reading scanner question - Page 2 - NJFBOA - Home of New Jersey's Camaros and Firebirds

grazi · 12-29-2011, 08:47 PM

So I just another logged another run while my car was running horrible like I mentioned up top. Hopefully WildBilly T or somebody can post up the Datamaster log but I am getting 15 degrees of spark retard at full throttle!?!? My short term fuel trim go as low as 105 and as high as 145? shouldnt they be steady around 128?

JL8Jeff · 12-29-2011, 09:29 PM

Did you swap the MAF for that run? It sounds like a vacuum leak with the fuel trims jumping around that much. Your EGR might be stuck open causing the extra air to get in leaning it out (and causing spark retard). I think it will add fuel until it hits a limit (25% I think). Do you hear any type of hissing or whistling like a vacuum leak?

grazi · 12-29-2011, 09:34 PM

Hey Jeff, I swapped the MAF for this run. I also plugged the vac line coming from EVAP purge solenoid valve(not sure who reccomended that). I dont hear any type of hissing. I sprayed some carb and choke cleaner around pcv valve, brake booster, throttle body with no change in idle.

sweetbmxrider · 12-30-2011, 07:08 AM

While looking at the datastream at idle, note the fuel trims. Then bring the rpms up steadily to about 3k and see if they change. That should help determine vacuum leak or not.

JL8Jeff · 12-30-2011, 07:40 AM

The EGR still sounds suspect especially since you had it out and noticed it binding. If it's not closed all the way, you'll basically have a constant vacuum leak that the computer doesn't know about.

sweetbmxrider · 12-30-2011, 07:41 AM

Definitely. Throw it out.

WildBillyT · 12-30-2011, 09:08 AM

http://www.njfboa.org/WBT/run2.uni

When the EGR valve gets activity you go pretty lean shortly after and the knock retard comes in. I'd look at the EGR valve as well.

grazi · 12-30-2011, 02:04 PM

OK Guys, Ill try to do that this weekend. The EGR was gummed up pretty bad when I took it out. I figured I'd try to clean it. I used to clean and reuse the EGR on my 6.0 diesel ford all the time. Can somebody explain why a sticking EGR would make so much retard. I understand the EGR not opening would make the motor think its getting air when its not and make it run rich but what tells the motor to retard? Its all retarded......Thanks guys.

WildBillyT · 12-30-2011, 02:34 PM

If the mixture is off it may ping and that causes the knock sensor to go off, and the computer will pull timing.

grazi · 12-30-2011, 02:48 PM

Oh, so I guess first thing to do is Plugs and Wires , replace EGR , and o2 sensors.

grazi · 12-30-2011, 02:52 PM

Could it be a bad knock module?

JL8Jeff · 12-30-2011, 03:15 PM

If the EGR is leaking you will be lean which will cause the pinging, the computer will pull timing and richen it up which will lead to the rich condition. The computer doesn't know the extra air is getting in and can't really compensate for it correctly. Same thing would happen if the EVAP purge was leaking, but there might be a sensor that can detect the flow in that situation, I'm not sure.

grazi · 02-05-2012, 11:53 AM

Update, replaced EGR valve, egr solenoid valve and vacuum lines, pcv hose and ccv hose and o2 sensors. Can somebody with datamaster look at the link on post 8 and look at rec # 1537, 1465, and 1618. Doesnt it look like my tps may be acting slow. My MAP pressure goes up to 12 or 13 before the tps registers anything. Also On 1465 my map goes from 10 or 12 to i think 28 for a split second. also in 1618, i start jumping through fuel cells funny before the tps even registers. Thanks for looking.