FJ62 3FE Cylinder 1 Not-Firing? Running Rich? (1 Viewer)

[cruisermatt]

I broke a bolt for cold start injector and fuel regulator. So it’s being held together with a single bolt each. Overtightened

Ah, I misread. I thought you meant cylinder head bolts. Yeah, those small bolts into the aluminum intake can be gummy. I don’t use a torque wrench on any of those, just a 1/4” ratchet. You’ll feel when it’s right

 

[knewjax]

Let me know if you ever figure out the bouncing idle. I had a pretty similar overall experience I still haven’t figured out.

bouncing idle / slight misfire - FJ62

Had plugs changed on my 1990 62 recently (along with new exhaust). What came out we’re not stock plugs bpr5es-11 (gap is wider than FSM) put in by PO. Replaced with Denso W16EXR-U stock ones. But I developed a very very slight bouncing / low idle and I think tiny misfire. I can hear the tiny...

forum.ih8mud.com

 

[88red]

One connector at a time. If it’s cracked, melted or locking tab is broken that’s just a large possibility you have a poor connection. That’s why it’s always the first thing I go to. Generally on a typical 250k mile 62 all the the injector plugs are broken, O2 sensor connectors or wiring is melted, TPS and IAC locking tabs broken, it’s all 30-32 year old plastic.

If you have more then one or two broken connectors I would just pull the whole harness. That sounds intimidating but it really is not bad.

Pull the upper intake plenum (6 bolts, few hoses, and a $12 gasket and you should be able to remove the entire engine harness fairly easily.

Once it’s on the bench it’s pretty simple to follow the schematic in the FSM and check the entire harness for resistance/continuity.

I have pretty much all the connectors sourced and can help you out with replacing whichever ones you need. I usually just replace the housings and leave the terminals alone unless they’re really bad.

Yes this is not a small task but in my opinion pretty much mandatory for any original FJ62 at this point. Your engine wiring needs to be verified as good as a baseline.

@cruisermatt can you point me towards your source for harness connectors? I have replaced fuel injector plugs, those are pretty easy to find.

 

[cruisermatt]

@cruisermatt can you point me towards your source for harness connectors? I have replaced fuel injector plugs, those are pretty easy to find.

send me a PM

 

[WILLD420]

Usually a hunting idle is a vacuum leak. Friend had that problem. Was the shaft seal and gasket on the IAC valve. Took a smoke test to find it. No fix though, every one he tried leaked, even though they all worked fine.

 

[vankho]

Let me know if you ever figure out the bouncing idle. I had a pretty similar overall experience I still haven’t figured out.

bouncing idle / slight misfire - FJ62

Had plugs changed on my 1990 62 recently (along with new exhaust). What came out we’re not stock plugs bpr5es-11 (gap is wider than FSM) put in by PO. Replaced with Denso W16EXR-U stock ones. But I developed a very very slight bouncing / low idle and I think tiny misfire. I can hear the tiny...

forum.ih8mud.com

I was able to resolve the bouncing idle. As @WILLD420 noted, it was due to a vacuum leak, which fortunately for me, was easy to find.

I had a missing bolt for the cold start injector. Once I got a new bolt, I got stable vacuum pressure and idle.

 

[knewjax]

I was able to resolve the bouncing idle. As @WILLD420 noted, it was due to a vacuum leak, which fortunately for me, was easy to find.

I had a missing bolt for the cold start injector. Once I got a new bolt, I got stable vacuum pressure and idle.

How did you end up finding it? I did the carb cleaner trick on all the lines, didn’t find anything. I planned on just replacing all my lines anyway since I’ve never replaced them, but curious how you tracked it down.

 

[vankho]

@knewjax For me, right off the bat, there was a very noticeable hissing sound. After being able to narrow it to a certain area, I attached a vacuum gauge to see if I could make a noticeable change in pressure. Again, for me it was a super obvious leak - but I know for others finding a vacuum leak can be a game of hide-and-seek. For what it's worth, I didn't have success with the carb cleaner / propane gas trick in the past.

I'd probably go with a vacuum gauge to confirm if there is a leak, then a smoke test to identify location.


In the video, my vacuum gauge is actually 10 cmHg off, so while in the video it's reading in the normal green zone, it's actually be a lower reading. Apologies for the loud wind noises.

 

[knewjax]

@knewjax For me, right off the bat, there was a very noticeable hissing sound. After being able to narrow it to a certain area, I attached a vacuum gauge to see if I could make a noticeable change in pressure. Again, for me it was a super obvious leak - but I know for others finding a vacuum leak can be a game of hide-and-seek. For what it's worth, I didn't have success with the carb cleaner / propane gas trick in the past.

I'd probably go with a vacuum gauge to confirm if there is a leak, then a smoke test to identify location.


In the video, my vacuum gauge is actually 10 cmHg off, so while in the video it's reading in the normal green zone, it's actually be a lower reading. Apologies for the loud wind noises.

Thanks for this. Just added the vacuum gauge to my harbor freight list.

 

[WILLD420]

A spray bottle of water can help and it's not flammable. If it sucks the water into a gasket, it will momentarily stutter or seal and change idle. I've never used flammable fluid to find a vacuum leak, too easy to start a fire.