**SOLVED** Rough Idle, less responsive, CEL codes 25 and 26 less power 1FZ-FE 1994 (2 Viewers)

[Desert Dino]

Had perfect time 4 days crossing the Negev desert from the Jordanian to Egyptian border. No gas station on the way.

on the last day i was driving very low on fuel, the last hour the red low gas light was on and the road was very bumpy. we arrived on the pavement, stopped to rest and make some coffee.

I never cleaned my 25 years fuel tank! I was lazy, I read in here that I should do it, but never got to do it.

When I started the rig it was vibrating rough no power only when in high RPM it worked without vibration, when coasting around 2000 RPM it was vibrating and I got check engine ON

I added 5 gallon gas, drove 20 miles to gas station got 40 gallons of fuel and 1 fuel additive and drove home it didn't help.

At home changed Air filter and plugs and more fuel additive still its very bad

Any Ideas?

 

[Irish Reiver]

I had those same codes on my '94 and spent a year trying to troubleshoot it. The only thing that cleared it was when i rerouted the O2 harnesses and brought them directly into the ECU rather than going over the transmission housing. The harnesses must have been damaged enough to cause signal loss from the O2.

 

[MoJ]

The comment about the shaking smoothing out at higher rpm reminds me of a similar problem I had several years ago on my 94. It ended up being the #6 injector. Also had code 25.

 

[Desert Dino]

I had those same codes on my '94 and spent a year trying to troubleshoot it. The only thing that cleared it was when i rerouted the O2 harnesses and brought them directly into the ECU rather than going over the transmission housing. The harnesses must have been damaged enough to cause signal loss from the O2.

@Irish Reiver did you see the problem of the O2 harness on OBD, before and after the fix my O2 are live and kicking you can see in the pic

 

[Desert Dino]

The comment about the shaking smoothing out at higher rpm reminds me of a similar problem I had several years ago on my 94. It ended up being the #6 injector. Also had code 25.

@MoJ so how did you fix it? yes it feels like i drive with 5 cylinders only

 

[Irish Reiver]

@Irish Reiver did you see the problem of the O2 harness on OBD, before and after the fix my O2 are live and kicking you can see in the pic

I had the same Toyocom OBD1 reader as you and both my O2 showed they were working but i still had the codes. Thats why it was so difficult to troubleshoot.

 

[landtank]

Check the intake tube for cracks.

 

[MoJ]

@MoJ so how did you fix it? yes it feels like i drive with 5 cylinders only

The injector was replaced. It was an odd situation in that the truck only had around 140k miles on it. As Landtank said, check the intake tube as the symptoms are similar. Although when I had a cracked intake tube mine would also stall in reverse.

 

[Desert Dino]

Check the intake tube for cracks.

It was replaced 2 years ago no problems there

 

[landtank]

how about the fuel pump relay?

 

[Desert Dino]

how about the fuel pump relay?

Don't think it will cause this kind of symptoms

 

[BILT4ME]

Don't think it will cause this kind of symptoms

Having this occur immediately following a low fuel event would indicate to me to be a fuel filter or fuel pump issue. I know you're in a hot area and running a fuel pump with little cooling around it may cause it to fail or be weak.

The thing that negates that is the fact that it runs better at high RPM. That is usually the opposite on a clogged fuel filter issue.

I would look at t injector wires to see if one or more is not firing properly or is hanging open due to grounding out.

Do you have an EGR? Is your harness still OK near that?

 

[Desert Dino]

Having this occur immediately following a low fuel event would indicate to me to be a fuel filter or fuel pump issue. I know you're in a hot area and running a fuel pump with little cooling around it may cause it to fail or be weak.

The thing that negates that is the fact that it runs better at high RPM. That is usually the opposite on a clogged fuel filter issue.

I would look at t injector wires to see if one or more is not firing properly or is hanging open due to grounding out.

Do you have an EGR? Is your harness still OK near that?

No EGR no PAIR I deleted them in 2017 yes harness is solid

 

[landtank]

If the truck runs better are higher RPMs it could definitely be the fuel pump relay. Low rpm’s the relay supplies low voltage to the fuel pump. At around 2000 rpm’s the relay switches to the high side and delivers a full 12v to the pump.

 

[Desert Dino]

If the truck runs better are higher RPMs it could definitely be the fuel pump relay. Low rpm’s the relay supplies low voltage to the fuel pump. At around 2000 rpm’s the relay switches to the high side and delivers a full 12v to the pump.

Thank you @landtank

this part was ordered
TOYOTA OEM FACTORY SPARK PLUG SET (1993-1997 LAND CRUISER) 90919-01176 (Qty 6)
OEM FACTORY FUEL FILTER 1996-1997 LX450 23300-69045

	Part Description	Price	Qty.	Subtotal
	Part No.: 90099-32089GROMMETReplaced by: 90068-32002	$2.73	1	$2.73
	Part No.: 12204-35040VALVE SUB-ASSY, VENT	$6.21	1	$6.21
	Part No.: 23206-66010BRACKET SUB-ASSY, FUReplaced by: 23206-66900	$94.11	1	$94.11

Gasket, Filter Element, Toyota 17841-68010	US $2.37	2 pcs.	US $4.74
Element Sub-Assy, Air Cleaner Filter, Toyota 17801-61030	US $34.15	2 pcs.	US $68.30

Gage Assy, Fuel Sender, Toyota 83320-69055	US $100.43	1 pc.	US $100.43
Pump Assy, Fuel, Toyota 23221-66040	US $254.06	1 pc.	US $254.06

Ring, O, Distributor Housing, Toyota 90099-14118	US $1.21	1 pc.	US $1.21
Gasket, Engine Oil Level Sensor, Toyota 90430-27001	US $0.75	1 pc.	US $0.75
Filter, Fuel Pump, Toyota 23217-16490	US $7.48	1 pc.	US $7.48
Rubber, Cushion(For Fuel Pump), Toyota 23249-74150	US $18.16	1 pc.	US $18.16
Clip(For Fuel Pump Filter), Toyota 23229-16010	US $0.60	1 pc.	US $0.60
Gasket, Fuel Pump Bracket, Toyota 77169-60010	US $8.03	1 pc.	US $8.03
Gasket, Cylinder Head Cover, Toyota 11213-66021	US $15.88	1 pc.	US $15.88
Gasket(For Spark Plug Tube), Toyota 11193-15010	US $5.83	6 pcs.	US $34.98

NOW we wait
is there a way to force the fuel pump to run at full speed under 2000 RPM just for diagnostics?

 

[Desert Dino]

I had the same Toyocom OBD1 reader as you and both my O2 showed they were working but i still had the codes. Thats why it was so difficult to troubleshoot.

@Irish Reiver except for the code did you have any other problems with the engine?

Rerouting the O2 sensors is way over my head

 

[FMC80]

The last time I had a 24 and 25 my O2 sensors s*** the bed and I replaced those and it fixed both codes.

 

[Irish Reiver]

@Irish Reiver except for the code did you have any other problems with the engine?

Rerouting the O2 sensors is way over my head

No other issues just the fault codes. Gas mileage and power was unaffected.
It is not as complicated as ir sounds to reroute the wiring. I know you deleted the PAIR, did you ever relocate the O2s into the exhaust manifold where the PAIR kit used to go?

 

[brettk]

No other issues just the fault codes. Gas mileage and power was unaffected.
It is not as complicated as ir sounds to reroute the wiring. I know you deleted the PAIR, did you ever relocate the O2s into the exhaust manifold where the PAIR kit used to go?

/\ this. If you deleted emissions, moving the 02 sensors from one hole to the next is cake.

O2 sensor wire location … for relocation to manifold (‘94)

I removed the PAIR system from my ‘94 and I’m currently neck deep relocating the o2 sensors to the exhaust manifold. I left the old non-working sensors in place and cut the wires. Putting new sensors in manifold where the PAIR tied in. I had no trouble pulling the passenger side wire through...

forum.ih8mud.com

 

[Desert Dino]

No other issues just the fault codes. Gas mileage and power was unaffected.
It is not as complicated as ir sounds to reroute the wiring. I know you deleted the PAIR, did you ever relocate the O2s into the exhaust manifold where the PAIR kit used to go?

Not yet They are in the OEM position In the long run I will move the O2 sensors to the PAIR location
in 2017 I got from Toyota Japan a recall campaign from 1995 that was preformed by a local Toyota dealer, although this rig was not imported to Israel by Toyota Israel and all was free of charge.

After 23 years of backyard mechanics Enola gets here day at Toyota dealership

My fzj80 is privet import not a trough Toyota dealership so it never visited the fancy dealership Enola is used to sweaty red necks drinking beer and even their way with here in the back yard Toyota Japan approved a recall campaign from 1995. Replacement of two O2 sensors free of charge

forum.ih8mud.com

@Irish Reiver we do not have the same problem I have issues you had bad signal or short disconnections between O2 sensors and ECM