high blm's

[trading t/a]

Had a slight exhaust leak(before the turbo) I fixed it checked for all other leaks(even blocked off all vaccum sources from the tb). BLM's never went below 160 with the leak 155 when the vaccum sources were blocked, fixed the leak now it sits at 128 but every few seconds it'll cycle to 160 then back down to 128 again(i assume when it cycles between open and closed loop. When it does that it stumbles at idle then when it goes back to closed loop in runs fine.

When i lock the chip into open loop it stays at 128, but the o2's never hit 500mv. they cycle between 150 or so up to 450. Haven't tried new o2 yet want to see if anybody else has any ideas.

I'm running an extender chip, msd 50's, pt-51 turbo, p&p big valve heads and matched intake, egr riser milled and filled, fp set to 45 psi(per the destructions that came with the chip )

Looking for other ideas

Pete

 

[TurboBob]

what MAF?
What chip number?
What are the settings in the Translator?
What are your cruising BLMs?


Bob

 

[trading t/a]

Stock maf, not using the translator at the moment only using the chip. dont have the number of the chip, but it's for 50's and it's a revision E I believe. It's for 93 octane.

Haven't checked cruising blms, car runs a little doggy down low till 5 psi or so then blows the tires off. It settles around 131 or so but haven't cruised with it. I just noticed the blm's after getting out of it and they went down to 131-134 at part throttle. Then the lean cruise kicked in .

 

[TurboBob]

well, running an Extender chip without a translator is a recipe for disaster.

How many screens in your MAF?

Bob

 

[trading t/a]

1 Screen front one. It was doing the same thing with a known good LT1 maf, I'm trying the regular maf to see if it's anything else that could be the problem. It seems to be isolated to 1 cell or so, if the rpms move up even 25(say 825-850 rpms) it goes to 128 or 131. Seems to be at that particular throttle angle that it goes to 160.

Gotta do more investigating with a propane tank.

I'll be in touch

Thanx Bob for any suggestions......

Pete

 

[TurboBob]

A slow O2 sensor (old, lead fouled) can do stuff like this. Especially an unheated one....

I had a cyberdyne O2 gauge cause issues like this also. But only with an unheated sensor.

Look for vaccuum leaks at the throttle shaft seals also.

If you lock the BLM with open loop idle at 128 - 135, does it idle decently or really rough? If it idles decently, why not leave it? If it had a carburetor you'd be tuning it by ear......

If you've never heard of a carburetor, ask your grandparents......

Bob

 

[trading t/a]

I'm not that young Bob, gonna be 30 this year. Remember cursing the quadrajet name for years


I'll be doing some propane searching, then if there's no leaks I'll change the o2, next then I'll just leave it. It is rich cause the spoolup is slow but from 5psi to 15 is a blink and then the tires just roast.

Maybe I'll try to trim some fuel with the trans + as a last resort.

Thanx again,
Pete