Surging when stopped

[1buick]

I have an 87 GN, the car surges lightly and has a light stumble also idles funny. I was thinking that it was a vacuum leak. I found a bad hose on the ajustable vp regulator and it helped but it's still doing the same thing only not quite as bad.
The car wasn't doing this until I drove it to work which is a 75 mile trip. Once I pulled in the parking lot the car was idling high, about 1500 rpm and then it lowered down to about 900rpm. Can anyone offer any suggestions?

 

[turbonut85]

Check all vac lines, MAF sensor, and make sure all your ground wires are tight. Then report back.

 

[1buick]

I checked for vac. leaks today and I found none. I was thinking MAF also. I just changed over to a translator and LT1 maf about a month ago. Do you think it could be bad? Any way to check it? Thanks for you help.

 

[83ttypecooled]

Hi,
I'm not personally familiar with that conversion. Can you easily reinstall the stock setup? If so, do so,and see what happens.

 

[turbonut85]

I would be more inclined to say vac leak or possibly a ground issue. Although, depending on which translator you have there could be a setting issue or maybe a loose connector?? Typically the LT1 MAF's either work, or they don't...unlike the stockers. Another thing you might check is your o2 numbers. (assuming you have a scantool of some sort.)

p.s. ^^^^ The above poster has a good idea here.

 

[Razor]

What are your BL numbers at idle?

 

[1buick]

Razor, the BLM's were 142, I changed back to my old maf meter and the car ran like it should or as well as an advance auto parts maf meter would permit.

What should the setting be on the translator for the LT1 maf? I think I have 3 switches up and the last one down. The on position is up right? I think I read the instructions correctly. If someone can post a diagram that would be great.

 

[turbonut85]

I believe BL's at 142 would indicate a lean condition...i.e.: exhaust leak before the turbo, vacuum leak, or intake leak after the MAF. Somewhere, the car is sucking un-metered air. Razor...correct me if I'm wrong. What are your o2 #'s in closed-loop? The last time I battled surging idle, I changed the MAF three different times, only getting slight improvements. My o2 #'s were low and they would continually drop further down to the low 100's. Turned out to be the 4 ground wires from the main engine harness (under the AC compressor on the Hot Air cars, back of the pass side head on the IC cars) were loose. Tightened them up and everything was back to normal.

 

[1buick]

I was thinking the same thing but once I changed the maf the surging stopped or was at a bare minimum, i could hardly see the tach needle move at all. The car ran and performed much better. The BLM's are around 128-130.

 

[turbonut85]

Sounds like you found the problem. Maybe try another LT1 MAF with your translator. If it were me, I'd try and pick one up out of a junkyard before getting a new one...(making sure that it''s the sensor and not the translator) Might save you some $green$. Good luck!!

 

[Razor]

MAF will do you in every time.