87 GN intermittently “skipping””

[Cape Cod GN]

Hey all, my 87 GN bucks and feels like it’s skipping for a few seconds then runs fine. At WOT it will almost feels like a misfire and sometimes cruising it will skip and “buck” lightly. Here are my scantool readings at idle and warmed up:
MAF: 4
LV8: 27
Volts:13.0
BLM: 142
Speed: 0
Coolant: 190.8
Air Temp:121.1
RPM: 850
TPS: 42
IAC: 25
O2 CC: 1

I was wondering if the O2 CC is to blame? I have read different posts that it should be between 1-250 fluctuations and others say readings at idle from 700-800.
Also looks like my BLMs are high at idle when I go WOT they drop to the 120’s.
Anyone have any ideas on diagnosis from their experiences with these symptoms.
Thanks.

 

[Pronto]

When driving around are the CCs moving steadiy up?

 

[Cape Cod GN]

When driving around are the CCs moving steadiy up?

I’ll have to check...

 

[mikestertwo]

What chip are you running? What mods if any? Do you have a Powerlogger?

 

[TurboTnZ06]

Pull the cam sensor cap off, see if the rotor wiggles too much.

 

[TexasT]

The cc is the o2 passing 450 on the way up and the way down. Should be steadily counting. The int is missing. BLM is way high. The o2 should be moving around as you drive, but when at wit and accelerating you want 750 or so. Some run less but that is lean and you are playing with fire.

 

[John Larkin]

Sounds like when my MAF went out. What MAF are you using?

 

[Cape Cod GN]

Sounds like when my MAF went out. What MAF are you using?

John I’m using the LT1 with MAF translator.

 

[Cape Cod GN]

The cc is the o2 passing 450 on the way up and the way down. Should be steadily counting. The int is missing. BLM is way high. The o2 should be moving around as you drive, but when at wit and accelerating you want 750 or so. Some run less but that is lean and you are playing with fire.

Thx for that info TexasT.

 

[Grumpy]

stock cam ?

 

[Cape Cod GN]

What chip are you running? What mods if any? Do you have a Powerlogger?

TT 5.7 yes 2.0

 

[Cape Cod GN]

TT 5.7 yes 2.0

Not many mods:
Alky, Lucas 42 pounders, Walbros 350 pump, precision 61/61 turbo. Also have rail fuel pressure gauge.

 

[Cape Cod GN]

stock cam ?

Yes sir.

stock cam ?

yes sir.

 

[John Larkin]

Second thought, my balancer was actually loose once and the crank sensor was losing contact intermittently. It is an infrequent but not uncommon issue. It has to be torqued to 220-ish lb-ft. And you have to remove the intercooler and intercooler fan to get to it. You can put a small pry bar behind it without removing anything and see if it has any wobble. Worth a check.

 

[juan89]

I had a similar issue . It was a cracked spark plug.
https://turbobuick.com/threads/cylinder-balance-test.463937/

Juan

 

[dynoman]

Does it do it only when in boost ? What spark plugs ?
Non resistor plugs have been known to do what you describe , it happened to me .

 

[Grumpy]

I'd be checking it for a wiped lobe. easy to check.

 

[mikestertwo]

I would also check the cam sensor timing.

 

[Cape Cod GN]

I would also check the cam sensor timing.

That’s what it was. I bought a new Cam Sensor. The Cam Sensor cap was cracked. Thank you all!