Startup Problems

[88GtHatchback]

Ive been Tweecing for about a month now and have the MAF transfer pretty close. I have an 8LD using the A9S strategy. I have a problem when I start it. In the morning, after it has sat overnight, it will start just fine. When it is warm, it will start fine but either surge and want to die, or it will just die. After its running, it idles fine. I would say for the first 30 sec or so, it will want to surge. I set the idle using EA but it didn't help. What do I need to do? Do I need to zero out some columns in the startup fuel table?

Thanks,
Clay

[93Cobra#2771]

What size injectors? Any vacuum or exhaust leaks?

[88GtHatchback]

It has 30lb injectors. No vacuum leaks. There is an exhaust leak where the mufflers connect to the h-pipe. I dont think that would matter because it is behind the O2 sensors.

Clay

[93Cobra#2771]

Correct, exhaust leak that far back shouldn't effect the O2's, will just sound like ass... :D

What do you have your high and low injector slopes set to? Have you used EA to establish the slopes?

[QWKSNKE]

sounds like the startup fuel table vs ECT needs to be toy'd with

[93Cobra#2771]

Prob. right, Lee. Just making sure nothing was screwy on the injector slopes...

[88GtHatchback]

EA calculated 31 high and 33 low.

[93Cobra#2771]

Next step: startup fuel table... :D

[Dale McPeters]

Next step: startup fuel table... :D

:D

Just a suggestion but try changing the 45 sec. row in the startup fuel table to all "0's". That is if no mechanical issues are present.

[88GtHatchback]

In my stock tune, the 45 sec row was already 0's. I changed the TB air flow back to stock and also the ISC neutral idle air flow to stock. Seems to be better than what EA sugested. I will mess with the startup fuel table and see if it helps.

Clay

[Dale McPeters]

My statements are made based on '88-'93 EEC-IV cars.

Since I do not know what your complete combination is just some suggestions stated below.

I would also recheck your maf curve and injector settings as the 31 & 33 do not seem right to me. It looks like you used the injector slopes to compensate for something else like the maf curve, load etc. being off....
Normally I have seen injector H/L slopes set the same 30 & 30 or 30ish & 36ish. Well except in some cases on some blower/power adder cars.
When I ran 30's I had them set to 30 & 30 using the X3Z based cobra setup. Of course I am always the odd ball.

If you used EA to calculate the injector settings before the MAF curve was dialed in correctly this maybe why they look so different to me.

One other thing that I would like to add is the MAF curve is the most important part of the equation....

Note this is just MHO, YMMV.

[88GtHatchback]

So would you suggest that I go back to 30 and 36 then work on the MAF curve some more? Ill give it a try. I did play with the startup fuel table and I think I got it a little better. I will see today when I drive it.

Thanks,
Clay

[93Cobra#2771]

Nope, I'd leave the EA suggest MAF and slopes, and focus on your startup fuel table...

[Dale McPeters]

Agreed.

The post that I made above was really more of an observation than suggesting that you start over...
I do however suggest that in the future if you ever do start on another tune that you dial in the MAF curve "before" running the injector stuff through EA.
The closer you can get the MAF the better off you will be, because if it is off you may run into problems down the road with your tune changing over time etc. etc. etc.

[88GtHatchback]

I will keep messing with the startup tables. I can see myself starting a new tune in the near future. Im going to the track this weekend so I dont have time to do it before then.

Clay

[86GT]

It might be better to set the slopes as Dale mentioned. This is only if you have the fuel pressure set to the factory setting of 39psi. The slopes are the one thing that you can get close by guessing.

The MAF on the other hand is the most important thing. If you artificially lowered it or raised it while compensating with the slopes then the LOAD calculations can be way out. This will ein affect mess with spark and fuel.

I would make sure the MAF is correct. Where did you get the original MAF curve? If it is unknown, then I would definatley set the slopes to what ever the injector size is plus or minus some 'x' amount for fuel pressure differences. Then soley concentrate on the MAF.

[86GT]

Another way to do this would be to place a stock MAF and MAF curve in and tune the injector slopes, breakpoint and offsets. Once all that is dialed in then swap in the new MAF and never touch the injector stuff again.

[Dale McPeters]

:D