The BLM's are going down when the EGR goes on. Does this sound like a bad injector because I feel it's the only explination.
91 GTA vert L98 with only SLP headers/exhaust. Nothing else has been done to the car so when I first scanned it I noticed rich BLM's like 116 and richer. If anything I was expecting the light-moderate loads to indicate lean seeing as the SD setup wouldn't register the headers. Immediatly I asked if the o2 sensor had been changed recently and what brand. Turns out the previous owner (who was with us) said it was replaced 3 years ago with a bosch single wire. Needless to say the night was over quickly when I sent them on their way on a quest for an AC Declo sensor. Turn the clock ahead 2 weeks to last night and the car is getting better mileage but still far from ideal (11mpg average). After pushing my ego aside I figured a test was in order so I leaned out the VE (btw, base bin AUJP) to see if it helped any. NOPE, my gut was right, something is a miss. By leaning things out a smidgen I could detect the ever slight difference in the engine during off throttle braking (rpm's dip lower and engine sounded off). So we sit there in a parking spot hanging out with a bunch of other f-body guys from the local club and it starts to stink rich EVEN with the BLM's at 133. I'm going through the datalog and quickly notice the EGR going on bringing the BLM's low REAL low as in 108 pegged.
So does this sound like a bad injector and if so, passenger side only? I'm not familiar with the EGR, does it pick-up from both heads or only the passenger side? The end of the evening was me bringing the VE back up so the non-EGR BLM's were back around 128. Then I disabled EGR and sent him on his way. Next week it's round 3, I can't see it being anything other than a bad injector but if somebody has any other idea's I'd love to hear them.

I should probably say why I think it's a bad injector; If the EGR is closed, any unburned fuel from a miss-fire or leaking injector will just be passed out the tail-pipe but with EGR on some of that fuel from the bad cylinder(s) will be redisbributed to ALL of the engines cylinders.

 

The bad injector is certainly a possibility but it could also be other factors. Possibly the EGR corrections are off for the given setup and its not reducing the PW enough to account for the EGR. After all, if the engine is running rich in some spots, the EGR will essentially be adding more fuel in as there is more partially burned fuel in the exhaust present. Just a thought.

 

I'm 3 for 3 on 91 modely year birds and crapped out injectors by ohming them out to find bad ones. I know its not a guarantee, but the Multecs died from injector services and just being exposed to air :-)

EGR does draw from both heads.

I have seen some clogged and/or sticking and causing some funky issues.

Another thing of note, make sure his intake isnt leaking coolant/oil/etc. The TPI intakes love to do that even moreso than regular carb or TBI intakes from what I have seen

Another thing I havbe found on a couple cars is people throw in 24# injectors like SVO cause their cheap and it will drive the BLM down to 108-112 range also.

later
Jeremy

 

You bought another car?.

 

Me? No, my new car is a 300c.

Jermey, the Multecs is the whole reason why I think an injector(s) are bad. I've had nothing but bad luck with them and going on 14 years who knows what kind of crap has gotten into the injectors.