I finally got this beast in and figured out why it would not start.

The engine is completely new and it idles poorly. If I can maintain 1500 to 2000 RPM, it runs smooth. But will not keep running without my foot on the gas a bit. It seems that when the ECM goes into close loop, the idle wants to take a dive and stall out.

I'm using the 32B ECM and have CATS. What tables and values will help get this engine to idle smooth. Tables like:

IAC STARTUP PARK POSITION (now set at 145)
IDLE SPEED ADDER PARK/NEUTRAL (now at 125)
WARM IAC PARK POSITION VS COOLANT (min value at 45)
DESIRED IDLE SPEED VS COOLANT (min set at 800RPM)

The engine has about 10 minutes on so far. I know that I need alot more break in time.

Can someone please give me some advice???? TIA

 

Almost sounds like there is a vacuum leak. Double check stuff like firing order, timing, fuel pressure and the rest of the mechanical items.

Then get a data log of engine. Usually on a new setup I don't worry about cold running until the tune is roughed in better. Run it until the engine is up to temperature, then data log. If the engine runs OK, then drive it a little while datalogging.

Using those logs look to see where changes are required. Make the changes, rinse and repeat.

RBob.

 

Like RBob stated first check for vacuum leaks and ignition routing.

What are the O2 readings and iac counts during the idle strugle area. Sounds like it may be running real lean or the min air is out of adjustment. As always new combos will take some time to get running properely.

 

eric, I think that you hit the nail right on the head. The BLM is at 158 and the INT is at 156,, and the ground prong on the #1 plug is whitish.

In the past, I ran some race fuel which contained some lead,,, should I replace the O2 sensor?

Also, I have the fuel injector constant at 23.8 for the 24#/hr SVO injectors. I was going to "burn" a new Eprom with this value set at 21.0. But my fuel pressure is currently 58psi,, so with that the injectors should flow about 30#/hr. (Even before the short block switch, the BLMs have been around 150.) I'm assuming that BLMs above 128, means a lean mixture and the ECM is compensating by adding more fuel. Is that correct?

Any advice concerning the above???

 

I wouldn't trust an O2 sensor that has tasted lead.

So, once you've checked for vac leaks, minimum air, etc, I'd recommend you set the injector constant to your best estimate of what they'll actually flow at your fuel pressure, and leave it alone from then.

Then, start working on your MAF tables -- I think you'll find you'll mostly be adding fuel, given your increased displacement. Like RBob mentioned, work towards getting the MAF tables correct for normal operating temps, then worry about the coolant temp enrichment, etc. for warmup.

(My TPI MAF experience is limited, and only with $6E, so other folks will have to chime in with the $32B-specific advice. In $32B, you also have a BPW vs load table, that could be tweaked in addition to or instead of the MAF tables. Bottom line IMHO is to get the base fueling correct across the whole load & rpm range, then worry about temp corrections, AE, and PE, etc.)

Also, I see in your mods that you have a descreened MAF, so expect to spend awhile getting the MAF tables correct.

You are correct that a BLM above 128 means the ECM is adding fuel. Keep in mind that doesn't necessarily mean that you are lean, only that the ECM thinks you're lean.

Good luck,

 

Dave, your post is right on.

I would be the first one to calibrate the MAF tables but there is a max value for each MAF table. I need values that are higher than that limit. So this leaves me with lowering the injector constant in order to reduce the BLM value from 158 to closer to 128.

(BTW: I got a '99 LS1 Camaro along with LS1Edit for tuning purposes. I purchased a larger diameter screenless MAF for the '99, and had to modify the MAF table to bring the PCM in balance for fueling. So I would prefer to modify the MAF tables in my '87 Camaro, but can not do so due to the limitations in the coding.)

The car idles much better with the 6E modified ARAP bin. I dont know why. But now I should be able to set minimum air and the IAC.

I have put together this SuperRam many times, so I am very conscious about vacuum leaks. I have not been able to find any, so I will sat what many people do: I have no vacuum leak.

 

doc your back. im living in northern oakland county still. toss me an email djfreggens@aol.com

 

No reason you can't increase the limit. Are you speaking of the max airflow vs RPM table? If so then increase it. All it is is a limiter.

If you are speaking of each MAF scalar table limit, then it gets tricky but not impossible. You can still increase the limit of each table.

RBob.

 

Rbob, thanks for the response.

Can you explain how the RPM vs MAF flow table works into things? How does the ECM use it and when (like close loop or open loop).

I figure that the ECM uses the 6 MAF tables directly in figuring the PW. I dont see how the RPM/MAF table comes into play. After all, the ECM receives a count value from the MAF and uses the 6 MAF tables to look up the MAF flow.

As far as modifying the 6 MAF tables, I would very much prefer to do this, but I cant due to the limits on each table. I believe from past post about a year ago, that I would have to modify the source code (or something like that) to get past this limit problem. I do not write source code or assembly language (what ever it is). I do know how to write Fortran.

One strange thing to report: In doing a scan with my crappy Xray 240, the MAF flow was like 15 gms/sec at 1500 to 2000 RPM on a 395 cu in motor,,, does that sound right???????????? I figure that it should have been about 50 gms/sec.

 

A lot of this has been covered before, search on MAF and grumpy, mine and funticks names.

The max airflow vs rpm table is always in effect. And limits the max airflow to be used for the PW calc. And is also the reason many claim to not peg the MAF.

The scalar tables (6 MAF tables) can have the limit on each table increased (up to 255 gms/sec). Search as mentioned and there are several good threads on the math along with explainations.

RBob.