98 v70 glt sudden drop in gas milage after campaign 81

paul c · Post by **paul c** » 19 Sep 2015, 10:26

it has 250 k on it, does 70% highway miles and usually around 23-24 mpg during the summer and 21-22 during the winter. it always had the interm stumble and found the old campaign 81 to reflash the ecm. in the meantime i bought a spare known good ecm for 20 bucks to use while i gave mine to a friend for the reflash (only one dealer i could find that still had the old compaq lap top that worked). it took the flash and if i remember right if it didn't fall into the campaign it wouldn't do the flash. but with the other ecm my milage dropped off to around 19 mpg. so when i picked up my old ecm i reset the adaptives with the vst in the used ecm and that seemed to help. so i figured i would see if the used ecm would also take the flash so i would have an updated spare. i put my original ecm back in and it seemed fine, no more stumble. now a couple of weeks later the thing is using a lot more fuel, i got only 17 mpg out of the last tank and 19 the one before. i had changed the cap and rotor last week since the old one got cruddy from the previous oil seal leak behind it. i repaired the b+ cable up at the fuse box, did the complete pcv vacuum harness, tb service, fuel filter, air filter and spark plugs about 25k ago. air filter is still clean and it runs fine. the only other thing i added was factory euro rails, load bars and thule bike racks that bolt to the load bars. if they cause that much drag they will come off now (lol). one of my questions is when putting the ecm back in after doing that campaign 81 do the adaptives need to be reset again? that is the only thing i didn't do when i swapped the original one back in. i did it the other day but was 1/2 way through the current tank of gas. i do have that spare ecm with the reflash ready to go after another tank or two if it doesn't improve. car runs fine also. tried to cover everything, sorry its long winded.

Post by **RussB** » 19 Sep 2015, 16:37

I'd disconnect the battery and reset the ecu

Post by **abscate** » 19 Sep 2015, 20:02

The chances are high the software was corrupted.

With a high mileage car, a compression test is always advisable before embarking on repairs on drive ability. Cleaning the IAC is definitely in order

paul c · Post by **paul c** » 19 Sep 2015, 21:15

abscate wrote:The chances are high the software was corrupted.

With a high mileage car, a compression test is always advisable before embarking on repairs on drive ability. Cleaning the IAC is definitely in order

software corrupted? can you explain please? thanks.

Post by **j-dawg** » 19 Sep 2015, 22:36

I could totally see that rack and bike mount costing you a few MPGs. Maybe not five to seven, but maybe some significant portion of that.

Post by **matthew1** » 19 Sep 2015, 22:38

j-dawg wrote:I could totally see that rack and bike mount costing you a few MPGs. Maybe not five to seven, but maybe some significant portion of that.

Good call. When my expedition basket (unloaded) is mounted I see a ~3 mpg loss at freeway speeds.

Post by **E Showell** » 21 Sep 2015, 19:39

Campaign 81, explain, please.

Post by **abscate** » 21 Sep 2015, 23:21

A 70 % highway in MA is probably 80 mph driving. You roof rack is costing you 2 mpg. 19 mpg highway still sucks though. Even my thirsty turbo does 25 mpg at 75

paul c · Post by **paul c** » 28 Sep 2015, 23:35

thanks for the suggestions. i can take the roof rack off easy enough all in one unit and drive it for a couple of days. i did find that the turbo has some significant oil seal leakage. i noticed the weep hole at the bottom of the intercooler has a good amount of oil coming out, enough to get the engine cradle wet. also the throttle body has fresh oil in it along with a good puff of blue smoke on accel. the milage has been around 21 - 22, just did a lot of idling those couple of days. i will be putting a good used turbo in on wednesday and will see if there is any improvement. then i will remove the load bars and see.

1ezliving4ume · Post by **1ezliving4ume** » 29 Sep 2015, 07:06

paul c wrote:thanks for the suggestions. i can take the roof rack off easy enough all in one unit and drive it for a couple of days. i did find that the turbo has some significant oil seal leakage. i noticed the weep hole at the bottom of the intercooler has a good amount of oil coming out, enough to get the engine cradle wet. also the throttle body has fresh oil in it along with a good puff of blue smoke on accel. the milage has been around 21 - 22, just did a lot of idling those couple of days. i will be putting a good used turbo in on wednesday and will see if there is any improvement. then i will remove the load bars and see.

You might think about rebuilding that used turbo. The kit is like, $60. and the removal and install into and out of the car is not easy. If nothing else check the TCV, the diagrams have a tendency to suck in.