930 Cold Start Issues and CO Fluctuations

RarlyL8 · RarlyL8's Garage

Everything is going pretty good with the 3.3 turbo SC. I'm putting miles on it now and enjoying the car after a pretty long expensive battle.

There is one final nagging issue that I need your input on.
Cold start problems and CO fluctuation.
At a temperature of 60-70*F I have to hit the key about a dozen times before the engine will stay running. It fires each time a little more than the previous until it is ready to run. If I unplug the WUR it will start much quicker (so that is what I have done for now). I re-adjusted the CO with the WUR unplugged and get readings all over the map, from a high of 6.5 to a low of 0.5 or so. The median reading is 3.0-3.2 %.

What is the deal with the WUR? This unit is adjustable, but the engine does not respond to it. I assume it is not working. The fuel pressure is OK and the CO is checked with the car fully warm. The car runs absolutely fantastic once it is started.
I have removed all the CIS components from the system except for the WUR, Throttle Bypass Valve and the Aux Air Valve, as seen in the Euro CIS schematic. The TBV and AAV are working properly.

Thanks for your input.

dean · 10-09-2002, 04:14 PM

I figure if it runs good when it is warm that is good enough for me. I think the CIS sucks. I don't have a AAV on my motor so I have to keep my foot on the throttle when it's cold.
Did you check the cold fuel pressures?
Sorry I couldn't help

Enjoy it when it's warm ;-)

TurboRuf · 10-09-2002, 07:05 PM

Rarly,

Glad to hear you are enjoying your car.

Did you ever put the Thermo Valve back in? I had a similar problem when I removed my TV from the equation. Since the distributor wasn't advancing on cold starts it would take a while to turn over. Connecting it back up would give me enough advance to cure the problem.

Enjoy the ride!

RarlyL8 · RarlyL8's Garage

No, the vacuum switch has not been connected. The CIS system mirrors the schematic for the Euro cars. That switch is not present in the Euro schematic.

This problem really feals like an A/F enrichment issue. The engine wants to start. It will sputter a second and die. The engine will sputter a bit longer with each hit of the key until it finally catches and chuggs up to 1800 rpm with the Aux Air Valve open. The AAV then starts to close and the idle runs down to 1000 rpm in a few minutes.
Once the car has been started, even for 60 seconds, it will immediately fire up after being shut down. She runs perfectly once started.

The sporatic CO readings might be due to a cheap meter (Gunson) or it could be that it is normal for the ratio to be different after a hard run vs sitting at idle for a time. The median numbers are between 3.0 - 3.2 so I'm not concerned about a lean condition.

The car is strong, real strong. It is living up to the hype that 400 crank hp is possible with just a few bolt on mods.

dean · 10-10-2002, 03:09 PM

My Gunson works very well once it is warm and not moved. The reading varies maybe .1%

930Chas · 930Chas's Garage

My Gunson doesn't work worth a damn. I got readings from .9 to 6.0. Right now, I'd like to think that the car is set at 3.0-3.5. I managed to get the gunson to sit there a short bit longer then any other setting. The car runs strong and idles well, but I definitely do not trust the Gunson. I've used it on friend's sportbikes with the same crappy results....anyone want to buy a used gastester?

dean · 10-10-2002, 05:39 PM

Wow, did you read and follow the instructions. Mine works so well that I found out that if you cover and uncover the hole for the mixture adj. the CO varies from 1% uncovered to 3% covered

juan ruiz · juan ruiz's Garage

Rarly L8 ,What is your AIR/FUEL RATIO?

930Chas · 930Chas's Garage

Blown, yeah, I read the instructions. Give me a little credit.

It just will not stabilize. Maybe it was made on a Friday afternoon...too close to beer-o-clock.

TurboRuf · 10-11-2002, 04:42 AM

My Gunson also works very well. The only thing with my particular unit is the time it takes to calibrate. I generally have to wait a full 4-5 minutes before it will stabilize. Once stabilized it will give a very accurate reading. My unit also requires several minutes to stabilize once CO adjustments are made. I generally wait about 4 minutes after I adjust CO to check the reading again.

Opps... getting off topic... sorry Rarly.

RarlyL8 · RarlyL8's Garage

That's not off topic at all. One of my concerns was the gas tester.
I'm seeing the same activity as Charlie, stabilization issues. I let this thing "warm up" for 30 minutes before testing. It seems to be good for one test then goes all over the place. I have to let it re-stablize for another 30 minutes before I can trust the next reading.

I don't know what my A/F ratio is. The meter I have is also cheap and is acurate at ~14.7 or so. I plan to use it simply to monitor the ratio under boost. Yellow and green indicator lights, not a numeric dial.

What do you think about the cold start issue? WUR?

juan ruiz · juan ruiz's Garage

Rarly Im not sure if is related but you may want to start looking into your Air/Fuel Ratio at 14s it seems way to Lean,Im not telling you what to do,but I went thru a similar pattern

RarlyL8 · RarlyL8's Garage

My ratio is not in the 14s. That is where the METER is most accurate. What I want to see is the meter to be in the yellow or green - ratios all BELOW 14.7 at all times, especially during on-boost events. No red readings allowed! HA!

dean · 10-11-2002, 12:23 PM

My Gunson takes 15 mins to warm up then if I make a change it sableizes in 5 seconds or so. What I found is that you have to leave the allen wrench in the hole or air gets by the meter and screws up the reading.

Rarly did you check the cold fuel pressure. I think that will eliminate the WUR