Bad fuel economy in 20v

[Matty104]

Tried having a search around BUT couldnt find anything that helpd me out,

I have a 20v Blacktop, used to get about 420km out of a tank around town and for about the last four tanks of gas i went down to about 320 , changed plugs to platnium, and ive got up to 370km but still alot lower than it should be

i tried running error codes and the enging lite just flashed , no pauses or anything, i think i was doing it rite , linked the t1 and e1 terminals , (thinks thats what the lables on the box said,

so does anyone have any ides??

Matt

[bluemaumau]

what mods, been under any stress lately?

[Distrb]

if the engine check light flashes with no pauses, then it means there are no error codes.

does the car warm up properly when driving? so not driving around on cold start?

[Bling]

what fuel you run?

[Matty104]

always run 98 from bp, and yea the engine warms up in normal time give or take a min or to probly coz of the cold weather at the moment haha ,

has a 2 1/4" exaust system, but it started when i had a 2 1/2" system so that pretty much rules that out,

other than that its just the pod filter and thats about it, but nothing was changed for a while before it happend, just happend all of a sudden, so did the plugs, ( and oil and filter at the same time) and gaind around 50km, driving a little bit harder than normal , but certianly not hard enough to loose anywhere near that much,

[sergei]

Do you have a multimeter?
If so while car is running and it is warmed up, can you please tell me what voltage you get between pin VF and E1 in the diagnostics connector? (multimeter should be set to 20V range, or 5V depending on model)
If you get 0V please tell me what voltage you get between OX1 and E1, and how often it fluctuates in 10seconds (multimeter set in 2V range).

[Matty104]

don't have one here at home, but i will do it at work tomorrow and post up, thanks sergei

[cogent]

02 sensor sounds most likely. ours went, replaced it with a TGP 4 wire from revhead and now its getting 500ish around town again. do sergeis tests first though - sounds like hes trying to diagnose the oxy sensor though.

[sergei]

Oh but when O2 sensor goes it is usually is a symptom not problem itself.
Otherwise you will have to replace it again in 1-3years (or sooner).
I successfully restored 10yo sensors with a butane torch.

[Matty104]

where is the oxy sensor located?

[sergei]

right after the flexy joint and before catalytic converter, where exhaust goes above subframe.
But if you measure those voltages you would know if the O2 sensor is working.

[Matty104]

oh yep ive seen that , well i will do those tests tomorrow and get bak to you , thanks for the help

[Bling]

next time you fill up, make it a rule to not rev it over 4k until the tank is empty, see how many kms you get doing that

[sergei]

With everything working fine you should get about 500kms from tank even with heavy foot.

[Caribeena]

With everything working fine you should get about 500kms from tank even with heavy foot.

agreed i can ge 550 if i nana it. You got any extra weight in it at all? like sub box etc? that can make a difference.

[malc]

Is the map sensor in the right position, has the car got aftermarket intake piping etc?

[Matty104]

d be in heaven if i got 500 km i think haha , i have a stainless intake with the pod sitting just behind the battery , and sensor is about half way down the pipe give or take a bit.

i do have a rather large sub box in the boot with two subs,


Did the test from VF1 to E1, ( i assume VF is the same as VF1) and got 2 volts dc, and did the otha one just to check and that came out at 0v

[sergei]

2V on VF1 means that ECU is running no compensation for Oxygen sensor (usually good thing as the fuel map in ECU is corresponding with Oxygen sensor reading).
0V constantly on OX1 means that oxygene sensor is not outputing anything.
Usually when you get 0v on OX1 VF is 0v as well. (unless you got 0v becuase of bad connection between probe and connector).

Did you manage to check for codes? If you don't get any codes, reset ECU (reset ecu anyway after you check for codes), and measure those voltages again (this time keep the car at 2500rpm).

[Willdat?]

tried injector cleaner? I went from 400km/tank back to the 550ish I used to with one dose of Prestones injector cleaner. I hate the lack of 98 available in Nelson...the closest place that has 98 is Greymouth

[IH8TEC]

tried injector cleaner? I went from 400km/tank back to the 550ish I used to with one dose of Prestones injector cleaner. I hate the lack of 98 available in Nelson...the closest place that has 98 is Greymouth

greymouth has 98 but nelson doesn't, wtf poor nelsoners