3FE engine "wobbling" or "pulsating" - Any ideas? (1 Viewer)

[ashooter]

92 FJ80 with 3FE engine... Seems like it runs fine when it's cool weather (40-50degF), even after the temp gauge comes up to normal. But the last few days, after the weather warms up to 60-70+, it feels like the engine is wobbling or pulsating.

Edit: Just double checked all the vacuum hoses and started it up again. To try to clarify the "wobbling/pulsating" - it almost feels like the engine is out of balance or something... like you can feel the engine turning, NOT like the accelerator is being rapidly pumped.

At idle, it's noticeable, but not horrible. Shift into gear and it becomes a lot more noticeable, as RPMs drop a little.... Then as you accelerate and engine RPMs speed up, becomes less noticeable - like the engine turning faster sort of levels things out.

I don't think it's a vacuum leak, since I replaced ALL the vacuum hoses, air intake "hoses", valve cover gasket, etc just a couple of years ago when I was having a problem with the engine dying when trying to idle.

Could it be the intake air flow meter?

If so, any suggestions about where to get one? Part No. 2250-61010 has been discontinued.

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[12bit]

I'm not sure of the source of your problem, but if you end up needing an AFM, I recently replaced mine with a Cardone 74-20070 from Amazon. It's a camry part that is compatible with the 3FE. It appears to be a remanufacured denso.

https://www.amazon.com/gp/aw/d/B000C45IGA/ref=ya_aw_od_pi?ie=UTF8&psc=1

 

[ashooter]

Direct replacement, or do you have to get "creative" to make it work?

 

[12bit]

Direct replacement, or do you have to get "creative" to make it work?

Yep. It's plug and play. No modification or adjustment required.

 

[ashooter]

Nobody's got any ideas?

 

[jonheld]

Page FI-66 of the FSM would be a good place to start.
When was the last tune-up and valve adjustment?

 

[ashooter]

Page FI-66 of the FSM would be a good place to start.
When was the last tune-up and valve adjustment?

View attachment 2852192

Thanks, jonheld.

I don't have my maintenance book handy, but tune-up was maybe 10k-15k miles ago. Valves haven't been touched in a LONG time...

The weird thing to me is the fact that when I start up the truck in the morning when it's been sitting all night, weather in the mid-upper 40's, it runs completely normally. Then drive around for 15-20 minutes, park it for 5-6 hours, weather warms up to 70ish, and the engine does this weird "wobble".

Could that be caused by valves needing adjustment? Bad plug or wire? Injector? Timing? Other idea???

Most things I can think of would seem like they'd cause the engine to run weirdly ALL the time, rather than being affected by ambient temperature.

 

[jonheld]

The AFM has an air intake temperature sensor. I posted the page of the FSM for you.
The 3FE wants a valve adjustment every 15 K miles. If yours hasn't been done in 30 years, you might want to consider it.

 

[ashooter]

Thanks again!

Waiting on some parts, but I will post here if/when I get it fixed.

 

[ashooter]

Okay, I tested the air flow meter that was on it, and it seemed within spec. But, I went ahead and installed the rebuilt one that 12bit posted the link to (also tested within spec). Drove around town off and on all day, starting temps in the 40's, engine warmed up, let it sit for a few hours, started up with ambient temps in the 70's, and all seemed to be running great. Smooth idle around 650ish every time after 4 or 5 starts - only the first start was at ambient temps under 70degF.

Then drove 4-5 miles down the highway, parked the truck for a couple of hours, started up and it's shaking and shimmying again. Shut it down and restarted to see if it would stop - no dice. Drove it the 4-5 miles home and it almost feels like you're driving over slightly washboarded pavement the whole time.

Does anybody have any idea what the heck is going on???

If it did it all the time, or only when cold, or every time after the engine warmed up, it wouldn't perplex me so much.

 

[Bryan Smith]

Following because this is the exact same thing I’m going through, washboard and all. Mine goes away when I get over 2100 rpm, does yours?

 

[ashooter]

Seems to decrease as RPMs go up, but at that point I just wanted to get home before something BAD happened. Whatever's going on feels worse than a rough or low idle.

I've got a set of new spark plugs I'll install this weekend. I don't know if that'll help anything, but she's due anyway.

 

[Izeloz]

Per Jon Held, make adjusting the valves a priority. It may not be the problem, but it can't possibly be helping and needs to be done.

 

[ashooter]

Per Jon Held, make adjusting the valves a priority. It may not be the problem, but it can't possibly be helping and needs to be done.

Valves were adjusted a few years ago - maybe 40-50k miles ago, though.

However, I don't see why valves needing adjustment would cause these symptoms. COULD they??? I don't claim know, which is why I'm here begging for clues.

 

[Izeloz]

I don't personally know. What I DO know is that it's best to fix known issues or maintenance lapses first before trying to fix a problem. I hope this doesn't come across harshly; I learned my lesson the lengthy and expensive way. If you don't have the Factory Service Manual yet, GET ONE! It will save you a lot of money if you keep your cruiser. If it ain't broke, don't fix it. The FSM has in-depth and specific tests you can perform on all systems and components so you don't buy parts you don't need. I am still struggling to get my 3FE to run perfectly the way I want it, but it's "good enough" for now. It's a journey and it's difficult to not get frustrated, but keep on keepin' on and I have faith you will solve your issue. Good luck! And please post up when you find the solution to your issue.

 

[ashooter]

SEEMS to be fixed! (21Dec edit - Nope, it's NOT fixed) I changed spark plugs, and one of them was pretty bad - gap was burned out quite a bit wider than spec. I'm assuming that the plug stopped firing correctly after it got warmed up to a certain point and that's what caused the engine to run out of whack.

When I went to log it into my maintenance log book, I noticed that the old plugs have been in there for about 9 years (oops!)... Last time I went to change the plugs, the place I ordered from had sent the wrong plugs, so I just pulled the old ones and made sure they were gapped right. Meant to order and install new plugs asap, but got distracted by life and never did it.

Still have valve adjustment on my to-do list.

 

[Izeloz]

Awesome to hear! Sometimes it's the simple stuff that is the culprit. Sometimes it's so simple it just doesn't show up on your radar (plenty of personal "oops!" experiences of my own). Valve adjustment should have it purring like a kitten with a chronic hard liquor and tobacco problem (3FE's aren't quiet under the best circumstances).

 

[ashooter]

Well, I spoke too soon. It is NOT fixed.

After driving right at 100 miles over several days with numerous starts and shut downs with NO problems... I drove about 20 miles down the highway today, shut down the truck for about 30 minutes, started up and the "wobble" is back.

When driving back home (20 miles on the highway), the engine seems to smooth out when it downshifts and RPMs go up to 3,000 or so. Cruising along at about 2000-2100 RPM, it feels like washboarded highway. When coasting downhill, the "wobble" seems to abate some. When sitting and idling about 650-700 RPM with transmission in Park, you can feel that something is wrong, but it's not super noticeable. Shift into Drive and RPMs drop by about 100, and the "wobble" in the engine becomes pretty noticeable.

Anybody have any more ideas???

 

[Bryan Smith]

I’ve been trying to track mine on the fuel side because I haven’t touched it myself.

I put a bottle of Lucas Blue Label injector cleaner in before my last fill up and have had much improved results. Like you I’m not sure I’m ready to call it fixed, but on the right path

 

[ashooter]

I’ve been trying to track mine on the fuel side because I haven’t touched it myself.

I put a bottle of Lucas Blue Label injector cleaner in before my last fill up and have had much improved results. Like you I’m not sure I’m ready to call it fixed, but on the right path

At this point I don't know what is causing this, but it definitely seems to be related to temp. After my 20 mile wobble session today, I let it sit for about 3 hours, fired it up and she purred like a sweet kitten.

It DEFINITELY seemed to get better after replacing the spark plugs, since I did a dozen or more starts and shut downs during that 100 miles after the new plugs, with no problems... Right now I'm GUESSING that maybe one of the plug wires is not making a solid connection after it heats up and expands, so just ordered everything for a complete tune-up (except plugs, which are new).