Hi guys,i have an 85 and i know this isn't the best ECM to work on.Looking at the stock tuning,with a stock car (minor modds) i was thinking if this tune has somewhere something to refinish to find some lost hp.I was thinking to the conservative/to much conservative AF/R at wot to avoid detonation.Monitoring my AFR with my Innovate wideband i see that my afr is 10.50 at wot.I think (but i'm a newbie) 10.50 is too much rich,even at wot.i know some guys here are in the 12.50 high 12's.Can i expect any improvement at wot with a afr in the 12.70s.There are some other place where i can put new numbers to raise some hp on a stock car or gain up a little throttle response,simply working on the tune?thanks guys

As for Pe tables you sure advice me to work on to lean out ,i have a 870 ECM and only this PE appears,i've opened some othe tables just in case:
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You almost can't go too rich at WOT. The engine gets real hot real fast and the rich mixture helps cool it.

Also, under heavy load at WOT is the worst time to get detonation, and a rich mixture helps to prevent it.

You will be at WOT for a relatively short time. If you're not racing and looking for ultimate power you're better off leaving it rich.

 

Cliff can you tell me why my PE spark vs AFR in the pics is empty? may be i have the wrong XDF for my $1f eprom?as you can see my spark degrees row is zero

 

He says he is running 10.5 AFR at WOT which is way too rich for power. He needs to lean the tune up to 12.8 or so at WOT. At 10.5 you are very close to rich misfire, I never leave a tune that rich. I would lean the WOT tune up at least 15% which should add a nice power increase and it will still be plenty safe.

Change your WOT vs coolant temp table from 22.66 to 15 and see where the WOT AFR is. After that change your WOT vs RPM table to negative numbers to try and lean the car up to mid 12's at WOT. Your PE spark is zero because the tuner probably added in all the additional spark timing in the main spark table. I see that your main spark tables are in the upper 20's until 4800 RPM where it goes to 32 degrees. This timing appears to be safe I would probably play around with more timing since most SBC make best power with 32 to 36 degrees or WOT timing. From 3200 RPM and above at WOT I would set all of the timing at 32 to 36 degrees and see how it runs.

 

Thanks Bjankusky it makes more sense now,that's what i mean :10.50 is waaay rich even for WOT,and i would lean out in the 12.70-12.80 range.The tune in the pics is a stock 85HLH $1f eprom, 870 ECM.My AFR reading comes from a Innovate LC-1 wideband sensor/gauge i can't exclude my readings are the results of an attempt of my ECM to compensate some air leak from intake or cuz i'm running an additional thermoswitch that open my fans at 82 Celsius and maintains a temperature above 85-88 celsius (185 F) that's too low for the stock tune.

 

The stock tune will not run rich because you are at 185 degrees. As shown on your OP the stock tune is designed to hold the correct AFR at any temperature above 133 degrees. The car goes into closed loop at 122 degrees. It is a common misconception that the stock tune will not work well at anything under 195 degrees but the truth is the car will work fine at anything over 133 degrees as far as power is concerned.

Do you have stock fuel injectors and fuel pressure? It appears to me that you may have increased the pressure or injector size without adjusting the tune for the change.

 

happy to hear about the temperature stuff,i'm currently running stock (85') 24lb inj's,(for a while i had Ford's 24lb and car was even richer),as for fuel pressure 85' prefers 35-38 psi cuz of the 24's vs 22lb@40 -43psi 86'>.I had an Ostrich waiting to go on my stock ECM,i had some newbie issues at my first attempt and it frightened me.Time to put my Ostrich on again and try some change to the stock tune.As you can see 85' tune tables aren't that clear as ARAP or ANHT,or, at least ,these appears to me...

 

I have tuned many 1985 TPI cars, and I agree with you they are not as clear but with enough effort they can be made to work fine.

Is that 35 to 38 PSI with the vacuum line disconnected?

 

ops...i've to say that it's slightly over,just cecked,vacuum disconnected i've 41 psi steady .My regulator bolt is fully loosened, tomorrow i will try to loosen more and re-ceck pressure.i've just lowered my pressure in the past...

 

It won't make much difference between 41 PSI and 38 PSI, you could just leave it if the lowest you can get is 41 PSI.

 

at light throttle the car runs 14.3-14.8 AFR, not that steady,,we can say it's about 14.7.It really smells rich,but the gauge says it's stechio.plugs are light brownish .idle is stumbling ,up and down,from 600 to 800 rpm,not that much,but not steady.Next to do it's a intake re-sealing.before touch the tune i want to be sure engine is perfect.

 

I also have an '85 and while I haven't run my car on the stock tune for a few years now I'm pretty sure it never ran in the 10:1 range at WOT even when I did. My current tune, which isn't anything too far from stock, gives me low 12:1 range at WOT.

Also, mine idles pretty smooth at low 500's RPMs when warm, bouncing around no more than +/- 50 RPM so it sounds like yours is not idling right. I would check your BLMs and make sure everything is in line before you go too far on the tune.

BTW: I am also running an Ostrich. Great little box.

 

My car surges too, about 100 RPMs. My target idle is 800 RPMs, mine is also an '85 with a flat tappet ZZ409 camshaft.

I was told the idle surge is because the camshaft is too big for the computer and it can't respond to the drastic changes in air/fuel ratio fast enough or something.

I don't know. He basically said that if I look at my O2 sensor on an oscilloscope, I'd see voltage going up and down, indicating rich/lean, rich/lean, rich/lean. He said every time it spikes upwards or spikes downwards that I'd probably hear it surge at the same time. He said when the RPMs raise, that voltage fluctuation on the O2 sensor will happen faster and the idle will seem smoother.

And I've noticed that too. My idle is set to target 1300 RPMs when really really cold. It slowly comes down, 1200, 1100, 1000. 900, 800 as it warms up. The idle doesn't surge until it reaches 800. So I may target 850 as a happy medium between lopey sound and smooth idle.

Just my experience. And I definitely think that you have a lot more power potential in the WOT AFR, and in your timing tables. From what I've learned with the extensive modifications that I've done, small things like that make the biggest difference.

I believe you are supposed to run in the 11:1 area stock at WOT. I would go all the way to 13:1, then work on timing.

 

i'm chasing this bouncing idle ,it's a long time issue,never solved it.it's an iac attempt to smooth the idle...i think it's a vacuum leak from intake base,upper intake /runners/plenum were sealed with new gaskets.Asap i'll post a video of WOT readings.

 

There are a bunch of things that can mess with idle so it's tough to know for sure. Mine didn't idle well at low RPMs (500-600) until I finally upgraded the injectors, so for me it looks like uneven injection was mostly to blame.

BLMs may help if it's something like a vacuum leak.

 

i always had low BLMs on this car,since i had log equipment,but the strange thing is when i datalog at WOT my wide band reads rich but BLMs and INTs are steady 128 as they are supposed to be (since at WOT engine runs in open loop).may be my misunderstanding but i tought 128BLM= 14.7 AFR,so why i've 10.70 AFR at wot and BLM are steady 128?

 

The BLM's are locked at 128 in open loop which means there is no fuel correction at that point, other then your adder tables. It does not mean you are at 14.7 AFR.

 

You need to work on the tune, with the correct the idle. With the correct changes you can get it to idle. Make sure your idle AFR is close to 14.7, make sure your idle timing is stable, make sure your IAC motor is near 20 counts at idle, slow up or speed up your IAC steps per second to keep the engine stable (Adjust this one last).

 

No, BLM=128 does not necessarily mean stoic. All it means the PCM is not correcting for whatever AFR it is targeting. During closed loop that is 14.7:1 but during PE it is something else. I don't know exactly what that "something else" is as I have never seen a way to modify it directly in the tune, but empirically it appears to be around 12:1.

Anyway, this may explain your excessive rich WOT. Low BLMs mean the PCM is leaning out the mixture during closed loop, but during PE a narrowband O2 won't provide any useful data so it goes into open loop. If the BLMs are low (as in your case) the PCM disregards them and resets the BLM to 128 -- meaning the AFR at WOT is relatively over rich compared to closed loop.

I suspect if you get your BLMs in closed loop close to 128 you will find your WOT AFR will go up to the 12's which is where it should be. Mean best torque can usually be achieved over a broad range of AFRs but until you get way too rich there is really no power loss. As such I would always err on the side of safety (low AFR) like Cliff suggests above. Definitely keep it below the 13s. Rule of thumb is something like 0.8 lambda or 11.8 AFR.

There is another thread going which ends up discussing whether high BLMs are used to enrich WOT. It seems like in some cases they are (though this doesn't apply to you):

http://forums.corvetteforum.com/c4-s...post1586726803

 

Rule of thumb in my opinion is .85 lambda or 12.8 AFR. Most engines makes best power between 12.8 to 13 AFR, I usually target 12.8. If I am running a forced induction car I may target 11.5 to 12 AFR since I am using the extra fuel to cool the combustion and prevent detonation.