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View Full Version : 98 2.8 intermittent lean codes? Anyone with experience on this please chime in...



ltipcke
02-19-2014, 07:41 PM
After over a year of owning Audis I finally got me first real CEL in one haha.

Its a 98 2.8 A4. Codes are P1136 and P1138 banks 1 and 2 system too lean - intermittent. Maybe its a vacc leak of some sort. I already replaced allll of the vac lines under the hood that run to the various sensors and solenoids and what not that sit on top of the throttle body. Also replaced all the of PCV stuff at the same time and the throttle body o-ring. Did all that stuff like 3000 miles ago to try to pick up a few MPGs (that and a few other things). Nothing seemed to help me get over 18 =( lol

Sprayed the common vac leak areas with some brake clean to see if i could get the engine to stumble. Got nothing. Also did a visual inspection of all the 25ish vac lines that i can see and they are all hooked up and none have popped off...cleaned the MAF at the same time as all of that other stuff. Car runs and drives fine tho, doesnt hunt up and down on the idle, idle doesnt even hang up high like cars usually do with vac leaks. It just gets shitty as gas mileage (17 mpg on the last tank but it is the dead of winter in MN so that makes a difference). I cleared the code and since then have put on about 200 miles without it coming back...some say it can be a goofy MAF sensor which i agree it could be. Others say it could be an oxygen sensor which i dont really agree with since the code is for both banks...unless they both went bad at the same time (unlikely?). Was also wondering about the purge valve for the EVAP system. Im guessing it would throw and EVAP leak code but i can hear that thing clicking from inside the car damn near! ha.

Sorry for the book...any way any ideas guys? Maybe someone with experience with this code and car? The intermittent lean part is what gets me wonderin...btw code came of as i was cruising down the highway at 65. Nothing happened before or after, it never hiccuped or anything the whole time.

Thanks in advance!

magnuts
02-19-2014, 10:31 PM
When mine did that, I needed the throttle body to be digitally adjusted.

ltipcke
02-20-2014, 07:24 PM
When mine did that, I needed the throttle body to be digitally adjusted.

was yours drive by wire or just a standard throttle cable throttle body?

seanf86
02-20-2014, 07:28 PM
mine did that I cleaned the maf and replaced the black pipe connecting the 2 valve covers to the intake, also replaced both front 02 sensors

ltipcke
02-20-2014, 08:11 PM
that pipe is brand new and I cleaned the MAF already (still could be bad)...what are you getting for MPGs if you roll on the highway? best ive ever gotten was 22...three people in the car, no roof rack, in the winter with blizzaks on a cold cold trip.

In the summer with the roof rack on and 2 mountain bikes and Sumi HTRZIII tires all highway i only got 18...im thinking its probably due to the large amount of drag tho lol.

seanf86
02-21-2014, 07:21 AM
Not sure what my hwy mpg was but in October I took it down to Fargo which was a 3.5 hr trip and i was impressed with the mileage which I wanna say 25 us mpg 2 of us in the car and summer tires on 16in OEM wheels

Sent from my XT1058 using Tapatalk

EugeneTakoev
02-21-2014, 11:58 AM
I am having a "system to lean code" come up and it has been coming back. Replaced O2 sensor, came back. Replaced MAF, came back. Now checking the brake vacuum system for possible leaks.

ltipcke
02-22-2014, 07:02 AM
id be stoked with 25 mpg! lol

and yeah vac leaks suck to find sometimes. I dont want to throw parts at this old dog and now have it fix the problem.

I cleared the code about 300 miles ago and it hasnt come back yet. UGH.

seanf86
02-22-2014, 07:34 AM
id be stoked with 25 mpg! lol

and yeah vac leaks suck to find sometimes. I dont want to throw parts at this old dog and now have it fix the problem.

I cleared the code about 300 miles ago and it hasnt come back yet. UGH.

don't even get me started with city mpg tho, thats like 10 lol its the auto trans I think that makes it so bad on fuel, also only have a pass side cat, driver side got blown out the tail pipe and spacer installed on rear 02. Did you check the hard plastic vac line going to the vacuum resovoir under the ps fluid resovoir, I changed the driver side vcg the other day and broke it in a few placed and replaced it with rubber. With the car off when you disconnect it it should hiss if not then theres a leak somewhere. As I keep thinking of more stuff I'll keep posting back haha

ltipcke
02-22-2014, 10:02 AM
don't even get me started with city mpg tho, thats like 10 lol its the auto trans I think that makes it so bad on fuel, also only have a pass side cat, driver side got blown out the tail pipe and spacer installed on rear 02. Did you check the hard plastic vac line going to the vacuum resovoir under the ps fluid resovoir, I changed the driver side vcg the other day and broke it in a few placed and replaced it with rubber. With the car off when you disconnect it it should hiss if not then theres a leak somewhere. As I keep thinking of more stuff I'll keep posting back haha

Ill check just to be sure! thanks for the input.

The intermittent lean shit is what is frustrating to me tho. i wish it was just dead set on running lean with a clear vac leak. the intermittent part makes me think its a sensor or solenoid failing...

ltipcke
02-24-2014, 09:10 PM
Ill check just to be sure! thanks for the input.

The intermittent lean shit is what is frustrating to me tho. i wish it was just dead set on running lean with a clear vac leak. the intermittent part makes me think its a sensor or solenoid failing...

Nobody else has any input on this?