Noticed some weird things when I added engine flush to my engine. Can anyone explain? (1 Viewer)

[Jhnpv]

Evening Folks,

I have been a bad boy and havent changed my oil in about 1 and a half years. Granted, I was deployed for about 8 months, so its not the worst! Decided to change my oil and use liquimoly engine flush to pic up any extra gunk that was in there. Now I know there are risks when using engine oil additives, especially an engine flush, but I decided to use it anyways.

What's interesting is that I have had a very low idle these past two months and I havent been able to figure out why. I usually get about 400 RPM and can hear/feel the engine bogging down. Following the liquimoly's instructions, I added the additive to the engine at operating temp (running), and quite literally the second after I added the additive, I heard my RPMs pick up. Checked the meter and it read 750 and was holding really strong. Thought this was interesting. I continued with the change, added fresh oil, and started it back up only to see 400rpm again. What could the engine flush have done, if anything, to increase RPM's. The only thing I can think of is that the additive is pretty thin, so maybe it thinned the oil a tad? Really not sure. Would love to hear what you guys think. Thanks!

 

[OffRoadScott]

Honestly I would toss the idea of the additive making a difference, could be a fluke though.

I would check the FSM and then check that your throttle cable is with in spec as far as the adjustment. If it is out of spec I would recommend replacing it.

 

[clx16]

With the oil cap off you have a vacuum leak and that can affect idle speed. Could that explain part of your issue?

 

[Godwin]

With the oil cap off you have a vacuum leak and that can affect idle speed. Could that explain part of your issue?

^^ this

 

[60wag]

The engine sets the idle speed, (warm) to 650 rpm with the idle air control valve. Its not a cable stop adjustment like on a 2F. If your idle is 400 rpm, the the IAC isn't working correctly. The additive has nothing to do with it.

 

[Jhnpv]

Will give all these a look. Thanks for the inputs gentlemen!

 

[Kernal]

Might want to look for other air/vacuum leaks also.

Check for cracked or disconnected vacuum hoses on top of the the engine ie: PCV, Breather, brake booster, and air intake hoses, check that the oil cap gasket is intact. Check the valve cover gasket, if you have significant oil leaking out from around that gasket the engine could be sucking unmetered air. Same for the spark plug tube seals (check for oil pooling down in the spark plug tubes). While you're there check that the PCV valve isn't plugged (clean with Carb cleaner and shake, should hear a rattle).

Storytime example: the day after I picked up a (used) 97 FZJ80 I was backing into the driveway and the engine wanted to stall, rpms dropped to maybe 400-500. On the 90 mile drive home the night before there were zero engine/idle issues.

Took at look at all the air/vacuum hoses then focused on the breather hose on top of the valve cover, saw a couple cracks on the end of the hose. When I went to remove the breather hose the rubber was so brittle the end broke into pieces. Replaced the hose, rpms back to normal (~650).

FWIW

 

[bicycleagent003]

Might want to look for other air/vacuum leaks also.

Check for cracked or disconnected vacuum hoses on top of the the engine ie: PCV, Breather, brake booster, and air intake hoses, check that the oil cap gasket is intact. Check the valve cover gasket, if you have significant oil leaking out from around that gasket the engine could be sucking unmetered air. Same for the spark plug tube seals (check for oil pooling down in the spark plug tubes). While you're there check that the PCV valve isn't plugged (clean with Carb cleaner and shake, should hear a rattle).

Storytime example: the day after I picked up a (used) 97 FZJ80 I was backing into the driveway and the engine wanted to stall, rpms dropped to maybe 400-500. On the 90 mile drive home the night before there were zero engine/idle issues.

Took at look at all the air/vacuum hoses then focused on the breather hose on top of the valve cover, saw a couple cracks on the end of the hose. When I went to remove the breather hose the rubber was so brittle the end broke into pieces. Replaced the hose, rpms back to normal (~650).

FWIW

How many people have sold their 80 because they had a gremlin like that (more often electrical, I'd say), only to have the purchaser get it squared away in an hour or two? Good detective work there.