North American Turbocoupe Organization



Terrible Fuel Economy = Bad O2 Sensor?
DanMarshall Offline
Junior Member
#1
Since Monday my 88 TC has done really poor on MPG. I put in $40 Sunday night and it being Wednesday at the time of this post, I've done about maybe 50-60 miles without really getting into boost (over 5 - 7 psi) or hardcore beating on the car with one or two exceptions. And those times i did really run out the gears it got up to 15psi and didn't really pull like normal. It felt like something was holding it back. I recently gutted the cat (because of the 25 year old rule in PA doesn't require you to have one) so i don't know if this could be part of the problem, but there is a strong scent of unburnt gas at idle or after reving the engine which points out the car is running very rich. I assuming this could be from a bad O2 sensor or Air Temp. Sensor (I pulled a code from this a few months back but never got around to doing it.) or a vacuum leak of some sort. Fuel pump was also replaced back in July just to put it our there. The car has only 130,000 miles with no abusive driving and religious oil changes and maintenance from the previous owner, so i don't believe the turbo is going bad.

What does this sound like to you guys? I need some help cause This terrible fuel economy is eating away at my wallet and making me very frustrated.
1988 TurboCoupe 5 Speed 130,000 miles
1998 Ford Escort SE (Daily Driver)
Reply

Joe F Offline
Posting Freak
#2
Gas smell at exhaust or engine compartment? If engine compartment might want to check for leaks at the fuel rail and make sure the fuel regulator has not gone T/U.
JR's Place - My '87 Turbocoupe
Reply

DanMarshall Offline
Junior Member
#3
Exhaust. It smells like unburnt fuel when the engine is revved outside the car.
1988 TurboCoupe 5 Speed 130,000 miles
1998 Ford Escort SE (Daily Driver)
Reply

Not B Anymore Offline
Administrator
#4
I vote FPR - take the vacuum hose off the regulator and give it a sniffy sniff. Wetness or strong smell of fuel is a good indicator it's bad.
Brian Leavitt
'86 TC 5-Speed -- MS2x w/COP | 83 lb. injectors | T3/T4 50 Trim Stage 3 .63AR | Full 3" Exhaust - No Cat | Motorsport FMIC | Ranger Roller | Ported E6 | Walbro 255HP | Kirban | 20psi | 120-amp 3G | 8.8" 3.55 rear | '03 Cobra Wheels
Reply

DanMarshall Offline
Junior Member
#5
Just drove the car and it started pinging on 93 octane fuel under no boost. Just pinging on normal driving. Pretty sure it is the O2 because it has never been replaced by a previous owner. Picking one up tomorrow and will clean the plugs too because i've been running rich for a while. Will report back with updates.
1988 TurboCoupe 5 Speed 130,000 miles
1998 Ford Escort SE (Daily Driver)
Reply

Not B Anymore Offline
Administrator
#6
It's possible that it's running rich because of a bad O2 sensor, but the problem of it not pulling 'like normal' has got nothing to do with the O2 sensor. The O2 sensor is completely ignored over ~2800 rpm or ~70% throttle. Also - the ACT sensor isn't going to affect fuel consumption much, if at all. IIRC all it does is add or remove a degree or two of timing depending on air temp.
Brian Leavitt
'86 TC 5-Speed -- MS2x w/COP | 83 lb. injectors | T3/T4 50 Trim Stage 3 .63AR | Full 3" Exhaust - No Cat | Motorsport FMIC | Ranger Roller | Ported E6 | Walbro 255HP | Kirban | 20psi | 120-amp 3G | 8.8" 3.55 rear | '03 Cobra Wheels
Reply

goldwing Offline
Senior Member
#7
You should get a gas smell out of the exhaust just because you don't have a working Cat.-Converter.
Whats your timing set at ?
T.C:87 5 speed
HOLSET(HE341/HY35W type-D),255 Walbro, No intercooler yet,8lbs boost,Timing @ 9,Low& C.C Plates & SN-95 Bumpsteer Kit, KYB-AGX Struts,Belt driven fan,Custom oil cooler feed,Relocated ECT,Relocated TFI,N/A Hood, showing 178K
Reply

Dan S Offline
Administrator
#8
I'll bet on the FPR.
Dan S
Custom 88 TC, Mandarin Copper Pearl Metallic
http://natomessageboard.com/ubbthreads.p...5#comments
1972 Ford F-100 SWB Styleside
2015 Lincoln MKC 2.3 EcoBoost AWD
Reply

zip Offline
Member
#9
Another vote for the Fuel Pressure Regulator, which is located on the fuel rail. Give it a check as Brian suggested or check the fuel pressure with a tester/gauge. The detonation your experiencing is probably being caused by the rich fuel mixture. Have you checked for any codes?
Matt
86 TC 5spd:QH/SD,Walbro190,CFI 52#, AFPR,WB,FMIC,3"dp to axle, .63 T3, E6,Stock Longblock.
Shelf:N/A 2.3, Die grinder, Carbide Burrs.
Reply

DanMarshall Offline
Junior Member
#10
probably is. Just spent $70 doing o2 sensor and spark plugs. Needed them badly from running so rich, but pinging still exists. So must likely be FPR or another sensor of sort. Gonna get the code grabbed by an OBD scanner this weekend so i can know for sure.
1988 TurboCoupe 5 Speed 130,000 miles
1998 Ford Escort SE (Daily Driver)
Reply





Users browsing this thread:
1 Guest(s)



Theme © iAndrew 2018 - Software MyBB