1997 Toyota 4Runner 2.7l 195,000 miles
Started about 3 weeks ago, I noticed a very slight mis driving on the highway after warmed up, then nothing for a week.
Then, about a week later, after warm started studdering when accelerating, but would come and go.
Then after warmed up starts studdering, and doesn't go away
Now studders from initial start, but when not driving, accelerating past about 1600 RPM engine runs smooth, then when releasing accelerator very rough idle.
What I've done:
Replaced spark plugs
Bought a coil, and swapped between both coils ~ no change.
Removed the throttle body, and thoroughly cleaned. I was surprised it was running; the port hole was completely clogged with carbon.
Cleaned the IAC, and tested under 12V that the cylinder door opened and closed on the different pins.
removed the entire fuel rail, and cleaned all the injectors with injector cleaner, via connecting to 12V battery and spraying carb cleaner through injector.
all injectors tested about the same in the 16.5 Ohm range.
Replaced Crank Position Sensor
Replaced Fuel Pressure Valve
I have codes p0-304, 300, 120, 401, & 402.
I pulled the EGR cleaned and tested vacuum on diaphragm, seemed OK.
**** Does anyone know if the 1997 2.7L has (2) o2 sensors? The scanner show B1-S1 & S2. the Live date on the S1 fluctuates as it should, the S2 shows 0V.
Fuel Trims at rough idle show ST mainly on the - side to as low as -10, and the LT runs up to about 13. Then when accelerated LT comes down to about 5 and ST in normal range between -3 to +3.
Needless to say I'm completely stumped, and at my wits ends, any help greatly appreciated.
You should check the TPS switch p0120 with your DVOM to see it has continuous values throughout with no skipping.
The other is the EGR codes. 401-402 One says too much flow and the other is too little. You need to find out why you would have both.
The 300 and 304 are just a product of the problems the other codes have created more than likely.
Thanks for the input. Yes, I did run the TPS through the paces with a volt meter, it reacted very smoothly from 0-5V, no jumps or reverse voltages etc. And yes that EGR issue, completely stumped.
It almost seems like a bad ground or vacuum line, but I always go to that since it has been my grimlin so many times and can be so hard to find.
I'm pretty sure your truck has an upstream sensor (might be called afr sensor) and a downstream 02 sensor.
I know that's not much but maybe something to check. I will see what I can find out.
It may not read the tps until warmed up so that might explain why it's worse when warm.
I really appreciate the input. Yes, the vacuum issue is where I want to go, but I've been all over engine with starting fluid, and nothing. The fuel trims seemed to almost guarantee it was vacuum, but I can't find anything. Really appreciate the help.
My strategy next is to plug off the EGR valve totally. Just make a blank gasket - sealing all the ports - and lets see if your engine will run better.
Really! OK, I'll do that, a blank gasket, huh? I didn't think it would run blocked off... will advise.
Basically EGR valve is not to be operational at idle but opens when off idle. When it opens at idle it affects the idle as now its a vacuum leak now. Now that is how it works in a conventional gas engine with no electronic sensor controls. But the basic operation is still the same. And this gasket blanking off will test that. If the engine has a smooth idle then you know its a EGR malfunction. You can erase the old codes and see what popus up. More than likely the EGR codes and then some will be displayed. Thats okay...but the 300 and 304 will not be as well as the TPS code.. Okay lets keep our fingers crossed....