hello ive got an 89 iroc 355 tpi with 268xfi cam with a pcmforless tune. The idle is really rough and it surges up and down.. then usually when i give it gas it wants to stall. i have an autoprom and tunerpro RT and i just learning how to use the program... i know its a complete newbie question.. but i would like to know what values to start changing so that i can get some results.... if more info is needed i can try to post up what the autoprom datalogs when its running. etc. ive done a heck of alot of searching and reading and its all a little too in depth for me right now.. i would just like to be pointed in the right direction. thanks Speed

Make sure you don't have a vacuum leak before you start changing the tune.

TPS is correct? What are your IAC counts at idle in closed loop? Upon startup I have some surging due to the IAC trying too hard to keep the engine running etc, but once it hits closed loop it runs perfect. I'm about to start adjusting the OPEN LOOP AFR RATIO % CHANGE VS COOLANT TEMP section and the other open loop tables to try and counter that on cold starts etc.

You need to get it up and running and tune P/T before you start messing w/ idle though. I tried that before and ended up chasing my tail more than helping.

Also... What size injectors and what injector constant are you using? What's the fuel pressure set at? You may need to play w/ your injector constant to richen/lean up the car some...

But you need to log and see how rich/lean it is running based off the BLM's etc...

Is it drivable at all? Or is it just quirky at idle?

Get a wideband before you (and we) go absolutely nuts trying to guess what's happening.

A solid 50% or more of "tune" problems are hardware problems (vacuum leaks, valve adjustments, spark plugs cracked, base timing not set, TPS out of whack, stuff disconnected, bad grounds, low fuel pressure, low compression pressure, exhaust leaks, broken crap - especially ignition components, melted plug wires).

I would have guessed that the MAF system would run like a champ with that cam and a bin with the injector constant changed for (you surely have) larger injectors, maybe a tad higher idle speed, maybe a tad lower closed loop gain, and some more AE.
Even stock bin should run "fine" to most people. If not, start diagnosing all possible hardware.

have 30 pound accel injectors.... the idle is really rough when i start it cold it goes from about 400 up to 1500 over and over[surging]. ive got the fuel pressure set to around 42. but when i watch my gauge it also increases and decreases with the idle. For the first ten minutes maybe the idle is like that and then when its get warm the surging goes away and seems to run alot smoother.
This is all with my pcmforless bin.
I tried running on the stockbin and it tries to idle steadily around 400 or 500 rpm but it just keeps dying right away.

think maybe i should crank up the fuel pressure??im worried the stock fuelpump wont like that.

il do some more datalogging with the autoprom and write down some values for ya... all i remember off hand was that the throttle position stayed at .57 volts.

i dont beleive i have any vacum leaks.. funny though... the idle surges up and down and i discovered when i diconnect a vacum line to the plenum so that it sucks more air the idle gets smoother.
thanks so far.
Speed

Well, it's probably too rich then. Have you looked at your spark plugs? Probably sooty after the surge.

What are teh BLMs when warm? If they are going down to 108, you'll need to lean out the injector constant (by increasing the injector flow constant).

If BLMs are near 128, then your warmup enrichment or afterstart enrichment or both are too much. If it's surging, it'd be ok to pull fuel in 5% decrements, unless you have a wideband which would make this a heck of a lot easier.

You should also check your IAC counts when warm, and try to open the throttle set screw to get them down below 20. Then, on the next cold start, watch what steps are needed for each temperature and use that for the Park Position vs coolant temp table. If the IAC is overreacting, it can surge. Disconnecting a vacuum line leans it out and gives it more stable air (usually it's too lean and makes it surge, but with your bin out of whack... it actually helps).

okay....BLMs when warm are 128 until you give it some gas and it goes down to 108.
iac counts after about 10 minutes of running are around 160.. im running about 44 to 45 psi of fuel i have 30lb injectors.. i cannot figure out how to check/ change the constant.. what table should i be looking for? when im rolling up the street and it give gas it falls on its face and dies... i decided to watch the volts to the fuel pump when i did this and they stay around 13.6 from idle to about 10 km/h then if i get on it [give it gas quickly] it immediatly drops to 12.something and then to 11.8 or so and thats when it dies.. this all happens in like a second. Im not sure why... fuelpump packing it in? Also What is an intergrator [INT] its values are in red and are around 105... what is this?

thanks for your help so far.

Two things are giving you indicators of what is happening.
The BLM is trying to remove fuel (108 is max amount of removal), the IAC is at 160 trying to get more air into the motor (160 is maximum it can go)
From there, you have too much fuel and not enough air.
Correct one or the other and things will get better.
With the IAC at maximum, you need to open the mechanical screw to let more air in at idle (then reset the TPS to be below 0.50 volts.)
I'll yeild to the MAF guys for how to get the fuel corrected.

How much power will the stock TPI fuel pumps support? Its probably old and wouldnt hurt to change it

stock supports 283 rear wheel horsepower.... time for a new fuel pump =(

"the idle is really rough when i start it cold it goes from about 400 up to 1500 over and over[surging]"

What are the idle rpm v coolant settings.I had the same prob with stock setting and cam until I adjusted them up.
The ECM was trying to acheive a idle that the cam would not let the motor run at ;hense the surge up and down.

injectors are way too big.

it was my understanding that the injectors should be fine as long as the computer is tuned for them.. my mail order tune should have covered that.

other opinons?

your BLM's are bottoming out. your pig rich due to injector sizing.

Try adjusting your injector constant up.Not optimum as it affects fueling across the whole range but if your numbers improve you know your injectors are too big.
People run 383's with 24lb's

When you're checking your fuel pressure at idle, you are doing it with the vacuum scource off the regulator, right?????

i use one of these gauges that mounts on the fuel rail.

Do you pull the vacuum scource off the regulator before you read that gauge?????? If your injector constant is set to 30, you should adjust your fuel pressure to 43 psi WITH THE VACUUM SCOURCE OFF OF THE REGULATOR.

The line should also be plugged when doing this yes?

It doesn't really matter. The only reason I bring it up is because he said the pressure would go up and down with idle.

It sounds to me like he's got it set to 42 PSI @ full vacuum idle, this would make the WOT and part throttle psi considerably higher. It would be one of the reasons he's running rich.

Certainly sounds like good simple advice to start with and makes sense to me. Of course I'm sure speedmachine would have SEARCHED for the CORRECT way to adjust the FPR before setting it now wouldnt he?

okay heres the update.. i ordered a walbro fuel pump from racetronix and installed it, new fuel filter, and the fuel pressure is set to 45psi with the vacum line unplugged. i got my afpr used as a throw in on a deal and it didnt come with the spacer washer that goes inbetween the spring on the diaphram and the adjustment skrew. so i made one.. however completly backed off the fuel pressure is 45psi.. so i think my little spacer washer that i made is toothick...

next step are probably to just buy a new adfr to try and rule out the problem ive got with my bbk one.... any suggestions on a brand?.. the accel one comes with a new diaphram and i think the holley one does too.ill do a search

the problem is im running rich with the 30pound injectors so i should reduce fuel pressure, but my reg doesnt go any lower than 45....no good

im thinkin about putting my 24 pound accel injectors in and then just increasing fuel pressure cause my new pump will handle it.... certainly for me all signs point to putting my smaller injectors in.

opinions?

Lee

put smaller spacer in reg.. got fuel pressure down to 43 psi. BLMs start at 128 but then go down to 108 and INT is at 104. Still runs rich, seriously considering swapping in the 24lb/hour injectors and crankng up the pressure.
Iac counts are around 100-110 tps is .57 volts.. no codes... Car defiently idles too high [900-1000 RPM]

You never mentioned what the injector size is set at in the bin? If it is in fact at 30# try raising that up and see if the blm/int gets better. If you are running 30# injectors and the bin is set at 24# that would be your problem. You can also compare the inj. pw in the data log after making the injector size change, should decrease.

In TunerPro RT it's in the "constants/scalars" section and it's called "Double fire FI size @ 40 psig". (Yeah they had to think of a different name for everything to keep us on our toes!) To make it leaner raise the number, conversly to make it richer, lower the number.

Now, when you change the constant it changes the "world" of fuel your engine gets. IOW it makes it richer or leaner at all rpm/engine loads etc. Its a good way to see if you're WAY lean or WAY rich. I've found that as I get my tune closer I end up with the constant back to the "actual" injector size. But it's a start.

30s have been givin me headache... i pulled my intake off and am putting the 24s on... ill post up blms etc. when its back together and running and change the constant from 31 to 24 or 25.... what fuel pressure do most guys run 24s at?

thanks guys

Set your constant to 24 same as your injector. Set your pressure at 43 to 45 with vacuum line to AFPR removed. Check your BLMS and your IAC then. Recheck your TPS too. Your idle is going to move as you dial tuning in thus these two items move.

Yep, what he said. I run my fuel pressure at 47-48 psi and my tps at .57-.59. Once you get it to idle close you can tweek the idle screw, tps and all to fine tune the idle. And it seems to be a range. I mean, it doesn't want to idle EXACTLY where I set it. Don't forget to do the "set the idle" routine so it knows where you left the tps, throttle screw etc. I shoot for 750-800 idle cause it just "likes" it better there and I have the small crank pulley (power pulleys) and a tad high idle keeps the volts from dipping way down. Which is another "idle" issue in that the fuel is affected by the volts via the "injector pw correction vs battery voltage" table. Then there's the MAF tables ....

I tuned a xfi268 355, heads, intake with 24 lbs injectors, ran pretty good. No problems at all. Tuned with WBO2.

This year the car have been updated with a HSR and I tuned it again. The DC is 100% now @ 5600 rpm with 50psi, but the tune is a bit rich at WOT 12.2 AFR. But I woulndt go with smaller than 24 lbs with a HSR intake on. He will probably upgrade to atleast 28lbs, depending on future mods............

/N.

okay heres the update, i pulled the intake off and repolished it and i put my 24 pound injectors in. i put her all back together and while i was at it i built a cold air intake. I changed the constant on my pcmforless chip from 30 to 24 and the car did not want to start/run. so just for giggles i decided to put a stock arap bin in and see if it would go... to my suprise it started and ran pretty good. So i then decided to change the constant on the stock arap bin to 24 and it didnt seem to run as crisp. so currently ive got just a completely stock arap bin in and it runs way better than before with the 30s and the mail order tune. i havent changed the fuel pressure yet so it is still at 43. I will post up blms etc soon.
im considering goin to a dyno with a wideband to try and dial in the air fuel ratio now that the car is streetworthy..

thanks for all input so far.

okay, changed the fuel pressure to 45 psi, blms are 128 but sometimes turn to 150 at idle and then the car dies. iac counts seem to hang out around 62-70. tps is .57. This is all on the stock arap... so im thinking of starting fresh with that bin instead of trying to doctor up my pcmforless bin. I havent changed anything yet. ive read up about the super apyn by traxion and was thinking maybe i should use one of those bins instead to start with?... i have to change the injector constant to 24 in the double fire FI size.. do i change the single fire FI to 24 as well or to 12? Here some of my other questions..
1. what table do i change to account for my 160 degree thermostat
2. what table do i change to delete egr and A.I.R.
3. what table should i change for a 2800 stall

thanks so far

If you are trying to run at 160 degs. I think that is too low. 180 would be better. Look for the open loop to closed loop tables for temps and times for changes, also the fan on/off tables. If you are planning a street driver, I don't think 160 degs. is good for the motor.

really.. well if it isnt healthy ill change it.. i read in a magasine it was good but it could have been a load of crap.What is stock again 185? or something maybe i will change it to 180.

Stock is probably more around 195. I run mine with a 180 stat and set the fan on at around 185. But radiator size, water pump, fan shroud, all play into the cooling. Low temps cause oil sludge buildup and actually lower H.P. Prostock guys always talk about their engines like to be hot, staging duals actually throw the launch setups off because the H.P. has increased with the rise in motor temps. Of course there is a limit to how hot is good. The higher OEM temps are good for emissions.
A cooler intake air charge is always helpful.

Smokey Yunick said you want hot oil and cool coolant for max life and power and he built some of the baddest stuff in his time. 180 vote here too

kk went to the dyno, got a local tuner named peter to tune the car... the air fuel was set to a perfect 13.1 across the board. however upon futher investigation to his tune i found that he didnt even change the injector constant to 24. i have changed the injector constant to 24 now, and timing is a problem.. it is set to 41 degrees... i have set base timing on car and computer to 9 degrees and max spark advance to 31 degrees.. the car doesnt like the change... im going to back off base timing to 7 degrees or so and so from there... this is with the stock spark advance table. i also have the "phantom lean condition" where crusing blms are 108 and idle they are 147 because of my cam.. what do i change to accomodate this?

thanks

Fix idle first, then cruise, then dyno. the changes you are making after the dyno will change the AFR at WOT.

No air to manifolds = 100 mv to rich O2 swing point. Air pump leans the AFR and the stock tune adjusts for that. The 100 mv is preloaded into the O2 swing points and then the 100 mv subtracted when the air is diverted to atmosphere.

when i drive at WOT the car throws the ESC failure code... thoughts on rectifying this?.. what would trigger that code?

Do you have the correct knock sensor? When I replaced my engine with a used one from an 89 it ran okay but failed e-test and didn't have much power. I realized it was an esc issue so I searched and found out they changed the knock sensors with the maf to sd change. Swapped the knock sensor from my 92 engine and it solved the problem. You can also check the resistance of the knock sensor to see if its the right one. I can't remember the specs though.

Not True!!! You can tune with your BPC~VS~EGR on a 7749 for injector pulse width and adjust your injector sizes on a 7730 ecm..

This is something people on the DYIPROM forum have been discussing for many years. Many people have gone out and heavily modified their engines and then purchased some aftermarket chips that claim they can make your engine run after the modification.

Then they might have to send the prom back 2, 3 or 100 times because something is not working right on their setup.

The only way you can get the most from your individual engine, sorry to say is get the software, hardware, and read the stickies on how to program your own chips. I am still learning and it really isn't that hard once you know the basics.

some of the basic and advanced things that are easy to do is..

1. Turn off VATS
2. Advance or retard timing
3. Adjust Fan turn on and off at different temps.
4. Major and minor fuel modications
5. Boost for Turbo's, Superchargers
6. Startup, AE, DE, PE, Knock

Some of the best software to use is either RT Tuner Pro or C.A.T.S.
Datalog software like DATA MASTER
Get Emulators like Autoprom or Ostrich from MOATES.NET

If you keep a copy of the basic bin your car uses you can always go back if you screw up..

new thread.. please take a look

http://www.thirdgen.org/techboard/di...c-stealth.html (tuning 355 vortec stealth ram... stumped)


Speed