CHeck engine light in 90 LX

Fox Body · 10-31-2002, 07:40 PM

Hey guys, the check engine light in my 90 LX 4-cyl keeps going on for about 1minute and going off for about 5 minutes. The guy who does the free diagnostic testing at the local AUtoZone says the light has to stay on for him to read it with the device they use, but the light only comes on while I'm driving in the car. Any suggestions as to what might be causing this?

Blue GT 5.0 · 11-01-2002, 11:15 AM

Mine does the same thing. I wouldn't worry about it. I think it has something to do with either the MAF or exhaust sensors.

84LX89GT · 11-27-2002, 12:23 AM

Unfortunately the EEC-IV (OBD1) cars have only on-demand testing and don't store continuous codes. Usually only hard faults will show up when testing the system. Most likely there is a sensor that is temporarily going out of range, then coming back again. It's hard to pinpoint those problems since they only happen when you're driving.

10-31-2002, 07:40 PM	#1
Fox Body Mustang Maniac Join Date: Sep 2000 Location: GA, U.S.A Posts: 2,266	CHeck engine light in 90 LX Hey guys, the check engine light in my 90 LX 4-cyl keeps going on for about 1minute and going off for about 5 minutes. The guy who does the free diagnostic testing at the local AUtoZone says the light has to stay on for him to read it with the device they use, but the light only comes on while I'm driving in the car. Any suggestions as to what might be causing this? __________________ 351W-powered 1979 Ford Mustang Ghia notchback '79 Video @ Idle Stock 5.8L under 4" cowl 'glass hood, C4 w/ Transgo shift kit, Holley 750 cfm, Edelbrock Performer RPM intake; Fluidyne Al radiator, Flexalite 175 electric fan, 1 5/8" MAC shorty headers, FRPP Al driveshaft; S&W 6-point cage; 2.5" Off road H-pipe, 2-chamber Flowmasters, 8.8" Rear w/ 3.55s; Weld wheels (15x6;15x8), Front: 225/60/15, Rear: 275/50/15 Nitto NT 555R Drag Radials; 14 x 4” K&N X-stream air filter. '92 GT (5-speed) Small In Car Video Stock 5.0L, 2-chamber Flowmasters, MAC CAI, Tri-Ax, Al pedals... "Red, thou art my companion. Hasten now your quickened metamorphosis to Green that I may conquer all who dare abide there beside me. May they be left thither behind burnt black." ---Fox Body

11-27-2002, 12:23 AM	#3
84LX89GT Mustangs Join Date: Jul 2000 Posts: 1,938	Unfortunately the EEC-IV (OBD1) cars have only on-demand testing and don't store continuous codes. Usually only hard faults will show up when testing the system. Most likely there is a sensor that is temporarily going out of range, then coming back again. It's hard to pinpoint those problems since they only happen when you're driving. __________________ 2005 Suzuki Hayabusa GSX1300-R 1980 Ford Thunderbird - 255 V8 ported heads, 5.0L ported stock headers, O.R. H-pipe and Flowmaster 2-chambers, dual roller timing chain hi-po Mack Truck hood emblem 1985 Mustang GT 5.0L T5, F-303, GT40p, headers, off-road h, flowmasters, MSD stuff, etc. Sold 02/06/04 1989 Mustang GT ET: 13.304@102.29 mph (5-24-03) Sold - 1998 Mustang Cobra coupe, 1/4 mile - street tires: 13.843@103.41 (bone stock)

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11-01-2002, 11:15 AM	#2
Blue GT 5.0 Registered Member Join Date: Feb 2002 Location: McSherrystown PA (near Gettysburg) Posts: 26	Mine does the same thing. I wouldn't worry about it. I think it has something to do with either the MAF or exhaust sensors.