New Felpro install, having problems

[Brooks]

Hi all, a friend and I spent the afternoon trying to work out some starting/idling issues on a new install.

The car in question has a 4.1 block, GN1, heads, 212 cam, PT-52 turbo, front mount, THDP, test pipe, and 2.5" duals.

I was wondering if anybody with a similar (or not to far off) combo would mind sharing thier file with us.

We were able to get the car to start and run for about 30 seconds but when it reached somewhere between 110-130 degrees it would die abruptly and not restart until it was below 90 degrees. Nothing we did would change this. I don't recall what all our settings were but the curves were very smooth (In hopes that any problems would come on gradually and would allow us to trouble shoot a little easier but this was not the case)

We did not enable closed loop control. We were only attempting to get the car to idle reliably.

Thanks for any help,

Charles Brooks

 

[TurboTR]

Probably all you have to do to figure out why it's dying really is to look at the a/f ratio while it runs. It's probably going pegged on lean as it warms up, to the point where it just dies. Check the a/f ratio either in the logging screen or just have it displayed in the dashboard at the bottom of the VE table display. The base VE setting might not be high enough where it's idling, so as the startup enrichment decays away as it warms up it gets progressively leaner, maybe to the point of dying. Plus of course there has to be enough bypass air available for it to idle, meaning the throttle blade has to be cracked open enough. Also, how much timing do you have it set for at idle?

TurboTR

 

[Brooks]

The reported AFR stayed steady at 15.94 and never changed the entire day, I suspect that something is amiss there.

Timing was never changed from the supplied map and was 35 degrees in the cells used for startup and idling.

Base VE was set to 60 to get the car to start and idle and it idled nicely with no stumble or anything.

We did try to vary the enrichment as a function of temperature but nothing we did made any difference until the car cooled down below 90 or so degrees.

I'll report back after I get another chance to tweak it.

Thanks for the input,

Charles Brooks

 

[TurboMike]

What injectors?

Have you tried loading the 'demo' program to see what would happen (you'll have to change the injector size option)?

 

[Brooks]

We're using 009's.

We began with the demo program and tweaked it until we got the engine to start, saved that file, then tweaked some more until we got it to idle. We saved THAT file and tweaked some more trying to get it to idle beyond 130 degrees.

We had to quit when my wife called and said I had to come home.



Charles Brooks

 

[TurboTR]

Well there you go, that is the problem, the a/f ratio reading is solidly pegged lean and it won't run well like that as you found Who knows how lean it really is, at least 15.9:1 and probably more. Plus, 35 deg is WAY too much timing for low speed cranking and idling. FWIW the factory setup cranks at 10 deg BTDC, and idles probably around 20'ish deg.

TurboTR

 

[Brooks]

We went pig rich trying to bring the AFR down because of that AFR reading . The car wouldn't run until we reduced the fuel corrections and leaned out the tables.

I seriously suspect that the sensor is inop right now.

We left the timing table alone because the engine started and ran smoothly once we tweaked the fueling.

Are you sure about those timing figures?

 

[Eric Stage I]

I just started playing around with my FAST system, but here is a file that is working well for me so far.

My combo is: 4.1, GN1 heads, PT70-1, 52# injectors, THDP, 3" Single Shot

Change the injector size for your 009's.

The demo file had VE's around the 20's for idle. I had to move mine up to 35-40 to get a good idle. The timing is 18 degrees.

Good Luck
Eric

 

[Craig Smith]

Look on your dashboard in C-Com and look for a voltage called UEGOS. It should stabilize around .45 to .49 volts. If it does, it basically implies that the sensor is working properly. If not, something is wrong (sensor, wiring, etc.) If this voltage is correct, the next thing I would have you do is dosconnect the sensor and read the voltage labeled UEGO on the dashboard. It should sit at about 3.5 volts with the sensor unplugged.

If these 2 voltages seem OK and you're still seeing the a/f ratio pegged lean, I would begin to suspect a lack of good exhaust flow across the sensor. Exhaust leaks and reversion in the pipe are the most common causes of this problem.

Also, where is your sensor located? Not that it's the problem here, but it should be in the downpipe, not in the collector.

Craig

 

[Brooks]

Thanks Eric, I won't be able to try it tonight but I'll send it on.!

Craig, thanks for the info. Yes the sensor is mounted in the downpipe, approximately 10" down from the turbo.

Charles Brooks