RedPhoenix

iTrader: (10)

Okay.... part 1943246 of the car running like ****.

The car bogs/misfires under load in lower rpms (below 3000? or so)

Even letting out the clutch the car starts to bog (load)

The car is pig rich...

After 3000 rpms, the car gets better (not great, but better).

My assumption is something to do with ignition... there is a weak spark somewhere (or multiple areas). The higher rpm's have the plugs firing more often than low rpms, therefore it has a better chance of burning off extra fuel.

Low rpms, the cylinders are getting flooded with fuel and cannot burn it off due to no/weak spark.


Fixes?
2 Coils (already replaced)
2 Cap/Rotors (just did, nothing...)
Wires (maybe)
Plugs (done multiple times)

http://www.youtube.com/watch?v=lGzBqwLz5j8


Since I am making the wires from scratch (MSD 8.5mm), I can do the rotor/cap asap.

Sound like a good assumption?

Ryeno

iTrader: (3)

not really helpful but i hate the 92-97 1uz engine. its really hard to diagnose problems on. As of right now my totaled 92 car has crap idle and crap start. I would personally advise you just to swap out that engine. But ya if you havent already swap out the caps/rotors and plug wires.

OneJay

iTrader: (14)

Sounds like maybe the bad wires, like you said. Or maybe a problem with the injectors? Maybe a couple are stuck open.

Ryeno

iTrader: (3)

Honestly i would say cap/rotor is more likely then bad wires. The odds of ALL your wirings going bad at once is like 0. Maybe if only 1 cylinder was misfiring i would say look at wires. But still it cant hurt replacing them.

OneJay

iTrader: (14)

Not all his wires have to be failing to cause a hesitation like that. It could only be one or two.

turbodremz

iTrader: (18)

I would say just start with the basics..cap/rotor/wires.

how is it at idle? any rpm fluctuation? misfires?

RedPhoenix

iTrader: (10)

Idles like a champ, but if you listen closely, there is a hint of a misfire... And to be fair, the 1uz can run on 6-7 cylinders and run great. A friend of mine had a injector unplugged for months and never knew... car ran great.

qksl2

How do the plugs look?

Ian

TumblerZ30

iTrader: (4)

....you are the most unhelpful and ridiculous member on any forum I have ever seen. Swap out that motor? That is an asinine statement. That motor was designed by engineers to function properly, therefore, it will.

^^^, also make sure your MAF is functioning properly. Are you running a piggy back or EMS?

TumblerZ30

iTrader: (4)

Also, when you check the plugs, test them to make sure you are getting a solid spark.

Ali SC3

iTrader: (10)

doesn't sound like spark to me if your car is idling fine.
check your timing and check for vac leaks.

to test the plug/wire is easy, you just unplug one at a time and if the engine doesn't stumble/change you've found your bad plug/wire.

RedPhoenix

iTrader: (10)

I probably should of posted my other links from my issues with this car. I have had this issue for months, but barely driving the car, makes them seem not so important... lol

I have tried...

3 MAF's
2 sets of main o2 sensors
2 TPS's
2 sets of plugs in less than 15k miles
Fuel Filter
Draining tank
Checked for vacuum leaks with starter fluid

No aftermarket computer.
EGR is removed, but blocked off properly with no code (for quite some time too)


I want to fix the issue before I install Megasquirt on it actually.

I have no pulled the plugs yet, this problem got horrendous last night coming back from a meet.

Since it is misfiring AND getting about 10mpg, I am assuming its ignition related, not fuel since its on ALL stock parts.

I did check the FPR, it works properly.

I do get an O2 code (start of the problems), but this is just a code saying that the o2 sensor is not getting a good reading, probably because of the fuel dumping all over it. For good measurement, I did replace both main sensors with Denso oem replacements... nothing changed.


Since I changed a rotor/cap on 1 bank when i bought the car 2 years ago, I picked up one for the other bank... I am assuming they are original, nearly 18 years old. Spark plug wires may be original too, not sure, but I am going to make a MSD 8.5mm kit, should be about the same price as a normal set for this car.

When I do the wires, I will check the plugs and probably do those... again. Could gap be an issue? I just buy the copper NGK plugs with their stock gapping.

RedPhoenix

iTrader: (10)

Only thing about the timing that doesn't make sense is the fact that has been getting progressively worse (something that I posted in another thread). If it was timing... it would just suck instantly being a tooth off. correct?

Vac leaks were checked with a whole can of starter fluid.

Would disconnecting the injector clip be safer than the spark plug wires while the car is on?

sc-driver

iTrader: (7)

Do you still have that O2 sensor code? any other ones?

Let's say you reset the ecu, how's the idle right after that?

Ali SC3

iTrader: (10)

ok good, sounds like youve been replacing a few things that will eliminate problems.
to answer your questions, timing can definately be a problem and would not suck instantly. it wont be a "tooth off". what it could be is a few degrees too advanced or retarted (rotation of the distributor), which the ecu can actually (believe it or not) compensate for a couple degrees here and there. now if it is off enough, under certain loads the ecu can compensate enough for you to not notice (like idle), but when you get into a heavy load you are going out of the range the ecu can compensate for. make sense? the severity of the load your engine is put under has unlimited factors, as in temperature, incline, elevation, extra weight, even proper gear selection.

what you need to do before replacing everything is look up in the manual to check/set your base timing. you set a jumper on the diagnostic port, which will make the ecu go to base timing (as in not compensating anymore). if your car cannot idle after doing this then it may be worth looking into further.

edit: just realized you already change the plugs a few times. you can try gapping the down below spec. this may help alleviate whatever the problem actually is.

I would not disconnect your injector clips, im not even sure you can that easily.
you can try d/c the plug wires, but this will only help if your problem is showing up on idle.
BTW, stock toyota wires are really good. unless something cause damage to them they would be the last thing I would check. I have abused mine, stretched them, rerouted them, and mines still give me enough spark for 9 pounds of boost on stock ignition system. the toyota ignition system is definitely overbuilt when functioning properly.