BLMs still 105 at idle... whats up?

[tpivette89]

ive had this rich condition for about 3 months now, and after i replaced the plugs/wires/fuel filter it ran much better and the richness seemed to be gone. i drove it like this for a few days thinking everything was good. then i decided to hook up my scan tool to make 100% sure the rich condition was indeed gone. well, it wasnt. even though the car felt much better, my BLMs at idle after the car was warmed up and in closed loop were a constant 105

any ideas what could be causing this? is it possible that my Tomco 30# injectors and high flow fuel pump are too much for the stock chip to handle? any suggestions welcome... i want to get this thing running right before the tracks close for the winter

BTW - i swapped out MAFs and got no change

 

[BRAD_PADGETT]

TPVETTE- I have a very simular car but I have not taken the time to figure out how to put my mods in a signature. My mods can be found at GNTTYp.org-Hot Air-Thread- What size injectors.

I have the same size injectors with a walbro 340 hot wired. ( I have a hot wire kit you can have for free w/o instructions. Racetronix will give you them). I was running rich as well with the fuel pressure setup. In order to get to an o2 sensor at WOT of .40-.42 I had the completely reduce the adjustable fuel pressure regulator(Postons resale) to the lowest amount. The lowest I was able to get to was 39ibs. Always rely on the knock gauge and the scan tool. Brad

 

[buickpower]

what maf do you run? one that reads too high can cause low blms according to eric marshall and some others. I think because the computer thinks the engine is ingesting more air than it is, and adds fuel accordingly.

 

[tpivette89]

Brad - my injectors are Tomco 30lb units. practically brand new with only about 300 miles or so. thanks for the offer on the free hotwire kit, but i already have one... i just havent installed it yet. i do have an Accufab AFPR, and while i do think its set a bit high (43lbs or so) i dont think that would throw my BLMs off that much? maybe im wrong. this weekend ill have to reduce FP and see what happens

BuickPower - currently im using the stock MAF. i tried a rebuilt unit and got the exact same results as the stocker. at idle with the car warmed up MAF readings are around 11 g/s. the idle was a bit high when i took that reading though... i think rpms were 1100 or 1200. sound about right to you or is it off?

 

[BRAD_PADGETT]

TPIVETTE89- I had problems with high idle as well last summer. My cure was replacing the stock MAF with the Tomco unit I got from Postons. The cost $130 and works with years 1984-1987. Good luck- Brad

 

[buickpower]

11 still sounds a tad high to me, but who knows. Is 1100-1200 what your car normally idles at or was it just not warmed up yet? When I had a stock reman. maf the car would idle at like 7 or 8g/s at a warm 800rpm idle. Switched to an LT1 out of a roadmaster and a regular translator and immediately it went down to a more accurate 5g/s at the same 800rpm idle. That cured my off idle hesitation right up, my best guess is because it was no longer loading up with fuel while idling.

 

[Jerryl]

MAF Idle values should be in the 4-7 range. Quick Reference GNTTYPE

Make sure your IAC and TPS are set correctly. Your Idle RPM should be in the 850 range in Park. You may also have a bad MAF but hard to say unless you get the RPM down.

 

[cool 84]

With the slightly bigger injectors and FP being just a little high, that could cause your problems. Are you running the stock 84 MAF with the 84 computer or 87 computer? The reason I ask is that the 84 MAF is calibrated different and the car will run rich at anything below WOT with the 87 computer. The other possiblility is the chip has just a bit too much fuel. Either way, your BLMs can go as low as 90 so you're still in the good range.

 

[boostmaster]

Lower your fuel pressure to around 38psi static, 43psi is too much fuel for a lightly modded car on the street and small injectors. Idle should be around 650-800 unless you have a huge cam.

 

[tpivette89]

looks like the thing to do here would be to reset my IAC and TPS values and try to get the idle down abit. then adjust fuel pressure to 38psi or so and see if the BLMs improve. im heading out to dinner, then when i get back i do the above procedures and see if anything happens