85 911 hesitation, low oil pressure gauge reading, I don't know where to start

[ferrispd]

Hi guys, I've been looking over the board here regarding my problem and cannot get a bead on where to start.
1985 911 the car starts, idles a little rough at first and then smooths out, then when warm it will idle poorly (sputter) again. When I drive it, there is significant hesitation and a dramatic decrease in power. The oil pressure gauge just barely wiggles when running. The oil (amount) gauge starts off low (in the red/bottom of gauge), then perks up to just under halfway mark when warm. The oil dipstick is between the two points when warm and then well below the bottom line when cold. I am running Valvoline VR1 20w-50 oil. I have changed the fuel filter, distributer cap, plugs and that red relay in the front hood fuse box recently. Can anyone point me in the right direction?

Thanks in advance

[steely]

I would recommend cleaning and testing the ICV. Then set the idle. There are other threads on this but here is one.
How can I clean and test the ICV

I'd also check all of the vacuum lines. There are threads on this too.

My oil gauges aren't the most accurate either. Go by the dipstick level when hot and you'll be good. I never have checked it cold.

[tdw28210]

Don't sweat the druck pressure. Pretty sure that gauge was designed primarily to keep Porsche mechanics in the latest British Knights shoes back in the day. : ).

Like steely said, trust the dipstick - but only after she is warmed up. Unless you have a lot of leaks or are seeing a TON of blue smoke coming out, your oil level will probably be fine for the next 500 miles. Check it again then.

[DRACO A5OG]

+1 on the DRUCK, do not sweat it but consider replacing it in the near future, it is a safety feature just in case you have a catastrophic oil leak and it dumps the oil from the engine, which is not good.

Your oil level readings are proper. The oil level only works when car is at operating temps 194. But if you have OCD like me check the dipstick when cold, there should be a bit of oil on the tip of the dip stick, which will indicate you have plenty of oil.

Now to your idle issue:

After she is nice and warmed up, pull into a safe area, engage emergency brake and remove oil filler cap. if idle does not drop, you have a vacuum leak. There is a cigar trick, purchase some #2 x 24-30"vacuum hose at the FLAPS and connect it to the cruise control vacuum line, lite the cigar and blow the smoke into the hose ( car off or course ), you may need to blow heavily to insure smoke is getting in, then observe especially around the rear of the throttle body. This is how we found my leak and buddy's 86 3.2.

ICV, when she "stutters" take a screw driver and tap on the ICV to see if clears her up. If so, remove and clean with carb cleaner while rattling the ICV until fluid comes out clear and spray a dab of silicon based lubrication, not wd40. Take care of the upper hose, do not damage the Large Elbow Throttle Body intake hose, the connector there is brittle.

As Steely suggested, check your base idle, it must be jumpered at relay terminal B&C in the engine bay when she is warmed up.

[tdw28210]

Originally Posted by DRACO A5OG

+1 on the DRUCK, do not sweat it but consider replacing it in the near future, it is a safety feature just in case you have a catastrophic oil leak and it dumps the oil from the engine, which is not good.

Your oil level readings are proper. The oil level only works when car is at operating temps 194. But if you have OCD like me check the dipstick when cold, there should be a bit of oil on the tip of the dip stick, which will indicate you have plenty of oil.

Now to your idle issue:

After she is nice and warmed up, pull into a safe area, engage emergency brake and remove oil filler cap. if idle does not drop, you have a vacuum leak. There is a cigar trick, purchase some #2 x 24-30"vacuum hose at the FLAPS and connect it to the cruise control vacuum line, lite the cigar and blow the smoke into the hose ( car off or course ), you may need to blow heavily to insure smoke is getting in, then observe especially around the rear of the throttle body. This is how we found my leak and buddy's 86 3.2.

ICV, when she "stutters" take a screw driver and tap on the ICV to see if clears her up. If so, remove and clean with carb cleaner while rattling the ICV until fluid comes out clear and spray a dab of silicon based lubrication, not wd40. Take care of the upper hose, do not damage the Large Elbow Throttle Body intake hose, the connector there is brittle.

As Steely suggested, check your base idle, it must be jumpered at relay terminal B&C in the engine bay when she is warmed up.

Nice post Draco, when are you moving to North Cackalacky? There is a nice house for sale in my 'hood.

But no shout out for the British Knights reference?? That was comedy GOLD!

[cabmandone]

Could this also possibly be a bad CHT? starts and runs rough and sputters once warmed up and has a lack of power.

[DRACO A5OG]

Maybe, take out the DVM and take a reading of the CHTS or put a paper clip in the connector to see if you can repeat the symptoms.

++++++++++++++


TDW, LOL, my sister lives up yonder and my Mom's in Sanger. When I grow up, I plan to retire in Sausalito

[fred cook]

If you decide to replace the oil pressure sender, remove the sender mounting block from the engine block before trying to unscrew the sender. Failure to do this can result in a ruined engine block! Don't even think that you can hold the mounting block steady while trying to remove the sender! You will have to loosen or temporarily remove the a/c mounting bracket to access the bolts for the sender block. Once it is off the car, put the block in a large bench vise and then remove the sender using a long wrench. When I did this job on my SC engine, it took a large amount of force to loosen the sender and it made a very loud "pop" when it came loose. Good luck resolving your car's issues!

[tdw28210]

Originally Posted by DRACO A5OG

Maybe, take out the DVM and take a reading of the CHTS or put a paper clip in the connector to see if you can repeat the symptoms.

++++++++++++++


TDW, LOL, my sister lives up yonder and my Mom's in Sanger. When I grow up, I plan to retire in Sausalito

Cool. Remind me to tell you about the time I hung with Carlos Santana in Sausalito. Let's just say one of us spent a lot of time at the "bakery" that day.

[scarceller]

I recommend you Test fuel pressure.
At idle it should be 2.0bar (30psi)
Then at idle disconnect the vacuum line on top of the regulator at the rear of the LHS fuel rail and with vacuum line disconnected it should read 2.5bar (36psi).

Then after verifying FP you really need to know what the mixture is at during idle. You need a CO meter or a WideBandO2 to test this. We need to know if your lean and by how much.

One last simple test is unplug the O2 sensor, does the problem go away? I've seen faulty O2 sensors that simply send >0.7vdc back to the DME at all times, if this happens the DME sees a false rich feedback signal from the sensor and then the DME leans the fuel mixture. Disconnect the O2 and leave it disconnected till you figure out your issue.

[DRACO A5OG]

Originally Posted by fred cook

If you decide to replace the oil pressure sender, remove the sender mounting block from the engine block before trying to unscrew the sender. Failure to do this can result in a ruined engine block! Don't even think that you can hold the mounting block steady while trying to remove the sender! You will have to loosen or temporarily remove the a/c mounting bracket to access the bolts for the sender block. Once it is off the car, put the block in a large bench vise and then remove the sender using a long wrench. When I did this job on my SC engine, it took a large amount of force to loosen the sender and it made a very loud "pop" when it came loose. Good luck resolving your car's issues!

+1, loosen the cam oil line and remove as a whole.

I did not do this and created a leak at the mounting block seal to the cam tower oil line, replaced o-ring and torqued to spec. Thank goodness I did not damage the engine block

But mine was not seized like some, I guess I was stoopid lucky

[Dpmulvan]

Where are the bolts for the oil sending block?? I don't see any on mine.

[ferrispd]

Thanks for all the posts :-) , Special thanks for the ones with links. It is easy to get lost in some of these threads when it is not a specific project. I am going to spend some time with the car tomorrow. I'll start with the ICV, O2 sensor and CHT sensor; since I have the tools to check those. I don't know what I would need to test fuel pressure, or even where the vacuum lines are, so I'll be doing some more searches if the first three don't work.