Plummeting BLM's at cruise...I'm lost....

[Missouri T]

Hi folks,

I'll be cruising along on the highway holding 128-130 BLM's and, all of a sudden, they'll drop straight to 115 and the car will stumble.
Then the BLM's will slowly creep back up to the 128-130 (takes about 5 seconds).
There is no rhythm to it at all, just out of the blue.
It happened 6 times on me in 16 miles one day going to work.

When this happens:
The O2's go up to the mid 800's.
The car will stumble and be sluggish to accelerate.
I checked fuel pressure (43PSI base with hose off, about 38 with hose on) when this happens today with my "windshield test gauge" and it is rock steady so no problem there.

Cruise is smooth as can be otherwise.

The only other oddity about my combo is the RPM's drop quite a bit (almost stalling every now and then) when coming to a stop. They do recover.

TT pump gas chip (actually an updated one Eric sent me that helped my idle-in-park-hot immensely)
4" Full Throttle Mass Air (new style mass air)
All numbers on the Scanmaster are spot-on, believe me....I'm extremely watchful of my sensor settings.

Any help is appreciated.

Thanks.

 

[affordablegn]

Stumble

Are you using a translator or translator pro.
I heard something about the 4" MAF from Full Throttle.
You must have a new or upgraded translator.
I am not sure on the version you need to have.
Which version translator are you using?
You might want to check with Mike at Full Throttle to verify this.
It's just an idea?

 

[TurboDave]

Hi folks,

I'll be cruising along on the highway holding 128-130 BLM's and, all of a sudden, they'll drop straight to 115 and the car will stumble.
Then the BLM's will slowly creep back up to the 128-130 (takes about 5 seconds).
There is no rhythm to it at all, just out of the blue.
It happened 6 times on me in 16 miles one day going to work.

When this happens:
The O2's go up to the mid 800's.
The car will stumble and be sluggish to accelerate.
I checked fuel pressure (43PSI base with hose off, about 38 with hose on) when this happens today with my "windshield test gauge" and it is rock steady so no problem there.

Cruise is smooth as can be otherwise.

The only other oddity about my combo is the RPM's drop quite a bit (almost stalling every now and then) when coming to a stop. They do recover.

TT pump gas chip (actually an updated one Eric sent me that helped my idle-in-park-hot immensely)
4" Full Throttle Mass Air (new style mass air)
All numbers on the Scanmaster are spot-on, believe me....I'm extremely watchful of my sensor settings.

Any help is appreciated.

Thanks.

I don't suppose you have Direct Scan or Power Logger do you? Something you can see your entire BLM matrix all at once?
The reason I ask is, your BLM's can't just drop suddenly as you describe, but what can happen is the load can change just enough to move into a BLM cell that may not be hit very often and hasn't had a chance to learn in well enough yet, or for some reason has learned badly.
Looking at the entire 16 cell matrix would show this immediately.

 

[Missouri T]

I don't suppose you have Direct Scan or Power Logger do you? Something you can see your entire BLM matrix all at once?
The reason I ask is, your BLM's can't just drop suddenly as you describe, but what can happen is the load can change just enough to move into a BLM cell that may not be hit very often and hasn't had a chance to learn in well enough yet, or for some reason has learned badly.
Looking at the entire 16 cell matrix would show this immediately.

Hi Dave,

Thanks for the input.
No sir, I only have the Scanmaster.

I am perplexed as can be about the drop.
I'm serious......they go from 128-130 immediately to 115, then the engine stumbles and is sluggish to accelerate until it gradually climbs back to the original 128-130 (about 5 seconds).

The car has well over 200 miles since I installed the updated chip from Eric and the subsequent ECM reset.

Think I should reset the ECM and try a relearn?

Thanks again,
Bill

 

[Missouri T]

Are you using a translator or translator pro.
I heard something about the 4" MAF from Full Throttle.
You must have a new or upgraded translator.
I am not sure on the version you need to have.
Which version translator are you using?
You might want to check with Mike at Full Throttle to verify this.
It's just an idea?

Thanks for the response.

I have a standard Translator.
I do have the latest version (6.25) so no problem there.

The 4" intake has been a REAL learning experience to say the least.