comanche250
Active member
- Joined
- Jul 12, 2024
- Location
- Okanagan, Canada
I've now gone 2 whole months of gentle city driving in my 1991 740 wagon with a turbo redblock and AW71L. I have been running stock boost, stock exhaust (minus the cat eww). Just to work and back with at least 20% highways driving. Every acceleration from a red light I get it just past the middle mark on the boost gauge to keep up with traffic, one would say just regular driving, how every normal person accelerates.
Here, just like this, this is how I drive
Note my fuel level, after 214 km of driving, or 132 miles. That's about a week of driving. I drive gently, do the speed limit, ect. Yet without fail, at 300 km or 186 miles, my fuel light comes on, and I gotta throw $70 CAD worth of fuel in it again. I average 14 MPG. Now if I was driving quick and being stupid yeah I'd expect that, but I was getting the same mileage in the fall when I had my MBC in and set to 12 psi, running it hard and driving dumb. I had my fun for those few weeks just to see what it was like, not my thing anymore I'd rather not risk killing my nice daily. But it gets the damn same mileage as my 3/4 ton carbureted squarebody chevy!
So lets talk about what I've done.
The motor has around 130k km on it. I swapped it and the transmission (and entire engine and dash wiring harness out of a 1992 940 sedan) it's in incredible condition, no ticking or tapping or leaks or anything, I could eat my lunch off the painted block. I've replaced the spark plugs with NGK BPR6ES, and replaced the leads, they're bright blue kinda annoying and flashy but whatever. New volvo OEM thermostat. I have tested the ECT sensor right at the EZK side of the connector and it is within spec. no vacuum leaks, I even resealed the entire HVAC unit, it'll hold vacuum overnight I can go out to the car the next day and twist the selector knob and I'll hear the flaps move still. I am pretty confident there is no fuel leaking itself, everything is dry and doesn't smell. I also tested the fuel rail pressure since I noticed if you don't let the pump prime for a few seconds it'll stutter when you crank it, but the pressure holds 41 psi at idle and goes to 47 when you rev it. I popped off the vacuum hose the the FPR it doesn't leak fuel but it does smell of fuel.
I replaced the OEM bosch oxygen sensor just the other day with an NGK unit, I noticed the engine has slightly differnt power but I can't really explain it, it just feels like the turbo has a fraction longer lag, it could just be placebo. I will have to drive a full tank and see if my mileage is different. I can usually tell right away because the fuel gauge unpegs off of full after like 13 km or 8 miles and hits the halfway mark around 150-160 km 93-100 miles. One thing I should mention is the bottom stud on the turbo to the downpipe flange has snapped, so its just the two studs holding that coupler on, right before the o2 sensor. I don't hear a leak and I don't feel one so I'm assuming its not leaking air in and skewing the sensor.
I just used my shitty scope on it this weekend since I was curious of the waveform, it seemed normal to me maybe one of you would know better?
I dunno I'm out of ideas, I keep getting the same "hurr durr you must be driving it wrong" responses and honestly the next person to say that I'm gonna grab their balls and fuken twist them so hard. I'm close to just selling it and buying a shitty little diesel golf or something.
Here, just like this, this is how I drive
So lets talk about what I've done.
The motor has around 130k km on it. I swapped it and the transmission (and entire engine and dash wiring harness out of a 1992 940 sedan) it's in incredible condition, no ticking or tapping or leaks or anything, I could eat my lunch off the painted block. I've replaced the spark plugs with NGK BPR6ES, and replaced the leads, they're bright blue kinda annoying and flashy but whatever. New volvo OEM thermostat. I have tested the ECT sensor right at the EZK side of the connector and it is within spec. no vacuum leaks, I even resealed the entire HVAC unit, it'll hold vacuum overnight I can go out to the car the next day and twist the selector knob and I'll hear the flaps move still. I am pretty confident there is no fuel leaking itself, everything is dry and doesn't smell. I also tested the fuel rail pressure since I noticed if you don't let the pump prime for a few seconds it'll stutter when you crank it, but the pressure holds 41 psi at idle and goes to 47 when you rev it. I popped off the vacuum hose the the FPR it doesn't leak fuel but it does smell of fuel.
I replaced the OEM bosch oxygen sensor just the other day with an NGK unit, I noticed the engine has slightly differnt power but I can't really explain it, it just feels like the turbo has a fraction longer lag, it could just be placebo. I will have to drive a full tank and see if my mileage is different. I can usually tell right away because the fuel gauge unpegs off of full after like 13 km or 8 miles and hits the halfway mark around 150-160 km 93-100 miles. One thing I should mention is the bottom stud on the turbo to the downpipe flange has snapped, so its just the two studs holding that coupler on, right before the o2 sensor. I don't hear a leak and I don't feel one so I'm assuming its not leaking air in and skewing the sensor.
I just used my shitty scope on it this weekend since I was curious of the waveform, it seemed normal to me maybe one of you would know better?
I dunno I'm out of ideas, I keep getting the same "hurr durr you must be driving it wrong" responses and honestly the next person to say that I'm gonna grab their balls and fuken twist them so hard. I'm close to just selling it and buying a shitty little diesel golf or something.