What do code 41 and 34 mean?

RNR247 · 11-04-2009, 10:46 PM

Hello,
I own a 1991 Carerra4 with erratic idle problem. The car runs strong when warm, but exhibits slight lean throttle hesitation when engine is cold. The control unit is logging code 41 and code 34. My question is could one of these codes directly affect the idle? On a separate note, 15K mile service and valve job was completed recently.

Any info is greatly appreciated.

jimq · 11-05-2009, 12:11 AM

we need pictures of the car so we can figure out what is wrong.
oh yea welcome

mojorizing · 11-05-2009, 04:37 AM

code 41 = ecu faulty
code 34 = hall signal
Try clearing codes, driving some, then reread to validate codes.

RNR247 · 11-05-2009, 12:10 PM

Hi Mojorizing,

I'll clear codes and validate once again. If codes don't go away, which is your prime suspect that is affecting the idle? And would you replace the ECU and/or distributor unit? Thx!

mojorizing · 11-05-2009, 02:30 PM

Check the condition of the dual dist. by pulling the connector off of each ign. power pack (coil). Engine should run equally well on either.
Realize that the O2 sensor is out of the loop for the first 30-45 seconds while the engine is warming up. Is this the only time you have rough idle?
Possible bad spark plug wires? Check for arcing while looking at engine bay at night.
I would think that those 2 codes are more of a symptom, than the cause of your idle problem.

What code scanner are you using?

RNR247 · 11-05-2009, 05:05 PM

The rougn idle actually starts after 20-30 seconds. Prior to that it idles at around 900 rpm. During rough idle it would drop about 300-500 rpms and then come back up again. When engine is warm, it idles perfectly. We've checked everything already and we're down to these codes as suspect to idle problem.

BTW, is the ECU the same as DME?

I believe my buddy's code scanner is a Hammer.

mojorizing · 11-05-2009, 05:24 PM

DME=ECU
Re-read codes and if hall sensor comes up again, go from there. Could there be magnetic debris/dust on the head of the sensor?

RNR247 · 11-05-2009, 06:17 PM

I'll check for debris on the head of the sensor otherwise I think I may have to replace dual distributor unit then if that doesn't solve it replace DME.

How technical is it to replace DME? In your opinion, is it a good DYI job?

Thanks.

mojorizing · 11-05-2009, 11:00 PM

The DME is definitely DIY
http://forums.rennlist.com/rennforum...placement.html Follow the steps that are pertinent.

RNR247 · 11-06-2009, 12:06 AM

Mahalo Brah! Thanks for the useful info. Now I just have to find a rebuilt DME on-line to replace my faulty ECU (code 41). I think I saw one in the internet for $600 rebuilt.

But first I have to focus on the hall sensor issue. I may end-up replacing the dual distributor. Motormeister is offering a rebuilt Bosch (w/vent kit) for $400.

11-04-2009, 10:46 PM	#1
RNR247 User Join Date: Nov 2009 Location: No. California Posts: 13	What do code 41 and 34 mean? Hello, I own a 1991 Carerra4 with erratic idle problem. The car runs strong when warm, but exhibits slight lean throttle hesitation when engine is cold. The control unit is logging code 41 and code 34. My question is could one of these codes directly affect the idle? On a separate note, 15K mile service and valve job was completed recently. Any info is greatly appreciated. Last edited by RNR247; 11-05-2009 at 03:57 AM. Reason: Topic Redirection

11-05-2009, 12:11 AM	#2
jimq Burgled Rennlist Member Join Date: Aug 2003 Location: Altamonte Springs, Fl/Gwynns Island, Va. Posts: 11,733	we need pictures of the car so we can figure out what is wrong. oh yea welcome __________________ jim *Conservatives....We work hard so you don't have to* 91 White C2 Cab tiptronic 03 Black 996TT X-50 Grocery getter 2002 Dodge Ram 5.9L Gas Hog Bend-Pak Scissor Lift 64 230SL Mercedes (SOLD after 18 years ) Some other Porsche's

11-05-2009, 12:10 PM	#4
RNR247 User Join Date: Nov 2009 Location: No. California Posts: 13	Hi Mojorizing, I'll clear codes and validate once again. If codes don't go away, which is your prime suspect that is affecting the idle? And would you replace the ECU and/or distributor unit? Thx! Last edited by RNR247; 11-05-2009 at 12:14 PM. Reason: additional question

11-05-2009, 05:05 PM	#6
RNR247 User Join Date: Nov 2009 Location: No. California Posts: 13	The rougn idle actually starts after 20-30 seconds. Prior to that it idles at around 900 rpm. During rough idle it would drop about 300-500 rpms and then come back up again. When engine is warm, it idles perfectly. We've checked everything already and we're down to these codes as suspect to idle problem. BTW, is the ECU the same as DME? I believe my buddy's code scanner is a Hammer. Last edited by RNR247; 11-05-2009 at 05:07 PM. Reason: clarification

11-05-2009, 06:17 PM	#8
RNR247 User Join Date: Nov 2009 Location: No. California Posts: 13	I'll check for debris on the head of the sensor otherwise I think I may have to replace dual distributor unit then if that doesn't solve it replace DME. How technical is it to replace DME? In your opinion, is it a good DYI job? Thanks.

11-06-2009, 12:06 AM	#10
RNR247 User Join Date: Nov 2009 Location: No. California Posts: 13	Mahalo Brah! Thanks for the useful info. Now I just have to find a rebuilt DME on-line to replace my faulty ECU (code 41). I think I saw one in the internet for $600 rebuilt. But first I have to focus on the hall sensor issue. I may end-up replacing the dual distributor. Motormeister is offering a rebuilt Bosch (w/vent kit) for $400.