I have installed the K&N and am getting ready to do the cut lid. Everything I read about the Map sensor system says that you can't do much without having the system re-programmed. If you do, you may end up with too lean of a mixture. I know what happens next and don't want to go there. I would like to make the mods in stages but it sound like I won't be able to based on the system. Anyone have ideas? :chevy

 

You can pretty much do any small mods you want to without any problems. You will probably run into a code 32, which you can completely ignore. Map systems accept more modifications than the Maf systems.

 

You can do the ignition & low temperature mods and some air flow changes. It's realy the larger increases in air flow and changes in manifold vacuum that give problems. You can use an AFPR to tune the fuel flow at WOT.

I've got data on mods to a '90 L98 that may be of interest; you've got mail.

 

Vice versa. MAF systems can take more modifications before requiring recalibration than a MAP system. -Matt-

 

I have headers, dual exhaust system, AFPR, K&N, open lid and hypertech chip stage 2 and a 160 thermostat. I have not started the engine yet - what can I aspect? Will I have problems? How can I avoid them?

I thought that the MAP and the oxygen sensor would take care of everything...

:confused: :eek:

 

From your description of the proposed mods you probably will not have any problems. The answer is to have a scan tool/software available and do before and after scans to determine if the ECM has adapted to the changes.

The MAP system computer has a number of "cells" (Block Learn Cells) which it uses to adapt to different scenarios. For example: the factory manual calls for a BLM Cell of "1". My car is presently using BLM Cell #4 with the minor mods I have.

The other things I would look at are the BLM Value and O2 ratio.

The recommended BLM Value is 128 (some sources say +-10). A BLM value less than 128 is supposed to indicate a long term RICH condition and a BLM value over 128 is supposed to indicate a long term LEAN condition.

The proper O2 ratio is 14.7

So to conclude, I would get a scanner and try it.

I am using Craig Moates software with an AKM Cable. Total investment-$35.00! :)

CAVEAT: I am by no means an expert on this subject and am still learning! The information and values that I have provided comes from personal experience, the factory manual and the book-How to Repair and Modify Chevrolet Fuel Injection by Ben Watson. To the best of my knowledge it is correct. :blueangel: [IMG][/IMG]

Let us know how you make out and GOOD LUCK!


[Modified by Wildride, 10:37 AM 12/10/2001]

 

Jim, the info you sent lists plugs, wires etc.. all of which I am in the process of doing. Everyone says the airfoil is useless and I'm not interested in doing heads or major engine work. Can the mods on your site(porting etc..) be done by an inexperienced hand or will I be making a good boat anchor for someone? I'll have the C-4 for the next four years or so(until my boys can ride in a C-5 with dual airbags) and I would like to see some performance gains without breaking the bank. Should I consider exhaust? Thanks for all of the previous info, it's been a big help. :chevy

 

I'm no expert at porting but just took it slowly. After a while you begin to get a feel and eye for it. It's a slow messy job with a Dremel, more tedious than difficult. Worst case scenario you can pick up a used intake without breaking the bank and still cheaper than having the porting done outside. Be careful to not let the cutter bit slip and score a gasket surface. But if that happens you can fill the gouge with some RTV (don't ask how I know) with excellent results.

If you are refering to porting the stock exhaust manifolds, well that's up to you. I don't have time slip proof of gains since I'm suffering from some knock retard of timing. It is a simple job to do; gaskets cost about $50 at the Chevy dealer. The only pita is the AIR down tube, but if you remove the inner fender well access panel it should be easier (of course you'll have to lift the A/C compressor to get the passenger side manifold out).

If you were refering to doing all other exhaust mods, definitely the powe is in there.

That was a great idea to log scanner data on all the BLM cells before and after the mods to see if you need a chip; cell #15 is used at WOT only so you realy only have 14 cells to concern with. You should probably also record manifold vacuum (use an external gauge) before and after the mods. Of course you'll need to do final tuning the AFPR with time slips but a scanner and O2 readings will work for the initial tune. If you do most of my mods I think 47-48 psi should be very close for fuel pressure.

My exhaust system was the greatest single cost, the valve train work was a close second.

I'm sure you'll like the results.