Notices
924/931/944/951/968 Forum Porsche 924, 924S, 931, 944, 944S, 944S2, 951, and 968 discussion, how-to guides, and technical help. (1976-1995)
Sponsored by:
Sponsored by:

Horrible fuel mileage. 1987 NA

Thread Tools
 
Search this Thread
 
Old 01-28-2004, 05:19 PM
  #16  
inactiveuser92616
Drifting
Thread Starter
 
inactiveuser92616's Avatar
 
Join Date: Nov 2003
Location: Northern Colorado
Posts: 2,273
Likes: 0
Received 2 Likes on 2 Posts
Default

oh yes, I just remembered another thing. The exhaust, after any duration of running, smells slightly of gasoline. There are signs of soot on the rear valence and exhaust tip. i have held a napkin behind the pipe and had it slowly turn black.... so this seems to indicate that the fuel is not leaking before entering the engine?
Old 01-28-2004, 05:23 PM
  #17  
944Play
Pro
 
944Play's Avatar
 
Join Date: Oct 2002
Location: Portland, OR
Posts: 617
Likes: 0
Received 0 Likes on 0 Posts
Default

What about the DME Temp II sensor?

BTW, I used to get 450 miles between fillup and reserve light when I was commuting a 100 mile round trip three times a week.
Old 02-08-2004, 08:15 PM
  #18  
inactiveuser92616
Drifting
Thread Starter
 
inactiveuser92616's Avatar
 
Join Date: Nov 2003
Location: Northern Colorado
Posts: 2,273
Likes: 0
Received 2 Likes on 2 Posts
Default

Ok, so I have done some more tests and such. The (new) oxygen sensor is reading a very steady .49Volts at idle, and steadily increases voltage as rpm go up. What I am reading from the fact that it can change, but doesnt bounce around at any speed, is that the O2 sensor works but that the car is ignoring it, instead running on unaltered fuel maps.

I also checked the fuel quality switch, it was where it should be (position 0, full CCW)

I am now wondering if the cuplrit is the engine temp sensor, since the manual states (and those responding to this post) that the engine will run rich with a broken temp sensor, as it will ignore the O2 sensor.

I went to test the temp sensor with my multimeter, but couldnt get to the connections in a practical way. I couldn't fit my hands on the engine side of the connector, (without removing intake tube) and could not find the one under the dash. If my temperature gauge in the dash reads correctly, is the sensor working right?
Old 02-08-2004, 09:08 PM
  #19  
roy_josef
Instructor
 
roy_josef's Avatar
 
Join Date: Jul 2001
Location: Blaine, WA
Posts: 197
Likes: 0
Received 0 Likes on 0 Posts
Default

Put your car on a sniffer and check emissions! A qualified tech. should be able to see whats going on right away. No more guessing/swapping parts and spending $$$.
Old 02-08-2004, 09:19 PM
  #20  
Mr. Avionics
Pro
 
Mr. Avionics's Avatar
 
Join Date: Nov 2002
Location: Ft. Lauderdale, Fl.
Posts: 564
Likes: 0
Received 1 Like on 1 Post
Default

Engine temp sensor huh?
I get arround 15-17 city driving and at the last fill up 19 with greater amount of highway driving, if you can call I95 in Ft. Lauderdale at rush hour highway driving. Guess maby I ought to check that little puppy out. Anybody got some hints on how to do it?
Bill
Old 02-08-2004, 11:48 PM
  #21  
Zero10
Race Car
 
Zero10's Avatar
 
Join Date: Nov 2003
Location: Calgary, AB
Posts: 4,593
Likes: 0
Received 2 Likes on 2 Posts
Default

The dash sensor uses a seperate sensor, sorry.
You should be able to unhook the sensor at the DME, and test it there. Let me look in my manuals tomorrow and I'll try to get you some pin numbers.

Near as I can tell, to check it at the sensor, you have to pull the intake manifold.
Old 02-08-2004, 11:51 PM
  #22  
inactiveuser92616
Drifting
Thread Starter
 
inactiveuser92616's Avatar
 
Join Date: Nov 2003
Location: Northern Colorado
Posts: 2,273
Likes: 0
Received 2 Likes on 2 Posts
Default

yeah.... from what I saw, based on the size of my hands, I would need to at the very least pull off the rubber elbow tube to unplug that sensor.

What worries me about doing that, is the tubes which plug into this tube. They seem to be attached with crimp pieces rather than hose clamps. To get the tube off would I just cut these clamps off? I dont think I have a tool to redo the crimps... would hoseclamps work for reassembly?
Old 02-09-2004, 01:47 AM
  #23  
ERAU-944
Race Car
 
ERAU-944's Avatar
 
Join Date: Apr 2002
Location: FloriDUH
Posts: 3,817
Likes: 0
Received 0 Likes on 0 Posts
Default

bill - sounds like you need an 02 sensor. buy one at napa (universal for $20) and solder it onto the line. i have this in my '84 and it works like a champ. i couldn't get more than 20 hwy with a bad 02. the last automatic parts car i had had a shot O2, and got very poor mileage on the way to titusville.

-Michael-
Old 02-09-2004, 06:42 AM
  #24  
Mr. Avionics
Pro
 
Mr. Avionics's Avatar
 
Join Date: Nov 2002
Location: Ft. Lauderdale, Fl.
Posts: 564
Likes: 0
Received 1 Like on 1 Post
Default

Michael,
Thanks, I'll give that a try. Ohhh Boy, another thing to add to my 100,000 mile things to do list.
Talk to you later,
Bill
Old 02-09-2004, 10:22 AM
  #25  
Zero10
Race Car
 
Zero10's Avatar
 
Join Date: Nov 2003
Location: Calgary, AB
Posts: 4,593
Likes: 0
Received 2 Likes on 2 Posts
Default

When I look at mine, some of them have been replaced with hose clamps.
However I know I have a couple vacuum leaks, so it beats me if it's right =)
Only thing is, once you take all that apart, you better hope it was the problem, otherwise it is quite tempting to kill it.
Old 03-17-2004, 03:03 AM
  #26  
inactiveuser92616
Drifting
Thread Starter
 
inactiveuser92616's Avatar
 
Join Date: Nov 2003
Location: Northern Colorado
Posts: 2,273
Likes: 0
Received 2 Likes on 2 Posts
Default

and Elf gets the prize! Took it into the shop finally (I had given up)
Turns out it was somewhat rich, they tuned it right on the emissions machine. But the big thing, my odometer is recording 60% actual mileage. Enough to fool me into believing my mileage was horrible, but not so drastic I got suspicious. Blast! Oh well... they washed the car too. So it was a $90 fine tune and wash. Just ordered the part, I expect some odometer teeth to be gone when I crack it open.
Old 03-17-2004, 10:14 AM
  #27  
josephsc
Race Car
 
josephsc's Avatar
 
Join Date: Jun 2003
Location: Albany, CA: celebrating 100 years of independence from Berkeley, CA
Posts: 4,887
Likes: 0
Received 2 Likes on 2 Posts
Default

Glad to hear that you figured out the problem. I guess we should put 'check odometer' on the list of possible gas mileage problems.
Old 03-17-2004, 06:27 PM
  #28  
Little Porsche Boy
Instructor
 
Little Porsche Boy's Avatar
 
Join Date: Mar 2004
Location: Auburn, Washington & San Diego ............................. Terry
Posts: 179
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally posted by patrat
... Turns out it was somewhat rich, they tuned it right on the emissions machine. ...
So, what was it that they actually did to lean-out the mixture?

From what you said about the smell of gas and soot around the exhaust tail pipe,
it sure sounded as if it was running rich.
Old 03-17-2004, 09:43 PM
  #29  
inactiveuser92616
Drifting
Thread Starter
 
inactiveuser92616's Avatar
 
Join Date: Nov 2003
Location: Northern Colorado
Posts: 2,273
Likes: 0
Received 2 Likes on 2 Posts
Default

Im guessing that they messed with the adjuster screw on the Air Meter, adjusting it till their emissions machine said it was burning clean. Supposedly, its now running cleaner than most MY2000 cars. Should help with the mileage. The odometer explains why every sensor I checked came out good.



Quick Reply: Horrible fuel mileage. 1987 NA



All times are GMT -3. The time now is 01:15 AM.