Weird idle issue

[84shortyota]

ive had my 93 FZJ for about a year now. Since I got it I have noticed an intermittent idle issue. It idles pretty good in park at around 750 RPM. It does have a little "shake" to it. I was told it had aftermarket cams in it, but this is unconfirmed. I'm not sure that would make a difference anyway. It seems more like a miss honestly. When I'm driving the truck it has a bit of a dead spot in it that eventually goes away with more throttle/speed. When I come to a stop its a crapshoot. It might idle ok at 750, it might idle at 450 and shake pretty bad...or it could be somewhere in between. I've done general tune up items, removed the EGR and PAIR valve, cleaned the throttle body (which was missing two mounting bolts) and other maintenance items. I've noticed a raw fuel smells of late, so a vapor canister is on the way. Any ideas on where to start? I love driving this thing, but the idle issue gets pretty annoying. Thanks in advance!

 

[84shortyota]

Any ideas? Got a big trip coming up!

 

[tominboise]

If you've replaced all the ignition components, what about the injectors? Have you run any cleaner thru the tank recently? How about the fuel filter? Has it been replaced in the recent past? Have you checked the timing to see where it might be set?

 

[84shortyota]

I haven't messed with the injectors. The fuel filter will be done this week. I haven't checked the timing, I need to borrow someones timing light. I have run fuel injector cleaner in it recently. No change.

 

[inkpot]

If you've replaced all the ignition components, what about the injectors? Have you run any cleaner thru the tank recently? How about the fuel filter? Has it been replaced in the recent past? Have you checked the timing to see where it might be set?

 

[inkpot]

Put a jumper wire in between ghe E1 and TE1 sockets in the diagnostic plug on the firewall. With ignition ON , the check engine light will blink. Solid steady blinks means no fairy recoded. Otherwise count the blinks . All codes are 2 digit and the sequence will repeat after the last code # blinks out.

 

[84shortyota]

No codes stored. I did have an O2 related code a few months ago. Ive replaced both sensors within the last 6 months. That's all the codes I've pulled since I've owned it.

 

[FJP971]

Have you replaced the PCV? If it's sticking or if the line is cracked it will have a rough idle.

 

[Hendrix834]

I have the same thing. By intermittent, do you mean it'll be consistently rough for a few weeks and then go away for a couple of months? That's what mine does and that's why it's so hard to diagnose. Occasionally, It'll throw a intake mixture code, but that's kind of rare and eventually, it'll go away (w/o me having to reset it). Keep us updated with what you find, I know there are some other owners with the same issue out there.

 

[Gabriel 71]

Writing harness might be crispy by the egr valve that's why mine has a slight stumble

 

[84shortyota]

Timing was wayyy off. It was past the marks on the timing cover. Not sure of the damage done cause I'm sure it's been that way for quite some time. Fingers crossed. On the harness.... What's the fix for that? It's in an awesome place to work on it. Haha.

 

[84shortyota]

Have you replaced the PCV? If it's sticking or if the line is cracked it will have a rough idle.

Yep, replaced it recently.

 

[84shortyota]

It ran well at 6* on the test drive. On the way home though it was hesitating under light throttle. When you give it some gas it smooths right out. I reset the ecu and it's running like crap now. Cut off on me twice at the light. This thing is killing me.

 

[84shortyota]

I have the same thing. By intermittent, do you mean it'll be consistently rough for a few weeks and then go away for a couple of months? That's what mine does and that's why it's so hard to diagnose. Occasionally, It'll throw a intake mixture code, but that's kind of rare and eventually, it'll go away (w/o me having to reset it). Keep us updated with what you find, I know there are some other owners with the same issue out there.

Nah, it's intermittent every time I drive it. At one stop light it might idle perfect. The next light it may or may not run like s***...

 

[84shortyota]

I also noticed a little pop back in the exhaust the second time I drove it after setting the timing at 6 *. This prompted me to reset the ecu....

 

[chap79]

After resetting the ECU it will take a few cycles for the computer to relearn everything. Cutting off during the first few drives and rough idle would be normal until the ECU is educated.

 

[84shortyota]

As I understand it, popping back through the exhaust usually indicates not enough timing. I'm at 6 degrees right now. Doesn't make sense...

 

[84shortyota]

Unrelated issue I've noticed lately. In higher gears under a light load it seems to have a vibration or shudder to it. It kinda makes me think trans or tcase. Could the VC cause such symptoms?

 

[84shortyota]

Anyone want to buy an FZJ? I cant figure this thing out. It just keeps getting worse the more I drive it.

 

[tominboise]

Is the EGR system still in place? If so, are all the vacuum lines in good shape? If the egr valve opens at idle it will cause a rough idle or even kill the engine if open far enough.