![]() |
|
|
|
Registered User
Join Date: Dec 2013
Posts: 344
|
'87 3.2 G50 - rough idle/stumble when accelerating
My car seemed to just develop this problem that I THINK has gotten progressively worse. Symptoms as follows:
* Rough idle, either hot or cold. It's idling very low, like 600 RPM, a lot of hunting - nearly stalls (has stalled a couple of times but it's rare) and occasional popping * On acceleration, there is a hesitation or stumble. It's like how it feels when the engine is lugging at low RPM. It seems that I get through a particular stumble and the engine is OK again... it's hard for me to tell if it's making full power, but at least some of the time, it pulls like a freight train Some things that have recently been done: * New cap and rotor. Smoothed out the engine a lot but didn't solve the problem * New air filter * 3 tankfulls of gas with a bottle of Techron in each * Took apart AFM and bent the wiper arm to ride in a new arc. Old one had a couple of bare spots, but I've seen worse in other threads on this forum I have a new O2 sensor on order, should arrive today. I'll install that and see if it helps at all. But I'm looking for other ideas. Any ideas on where else I should start? Thanks -Glenn |
||
![]() |
|
Registered User
Join Date: Dec 2013
Posts: 344
|
Just another observation.. the stumble happens at full throttle, too - althought it seems, less frequently. Doesn't that mean it can't be the O2 sensor?
Thanks -Glenn |
||
![]() |
|
Registered User
Join Date: Dec 2013
Posts: 344
|
p.s. the car has 234,000 miles on it, 10,000 of which were done by me over the last 7 months, in sheer bliss
|
||
![]() |
|
Yes it runs
|
If you unplug the O2 sensor and it smooths out, you will know it's the O2 sensor. It switches to a different mode of control in the ECU. If you unplug it and it doesn't smooth out, it's something else.
Another suggestion is new wires. Also temp sensor. I don't know of any tricks to test that. |
||
![]() |
|
Registered User
Join Date: Dec 2013
Posts: 344
|
Ok. That's an easy enough thing to test, thanks.
|
||
![]() |
|
Yes it runs
|
Ah!! Full throttle stumbling would indicate it's not the O2 sensor. The "wide open" sensor takes the O2 sensor out of the mapping equation.
|
||
![]() |
|
![]() |
MBruns for President
|
I had this issue on my old 3.2 - I changed the coil and the plug wires and it went away. Definitely seemed to be ignition related,.
__________________
Current Whip: - 2003 996 Twin Turbo - 39K miles - Lapis Blue/Grey Past: 1974 IROC (3.6) , 1987 Cabriolet (3.4) , 1990 C2 Targa, 1989 S2 |
||
![]() |
|
Bye, Bye.
Join Date: Apr 2003
Location: Planet Earth
Posts: 6,167
|
+1 on the O2 advice above. I would also change plugs (wires and/or coil?) to go with that new cap and rotor.
__________________
Elvis has left the building. |
||
![]() |
|
Registered User
Join Date: Dec 2013
Posts: 344
|
Another possible clue: There is no fast idle. The pattern of it starting around 1000-1100 rpm and then selling down to 800 isn't happening anymore. Does that mean anything?
|
||
![]() |
|
Registered User
Join Date: Dec 2013
Posts: 344
|
Found the problem! One of the plug wires wasn't fully seated. What boneheaded did that?!?! Oh wait a minute... That was me :-/
Well I just fixed it and took it for a drive, and OMG, what a car. The sound of the engine echoes in my head even after shutting it off... Wow. Thanks all!!! |
||
![]() |
|
Registered User
Join Date: Dec 2013
Posts: 344
|
Just not nearly as badly as before. Is it possible the plug has been fouled?
|
||
![]() |
|
Registered User
Join Date: Dec 2013
Posts: 344
|
Not sure what happened with that last post... What I meant to say is that, while it is MUCH better, still a mild stumble happening. Is it possible the plug is fouled?
Sent from my RM-877_nam_att_205 using Tapatalk |
||
![]() |
|
Bye, Bye.
Join Date: Apr 2003
Location: Planet Earth
Posts: 6,167
|
I would just change the plugs. Cheap and easy...and just good maintenance.
__________________
Elvis has left the building. |
||
![]() |
|
Registered User
Join Date: Nov 2013
Location: Main Line, PA
Posts: 1,226
|
Change the plugs. Costs what, $20? Check to make sure you have the wonderful Porsche specialty tool first.
__________________
1985 911 3.2 Carrera Coupe - Constant Project - 2550lbs 2005 E46 M3- Daily Beater - 3350lbs |
||
![]() |
|
Registered User
Join Date: Dec 2013
Posts: 344
|
is this the tool? 1987 Porsche 911 Carrera Coupe - Ignition - Page 2
|
||
![]() |
|
Registered User
Join Date: Dec 2013
Posts: 344
|
sorry, bad link. Is this it? Pelican Parts - Product Information: TOL-SK4490
|
||
![]() |
|
Registered
Join Date: Jul 2013
Location: Plano, TX
Posts: 306
|
they're probably referring to this tool - in your tool kit.
![]()
__________________
'04 GT3 '97 C4S '90 C2 '86 951 |
||
![]() |
|
Registered User
Join Date: Dec 2013
Posts: 344
|
Oh. I do have that. Wondered what that was...
|
||
![]() |
|
![]() |
Registered
|
You probably need to check for vacuum leaks, while your back there. A ton of threads on that. If you haven't got the Bentley, you might want to invest in one.
|
||
![]() |
|
Member 911 Anonymous
|
You probably did this, but did you replace the Fuel Filter?
__________________
'85 Carrera Targa Factory Marble Grey/Black * Turbo Tail * 930 Steering Wheel* Sport Seats * 17" Fuchs (r) * 3.4 * 964 Cams * 915 * LSD * Factory SS * Turbo Tie Rods * Bilsteins * Euro Pre-Muff * SW Chip on 4K DME * NGK * Sienes GSK * Targa Body Brace PCA/POC |
||
![]() |
|