6 mpg?

[whitecobra98]

i have been getting horrible gas mileage lately in my '87....have a basically stock setup (TE44, 3in DP, 42.5 inj) starts up fine, idles decent, but leaves huge black soot marks ont he driveway...doesn't smell like fuel when i'm driving, but its obvious something is amiss...scanmaster numbers look to be within the normal parameters, but only getting 6 mpg....have a #1 TT chip in there now...calls for a #2, waiting for that to come in...what else could it be?

 

[SPOOLN]

Mpg

Is your chip burnt for 009 injectors, whats your fuel pressure set on? Is your mass air sensor reading right? it might be bad...

 

[bison]

Is the ecm going in closed loop? When driving where is the blm

 

[turbojd]

Maybe the o2 sensor.

 

[slow305]

You know, I'm having the same problems with basically the same setup. Black soot marks and everything. I think the only difference is I have a the LS1 MAF with Gen II and a Full Throttle chip. Let me know if you get this figured out.

 

[turbo39151]

How old are the injectors? Have you run any kind of cleaner? (ie: seafoam) Pull the plugs and see what they look like. Is the chip matched to the injectors? Cat or no cat? If there is a cat, pull it and check it. I had a stock one on mine that made no noise even though when I pulled it out, the guts were all loose and rattling around. I had been getting about 10-12 mpg. I put a test pipe, along with new injectors and matching chip and the power and MPG came back!

 

[whitecobra98]

Is your chip burnt for 009 injectors, whats your fuel pressure set on? Is your mass air sensor reading right? it might be bad...

yep its erics tt chip for 42.5 inj

 

[whitecobra98]

Is the ecm going in closed loop? When driving where is the blm

when the car is warm and im cruising the blms are around 115-120

 

[whitecobra98]

Maybe the o2 sensor.

new ac delco o2 sensor less than 500 miles ago

 

[whitecobra98]

How old are the injectors? Have you run any kind of cleaner? (ie: seafoam) Pull the plugs and see what they look like. Is the chip matched to the injectors? Cat or no cat? If there is a cat, pull it and check it. I had a stock one on mine that made no noise even though when I pulled it out, the guts were all loose and rattling around. I had been getting about 10-12 mpg. I put a test pipe, along with new injectors and matching chip and the power and MPG came back!

injectors are fairly new 8 months old? no cat on the car...fuel pressure is 42 line off

 

[it's just a six]

Is the ecm going in closed loop? When driving where is the blm

X2

 

[bison]

when the car is warm and im cruising the blms are around 115-120

Thats no good. Should be around 128. Do you have any pre O2 sensor exhaust leaks. Sounds like its adding fuel when it shoudnt be adding. Ambient air entering the exhaust pre sensor will cause problems since the ecm will see it as lean.

 

[whitecobra98]

Thats no good. Should be around 128. Do you have any pre O2 sensor exhaust leaks. Sounds like its adding fuel when it shoudnt be adding. Ambient air entering the exhaust pre sensor will cause problems since the ecm will see it as lean.

i dont hear any, but i will double check...FWIW I did put the TTchip #2 in it, but it ran horrible....but I was able to trace that prob to a faulty charging system after i took it out and put the #1 chip back in

 

[whitecobra98]

ttt

 

[fuzzyGN]

Is your temp sensor (the one that feeds the ECM) stuck low? That will make the car run extremly rich all the time. The ECM thinks it needs the extra fuel because the air is so cold when in reality it isn't needed. Simple fix. Check the scan data, it is an easy one to overlook.

 

[whitecobra98]

Is your temp sensor (the one that feeds the ECM) stuck low? That will make the car run extremly rich all the time. The ECM thinks it needs the extra fuel because the air is so cold when in reality it isn't needed. Simple fix. Check the scan data, it is an easy one to overlook.

ill double check the scanmaster numbers if its not raining when I get home...whats the simple fix? just getting another one? thats the one located in the air filter housing correct?

 

[BlackBandit]

Thats no good. Should be around 128. Do you have any pre O2 sensor exhaust leaks. Sounds like its adding fuel when it shoudnt be adding. Ambient air entering the exhaust pre sensor will cause problems since the ecm will see it as lean.

I think you mean it sounds like it's pullingfuel. As long as your BLM's don't hit there limits you should be fine. If you can get it to set around 128 you're doing good because you're ECU retains the most adjustablity but if they're at 120 your base mixture was rich but the ECU has corrected so you should be fine.

 

[whitecobra98]

I think you mean it sounds like it's pullingfuel. As long as your BLM's don't hit there limits you should be fine. If you can get it to set around 128 you're doing good because you're ECU retains the most adjustablity but if they're at 120 your base mixture was rich but the ECU has corrected so you should be fine.

thats what i thought...i thought if it was within 10 % it was still good

 

[d0n_3d]

If your BLM and INT are + or - 10 from 128 in all ranges, you are fine. You got a gas leak somewhere you don't know about???

 

[whitecobra98]

If your BLM and INT are + or - 10 from 128 in all ranges, you are fine. You got a gas leak somewhere you don't know about???

not that i see...garage floor is clean