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GLTHFJ60 said:
Gotcha, so it's intermittent. Stan is right in that because this EFI system is pre OBD2 we don't have the diagnostic or telemetry advantages of OBD2, so it's more difficult to figure out which sensor is malfunctioning.

I find it really hard to believe that there are no codes, especially because you completely removed the EGR. At very least there should be an EGR code.

Can you drive it for maybe 50 miles and let us know if the CEL comes on or if the driveability changes?
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On the OBDI trucks it won't throw a code. The OBDII trucks require a resistor to fool the EGR temp gauge so it won't throw a code.

At least that is my understanding of the 1FZ desmog when I looked in to it a few years back.



While this is most likely not the actual problem a friend of mine did have a trooper that was having slightly similar problems and after months and months it turned out the ECU had become damaged somehow and intermittently having issues. Sounds strange as to me a ECU going bad would be bad all the time or at least all the time after it warmed up and got hot. But a ECU from the junkyard fixed it right up. I wouldn't recommend chasing that rabbit now though as i'm sure with the help of the knowledge from Johnny and the rest of the club it the answer will be found.
 
Intermittent could be TPS. @84shortyota have you received the new TPS yet?
 
lumbee1 said:
Intermittent could be TPS. @84shortyota have you received the new TPS yet?
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No, it won't be here til Tuesday unfortunately cause of the holiday.
 
GLTHFJ60 said:
Gotcha, so it's intermittent. Stan is right in that because this EFI system is pre OBD2 we don't have the diagnostic or telemetry advantages of OBD2, so it's more difficult to figure out which sensor is malfunctioning.

I find it really hard to believe that there are no codes, especially because you completely removed the EGR. At very least there should be an EGR code.

Can you drive it for maybe 50 miles and let us know if the CEL comes on or if the driveability changes?
Click to expand...

Yeah, I'm about to head out now and drive it some more. The TPS doesn't seem to want to hold a steady resistance value, so I'm hoping that the main issue.
 
When my TPS was going bad / went bad, the truck ran fine when it was cold. As it warmed up, the idle got higher and higher. Sometimes it was idling at 1100 and other times 2000.

Before the TPS went bad, I had another issue with too low idle. I lost battery power after leaving the lights on. I jumped the truck but never drove it. In the driveway it would idle at 600rpm and shake like it was misfiring. I checked all the vacuum lines, grounds, intake tube, etc. but was unable to determine what was causing the low idle and shake. I replaced the plugs and rotor. The truck still didn't idle perfectly but I took it for a drive anyways. I noticed on the drive that the longer I drove it the smoother the idle got. I put in about 15 miles driving it around the area before bringing it home. Once I was back in the driveway, the idle was significantly smoother. My only suspicion was that the computer just needed some miles to relearn driving style and conditions.
 
It about 15 miles in to my drive and it's very unpleasant. It still has some hesitation off the line, it still has a miss/surge at speed in higher gears. I was cruising down the road at about 55 and slowed down to make a left. When I reapplied throttle it didn't do anything. It held at about 30 mph and wouldn't take anymore throttle input. It just feels overall like there is something, electrical or fuel related, that is restricting it somehow. I've never had issues like this in any other rig I've had so I'm at a loss at this point.
 
Lord how I fear the day this stuff starts happening to Heather's truck. This is just a thought...

Aside from a low voltage issue causing some sort of problem on the electrical side, everything you have mentioned makes me think something in the fuel/air delivery/mix. Whatever it is, it also sounds like the ECU is "chasing" it. I do not know the ECU at all, but does it have some sort of fail safe mode? My wife's Volvo did.

If the Gods are with you, it is the TPS and once swapped in the ECU will settle down. Go out and curse at it tonight, button it up and enjoy the weekend then install the new part Tues and cross your fingers. :)
 
It's been a nightmare. It's got to stop at some point, I can only spend so much money on this thing. As far as a fail safe mode, I have no idea. Electronics and wiring are not my thing at all. One other thing I noticed on the drive was every time I let off the throttle the applied throttle quickly it was harsh, like driveline slop. There was no "cushion" in the throttle.
 
if you're talking about a "limp" mode that many Euro cars have then the answer is no the 1FZ doesn't have that.
 
lt1fire said:
On the OBDI trucks it won't throw a code. The OBDII trucks require a resistor to fool the EGR temp gauge so it won't throw a code.

At least that is my understanding of the 1FZ desmog when I looked in to it a few years back.



While this is most likely not the actual problem a friend of mine did have a trooper that was having slightly similar problems and after months and months it turned out the ECU had become damaged somehow and intermittently having issues. Sounds strange as to me a ECU going bad would be bad all the time or at least all the time after it warmed up and got hot. But a ECU from the junkyard fixed it right up. I wouldn't recommend chasing that rabbit now though as i'm sure with the help of the knowledge from Johnny and the rest of the club it the answer will be found.
Click to expand...
I wish there were FZJ's in the junkyard to get parts off of. Ive never seen one around here!
 
TPS showed up today, got it installed in factory specs. Took off out of the drive way and it actually felt pretty good. Got to the first stop sign and back to the same old s*** once I took off. Hesitation, no power, etc. it's weird that when it first started doing this it was the same scenario. Initial test drive went great. Once I drove it a few miles it started acting weird. Maybe it's a temperature related thing? Would a temp. Sensor give any of these symptoms?
 
Should there be any change in idle when I unplug the IAC?
 
Anyone near me have a 93 or similar 80 that I could maybe swap some parts on. Maybe IAC and ECM etc?
 
I have some 95 parts but dont know the difference. Im guessing ecu would not swap. Ill see if i have an IAC
 
I'm not sure if the ecu would swap or not??
 
I checked the terminals on the camshaft sensor and I'm getting a really high resistance across two of the terminals. Pretty much all of the symptoms my 80 is having are related to a camshaft position sensor going bad. Has anyone ever had one of these go bad?
 
Same thing with crankshaft sensor...edit: apparently the 93-94 doesn't have one of these.
 
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Have you chevk or cleaned your maf sensor. Also it could be that your distributor is a tooth off that will cause the ajustment problem
 
I have cleaned the maf. I'm going to check the distributor tomorrow.
 
There is no reason to throw parts at this as that will get EXPENSIVE quick-like.

There is no MAF on a 1993-1994 OBD1 truck. It has an Air Flow Meter which is significantly more stupid than even the stupid MAF. Your truck does not have a crankshaft position sensor as that did not come online till 1995.

The camshaft position sensor: yes, I have seen these go bad over time. Swap out with an dizzy from a 8/1993-1/998 1FZ-FE and see if the conditions get better.

ECU-wise, you will need one for a 1993 as there were a couple of different ECU part supersessions during this time period. Ideally you want to try one that is 89661-60170 or 89661-60221. You cannot use an OBDII ECU. Won't work for many reasons.

IAC sensor will be the same for the entire run of the 1FZ-FE.

My money: O2 sensors. These are 100K interval swap items in my opinion and they are important to how the entire EFI system operates within the 1FZ-FE ECU logic.
 
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