88 lx 5.0 needs help!

pearce9906 · 12-14-2007, 12:48 AM

Well, I changed plugs out again, to no avail. EGR was bad, replaced it, as well as TPS, still not fixed. Noticed there were two vacuum solenoids on the right front inner fender on the the rear of the engine compartment that were damp with some gas, presumably from where the reg went bad and flooded the plenum and vacuum lines, I took them apart and cleaned them, that seemed to do the trick with getting the car running right and taking out the majority of the miss. But now I have severe idle surge, almost dropping to the point of killing itself, also running super rich. I've tried almost everything I can think of to narrow the problem down, but am having a heck of a time with it. Any ideas?
Keep in mind, I have just bought this car and don't have much idea about what mods previous owners have done to tune the car.

bailey_57 · 12-18-2007, 10:45 PM

did you replace the tps and set it? surging idle is a problem as old as the 5.0. if you go through a search for surging idle you probably will find quite a few threads. also before i had any mods, i had a surging idle and chased all the gremlins. i got rid of mine with a 1/8th in drill bit through the throttle blade. good luck.

pearce9906 · 12-19-2007, 01:56 AM

thanks for the reply baily_57, tomorrow is my day off so I plan to work on the car all day, hopefully I can chase my demon down, plan on setting the tps voltage, checking fuel pressure, checking compression, and possibly trying the codes, not throwing a check engine light tho, could mean the previous owner installed a chip or removed the bulb tho. Hopefully something will turn up tomorrow though, I am about at wit's end on this problem. Getting super frustrated. I'll post what I find. Thanks again.

USMC302 · 12-19-2007, 10:34 AM

Might be a good idea to throw in some new o2 sensors.

pearce9906 · 12-19-2007, 11:19 AM

Haven't checked the TPS voltage yet, but bought a code reader today, turns out I had a few codes, IAC valve, coolant sensor, which was my fault because I unplugged them whileengine was running, but also the fuel pump relay circuit was bad, pump is running all the time, which to my thinking would explain the rich condition and also the idle surge, if the motor is loading up with fuel at idle it would pretty much be flooding itself out. Correct? Also, the fuel pressure regulator is bad once again, I guess the pump running all the time is just building up too much pressure in the line and the diaphram in the reg is blowing out.

USMC302 · 12-19-2007, 11:45 AM

It's supposed to run all the time when the engine is running.. What makes you say the FPR is bad again? You need to set the TPS, before we try to point fingers at anything else....

pearce9906 · 12-19-2007, 06:33 PM

ECM says relay is bad. Trouble code 87. Also, even with the relay removed, fuel pump still runs when ignition is turned on, TPS voltage is now set at .96. Car runs, but still surging after about 3 minutes, also, fuel injecters are getting wet with fuel, on the outside. Not a leak on the fuel rail, it is a mist/smoke coming from around the injectors at about five minutes idle time, after the motor starts loading up with fuel.

Any idea why the fuel pump would run all the time (without the relay)?

12-14-2007, 12:48 AM	#1
pearce9906 Registered Member Join Date: Nov 2007 Location: OHIO Posts: 20	Re: 88 lx 5.0 needs help! Well, I changed plugs out again, to no avail. EGR was bad, replaced it, as well as TPS, still not fixed. Noticed there were two vacuum solenoids on the right front inner fender on the the rear of the engine compartment that were damp with some gas, presumably from where the reg went bad and flooded the plenum and vacuum lines, I took them apart and cleaned them, that seemed to do the trick with getting the car running right and taking out the majority of the miss. But now I have severe idle surge, almost dropping to the point of killing itself, also running super rich. I've tried almost everything I can think of to narrow the problem down, but am having a heck of a time with it. Any ideas? Keep in mind, I have just bought this car and don't have much idea about what mods previous owners have done to tune the car.

12-18-2007, 10:45 PM	#2
bailey_57 Registered Member Join Date: Mar 2000 Location: Berwick,Pa Posts: 127	Re: 88 lx 5.0 needs help! did you replace the tps and set it? surging idle is a problem as old as the 5.0. if you go through a search for surging idle you probably will find quite a few threads. also before i had any mods, i had a surging idle and chased all the gremlins. i got rid of mine with a 1/8th in drill bit through the throttle blade. good luck. __________________ '89 GT hatch back performer rpm intake, performer rpm cylinder heads, fms e-303 cam, kirban adj fp regulator, holley 65mm tb, harland sharp 1.6 roller rockers, alum driveshaft, 3.73 gears (283 rwhp, 303 rwtq new numbers with new heads)

12-19-2007, 01:56 AM	#3
pearce9906 Registered Member Join Date: Nov 2007 Location: OHIO Posts: 20	Re: 88 lx 5.0 needs help! thanks for the reply baily_57, tomorrow is my day off so I plan to work on the car all day, hopefully I can chase my demon down, plan on setting the tps voltage, checking fuel pressure, checking compression, and possibly trying the codes, not throwing a check engine light tho, could mean the previous owner installed a chip or removed the bulb tho. Hopefully something will turn up tomorrow though, I am about at wit's end on this problem. Getting super frustrated. I'll post what I find. Thanks again.

12-19-2007, 10:34 AM	#4
USMC302 Registered Member Join Date: Apr 2001 Location: Gallatin, Tn Posts: 1,326	Re: 88 lx 5.0 needs help! Might be a good idea to throw in some new o2 sensors. __________________

12-19-2007, 11:19 AM	#5
pearce9906 Registered Member Join Date: Nov 2007 Location: OHIO Posts: 20	Re: 88 lx 5.0 needs help! Haven't checked the TPS voltage yet, but bought a code reader today, turns out I had a few codes, IAC valve, coolant sensor, which was my fault because I unplugged them whileengine was running, but also the fuel pump relay circuit was bad, pump is running all the time, which to my thinking would explain the rich condition and also the idle surge, if the motor is loading up with fuel at idle it would pretty much be flooding itself out. Correct? Also, the fuel pressure regulator is bad once again, I guess the pump running all the time is just building up too much pressure in the line and the diaphram in the reg is blowing out.

12-19-2007, 11:45 AM	#6
USMC302 Registered Member Join Date: Apr 2001 Location: Gallatin, Tn Posts: 1,326	Re: 88 lx 5.0 needs help! It's supposed to run all the time when the engine is running.. What makes you say the FPR is bad again? You need to set the TPS, before we try to point fingers at anything else.... __________________

12-19-2007, 06:33 PM	#7
pearce9906 Registered Member Join Date: Nov 2007 Location: OHIO Posts: 20	Re: 88 lx 5.0 needs help! ECM says relay is bad. Trouble code 87. Also, even with the relay removed, fuel pump still runs when ignition is turned on, TPS voltage is now set at .96. Car runs, but still surging after about 3 minutes, also, fuel injecters are getting wet with fuel, on the outside. Not a leak on the fuel rail, it is a mist/smoke coming from around the injectors at about five minutes idle time, after the motor starts loading up with fuel. Any idea why the fuel pump would run all the time (without the relay)?