Erik Beeman

Ok, so a few more bits of information that I can give.


It's doing it when the motor is cold, and this is when it's the worst. It never goes away, but it gets better as it warms up.


I was crusing at 60mph tonight, and it was not doing the sputter problem. I stepped it up to 75-80, and it started. The throttle difference between 60 and 80 is not much, but it is a bit different. So it seems like it is only happening at a certain throttle, not certain RPM. My GUESS would be, but not accurate because I have no way of telling, but would be 1/4 throttle.

I also want to throw in there that I came off a stop light, easy on the gas, and waited for it to start sputtering. As soon as it did, I tried my best to hold that exact throttle position. I did (the best I could, but remember even the slightest differnce can throw the throttle position % off), and it held that sputter until I got on the gas more.

Also, it's more noticable after coming out of drifts. I get on the gas hard, full throttle just bangin' the revv limiter, then pull out of it and easy throttle. It gets choked up pretty bad for the next 30 seconds or so.



PS. Sorry guys for keeping a dead thread alive. I'm just trying to give information as I come across it (by putting more seat time in the truck), so I can, in return, hopefully get the most information back.

automated11

Im thinking its a dead spot on the TPS I would check the resistance through the full range of motion and make sure there are no dead spots on the circuit.

Erik Beeman

I finally broke down and said forget it. I took it to the shop to have it diagnosed.


The O2 sensor is shot.
The exhaust valves are tight.
And there is no vacuum in the throttle body (which I don't understand because the lines all come from that bar that is mounted on the head, and I have vacuum in the back hoses)

Erik Beeman

I check valves, all were within spec. I forgot that the 268 cam MAY have some overlap. Does anybody know this? And I also looked into the vacuum, or lack of, and the factory Toyota service manual states that there is no throttle body vacuum at idle, which is when we tested it. It has to be TPS at this point.


I replaced today with a factory replacement Denso O2 sensor. I installed it, and fired it up. It immediately ran smoother on idle, and finally at last the AFR's stopped jumping all around. The AFR's were smooth just like my 88. I went to take it for a test drive, and it's still sputtering. Although the sputter, I did notice that the AFR is a lot more stable all throughout the throttle position, and at idle. What the wierd part is, is that it's still sputtering, but it's no longer jumping super lean. It's sputter while the AFR is 14.5- 15.5, which is OK.

I am going to head to the junkyard tomorrow to see if I can find a TPS to use, I am not paying factory Toyota $$$ for a new TPS!


Thoughts, or criticism?

abecedarian

You won't have any vacuum on any of the ports ahead of the throttle body unless the throttle is open or partially open. Those are all 'ported' vacuum lines so take that for what you will. Engine vacuum should be taken from a major port on the plenum / upper manifold like the brake booster line or pretty much any line off the manifold.

Erik Beeman

Yup, I've figured that out

abecedarian

The way the Toyota EFI system works is that at part-throttle conditions, it oscillates from rich to lean and back. This helps the converter a bit, but if the engine itself is sensitive to rich / lean conditions even if the mixture isn't really that far out the normal operation of the ECU could cause intermittent misfires.

Now you're saying the mixture is shifting between 14.5 to 15.5? Well, that itself says something's up. 14.7 is stoichiometric so it seems you're spending a little more time lean than you are rich.

Wonder why....
Any exhaust leaks?
What are your plug gaps set at and what is the temp range of the plugs?

Erik Beeman

As far as exhaust leaks, I don't think so. There is a little whine (you can hear it in the video, sounds like a supercharger), and I don't know if that's an exhaust leak or not. But I don't think that is a problem. And the plugs are set at .031" (factory spec), and they are Bosch Platinums.


I don't think 14-5'-15.5 is too bad. My 88' ran 14.8's all day long and that thing runs like a champ. I'd rather run a little lean and make more power and fuel economy, and. The Red Truck (the 92' that this thread is about) runs 11.2's ish when WFO, which is decently rich and is OK for my tastes. It seems like the factory ECU maps are well set up.

abecedarian

yeah, overall, a tad lean is where you should be for fuel economy and mileage.
This roughness is still bothering me though and I wonder if it's not from the tad rich mixture, though.

Erik Beeman

Ok, so I took it down to the Toyota dealership this morning since I cannot figure this out, and I don't know if anyone on here could, either. I need it to drive and pass smog before 8/30/09, otherwise I'm going to have lots of DMV fees.


They said the EGR canister is bad. They didn't replace it because I told them I'll do it myself, but they did show me how to bypass it for the drive home. I picked it up, and while there I bypassed it (they won't do it because it's not factory work), and boom, what do you know, it ran with no sputtering. Nothing at all, no problems around town or on the freeway. I took the freeway home to see if it sputtered, drove it at 65 and 80mph, and was smooth all throughout. Here in California it will not pass smog with the vacuum lines disconnected (bypassing it), so I need to get a new EGR canister or a good used one, and install it.


On another note, it does still choke up while revving it. At a stop, I can slowly rev it, or hold it in one spot, and it will do a pop/sputter thing. Kinda sounds like timing, but timing is set right on @ 7*. I will take a photo of the EGR canister that I need, and will try and get a video of the sputtering (I'll take video of the exhaust so you can hear it).

abecedarian

Do you mean the evaporation / charcoal canister, passenger side on the firewall?

Erik Beeman

No. I took a picture of it, it's seen here. It's the little canister that has the "3" sticker on it.





Here is a short (2 minute) video of the AFR's. This is with the new O2 sensor and timing adjustment. It's actually pretty stable, even when revving it. It's pretty close to my 88'.

jnel5051

I have the same problem with my 88 toyota Pickup how did u bypass the EGR I would like to try that and see if that works for me

Erik Beeman

You simply disconnect the vacuum lines that go to the canister.


I have about 80 miles of driving without the EGR stuff, and it's run perfect. I have not had any problems or sputtering whatsoever. Although, it did throw check engine light code 71 after about 10 miles of driving. I didn't clear it because it will simply turn on again until I can get around to fixing or replacing that canister.

bobcat52722

I have an 1987 runner with the same problems. It just started sputtering on the highway and now it has gotten worse. I changed fuel filter- cap,rotor and wires with no difference. My friend said that the cat could be clogged? I pulled the codes and it came up with a code 6? what does that mean?

Erik Beeman

There is no code 6. Check again.




Anways, I ended up figuring it out, and it ended up passing smog. The timing was infact wrong! And I have a bad EGR valve, and the #4 exhaust valve was .005" too TIGHT! I don't know how that happens, but it was causing it to stay open just the tad bit, and it was misfiring cylinder 4! I passed smog now, and now I have 2 years to get this turbo set up going before I have to see any BS from California smog


Thank you everyone for the help, it's such a relief to know that I have this figured out.

bobcat52722

thanks for your help, I'll try that but my repair guide says a code 6 is RPM signal; NO "Ne signal to ECU when engine speed is above 1,500 rpm