Guys,

I have been trying to get my Xfire thru emissions here in NW Illinois. Since I am in Dupage County(nw of Chicago), we have a drive cycle on a dyno. The idiots that drive these cars are used to getting into the minivan and pressing on the accelerator. I get a lot of "Wow, this car has power" stuff. Their inability to drive a manual trans makes getting thru emissions even more difficult. I need lots or margin for error. One guy will drive it and pass, the next won't. I have been doing scans and suspected the spikes in the HC to be caused by lean misfire. And it seems that the BLMs get high at the points in the drive cycle where HC goes ballistic. I have isolated one particular area in the 1700-1850rpm range and between 30-40kPa. I'll get BLM's up to 150 at times. My question is "How do you tune for this?" Where do you make the changes in the Fuel Map #1? Or #2?
I would be interested in hearing how tuners like Trax and Glenn address this area. I am using a 7747 so the Fuel Map is incremented by 400rpm starting at 400 and units of 10 for kPa.
Thanks for your help. :hail:

 

my advice is to say go ahead and increase the values at 1600rpm 2000rpm 30-40kpa. asll four by a little bit one at a time and see which one nails it. it might take a small increase in all four of theose values to nail it. the ecm wil obviously use the closets value for sure but with the slow buad rate of rht eecm its hard to say that is this really to value. hopefully r-bob will pop in and offer his advice. im not one for playing with $42 much. but he knows it inside and out.

 

funstick,

Thanks. I will be trying that. Hopefully, Rbob and some of the others will chime in as well.

 

Anybody?

 

What bin editor are you using?

I'd say that it may be most important to coach the person doing the testing. Get them to drive the vehicle properly. On one of the Mazda boards folks there with the factory turbo cars need to do the same thing. Keep from having the test person from hitting the go pedal too hard and building boost.

I have not had to do tuning for emissions but have looked at the differences between newer and older bins. Reduce AE as much as possible. Lower the O2 calibration window values. Do a good job tuning the VE table. Coach the test driver. Make sure the cat is in good shape. No exhaust leaks. Coach the test driver. Disable PE mode. Timing also plays a role. Use the hot water jacket in the intake manifold.

RBob.

 

Rbob,

Yes, the "drivers" are terrible. And that's exactly what happens. They're not used to driving a car with 350hp, and so they cannot smoothly apply the accelerator. They're constantly going back and forth with it. Up and down. I am using TC for editing the bin file.
Currently the bin has the PE enabled at 85%TPS. And the HC spikes when there is a change in velocity. In particular when they either let off or tip in. Once in steady cruise rpm, the motor is below the HC standards. I have done scans and am in the process of trying to "tune" bin file closer to 128. The HC spikes I get from the graphs provided by Emission Lab correspond with the higher INT's (tuning ala Glenn with locked BLM's) I see on the scans. As I said earlier, in particular there is an area between 1700 and 1850 with INT between 140-158. And it seems to occur between the 30-60kPA levels. That translates into the mph points where the HC tends to spike, so I am thinking "lean misfire". Thoughts? Again, how would you address the BLM's in the "no man's land" areas of the Fuel Map?

 

For tip-in reduce the AE (you are not trying for go-power, just emissions).

For let-off, delay IAC closing more then it is now. Force the engine to not change as rapidly as the test driver changes the go pedal. There are lag filters for the closing rate along with the delays before closing.

Coach the test driver. Takes some finesse but the results are worth it.

For the hard-to-get VE areas, a higher gear and a hill help. Just need to stay there long enough to get a decent reading.

Lean misfire is possible. The HEI coils are weak. I've recently changed to a cannister coil, oil filled. Made a world of difference. Used the $17 Summit coil.

Check out the ARPC bin, it is a '91 305 '747 w/stick. Emissions were tightened by then.

RBob.

 

Rbob,

Thanks. Will do. The areas I was addressing are not the ones hard to reach. They are the ones that exist between the cells available for tuning. As you know the 7747 doesn't have the "granularity" of the more recent definitions. So I am relegated to hunting down tuning sort of like playing "battleship". Shoot around the edges till I find the combination of cells that affect whats going on in between them. Just wondering if there was a "rule of thumb" or some tip guys like you have discovered.

 

Ah-ha, I see said the blind man. Yes this can be a problem (small VE table). The SA table then needs to be used. It has a higher granularity then the VE table. Every 5 KPA by every 200 RPM in the area of question. Reducing SA will enrich and increasing SA will lean a mixture.

Smooth out the VE table and fine tune it with SA.

RBob.

 

Rbob,

Just got back from scan doing exactly what you have suggested. And it has made a significant difference. One more tune and scan for today. Jeez, this stuff is addictive. But there has to be more in life. Isn't there??

 

That is good news. Think this is addictive? Start with code mods. . . Just can't stop.

Of course there is the fairer sex. . .

RBob.