1FZ-FE - Jumpy bumpy and lumpy......

[Mr Maui]

Hey! First of all thanks to this forum, great source of knowledge! I have a 1996 petrol 4.5l Auto. I love it and use it everyday for work. Its got a LPG conversion, when I bought it had classic rough idle and stuttering problem, I ran it mainly on LPG so only got round to fixing it this summer. Changed the O2 sensor (Mine only has 1) This immediatly solved the rough idle and lack of guts up to 3k revs. It always then had a slight issue once up to speed and you let off the accelerator it felt like being slighty pulled back, little loss of power 2 secs on 2 sec off. This would go one you put you foot down or slowed up...... I didnt mind this, however slowly the problem of the stuttering and rough idle has come back...... With vengance.

Now it regularly stalls on idle, splutters and stammers up to 3k revs when you pass this it drives fine. It also has erratic revs on idle, it goes up and down from 0 - 2k randomly..... Also when you drive slow if tried to rev up and pull through a slow maneuver..... Its go so bad I hate driving it

Do you think this could just be bad O2 sensor again? I couldn't find the exact one to buy so when it arrived the plug didnt match, I had to splice it to the old clip, also one of the wires (Blue & White) from the loom was joined with a another that runs off up into the engine bay, I cant see where it goes....... The sensor fitted into the exhaust ok. just the wires different.

So I am left wondering if I got the wrong sensor, or it failed..... The garage it was at the other day said they 'tested it' but im not convinced.....

It also had a split in the air intake pipe between the filter and engine, this I replaced but it made no difference. I have seen that a dirty or bad MAF sensor could be the problem..... I dont think I have one, i think this is a VAF? Could this be an issue?

Finally the exhaust is sounding pretty gurgly, when I first replaced the O2 sensor the bolts were seized so I had to remove the exhaust section from manifold to the CAT, I discovered that someone had rung the bolts previously on the connection to the manifold from the engine, this made it a total bitch to do and I dont think its sealed 100%.....

Thanks in advance for the help, my knowledge is limited and I know there maybe a few issues here.....

Cheers

 

[Irish Reiver]

I think you need to fix the O2 issue first. A 1996 truck in the US is ODB2 and has 2 sensors - one upstream of the the cats and one downstream. Even the earlier ODB1 motors had 2 sensors although they were both upstream of the cats. Are you able to confirm if the engine is OBD1 or 2?

 

[Mr Maui]

Thanks, yes its OBD1 I'm going to read the codes today, I looked everywhere down the exhaust and couldn't for the life of me see another sensor .... I'll check again tho.

Ill probs order a new sensor, was looking at this one - Lambda Sensor fits TOYOTA LAND CRUISER FZJ80 4.5 92 to 97 1FZ-FE Oxygen ADL New 5050063019797 | eBay

 

[Mr Maui]

Thanks, yes its OBD1 I'm going to read the codes today, I looked everywhere down the exhaust and couldn't for the life of me see another sensor .... I'll check again tho.

Ill probs order a new sensor, was looking at this one - Lambda Sensor fits TOYOTA LAND CRUISER FZJ80 4.5 92 to 97 1FZ-FE Oxygen ADL New 5050063019797 | eBay

Ok so that's not the correct plug. It's the same as the one I ordered, anyone know where I can get the correct plug? Mine looks like this -

 

[Irish Reiver]

How many cats do you have?

 

[BILT4ME]

Ok so that's not the correct plug. It's the same as the one I ordered, anyone know where I can get the correct plug? Mine looks like this -

View attachment 2264726

Possibly check Wits' End ( @NLXTACY ), as he has newer O2's modded to fit the OBD1 trucks. Worth a check anyway.

You have a lot of wire connectors in that harness. Maybe those are a problem?

 

[Mr Maui]

Ok so I have 2 cats.... one straight after the other. There is definitely only 1 sensor, I've checked every inch of the exhaust.

I've ordered a waterproof connector for the 4 wires so I can re do the join from bare wire to the plug. I'm not 100% on which way round the wires go. I saw the 'repurpose' post explaining the wire swap but my colours are different. I have 2 white 1 black and a grey....

 

[ajax1]

Why not order the correct sensor from Toyota ? You have a maf not a vafm

 

[Mr Maui]

Why not order the correct sensor from Toyota ? You have a maf not a vafm

They no longer stock this part for obd1 sensors, I cant find one anywhere online that has the right plug.

So I checked and I do seem to have the wires the right way around, the connections are corroded tho so I am hoping this will improve. It's now so bad I cant drive it. With it unplugged completely it's better but not great.

Thanks for confirming it's a MAF, I couldn't work out how to get it out to clean it, theres no screws like on other models, maybe I have to take out the whole section? No easy way to see how to remove the sensor for cleaning

 

[ajax1]

Well I don’t know what you have going on but in North America od1 would be a vafm and the exhaust the cats are side by side with a o2 sensor in front of each cat. For oem you can get ntk from rock auto they list both of them. For obd2 which would be a mAf sensor and the exhaust would be two cats running in line with sensor in the front and and one after the cat in back. Now you might have different exhaust set up aftermarket. You should post pics of the exhaust and whole engine bay. Do you have a plug in port under the steering wheel, that is where you would read code on obd2 with scan tool. The obd1 just has one in the engine you read by shorting out two ports on it and count engine light flashes

 

[Mr Maui]

Well I don’t know what you have going on but in North America od1 would be a vafm and the exhaust the cats are side by side with a o2 sensor in front of each cat. For oem you can get ntk from rock auto they list both of them. For obd2 which would be a mAf sensor and the exhaust would be two cats running in line with sensor in the front and and one after the cat in back. Now you might have different exhaust set up aftermarket. You should post pics of the exhaust and whole engine bay. Do you have a plug in port under the steering wheel, that is where you would read code on obd2 with scan tool. The obd1 just has one in the engine you read by shorting out two ports on it and count engine light flashes

Thanks, its def OBD1, I posted a picture of the Air Flow Meter above, it doesn't look like the MAF's i have seen on other models which is why I thought it might be a VAF....

Another member has confirmed it's a MAF but do you get them with OBD1?

I've read the codes and it's only showing 21 which is O2 sensor I believe, I'll be re wiring it tomorrow to check the corrosion issue, then I thought I would see if the codes still there. Do I need to clear them or does it reset automatically?

It's different everytime I start it atm, now almost impossible to drive, it's fine when you floor it hard but anything below 3k revs and it nearly stalls

 

[Irish Reiver]

The physical layout of what you describe (2 cats in line, MAF not AFM) points to an OBD2 setup. Can you confirm there is no OBD2 connector in the cabin (drivers side in the US but not sure on a RHD). An OBD1 with both O2's disconnected will still run pretty well (I did it for 9 months). Ike @ajax1 mentioned, you may have an aftermarket exhaust which has eliminated the downstream O2 sensor.
@Onur, are you able to help with an O2 PN / specification for this market?

 

[OGBeno]

@Onur, are you able to help with an O2 PN / specification for this market?

Sure. That's not a problem.

OP: Use this thread to find the correct Toyota part numbers for the O2 sensor harness side connector.

FAQ - 1995-1997 1FZ-FE FZJ80 OBD2 Main Engine Wiring Harness Connector Information

The following posts are to document the 1FZ-FE US market 80 series 1995-1997 OBD2 main engine wiring harness connectors. While this is not exhaustive in the sense that it covers every single connector, it does cover about 95% of them. The remaining 5% or so are not sourceable outside of the...

forum.ih8mud.com

For a European market FZJ80, there is only 1 O2 sensor. Not 2.

89465-69085 is the part number. It is still readily available from Toyota. This will be the upline O2 sensor for air-fuel ratio in a OBD2 system.

The ECU in this specification vehicle probably does not have a O2 sensor input for the 2nd O2 probably because the market did not require a reading for catalyst efficiency (which is what the 2nd O2 measures). The engine ECU part number is way different than the US market OBD2 vehicle that requires a 2nd O2

I'd say get the correct O2 sensor from Toyota and away you go.

Hope that helps.

 

[Mr Maui]

super thanks @Onur For the info, I'll look into it tomorrow.

 

[Mr Maui]

Excuse the lack of knowledge here - I have located and read the OBD1 port, I'm looking for an obd2 which everyone seems to think I have but I really cant find one. I'm also assuming it wouldnt have both! Which is why I cant find it!

 

[Irish Reiver]

Excuse the lack of knowledge here - I have located and read the OBD1 port, I'm looking for an obd2 which everyone seems to think I have but I really cant find one. I'm also assuming it wouldnt have both! Which is why I cant find it!

Scratch the OBD search and just order the O2 part number that Onur mentioned. Once it is installed, reset the ECU (and codes) by disconnecting the battery or pulling the EFI fuse. It will run a little rough to begin with as the ECU gets itself back up to speed.

 

[greentruck]

Yeah, try the OEM O2 sensor. In the US, lots of people report issues with using aftermarket ones, so getting that right is a point of departure to eliminate issue swith it.

You'd still be well-advised to clean up that wiring, especially after noting corrosion. A corroded circuit kind of fits with your recall of the problem getting worse over time, as corrosion eats away at connectivity - quite possibly part of the problem now, but will be a problem later.

 

[Mr Maui]

Ok update, I've wired the plugs properly and disconnect the battery! She runs! Much much nicer. But rough at start but after a 20min drive it's much better.

However it's still reving strange, when your doing slow maneuvers it chugs and revs itself, you have to be good on the brakes not to lurch to much.

It also still feels like your being pulled back slightly when your at speed. 2.5k revs and 50mph

I've ordered some MAF cleaner to try next. Any thoughts?

Cheers

 

[Irish Reiver]

At the low revs, it maybe your A/C kicking in. On my '94 if the A/C compressor kicks in the revs wil jump from 650 ish to 1000ish.

 

[greentruck]

SNIP

However it's still reving strange, when your doing slow maneuvers it chugs and revs itself, you have to be good on the brakes not to lurch to much.

Check your throttle cable to ensure it's free to open and close completely, not hanging up anywhere. Your symptoms don't exactly match, but it's low-hanging fruit tio be sure it's working properly.