Been playing with the tune on my black car, just got it running again. This is just throwing flags my way right now because it doesn't seem right. At idle, which is set to 1000 RPM and it's pulling about 75-80 KPA MAP with closed TPS Spark Advance at 30 right now (bumping that up a little tomorrow), to get it to idle relatively smoothly my ve tables are at 35% for that parameter. That just seems awfully low for the size cam I'm running (GM847 comparable). And I still get black plugs after about 5 minutes of running.

Does that seem wrong to anyone else?

 

Add some more timing...both in the closed spark advance table as well as the normal timing table. you need to build some cylinder pressure the cam overlap is bleeding off. I don't think that your car will run right (or certainly idle right) until you can get down to a relatively stable 60-65 kPa at idle. Timing will help get you there.

I agree with the lower VE at idle. But remember you have a 93 so you can use VEMaster and TunerCat to get the VE spot on at all rpm excepting wot. Use it to get the car in a better state of tune for idle and drivability situations.

What does your blms and int try and do when you go closed loop. If it is as you say....dead rich than you need to look for mechanical/electrical problems for the richness. If none than you adjust the VE and IFR in the constants table until you can control the idle with the puter.

Perry

 

Yeah, todays goal is to do some timing work and see if that helps.

My LTerms and STerms will do one of two things if I let the car go to closed loop. Either both sides dump to full rich (108/1 on each side) OR One side goes full rich and the other side goes full lean. No if's and's or but's about it, one of those two will happen.

My richness problem before was aparrently a poor seal between the manifold and head surfaces. I ended up pulling the heads/manifold and sending them to Golen Engine Service for mock-up on a block and manifold machining if necessary. Chad said I should have NO PROBLEM getting a seal now as they checked and double checked it and ended up making side and front/rear rail cuts on the manifold.

Questions: You said IFR table. What's that, as I haven't heard one put to me as "IFR" before.

If I'm playing with the timing, will that change the requirement for fuel?? I.E. more timing which brings up vacuum (hopefully) will want more fuel??

The low vacuum I'm getting right now is causing the car to run at abour 41 PSI of fuel pressure on a 43.5-44 PSI WOT setting. That would play into the car running rich, right?

Last thing, I'm going to try to do tuning to get it to run right, but given the nature of the problem and the fact that it's chased me from my stock shortblock to this new motor, I don't think it's going to work. I still feel that there's an unknown issue causing a extreme rich condition. The only reason I can think of that my intake manifold gaskets wouldn't be sealing at this point is if somehow my block, when getting decked, one side was improperly cut.

 

I've tuned big cam cars before that started out with the same problems you have. So it may not be mechanical.

You need to go to LS1Tech and make certain you read all their stickies about tuning. Than add the necessary timing. maybe go to 32 deg minimum or more everywhere in the idle MAP and rpm range. So you need that advance from 400rpm to 1400 rpm pretty much up to 80 kPa map. That should stabilize you in the 60-62 kPa range. Than you can work on the tune a bit.

Hopefully you have a WB and an extra bung in one or both of the collectors. It is most helpful.

The other issue (split blms) you can google search on. There is a wealth of info out there. You need to get your IAC counts down to 30-60 at idle. I'll bet they are maxed and you are getting your idle air through the main plenum by cracking the throttle blades, which is causing its own problems.

IFR is injector flow rate, which is a single number in Tunercat. It is a table in the LS1 computer. So just make certain you have they major "****" kinda close to a real number.

Perry

 

The blue area is where the car is idling. That's about 25% VE @ 1000 RPM 75-80 KPA MAP. I upped the timing to 34* Closed and in the table, and it's pulling 8-10 In/Hg now, but that VE table is just way out in left field.

My IAC counts are actually around 20 at idle and the blades are CLOSED, so my sometimes split fuel trims isn't a product of the IAC passages and airflow. Right now the consistent result is a full rich signal on both sides again, just like before.

Also remember that this problem has chased me from a stock bottom end/ported head/224/230 cam setup to my current 355/heads/Joe O cam setup.

I'm starting to think that I have a internal vacuum leak. I don't know if my intake manifold gaskets failed again or what, but this is really getting tiring. I think I'm going to try and double stack the intake manifold gaskets, but after that I don't know what to do.

*Edit* I was asked to pull the pic.

 

Found out why it's acting funny. Same thing, again.

http://community.webshots.com/album/460272038haJSmQ



The crazy part is that the heads and manifold were mocked up on a block and VERIFIED to be getting a good seal. So why in the heck are they continuing to lose seal and allow oil/vapors in to the intake runners????

The runners and inside of the manifold as well as the throttlebody gasket even were all just soaked and saturated with oil.

 

why dont you run an open loop lune, with a cam that size? I am also running a big cam, and my car idles around 70-75Kpa, with 34° of timing. So more timing will actually lower the kPa? I am running an open loop tune, and I am wondering if I should also up my timing to get the KPa down? Thanks guys..

 

I run a 233/239/112. I used to run it on a 93 ECM, but I've converted to a 94+ setup although I still run speed density.

My BLMs at idle are right around 128. The car idles at 60-65 KPA with some deviation from that depending on ambient factors.

An important factor to consider with a bigger cam is that values of 128 shown in datalogging software won't actually correspond to the same real air fuel ratio of a car without a cam. The overlap of the bigger cam will throw things off, so if you want a "cleaner" exhaust, you will probably want to aim a little higher than 128. You can use vemaster if you don't want to play with it yourself. Your car may or may not like a leaner idle (although technically it's not) so it's worth a shot. For lower RPM/load part throttle though, you may find that slightly richer mixture (again, around 128) will help with the driveability (more noticeable on manual cars). In the long run, it's up to you to decide, but like I already said, experimenting with it won't hurt.

 

Or do a little hack to allow open loop at a idle only.

All of his problems stem from oil consumption. A problem hes been battling for 2 years now.

 

how do you get it to work in open loop at idle only?

 

There's a big thread about that, search for it. I believe it has to do with setting PE mode to engage at TPS = 0% in the idle rpm range.