85 911 engine lugs .

[Nick Triesch]

My car is still tuned up but has developed engine lugging in third gear at 30 mph. Sometimes in second gear. I checked all the spark wires. They were new 6 thousand miles ago. Tighten all hoses to fuel injection. Checked idle. Added good gas and some Techron. Car had top end 6000 miles ago. Still has plenty of power at higher rpm’s. Lugging has been getting worse. I would very much like some ideas why this could be happening . Thank you , Nick.

[Nick Triesch]

Hi. Bucking would be a better word to use. Still checking connections. Will check battery, just installed a new one.

[Jeff Higgins]

What on earth are you doing in 3rd gear at only 30 mph? This isn't a diesel pickup truck... What kind of rpm's is it down to at that speed in that gear? I'd guess somewhere around 2,000? Or less?

[Nick Triesch]

I know that was low at 30 in third gear I was just testing because it bucks a lot in second gear just driving around the neighborhood. Never did that before.

[Nick Triesch]

I made a mistake, bucking at 40 mph in third gear . Never did before.

[917_Langheck]

When was the last time the O2 sensor was changed? A new one on my '84 helped with this issue quite a bit.

[Nick Triesch]

Thank you. But all parts are new from top end. Wires, plugs, sensors, clutch, flywheel, injectors, 02, car has run great since top end . This just started with a rough idle I can’t seem to correct. I did order a new ICV valve . I checked fuel pump relay , it was popping out a bit. New battery is installed tight. My car was running so great! You would think that a 37 year old car would work better. So in short, car has rough idle and is bucking at lower and medium rpm’s.

[proporsche]

disconnect the oxy sensor and see..? what grade of fuel are you using?

Ivan

[Nick Triesch]

Ivan , 91 grade. Tomorrow I will check the intake bolts on top. If the bolts become loose it can cause the problem I believe. But does not seem likely after only 6000 miles after top end 3 years ago. I did not drive much in 22 because of multiple myeloma. Better now.

[917_Langheck]

What is the status of the fuel pressure regulator and dampers? All the vac lines good and solid, all connected?

[proporsche]

Originally Posted by Nick Triesch

Ivan , 91 grade. Tomorrow I will check the intake bolts on top. If the bolts become loose it can cause the problem I believe. But does not seem likely after only 6000 miles after top end 3 years ago. I did not drive much in 22 because of multiple myeloma. Better now.

get that sensor off and try to find at least 93...or even better go to paint shop store and get 1 gallon of Toluene..put half in the tank plus some gasoline and drive it..you will be surprised the outcome..I used to use it back in LA in my 911, sweet souse it is;-) It has been used for racing..

ivan

[FA-18C]

I would add to the list of simple things maybe replace the fuel filter. Did you happen to drain the fuel tank when doing your top end?

[Nick Triesch]

I will check all those things but I now remember that years ago I had a similar miss problem and it turned out the bolts on the intake manafolds were loose. Seems unlikely but I could tighten them I believe to 18 foot pounds. Whatever is going on it is at the early stages. My car has been running perfectly since for 3 years after top end. I will get to this stuff. But wife is very sick now . Thank you very much for all the input. I can’t remember if I can get to all the intake bolts without taking to many parts off.

[wazzz]

Yes you can reach all bolts without removing anything by using a small 1/4 torque wrench ratchet with extensions and universal joint. Nominal torque is 25Nm. Don't know what that makes in fp.

[proporsche]

i`d look somewhere else..i did my engine cc 45k miles ago and no intake leak whatsoever;-) The guy who did your engine was pretty much excellent mechanic...

Ivan

[Nick Triesch]

Ok Ivan. You are right , the guy who did the engine work is a legend! He is not only a great mechanic but he loves the work. He told me they sometimes must make parts for old 356 cars. When you walk in the door, first thing you see are a couple of 356s up on the racks ! I may take it to the shop, I have been pretty sick but better now. I was down for a year.

[Nick Triesch]

Thanks wazzz

[proporsche]

Originally Posted by Nick Triesch

Ok Ivan. You are right , the guy who did the engine work is a legend! He is not only a great mechanic but he loves the work. He told me they sometimes must make parts for old 356 cars. When you walk in the door, first thing you see are a couple of 356s up on the racks ! I may take it to the shop, I have been pretty sick but better now. I was down for a year.

oh dear, screw the problem ..get well 1st...
Ivan

[Nick Triesch]

Ivan , just for the hell of it I checked the torque on an intake bolt on both sides. You were right, tight as a drum. I will do what I can that you guys recommend. I wish I could bend my body.

[Nick Triesch]

Cleaning or replacing the ICV may help the idle problem but it would not explain the bucking that it did not do before. Now I can have very little bucking flying down the road but I sure feel it slowing down to come in a neighborhood driving home in second gear. Should be smooth.