1993 80 with serious stuttering... you know. Where should I spend my money first??

[Pike]

I also had codes 25 and 26 on and off. the wire repair was pretty far up the harness, looks like it was rubbing on the front drive shaft at some point and got chafed through. how did the pins in the o2 sensor connectors look, maybe some corrosion in the connectors

Ok, so yours was the left or inner O2?

 

[bigredmachine]

I'm guessing yes as I don't have the stock exhaust any more, its the harness that goes up towards the trans not back behind the r/f fender liner. the damage was about a foot or so up the harness and never would have found it if I didn't peel back the wire loom.

 

[Pike]

Update:
Heres what I changed and still have the issue:

• Fuel pump
• Fuel sock
• Fuel filter
• rebuilt the injectors
• New wires
• New plugs
• New cap
• new rotor
• new coil pack
• checked both 02 wire looms all the way back to the harness - no breaks
• Checked the harness next to the EGR. no breaks.
• Checked timing, at 4 degrees
• Checked intake tube for cracks.
• sprayed starter fluid everywhere looking for vacuum leaks.

I unplugged the 02's and ran it and it did run much better but after about 20 min highway the stubbing and stuttering started again, loosing power and causing me to pull off the road.

Votes on next?

• MAF
• TPS
• ECU
• New wiring harness
• new tranny harness
• new throttle cable
• ?

Talked to a few folks and they think its weird that this only happens after 20-40 mins of highway driving.

Any help would be appreciated! This is not super fun for the daily.

Thanks for the help!

Jeff

 

[ajax1]

What o2 sensors are you running? My code 25 26 was the sensors they were 22 years old, replaced with ntk sensors from Toyota. This cleared the codes but I did not have any issues you describe. Have you checked tps sensor and afm? I would do as mention and swap afm with somebody. No new harness available

 

[Pike]

What o2 sensors are you running? My code 25 26 was the sensors they were 22 years old, replaced with ntk sensors from Toyota. This cleared the codes but I did not have any issues you describe. Have you checked tps sensor and afm? I would do as mention and swap afm with somebody. No new harness available

They are OEM 02’s. If I have the same problem with the 02’s connected and disconnected shouldn’t that eliminate them as the problem?

 

[gummycarbs]

Have removed the ECU, taken off the cover, and looked for damage?

All my crazy Lexus issues SOLVED!! (ECU-leaking capacitor) - ClubLexus - Lexus Forum Discussion

I checked mine and -- to my surprise -- it was perfect.

Have you checked all the VSVs according to the FSM, and made sure air passes through them and all the related vacuum hoses and passages? Several of mine were packed with carbon from a failed EGR modulator.

I had a similar power issue (stumbling, loss of power, ran great at full throttle), but mine was only when cold. And I don't know what exactly fixed it!

 

[Pike]

I haven’t checked the ECU but I’ll do that next. I removed the EGR and did a heathy clean when I replaced the engine. I’ll do a double check though! Thanks!!!

 

[gummycarbs]

One other thing, when I replaced my fuel pump, I replaced the tank check valve that's next to it. The only reason I did so is because it was cheap, and I was already buying some parts. You can reach it with nimble fingers by dropping the tank a few inches. (The fuel pump didn't fix the problem, since the replacement failed within a few months and I went back to the original after the problem had resolved itself)

I'm not saying the tank check valve fixed my problem, but it's something I did before parking the vehicle for around a month to paint it, and when I finished my paint work it ran great. I also had fuel treatment with PEA while it sat. Who knows, maybe there was some mysterious glob of varnish.

 

[thebus]

MAF..get a used one...do not even bother with aftermarket.

 

[Jgrauman]

MAF..get a used one...do not even bother with aftermarket.

This. I pulled the no no screws on the afm when I first bought it. Soldered the pins back. 6 months later and was having your exact issues. Pulled the cap off the afm and soldered the pins again and runs like new.

 

[jeeprjames]

I removed the screws of death on my MAF like an idiot thinking I could clean it like every other vehicle I've owned. Luckily, I found a used one in the Mud classifieds from someone parting out an 80.

 

[jeeprjames]

Have you checked your fusible link located on the battery box? That can cause weird stuff to happen as well.

 

[Pike]

ALL FIXED!!!


It was the MAF folks. Got a used one off Cruiser Parts and boom. No more issue.

Thanks to everyone’s help and advice! Y’all kept me sane through the process.

Jeff

 

[wlittleman]

So, I went a little further than Pike dealing with similar symptoms. I did the following with no success:

• Added Chevron Techron fuel injector cleaner
• Replaced O2 sensors
• Checked O2 sensor connectors (they were wet and corroded, which fixed the Code 26 issue, but not the Code 71 issue)
• Replaced the engine coolant thermostat
• Replaced wires
• New plugs
• Replaced some of the vacuum lines
• New cap and rotor
• Checked both harness next to the EGR. Wire insulation was worn, but I covered it with silicone tape
• Checked wiring harness near ECU
• Installed new ECU
• Installed another working air flow meter
• Checked intake tube for cracks

The engine stumbling problem got more frequent and worse over a 4 year period. I was about to throw money at a shop, but I was skeptical that they would find the problem.

So, what fixed my problem? TIGHTENING THE VALVE COVER BOLTS!!!

Apparently, un-metered air was being brought into the engine via a leaking valve cover gasket. I only discovered this when I removed the oil filler cap while the engine was running, and it caused the engine to stumble and nearly die. The same would happen if I pull out the dip stick. After verifying that air was not leaking in through the oil filler cap or dip stick, I decided to check the valve cover bolts, and discovered 2 very loose bolts at the rear - they were so loose that I could spin them with my fingers. After tightening those bolts, resetting the ECU, letting the ECU go through the relearn/re-calibrate process, the engine ran smooth. I addition, the reoccurring code 71 never came back. It has been 3 months of problem free driving! I hope this helps the numerous folks with this similar problem.