PRP questions

[oxfordgt]

I'm new to tuning but figured most of it out. I have a 99 GT. I have the maf transfer dialed in perfect and idle, part throttle and WOT are all done. I'm only having a few issues.

First is cold start. Only the first start of the day idles drops low for about 30 sec and sometimes stalls. ISC is .0 integrator and .35 DC. A/F is dead on when warm but lean for those first 30 sec. I've tried adding air after startup and it got a bit better but not much.

Second is lean tip in. No matter what rpm or load. I've tried transient fuel but not seeing much change. I scaled LWFM even tho I know it does nothing on a 99.

Third is coasting fuel shut off. It rarely kicks in. Never on normal part throttle driving and only kicks in after a 7000rpm pull.

Where should I be looking to make changes for these problems.

 

[decipha]

you need to kick up the startup enrichment fuel table for those 30 seconds your lean

for lean tip in you can reduce the manifold volume, go cut it in half and see how he likes it

dfso has a bunch of scalars to enable it, make sure all of those scalars are within range

 

[oxfordgt]

No startup enrichment only an enleanment table in my pcm and I zeroed that out. Strange thing is when i give it a little pedal rpm does come up and gets richer which is why I have been trying to add air through the multiplier after startup.

Will reducing the manifold volume have any negative effect on WOT? BTW I am using an edelbrock intake.

What is within range? They are all set to stock still.

 

[RacerXHG]

As far as startup, make sure your MAF transfer function is as close as you can get it for low counts. At cold startup, it actually is in open loop then goes to closed loop after a time/temp limit is met. Do you have aftermarket cams? LT headers? You could raise Idle Speed RPM Adder for ECT @ Startup. Add to O2 Transport Delay for LTs.
For Lean tip in, set the Open Loop Delay Blending Ramp for 1.9 and Open Loop Timer for WOT to 0.
For CFSO, have you checked RPM Below to Turn Fuel On, Min RPM to Enter, Max Load to Enter and the other parameters in that section. This can be an interesting area with an auto trans and TC lockup schedule.

 

[oxfordgt]

MAF transfer is dead on. 14.7 in open loop and STFT switch between .99 and 1.01 at idle. Yes I have very large custom cams, longtubes and ported TFS heads. I have the idle speed adder for ECT set to add 300rpm already but it won't do it. Already added the delay. I have tried everything I could find to try, cold start is just killing me.

I'll try the tip in changes, hopefully it stops raining so I can test it.

All CFSO parameters are currently set to stock.

 

[oxfordgt]

I tried adding air and taking air away in idle air multiplier with no luck. I tried changing manifold volume lower and it made everything worse.

I dont have open loop delay blend and open loop timer was already at 0. I tried messing with transient fuel tables but nothing.

No luck on messing with CFSO tables.

Pulling my hair out here.

 

[RacerXHG]

You may want to try this file in your tune for chits and giggles:
View attachment 61517

 

[97RioRedSnake]

I had a similar problem after dialing in my MAF transfer function for the first time. A/F mixture would go lean within the first 30 seconds to a minute after startup, idle rough, accelerate rough and then all of a sudden it would be back to (around) stoich and run perfectly.

I have two suggestions for you:

1. In the "Open Closed Loop" menu in the advantage software there is a time delay for closed loop and other delays related to triggering closed loop in the scalars. Try increasing these values by a significant amount (I doubled them a few times).

In my datalogs I was seeing somewhat erratic O2 sensor activity in these first 30-60 seconds after startup when my car would be running like crap. One O2 would be switching, the other wouldn't be, or both wouldn't be. I theorized that my O2 sensors were not heating up fast enough/staying hot enough after initial startup since I've added longtubes and found out I had an exhaust leak near the PS header collector.

I believe that increasing the closed loop delay gave my O2's more time to heat up and start functioning properly before the PCM dumped the responsibility of controlling the A/F mixture on them.

2. Check for exhaust leaks.

Like I mentioned, I had an exhaust leak near one of my header collectors and I'd have to assume that this made the situation worse since more heat was allowed to escape near the O2 sensor location.

Even with the exhaust leak, my car ran 100% better after cold start-up by increasing the closed loop delay.

Hope this helps.

 

[oxfordgt]

I had a similar problem after dialing in my MAF transfer function for the first time. A/F mixture would go lean within the first 30 seconds to a minute after startup, idle rough, accelerate rough and then all of a sudden it would be back to (around) stoich and run perfectly.

I have two suggestions for you:

1. In the "Open Closed Loop" menu in the advantage software there is a time delay for closed loop and other delays related to triggering closed loop in the scalars. Try increasing these values by a significant amount (I doubled them a few times).

In my datalogs I was seeing somewhat erratic O2 sensor activity in these first 30-60 seconds after startup when my car would be running like crap. One O2 would be switching, the other wouldn't be, or both wouldn't be. I theorized that my O2 sensors were not heating up fast enough/staying hot enough after initial startup since I've added longtubes and found out I had an exhaust leak near the PS header collector.

I believe that increasing the closed loop delay gave my O2's more time to heat up and start functioning properly before the PCM dumped the responsibility of controlling the A/F mixture on them.

2. Check for exhaust leaks.

Like I mentioned, I had an exhaust leak near one of my header collectors and I'd have to assume that this made the situation worse since more heat was allowed to escape near the O2 sensor location.

Even with the exhaust leak, my car ran 100% better after cold start-up by increasing the closed loop delay.

Hope this helps.

I changed the delay and it was a bit better but still idled at about 500rpm and lean for about 20 sec.

 

[oxfordgt]

You may want to try this file in your tune for chits and giggles:
View attachment 61517

I tried it out. Looks like it was just an ISC change. Didn't have the time to let it warm up to check what it did to the integrator I'll try tomorrow.

 

[decipha]

if its lean you need to kick up the startup enrichment table, you may not have access to it

 

[oxfordgt]

I don't have that table

 

[15PSI]

decipha - Are you refering to Startup Cold Fuel? I forget if that table was available before SCT gave me calibrator status. I know that the base software is missing a lot of stuff, especially the drive-by-wire scalar etc...

 

[oxfordgt]

Ok I think I'm getting there. I used the file RacerXHG gave me but made a few changest. I readjusted the TB with the IAC unplugged then adjusted the ISC. I returned some of the transient tables back to stock mostly the decel ones. I adjusted the fuel in the puddle table. Then adjusted the spark table. I raised the spark below idle to above spark at idle and spark above idle to below idle, just the individual cells. Last thing I did was change the base fuel to .980 at idle load.

I did everything but TB adjustment and ISC adjustment before first startup of the day. First start it started up and idled just a bit low. After it warmed up and I adjusted the TB and ISC it would start and Idle up to 1300rpm for 10sec as commanded then drop to 850rpm and hold steady as a rock. That was the first time it ever idled up after startup like it's supposed to. Vacuum was at 11inHG and steady, A/F was dead on (STFT .98-1.02) and ISC was at .06 integrator and 14% DC.

When I reved the engine there was no lean tip in like there normally is and it came right back down to idle.

Spark at idle is at 29*-32* which seems pretty high. There is no retard at operating temp (190*) and ACT was at 58* so no retard commanded. Do you guys think I should adjust this?

I wish the weather was better so I can test it and see if lean tip in is gone and CFSO works.

Thanks for all your help guys. Seems like I'm almost there.

 

[oxfordgt]

Since I searched for a fix and found hundreds of threads about lean tip in but no one ever updates how the fixed it I will update. I fixed lean tip in by adding 10% to the entire transient fuel values table. It also seemed to help cold start. Still coasting fuel shut off only works if I'm going over 70mph.