I have a stock 89 L98 w/ stock TPI intake, but Bosch III injectors from SB. Fuel system and ignition system are both new end-to-end. Fuel pressure is 65 w/o vacuum, afpr drops it to 43 1/2 as it should. Timing is bang on 6 btdc. TPS is at .54 w/ car off. IAC cleaned and idle reset.

At idle, my BLMs are at the floor at 108-112. Any other situation they're close to 128. Had a mail-in-tune done and my idle BLMs on that one are the same, even though the rest of the rev range is a bit better.

I can't find any leaks in the manifold nor vacuum system.

I'm trying to figure out if this is simply a difference with these injectors that I can tune around, or if I should ditch them for something else entirely.

Any advise would be greatly appreciated.

 

So you're trying a STOCK tune and the mail tune?

If yes and no vac leaks might be time to check a new o2.

 

I did try both stock tune and mail tune, same BLM values at idle.

I had a fogger on vac and couldn't find any leaks.

I have a spare O2 so I'll swap it and re-check. Cheers VI

 

Can you show us a datalog?

 

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Try the O2 sensor. Then if that's not it, you can eliminate some problems by correcting the fueling via tune. If it takes it and fixes it then that tells you which path to take for finding the cause.

 

I went and did a datalog with the stock tune and BLMs were way better for what-ever reason. The stock tune overall was lean, so I guess I'll be swapping back to the mail tune anyways as that was addressed with it.

I did see the O2 reading jump from 150-200 to over 1000 intermittently. Edit: The more I read the more that looks sort of normal? No idea, I'll probably swap that O2 anyways.

Attached is the xdl from TunerPro RT

Using: $6E-1227265-V1.2.adx

 

Unless I missed something your fp should be at 43 without vacuum.

 

engine off 65 (prime), engine on/vac off 43.5, engine on/vac on varies depending on vac of course

 

128 divided by 133 = .96240602 x 22.4 = 21.5. Change your flowrate to 21.5 lbs. based on your log.

 

I haven't looked at the log but changing injector constant is not how you fix this issue unless you changed flow rate. and that also wouldn't make sense that the oem tune is better.

 

You know what they say about opinions. His blm averages in the log were about 133 so my method would absolutely work in bringing his averages down. Or, he could turn fuel pressure up until his blm average came in closer to 128. Mass air cars don't have VE tables to tune like your 92.

 

My opinion (with the limited info given from the OP) is that this is the WRONG way to bandaid your car.

 

And you have that right! Bring his blm averages closer to 128 will only make it run better. What is it that you propose?

 

The low BLMs were present in both tunes, that is what prompted me to post. Of course when I checked/logged yesterday, they were way better. I dug out my new O2 from my parts pile, so I'll put that in before moving forward.

I'll run both tunes again after that to see if I can replicate my original issue. If not, could have just been an intermittent O2 sensor. I can't exactly modify my tune until I get a chip burner though.

 

Mr ****** I already proposed something. And asked more questions along the way that still need answering.
Until the answers and o2 are checked I will not suggest anything further as that is incompetent.

OP you've said that the stock tune has an idle BLM issue and that it doesn't. So which is it?
You need to narrow it down to using one tune or the other. Don't flip flop.

 

And no it won't really with your solution. This is a bandaid solution to a single minded BLM view. You don't tune BLMs with injector constant. There's a MAF calibration table you use. What you propose is not an EFI solution to an EFI problem. It's a carb solution to an EFI problem. It doesn't work that way if you want something done right.

You don't flood a sink to fill a cup.

 

I was clear that both tunes exhibited the low BLM issue. The only flip flopping occurring is in political speeches. Maybe you misread.

However, I was asked to provide a datalog (by MrWillys). I did. When I did, the issue was not present. That makes it an intermittent issue.

It was initially suggested to swap the O2 sensor (by you, Vanilla Ice). I said that I have one, and will be doing so. After that, if the low BLM issue does not surface again, then it was most likely down to an intermittently bad O2 sensor, correctly diagnosed by you.

If it does surface again, then it's something else screwing up, and probably not a tuning issue.

 

No worries, I was under the impression from the log post that the stock tune did in fact correct the BLM idle issue but you were going to swap the O2 anyway.

 

Your o2 crossing over from rich to lean is normal operation and how the system functions and your o2 is operating correctly.

 

Actually a global adjustment being made first won't throw off the PE tables like your method. I do the same with SD cars so extra work in PE is not needed.