Bently_Coop

Recently given a 98 Civic LX four door. Automatic 236500 miles, Has not passed emissions in a few years.

Currently has 3 codes right now:

P0135- O2 Sensor, Replaced the pre cat sensor with a Denso from Napa. NTK would have had to order. Since I dont have a scanner I dont know if that cleared yet.

P0700 Trans Control- My guess is this is related to the shift solenoid. Are these boards seperate from the ECU? Or one and the same? Do they fry often? I havent opened mine yet but may do so tommorow.

P0758 Shift Solenoid- Ohm tested both sides of the solenoid at 14 each. I am thinking it could be a mechanical failure.

I realize this is an old thread, however may be related:
https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/98-civic-automatic-wont-shift-its-own-must-manually-move-shifter-1861140/

Tommorow I plan on removing the solenoid and checking it with alligator clips to the battery. I have seen a couple youtube videos regarding this. If the solenoid is mechanically faulty I will probably replace. I am also thinking new transmission fluid is needed.

Any other ideas or help with this?

eghatch9295

iTrader: (1)

tcu is integrated into the ecu in your car.

Bently_Coop

Are these common failure points?

eghatch9295

iTrader: (1)

no, but at those miles who knows. they failed constantly on the 90-93 accords. further troubleshooting is key before you spend money on a new ecu, but check out car-part.com if you end up needing one. theyre where i order most of my used oem stuff from.

edit: to check if you've cleared a code, remove the backup fuse from the fusebox, and jump the service connector in the passenger side kick panel to read the codes. the procedure is in the faq's

NotARaCist

iTrader: (1)

P0700 is thrown whenever another transmission code is thrown. Before you worry about it, you need to diagnose and fix P0758. You also don't need a code scanner to pull codes - check the FAQ sticky, and you'll find a how-to for doing it with a paperclip.

When I get home shortly, I'll try to find the diagnostics page for P0758 and post it for you.

Bently_Coop

Ok, thanks. Paper clip method?

Thanks, I did read several things saying they should meter between 12-25 ohms. This one is at 14 ohms. I need to remove it and check the mechanical function. Also thinking of removing the ECU and taking a look inside for blown or burnt pieces.

NotARaCist

iTrader: (1)

Bently_Coop

Cool thanks, Ill test it out tonight.

Bently_Coop

Ok so it looks like the O2 is cleared. First I did the alligator clip from shift solenoid to battery and got solid clicks. Then did the electrical check and came up with nothing. Voltage was at .01, I didn't get a value for resistance. Doesn't seem right. At the solenoid was still 14ohms, the linear checked out as well. Took the car off jack stands started it up and added another half quart of ATF.

Which brings me my next question. When I got the car I checked the fluid and it seemed low, but it was pointed down hill. Once the codes were checked at Oreilly's I checked it again an the fluid was on the low end of the dip stick. I then added a half quart of Valvoline Import ATF. Before driving I let it run for a minute and added another half quart. I drove around in D4 and it seemed to shift through the gears. Is it possible if the fluid was low would that cause a code and require manual shifting? Also what if when I was testing the solenoid on the battery it was forcing it to work? I drove the car for about 5 miles and it worked great compared to before. Driving up and down hills accelerating on hills. I am lost, going to test more tommorow and see what happens, maybe it will check out for emissions so I can daily it. Thanks for your help so far, will let you know what happens.

eghatch9295

iTrader: (1)

kind of shady, but disable the obd-2 port. im not going to give instructions so all the idiots here can do it, but you seem competent enough to figure it out. in ohio, if it won't scan, they put it on a dyno and do the tail pipe sniffer test. since you've fixed the emissions issues, your car would pass.

Bently_Coop

EG- no need to disable the obd2 the lights are gone.

Got a few things taken care of today in the tune up department- PCV valve, oil change, air filter and spark plugs. Next thing will be changing the thermostat because of the surging idle from 1k to 2k.

eghatch9295

iTrader: (1)

probably not a thermostat with the idle surge. remove and clean your idle air control valve

Bently_Coop

I was just looking at the same thing, just found some threads on removing the lower intake box and cleaning it out. Will have to get a new TB gasket tommorow for this as well. Thermostat and coolant may be good insurance though, not sure how long its been in there.

Bently_Coop

Pulled the throttle body today and started cleaning it. Also cleaning the IACV. Thing was pretty nasty. Tommorow Ill get it back together and see how it turns out. I also got a new T-Body gasket for it.

eghatch9295

iTrader: (1)

yeah, nothing at all wrong with replacing cheap-o wear parts. just very very very unlikely that a thermostat would affect your idle in that way

Bently_Coop

Cleaned the throttle body and IACV thoroughly today. Didn't change anything. Still has a fluctuating idle. I am thinking that the IACV may be bad or the thermostat is partially open. I placed an order for a new thermostat through AFH parts. Waiting for it to arrive then swap and bleed the system. It only seems to fluctuate in park or neutral.

Any thoughts?

Bently_Coop

Update:

Picked up a 3 day permit put 5 gallons of fresh gas in it, not sure how long its been sitting. Then as I leave the gas station the check engine light comes on. Went to Oreilly and through a P0505 idle air control code. Just picked up a iacv at vatozone and am going to switch it out. Hoping this will be done.

Bently_Coop

Put a new IACV in from vatozone. Duralast box and was an actual Denso sensor which was used OEM from Honda. Idle before on stock tach was fluctuating around 1k-2k in Park or Nuetral, Drive and Reverse was around 1500 rpm. With the new one it was at 1k and not moving, in gear around 700. Which is perfect. Next up will be exhaust fix, need a muffler the pipe between the rear flange and muffler is rotted out.

eghatch9295

iTrader: (1)

i figured that was it. 1k is a little high, you can adjust it via the screw on the throttle body. i cant remember the exact spec for the y7, i think 800-850

Bently_Coop

Ill probably leave it alone. Thanks for the help.

Bently_Coop

Was cruising around today watching the RPM's and its perfect. Under 1k at idle so I won't mess with it. Passed emissions, fortunately only a plug in car since I don't have a muffler connected. Lol. I do need to fix the rear brakes though, while getting a estimate for exhaust they noticed brake fluid all over the left rear wheel. Wheel cylinder blown. Everything will get replaced or fixed in the rear drums.

Bently_Coop

Mods please close. Thanks. Problems resolved.

donald1557

Hi my name is donald I have a 1998 honda civic lx it use to shift into 2nd gear at about 2500rpm but now it doesnt want to sgift until 4k rpm what could be wrong? It also won't drop the gears unless I take my foot half way off the gas pedal

Bently_Coop

I would suggest starting your own thread as your car may have seperaate symptoms. However first thing would be to flush the transmission and check if the solenoids are functioning properly. Use the links provided in this thread and the other documentation. These should be a good starting point.