80 Troubleshooting Help. (1 Viewer)

[Zen80]

Happy holidays all.

Well with gas prices lower I've started driving the cruiser more now, but it now has a slight "hesitation" when taking off from lights. At first I thought it was engine related and was planing on doing a tune up, but yesterday when I was leaving work I started it up and it ran fine. However, when I shifted into reverse the engine bogged and dropped a couple hundred RPM's, then when I shifted into netural the engine idled fine. The same thing occured when I shifted back into reverse. So I think it has someting to do with the transmission, any suggestions?

 

[Beowulf]

The 2 primary causes of this behavior with the 93-97 are:
1. Cracked intake hose
2. Main engine wiring harness; commonly in the area where the harness passes close to the EGR valve but others have had problems where it enters the firewall and behind the ECM (inside the cabin.)

What year is your truck?
-Mike-

 

[SteveLCetc]

I had a cracked intake hose on my '97 ('96? I forget). Anyway I had a trouble code, but no hesitation. If you don't have a trouble code I'd suspect the harness.

 

[Zen80]

Beo,
Sorry, it's a '97 that just hit 200K. The intake hose had no apparent cracks, however the I did have to tighten the hose clamps. This didn't have any effect with the bogging. I did pull the codes and I'm getting a P401 that I've been struggling with, but thats all. Could I be running too rich with the P401, causing the low RPM bog? The exhaust smells too rich.

 

[Beowulf]

The P0401 will not cause the vehicle to run bad or to run rich. The P0401 is a well documented issue that can be fixed fairly easily once you isolate the failing part. There is a lot of information on this code in the 80 section.

The intake hose must be inspected very carefully. If unmetered air is getting in the intake as detected by the ECM monitoring the O2 sensors, it will call for more fuel which is what you are seeing.

If the wiring harness is the failing part there are a lot of different symptoms depending on which wires are shorted together or open. Since there are dozens of wires in that harness you could be seeing a failed injector or a stuck injector or a lot of different things. The harness can be "tested" by wiggling it (simulating the engine torquing) while the engine is running. If you can make it stumble by moving the harness then you have found the issue.

My money is on the intake hose though.

-Mike-

 

[OGBeno]

It's so nice not having to have to worry about emission systems and the like.





That said, while the intake hose is a good starting place (and simple), some other places to check for issues:

1. Throttle cable (kickdown cable): it's the one underneath the cruise control and acceleration cable. Make sure it is within spec. in terms of spacing between the two nuts and that it conforms to the FSM picture.

2. Fuel filter (when was the last documented changing?)

3. Vacuum hoses--make sure that there are none cracked, etc. These are really cheap in bulk from Toyota.

4. When was the last tune-up? (plugs, wires, dizzy cap, rotor, PCV/grommet and related plumbing)

5. (very remotely) timing, IAC valve, O2 sensors (though I think bad O2 sensors cause more trouble to the 1FZ than most of us would like to admit), throttle body (take it off and give it a good stiff wire brush clean--you'll be amazed at the carbon buildup).

Good luck Chad.



-o-

 

[Ruadhrigh]

not much of your list addresses him running rich. save for the timing and maybe vacuum hoses.

 

[DanS HJ-45]

It's so nice not having to have to worry about emission systems and the like.

Even nicer to also not have to worry about ignition systems too.

Good to see that the trouble code is that well documented.

Dan

 

[OGBeno]

not much of your list addresses him running rich. save for the timing and maybe vacuum hoses.

Bad O2 sensors will make him run rich...

 

[alia176]

It's so nice not having to have to worry about emission systems and the like.

I guess you're stuck in the Sandoval county for a long, long time

 

[Beowulf]

I guess you're stuck in the Sandoval county for a long, long time

The greenies and liberal whack-o's managed to change that during the last election. The new omission laws go into effect for Sandoval county in January.

Doesn't anyone read the paper any more?

-Mike-

 

[SteveLCetc]

Haven't heard a thing about it. Got a link?

The greenies and liberal whack-o's managed to change that during the last election. The new omission laws go into effect for Sandoval county in January.

Doesn't anyone read the paper any more?

-Mike-

 

[Beowulf]

Haven't heard a thing about it. Got a link?

I thought you were the one that told me about it.

-Mike-

 

[SteveLCetc]

Nope. Don't tell me I have to move again... Nah, I think it's alarmist bs. Sandoval County wouldn't fall for that propaganda, would it??? Now Bernalillo Co, that's different. They're the ones, after all, that wouldn't give Bill Gates a $25k tax credit to start Microsoft in Albuquerque... Must be lead in the water down there.

 

[evanz80]

I'm thinking Mikey's pulling someone's leg here...

 

[Beowulf]

I'm thinking Mikey's pulling someone's leg here...

Only if you are worried about omission laws.

-Mike-

 

[Zen80]

Toyota cap/rotor/plugs and wires did the trick. There's a little stumbling at idle, but it's no longer lugging like before. Thanks for the input all.

 

[Beowulf]

There's a little stumbling at idle, but it's no longer lugging like before.

Periodic tune-ups (~30k) are a given. The minor stumbling at idle is normal for these engines after they have a lot of miles. You can fit a MAF from a later model Toyota/Lexus by using Landtank's MAF housing. It works.

-Mike-

 

[OGBeno]

The minor stumbling at idle is normal for these engines after they have a lot of miles.

Never heard this before as a "normal" operational condition.

 

[pappy]

Seafoam helped my idle. Took several cans, but my engine is running smoother.