BLM Stuck at 145. ‘87 GN


Jul 24, 2010
BLM is stuck at 145 unless I decelerate.

I have checked for vacuum leaks and have found none. The car runs great.

What else coukd cause the high BLM?

Note: When in cruise this car was nearly always +\- 5 of 128 on the Scanmaster or laptop when connected to the PowerLogger.

This 145 thing is recent and I really don’t want to drive it this way.

I’m scared to death to bring it to a repair shop. We know what’s gonna happen.

I’m thinking of buying a smoke machine for the possible vac leak.
I’m thinking of buying a smoke machine for the possible vac leak.
I would 100% recommend this.

I was able to find a leak that was happening at the IAC connector...
2 more common locations:
1. The ft of the plenum just behind the IAC. No bolt there. The plenum warps and then...
2. The EGR. Could be the gasket or the diaphragm.
A smoke test may be a real eye opener!
Without a machine, I have restricted the tail pipes with wet rags, and then gave the intake a shot of
either light oil like 3 in 1, WD 40. Something to make smoke.
I got mine from amazon. Hazzard Fraught might have them too :)
o2 sensor
You nailed it. I installed a new AC Delco O2 and the BLM’s are now +\- 5 of 128.

And I was wrong about there being a Delco in there. There was a Denso in there that a TR shop up here in the northeast said they changed out. They didn’t.

I also bought a smoke machine. Found one tiny leak but that wasn’t the cause.

when my BLM's start moving around to a abnormal # I check fuel pressure first. I see you log it. A + or - in fuel pressure can make it off.
Thats my first goto check,It cost nothing takes just a minute to check. Its a dirty shame a 02 only lasted 5000 miles do you run Race gas?