I'm pretty sure something is wrong with my as i got about 13mpg.....my mpg started dropping off awhile ago I noticed and it seems to be getting worse and worse. open loop it it runs much better, once in closed loop car idles a little ruff but nothing horrible and hesitates slightly from a stop. also this only happens in closed loop if I put the car in nuetral and hold the revs at 1.5k or 2k or wherever it wont hold stead bounces up and down can't hold constant, does not do this in open loop.

I'm no master at this logging stuff but im pretty sure something not right with the 02 readings thanks for the help.

Heres my log file of car idling while warmed up its a .csv file: http://rapidshare.com/files/136172539/idlelog.csv.html

 

Took a very quick look and o2's seem OK. They are showing the PCM is trying to keep your car a bit leaner since it is running rich. You are rich, of course and will need to tune for that.

Is what you are showing in your sig all that you have done?

Does it need a tuneup?

 

It is pulling fuel quite a bit. It is unlikely though that without being up against the 108 blm limit (which you may be other than idle speed) that your mileage would be affected. The reason being is that your computer will always adjust to stoich and settle there. Your car has good vaccum for a stock cammed ride. Your airflow looks very good and exactly what i expect to see from a stock cammed engine. Timing is also as expected.

Since you say it runs well in open loop, which ignores o2 sensors, i would almost straight away say it was your o2 sensors that have gone bad. However, does it run well on a hot start which will force open loop? It could be something aggrivated by heat.

I would be looking at my fuel pressure regulator if i was you, that is the only way fuel can get into the stream outside of a bad injector, which should present on one side not both. The odds of two injectors going bad on opposite sides of the engine is not unheard of either though.

A general tuneup would not be a bad idea. Clean your maf with some of the maf cleaner from crc. Put new o2 sensors in, Check for fuel in the vac line from the regulator. Do all of these one at a time and note any changes.

What do the fuel trims look like up at road speed. If it was the maf being dirty what you have for fuel trims indicates about a 10% error or about half a gram/sec off of what should be. Which is a very small miscalibration, if it shows good trims while on the highway it could be as easy as a dirty maf.

 

Car has pretty new wires and plugs maf is not dirty also tried running with maf unplugged same result o2 sensors are fairly new too all installed installed after headers just over a year ago. I will check the injectors and regulator tommrow. Could a bad fuel pump be causing this? heres another log I used datamaster to do it, but I guess since I just have to trial I can export it as a datamaster file so I figured out how to export it as a .csv hopefully I included all of the cells that I needed to Its quite long and I also drive it.
Thanks for all the help really appreciate it.

Link: http://rapidshare.com/files/13640552...roz28.csv.html

EDIT: also forgot to add when I play back the datamaster file the Longterm fuel count constantly stay pink indicating rich condition, and the short term move from blue to pink so I don't know if that helps. and car is 115k miles in it.

 

All your low speed airflows are pulling fuel like mad, gets worse as airflow gets less, I think you're getting unmetered fuel somewhere. As airflow and fuel flow increase the % error of extra fuel from a steady leak will be much less maybe even not noticable. Which is what your log shows imo.

Thats my best guess for right now. Only other thing i can imagine is something wrong with your o2 sensors, either the heater or they are just fouled. I suppose the the egr could be futzing with it, but any thing i mess with is not usually equipped with egr. Charcoal canister malfuction could cause a bit of a problem too.

 

yeah my egr isn't connected everything is plugged off along with the vac. line. so should I still be checking the injectors regulator and pump? I guess it could be the o2 sensors its just wierd that its been getting worse over time.

 

Yup injectors and regulator would be where I would look first. We can discuss the other stuff after you eliminate those two which are most likely.

 

Well I pulled the fuel rail today and primed the fuel system none of the injectors leaked..wasn't to sure how to test the regulator but i pulled the vac. line and it was dry no fuel or anything. also with a guage connected it works as it should in the high 30's with it connected and lik 43 when dissconnected. I also checked my o2 milivolts with out starting the car they both started at about 450mv and after about the 30 seconds the left one sat a 4mv and the right one at 8mv is that right?

 

Well I think I'm about to just go ahead and get some new o2 sensors, I can't find anything else wrong. The car runs normal fine in open loop then when it goes into closed loop I can feel the idle get a little rough and it stumbles just a bit from a stop. I don't know what else to try.

 

What makes me think that it is not your o2's is the fact that the banks are, on average, within a few points of each other. If they were bad, they generally would be skewed. Did you adjust the MAF to see if that helps?

 

I don't really think its the o2's either they are fairly new anyway, but as soon as the car goes into closed loop it starts acting idles kinda rough if i rev it to a certain rpm and hold it, it will bounce up and down a couple hundred rpms like I'm playing with the gas pedal but I'm not. in open loop none of this happens runs fine.

When you say adjust the MAF you mean by tuning? lol becuase i have no idea how to do that I'm sure I will screw it up worse than it is, and car does same thing with maf unplugged, so I'm pretty sure its not the maf.

This problem is really starting to **** me of now lol

 

Thats all i can figure is its the o2's. I cannot think of a single other reason his car would think that both banks were running rich unless his maf was really far off, but his maf readings are in the ballpark for almost every lt1 i have tuned. Although, it is worse at idle and low speed cruise and it takes a very small change to make a large error there. I have to assume that it is not the maf because he says it runs like **** when the o2's are in use in closed loop, but its fine in open loop so the maf is correct there and the fuel trims are wrong in closed loop.

Only other thing I can even imagine is too much back pressure from a clogged up cat or some other obstruction in the exhaust. Maybe theres oil on the o2 harness or something is keeping it from getting air through the harness wires. But that is a pretty good stretch.

Its very very odd that something is not mechanicly wrong for both sides to have the same error in calibration like 95blackhawk said. Find you a buddy and steal his working o2 sensors

 

wow....so guess what I decided I was gonna lash my rockers tighter since I only has them at 1/4 past zero lash...well it turns out on the drivers side I have a bent pushrod...although its not to bad it was bad enough to wear the rocker had some marks on it I checked another one on the drivers side it seemed to be good..So im assuming im going to find the same thing on the passanger side. Could this be the cause of my problem lol....I'm suprised it didn't tick or anything maybe I just thought it was the normal sound for my roller rockers, but now that I think of it take a look at a post I made here awhile ago well I guess I found out what it was..https://www.camaroz28.com/forums/sho...d.php?t=606093

 

ok so on each side I had one rocker that had a damaged tip, the part that sits on top of the valve spring. the pushrods aren't visibly bent but when I roll them on a glass table they don't roll exactly straight, but its not that bad so I ordered all new ones..I'm assuming that must be bent to damage the rocker.

 

Do a leakdown/compression test on the cylinders with the damaged rockers?

Can you post pics of exactly what you're talking about here with the rocker damage, I cannot exactly picture it.