Initial startup after H/C install runs rich

[mathia]

I'm tuning the ls1 in my 2001 Corvette after installing the following:
WCCH Edelbrock heads
224/228 114+4 cam
Fast 90 intake
90mm LS2 throttle
Dynatech long tube headers
Fast 36lb/hr injectors

I've entered the data for the injectors which I found on here and I adjusted the throttle area scalar for the 90mm throttle. I increased the idle speed and tweaked the Idle Overspeed/Underspeed Spark vs RPM Error table and the car starts and idles ok so now I'm beginning the tuning process.

I'm following the Calibrated Success DVDs and I'm starting by tuning the MAF in open loop. My wideband is showing the car is running rich (.93 lambda) and it smells like it, but this is confusing me. Shouldn't what is basically a factory tune be running lean because with all of the upgrades more air is getting into the cylinder at any give MAF reading than when the motor was stock?

I've only run it in neutral from idle to 3k so far but I was surprised to see it rich (around .96 at idle and .92 at 3k). Just wondering if I've got something setup wrong. The car does have some old gas in it.

[AutoWiz]

114+4 sounds like you should be able to get a pretty respectable idle out of it. i believe the right way to tune your 2001 corvette is by failing the maf, turning off power enrichment, disabling decal fuel cut, disabling cat over temp protection, writing that to your ecu, and in vcm scanner configuring histogram #3 which should primary ve vs rpm vs map. this is how you will first correct your ve table. then once your ve table is right, you will enable the maf, and fail the map write ecu, then configure histogram #8 for tuning the maf. then reset power enrichment, decel fuel cut, and cat over temp protection and you should have a good tune.

[mathia]

Thanks for the reply. Yeah, that's my understanding of what I need to do too, it's just I'm starting with the MAF first as that's what Greg Banish does in his Calibrated Success DVDs. From what I've read, it doesn't matter if you do MAF or VE tables first, you just have to make sure you disable the one you're not working on.

I just thought when you make most NA mods to a stock setup you're always going to make it run lean with the stock tune as you get more air in the cylinder. I could see if I had a big cam, that at low RPMs the overlap would let some unburned gas out the exhaust making it rich, but I've got a fairly mild cam.

So far I've only done a handful of scan up to 3k rpm while the car is on jack stands. Maybe I need to drive it and put some load on it to get some better data. Also, I need to put some fresh gas in there. There was just few gallons of over a year old gas in there.

[FC3S Murray]

Yes you definitely need to put a load on it & get some good gas in it. Will help immensely and you should be on your way by the sound of it. You already got the basics down so it won't be too hard.

I put in about 25+ hours until I got my H/C damn near perfect. It's worth the effort. Good luck.

[mowton]

Don't disable PE, no need to and why would you? Its there to provide additional fueling to safe your engine....PE is a fixed adder to the MAF cell value you are tuning so any errors are going to be a reflection of the MAF values and would get corrected just like in non-PE by the error value. As in any tuning process the key to accurate and stable tunes is how you collect your error data. Very steady driving, no large transients of the pedal, take several seoarate logs based on a specific area of the MAF or VE table and save for later evaluation. Several logs of good steady state data developed specific for a particular area is way better than just one long log. Also remember you can develop a myriad of filters after the log data has been collected to corden off specific data that you are interested in. This is how you can filter out PE, decel, pedal transients etc.

As far as rich, what did you do with the Open Loop Eq table? From the factory it is set rich because it supports cold start open loop until closed loop mode is enable and is used when open loop is forced as a result of certain airflow failures and is purposely set rich to protect the engine. If you are tuning in open loop you need to set all the values from 176 F (operating temp) and up to 1.0 (stoich) and then you should see leaner values as you would expect.

Tune the MAF first and make sure you set the High RPM disable/enable to 400/390 respectively to set the MAf only mode. Tune VE next by setting MAF High Fail to 0 and DTC P0101-103 (maf) to fail on first error. Make sure you have a check engine light when you fire it up. Street tuning will require several hills, maybe haul a trailer and gear changes to navigate through as many cells as possible.

Ed M

[mathia]

Thanks for the tips guys! I got it off the jack stands with fresh gas in it and then I was seeing it lean in my scans as I was expecting. I've made a couple of adjustments to the MAF table now and it runs and smells much better.

It does seem pretty hard to collect all the data with street tuning. So far I've just hit the freeway at normal-ish speeds and I don't think I've hit more than 6500 Hz. I do need to get my filters set up too. I haven't messed with filters at all, are there files for those that I can download?

Also, how close does it need to be to be safe to drive? I know too rich can kill your cats (I still have them) and O2 sensors and too lean can melt things in the motor. After my last round I'm seeing lambda error from around 0.96 to 1.02, with it being rich down low and leaner up top (where I haven't collected a lot of data yet). I'm ok to drive around town at part throttle like that?

[mathia]

Don't disable PE, no need to and why would you? Its there to provide additional fueling to safe your engine....PE is a fixed adder to the MAF cell value you are tuning so any errors are going to be a reflection of the MAF values and would get corrected just like in non-PE by the error value.

So if I'm following you correctly, your saying that Power Enrichment (PE) is going to affect the commanded lambda and so while I'll have a richer reading at the wide band, I'll also have a richer commanded lambda and so they will cancel out when lambda error is calculate.

As in any tuning process the key to accurate and stable tunes is how you collect your error data. Very steady driving, no large transients of the pedal, take several seoarate logs based on a specific area of the MAF or VE table and save for later evaluation. Several logs of good steady state data developed specific for a particular area is way better than just one long log. Also remember you can develop a myriad of filters after the log data has been collected to corden off specific data that you are interested in. This is how you can filter out PE, decel, pedal transients etc.

Yeah, I need to look into filters.

As far as rich, what did you do with the Open Loop Eq table? From the factory it is set rich because it supports cold start open loop until closed loop mode is enable and is used when open loop is forced as a result of certain airflow failures and is purposely set rich to protect the engine. If you are tuning in open loop you need to set all the values from 176 F (operating temp) and up to 1.0 (stoich) and then you should see leaner values as you would expect.

I did adjust those all to 1.0 right from the get go, so that's why I was surprise it was rich. I think it was a combo of the old gas and collecting data with no load (just rev'ing in neutral on jackstands) cause once I got in on the road with fresh gas it was lean.

Tune the MAF first and make sure you set the High RPM disable/enable to 400/390 respectively to set the MAf only mode. Tune VE next by setting MAF High Fail to 0 and DTC P0101-103 (maf) to fail on first error. Make sure you have a check engine light when you fire it up. Street tuning will require several hills, maybe haul a trailer and gear changes to navigate through as many cells as possible.

Just got back from my first drive on the freeway and I can see what you mean about needing a hill to hit those higher cells. Thanks for all your advice! I just checked out you website. That's a great idea. There's a lot of info online, but it's really time consuming to sift through it all. I'd love to have someone knowledgeable sitting next to me while I'm doing this, and real time support seems like the next best thing. I'm still not sure I have enough time to tune this myself right now, so I may be taking it to a shop or may hit you up for your services.

[mowton]

So if I'm following you correctly, your saying that Power Enrichment (PE) is going to affect the commanded lambda and so while I'll have a richer reading at the wide band, I'll also have a richer commanded lambda and so they will cancel out when lambda error is calculate.


Yeah, I need to look into filters.


I did adjust those all to 1.0 right from the get go, so that's why I was surprise it was rich. I think it was a combo of the old gas and collecting data with no load (just rev'ing in neutral on jackstands) cause once I got in on the road with fresh gas it was lean.


Just got back from my first drive on the freeway and I can see what you mean about needing a hill to hit those higher cells. Thanks for all your advice! I just checked out you website. That's a great idea. There's a lot of info online, but it's really time consuming to sift through it all. I'd love to have someone knowledgeable sitting next to me while I'm doing this, and real time support seems like the next best thing. I'm still not sure I have enough time to tune this myself right now, so I may be taking it to a shop or may hit you up for your services.

Yes on the Lambda question and filters will help alot.

Glad the richness worked out for you as well.

Lastly thankyou for the website look and are available for any consulting, training or tuning you may be interested in. Will be there right next to you :-)

Ed M