If you have access to a scan tool you can check the mixture my monitoring the Integrator values. There is a way to monitor the O2 sensor without a scan tool, but I don't have the procedure handy.

For checking the EGR valve, you cannot just hook up vacuum to it while the engine is running to see if it stalls. The EGR vlave is a negative back pressure type valve. It should hold vacuum when the engine isn't running, but as soon as it sees exhaust pressure it will close. However, doing this test will tell you if the EGR passages in the lower manifold are clear.

There is a flow chart in the FSM that describes how to check the EGR system (it's not the same chart for a Code 32). If you don't have a FSM, I will try to scan and post the flow chart.

In the mean time, check for any vacuum leaks. vacuum leaks can cause the mixture to run lean.

87fbird

i think i actually have my timing set wrong i think its actually set a 6 degrees after top dead center because its set at the first notch on the left of the 0

paulo57509

Timing marks to the left (anti-clockwise) of the "zero" mark is before TDC.

87fbird

alright thanks for clearing that up for me, i did the timing myself and i wasnt entirel sure i had it right

Guest

They should have noticed if they actually checked it right, but did you disconnect the EST when you set the timing? If not its about 15 or so degrees off and may explain the stalling if nothing else.

87fbird

yes i did disconnect the EST but they werent able to check the timing because the car was stalling, that was another reason why I failed

paulo57509

Attached are the pages from the FSM describing how to check the EGR system when no Code 32 is set. Sorry about the scan quality. It's the best I can do considering the thickness of the book and the flatbed scanner.

Good luck.