r_liebo

Going to take my 99 in shortly, but thought I'd seek some help here to see if anyone had any ideas.

A/c was fading slowly over a year, just had it tested and recharged. Day 1 after fix ice cold. Now it works intermittently -- ice cold at start up then fades, then ice later.

A new problem just started though (possibly bad news). Idle is fine with A/C off, but when compressor is on, idle surges between 600 --1100. Almost stalled once.

Also, I think there's some light greyish smoke coming from rt. exhaust more so than normal.
Engine temp fine, oil pressure fine (but it fluctuates with the idle problem slightly). My oil is low, but not sure that would be the issue.

RMS has been replaced a year ago, no check engine lights, but I'm fearing engine is near death.

Any help appreciated, particularly if indy shop could have done something in the a/c service that caused the idle issue to crop up (my tech know-how is very limited)

chsu74

You are lucky to have Jake at Flat-6 only 80 miles away from you. He is the foremost expert on M96 engines.

r_liebo

Not so confident it can make 80 miles . . .

logray

Does the car drive and idle fine without the air conditioning on?

If so, then don't use the air conditioner until you can have someone look at it. You might just need a new compressor and/or clutch mechanism.

If the smoke goes away once the engine warms up some I wouldn't worry too much about it, it could just be condensation burning off. A little bit of smoke on startup is also not a problem and is common on flat 6 engines.

Also put some oil in it! Driving any car low on oil is a bad idea.

r_liebo

Seems to drive ok without a/c on, and I'm for sure keeping it off until I get to the shop.
smoke doesn't seem to be the normal startup smoke, and there's also a slight "burny" smell that smells sort of like burnt rubber.

fpb111

Burnt rubber smell is pretty normal after driving it, especially with any enthusiasm. Theory is that rubber "dust" from the tires that is deposited on the hot mufflers, that live 8-10" behind the tires, is being burned off.

Pac996

Yes it is near death with out understanding to keep the oil level up. Anyway the a/c fix probably has the refrigerant level low again. When the level gets low the a/c compressor will cutt off and on depending on if a concentration of refrigerant is being sucked by the compressor. That can give the engine surges.

The smoke out the tail pipe might of always been there but most cars smoke when the oil is low. I'm sure you mean the oil isn't past the low mark

If you are going to labor through another wait at the car shop make sure he double checks the refrigerant pressures and if it is low there is a leak. In the case of a leak make sure he puts some dye in the refrigerant. The dyes are the glow under black light type and are a pale yellow if viewed in concentrate or visible at a leak with the naked eye if the leak is bad enough.

The smoke out the back might just be an old engine that you can't do anything about. You could try a fuel additive to clean the engine once in a while. Make sure the air filter is clean and that the throttle body isn't gummed up.

Other than that crusie and enjoy.

r_liebo

Oil is actually fine. It's in the middle range, and fine on the dipstick. Just lower than I anticipated.

The leak test was done. No leaks. The refrigerant was added, and it worked stellar for one day, then ok for day 2, and not really at all day 3.
Since before recharging the A/C died slowly over 6 months, and then worked perfectly for one day after recharge, can't believe it's a refrigerant issue, unless the shop somehow created a leak.

I've driven this 911 for 2 years and a Boxster S for 3 before that. I know very well the "normal" burn smells that come from regular operation, particularly hard driving, and also the normal puffs of smoke that come from startup.

This was a different smell. Like a campfire. Smoke from only one exhaust port, and it didn't look like engine smoke. It looked like smoke smoke. It also filtered out after the car was shut off for about 10 seconds -- thought I had an engine fire.

Then, it stopped. Restarted later with compressor off, all was perfectly normal. No smoke, no rough idle.

I'm hoping it's a fried compressor. Perhaps it siezed, and in continuing to draw current in it's death throws it caused the RPMs to fluctuate.

I'll know more when I take it in Friday. IF it is the compressor, I'm worried the indy shop may have caused it. Seems like odd timing. Still rather fight that battle than have a dead engine though.

Fingers crossed.

springgeyser

Check the IAC valve. Idle rpm should be the same whether the AC compressor is on or not. I used throttle body cleaning fluid to fix my idle issue on my commuter car.

Maybe your condenser is dirty and needs to be clean to deal with the 'fading' issue. I've been meaning to clean my radiators and condenser for awhile now.