I am trying to change me lower VE tables. I did a search and can't find how to convert MAP readings in Hg. to Kpa. My scan tool doesn't show MAP in volts either. Am I going about this wrong?

 

Are you sure your scanner can't be switched to read in metric units? They are actually easier to use for VE tuning. If not, try this:

What does your scanner show for MAP when you first turn on the key (but before you start the engine)? That MAP reading will correspond to (approx) 1 atmosphere of pressure "absolute" (or "a" for short - 1 atmosphere absolute is also written 1 atm a). 1 atm a equals about 30 in HG a, or 100 kPa.

At the bottom end of the scale - a perfect vacuum, or 0 atmospheric pressure absolute - the reading would be 0 kPa or 0 in Hg a or 0 atm a.

So the MAP scale (MAP means Manifold Absolute Pressure) goes from 0-100 kPa, or 0-30 in Hg a (approx), or 0-1 atm a. That should give you enough info to work out the conversion from one unit of measure to the other. If you are still stuck, try to look up 'absolute vs gage pressure', or 'engine manifold pressure'. Google is a good search engine.

HTH

 

Well I feel pretty stupid, but I am actually smarter now. Thank you, I use Diacom + and all I did was change it to metric. I didn't even think about it. The answer was right in front of me. Again you lead me in the right direction. I know that some questions that are asked seem obvious to some, but they really are invaluable to others. Keep up the good work, I'm learning!!!!

 

I am home on Sat night because I am a slave to my car. The way I see it, I have a 4 day weekend to work on my car. I have run into yet another problem. I hope this one is easy also. I did tune my lower VE tables a bit and got the BLM's up off of 108 all the time. My 92 has a left and a right BLM and seperate O2 sensors. The left BLM moves around 124 or so.(at idle) The right still sits on 108 most of the time. The right integrator isn't tapped out, but it is close. I know that there has to be a problem. (seems to be a miss) I swapped the injectors from one side to the other. No change. I checked the spark plugs, and found nothing conclusive. I also checked for a vacuum leak with oxygen. Again, nothing concrete. This is a new engine with a 224/230 Extreme energy cam and all the normal goodies. ANY advise is welcomed.

 

Good start on swapping sides of injectors and stuff. Did you have a chance to swap the O2 sensors?

Other than the things you mentioned, an exhaust leak in front of the O2 sensor can mess up readings (manifold flange to the head). I wouldn't be surprised if the side showing 'correct' was actually the problem if the calibration is pretty much stock and that cam was put in. Good luck! -Matt-

 

Thanks for answering during the "big" weekend. I had the exact same problem with one wire O2's. Then I put on 3-wire heated O2's because I thought that the 1-wire sensors seemed sluggish. I also have headers. Long story short, I am using brand new sensors with the same results. I did like the idea of checking the primary tube temps. I was wondering how I would figure out if all the plugs were firing, even though I took them out and looked at them. Exhaust leaks-well I don't see any soot and I can't feel or hear any leaks. Sorry I didn't tell you this sooner, but I have programming for a Hot Cam, because I just took it out. I bumped up the fuel pressure from about 30 to 45 lbs. That is why I was at 108 on my BLM's. I figured that I had to reprogram anyway, and I thought the extra pressure couldn't hurt. Aren't cars fun? :(

 

Um, let's think about this again. The right bank shows 108 BLM's, the other one is 124ish.

Matt is right, the problem could be on either side I guess. I still think you have to swap O2 sensors and see if the condition follows the sensors (just to rule them out) - also to verify the right sensor is making good electrical contact.

If the situation stays the same, you could try to observe the right O2 reading in Diacom (I'm guessing you can read that sensor separate from the other?) while you electrically disconnect the right injectors one by one. If you get to the injector on a dead cylinder, you should see the O2 readings start to tansition again. That would be a trouble-shoooting case for a right-bank-rich scenario. (And it's easy to fry a plug wire on headers - been there, etc)

If it's really a left-bank-lean problem, then it would probably be either a vacuum leak (intake gasket slipped on assembly? - that happens); or one injector not making contact (?). I usually put a big screwdriver on each of the injectors while it's running to feel the click as they open/close.

One other thought - when you put on the 3-wire O2's, did you use the weatherpak connectors? Soldering on the O2 pigtail is a no-no, it needs to be crimped.

HTH




[Modified by DOCTOR J, 12:28 AM 5/27/2002]

 

Ok, you got me on the solder part. I did solder on the weather connectors. Can you tell me more about the solder-vs-crimp connection? If I have to get under there to change the connection, I will swap sides on the sensors as well.

 

Well, this is only what I gather from reading the sensor manufacturers' spec sheets - lambda sensors really aren't my field of expertise:

To make a long story short, lambda sensors compare the partial pressure of O2 in the exhaust against the O2 in free air, across some kind of zirconium oxide matrix (?) - the differential in partial pressure creates a reference voltage.

The air used for comparison is drawn in thru the copper wire pigtail. If you solder on the pigtail, you cut off the reference air source, and the sensor won't work. Hence the need for crimps.

I don't know if all that is true, but the specs say not to solder on the O2 sensor wire. I don't, and haven't had a problem so far. YMMV.

There is one Bosch spec sheet on the DIY EFI incoming site - you may be able to find more on the Delco site, I haven't looked lately.